Patent Application
20090017733
The present invention relates to a substrate processing apparatus, and more particularly to a substrate processing apparatus having a polishing unit for polishing a peripheral portion of a substrate such as a semiconductor wafer. The present invention also relates a substrate processing method, and more particularly to a substrate polishing method of polishing a peripheral portion of a substrate such as a semiconductor wafer.
In recent years, according to finer structures and higher integration of semiconductor devices, it has become more important to manage particles. One of the major problems in managing particles is dust caused by surface roughness produced at a peripheral portion (a bevel portion and an edge portion) of a substrate, such as a semiconductor wafer, in a manufacturing process of semiconductor devices.
Further, in the following description, a notch means a V-shaped incision (V-shaped notch) or a linear incision (orientation flat) formed in an outer circumferential portion of a silicon wafer or the like for indicating an orientation of the wafer. The notch is provided at a peripheral portion of a wafer. Specifically, the notch is formed in a recessed manner at a peripheral portion of a wafer.
There has heretofore been known a polishing apparatus (peripheral portion polishing apparatus) for polishing a peripheral portion of a wafer. Such a polishing apparatus has been used for shaping an outer circumferential portion of a wafer prior to a formation process of semiconductor devices. Recently, such a polishing apparatus has been used for removing films as a pollution source attached to a peripheral portion of a wafer in a formation process of semiconductor devices or for removing surface roughness produced at a peripheral portion of a wafer, for example, for separating needle projections formed after formation of deep trenches in the wafer. When objects attached to a peripheral portion of a wafer are removed in advance, it is possible to prevent contamination of wafers, which would be caused by a transfer robot for holding and transferring wafers. Further, when surface roughness is removed in advance from a peripheral portion of a wafer, it is possible to prevent dust from being produced by separation of objects formed on the peripheral portion of the wafer.
Further, there has practically been used a substrate processing apparatus having process units including a polishing apparatus (polishing unit) for polishing a peripheral portion of a wafer, a cleaning unit for cleaning the wafer, and a drying unit for drying the wafer. This substrate processing apparatus is employed to perform a sequence of processes on a wafer which include polishing a peripheral portion of the wafer. According to such a substrate processing apparatus, it is possible to perform a sequence of processes, including polishing a peripheral portion of a wafer and cleaning and drying the polished wafer, all at once in a single substrate processing apparatus. Thus, such a substrate processing apparatus has an excellent efficiency.
Meanwhile, a polishing unit provided in a substrate processing apparatus includes a bevel polishing device for polishing a bevel portion of a wafer or a notch polishing device for polishing a notch of a wafer. The bevel polishing device or the notch polishing device is arranged in the polishing unit so as to surround a wafer to be polished. In order to improve an efficiency of a polishing process in such a substrate processing apparatus, it is necessary to properly arrange the polishing unit. For example, a plurality of polishing units having the above structure should be provided in a substrate processing apparatus.
Further, in a case of a conventional substrate processing apparatus having a plurality of polishing units, an arrangement of the polishing units is determined in consideration of a space required for a transfer robot to transfer a wafer to or from the respective polishing units and spaces required for the polishing units. Thus, no attention is paid to the accessibility of an operator to bevel polishing devices or notch polishing devices in the polishing units when the operator replaces polishing tapes or polishing pads. Accordingly, the operator has to work with a poor efficiency. In order to resolve such drawbacks, it is desirable to arrange the substrate processing apparatus such that an operator can efficiently conduct replacement of expendable parts, such as polishing tapes and polishing pads in the polishing units, and maintenance of respective components.
Further, if a polishing liquid such as slurry or abrasive particles scatter at the time of polishing by a polishing unit, the polishing liquid or the abrasive particles may contaminate respective portions in the polishing unit or a polished wafer to cause further contamination of other areas to which the polished wafer is transferred. In such a case, it is necessary to frequently clean units such as a polishing unit and a transferring unit in the substrate processing apparatus. Thus, maintenance operation becomes a heavy load on an operator. Additionally, the operator has to have access to the polishing unit or other units to conduct cleaning. Accordingly, an operational efficiency is decreased. In order to reduce loads of maintenance operation, it is desirable that contamination of portions of the polishing unit and a wafer is prevented at the time of polishing.
The present invention has been made in view of the above drawbacks. It is, therefore, a first object of the present invention to provide a substrate processing apparatus which has an improved process efficiency of polishing a substrate, allows maintenance operation to be efficiently conducted in a short time of period, and can reduce loads of maintenance operation.
A second object of the present invention is to provide a substrate polishing method which can improve a process efficiency of polishing a substrate, allows maintenance operation to be efficiently conducted in a short time of period, and can reduce loads of maintenance operation.
A third object of the present invention is to provide a substrate processing method which can improve a process efficiency of polishing a substrate, allows maintenance operation to be efficiently conducted in a short time of period, and can reduce loads of maintenance operation.
According to a first aspect of the present invention, there is provided a substrate processing apparatus having at least two polishing units for polishing a peripheral portion of a substrate, such as a semiconductor wafer, which is suitable for removing surface roughness produced at a peripheral portion of a substrate or films as a pollution source attached to a peripheral portion of a substrate. Each of the two polishing units includes a bevel polishing device and/or a notch polishing device for polishing a peripheral portion of a substrate. The substrate processing apparatus has a maintenance space formed between the two polishing units. The bevel polishing device and/or the notch polishing device in each of the two polishing units faces the maintenance space so as to be accessible from the maintenance space.
Each of the two polishing unit may be housed in a casing having a hatch provided at a position facing the maintenance space. The bevel polishing device and/or the notch polishing device in each of the two polishing units may be accessible from the maintenance space by opening the hatch.
With the above arrangement, an operator is accessible to the bevel polishing devices and/or the notch polishing devices in the two polishing units from the same space without moving the bevel polishing device and/or the notch polishing device in each of the polishing units. Accordingly, it is possible to efficiently conduct maintenance operation of the bevel polishing devices and/or the notch polishing devices in the polishing units in a short time of period. As a result, convenience of maintenance for the substrate processing apparatus can be improved.
Thus, an arrangement of the units in the substrate processing apparatus and an arrangement of components in the units are designed to improve a process efficiency of polishing a substrate. The operator is accessible to the units from a common space to efficiently conduct maintenance operation in a short time of period. Further, it is possible to prevent contamination of the units and the substrate during polishing so as to reduce loads of maintenance operation.
The bevel polishing device may include a polishing tape, a bevel polishing head for pressing the polishing tape against the peripheral portion of the substrate, and a polishing tape supply/recovery mechanism for supplying the polishing tape to the bevel polishing head and recovering the polishing tape from the bevel polishing head. The polishing tape in the polishing tape supply/recovery mechanism may be adapted to be replaced from the maintenance space. The notch polishing device may include a polishing tape, a notch polishing head for pressing the polishing tape against a notch of the substrate, and a polishing tape supply/recovery mechanism for supplying the polishing tape to the notch polishing head and recovering the polishing tape from the notch polishing head. The polishing tape in the polishing tape supply/recovery mechanism may be adapted to be replaced from the maintenance space.
With the above arrangement, since the polishing tape can be replaced from the maintenance space, the maintenance operation can be conducted efficiently from the exterior of the polishing units in a short time of period. Accordingly, convenience of maintenance for the substrate processing apparatus can be improved.
The casing may have sidewalls on four sides thereof. One of the bevel polishing device and the notch polishing device may be disposed near a first of the sidewalls of the casing. The first of the sidewalls of the casing faces the maintenance space. Another of the bevel polishing device and the notch polishing device may be disposed near a second of the sidewalls of the casing which is adjacent to the first of the sidewalls of the casing. The second of the sidewalls of the casing faces a housing for the substrate processing apparatus.
With the above arrangement, useless spaces can be eliminated in the polishing units. Further, the bevel polishing device or the notch polishing device is accessible from the maintenance space or the housing for the substrate processing apparatus which is adjacent to the maintenance space. Accordingly, it is possible to efficiently conduct maintenance operation in a short period of time.
The casing may have a hatch provided in the second of the sidewalls thereof. The housing for the substrate processing apparatus may have a door provided at a position facing the second of the sidewalls of the casing. The substrate processing apparatus may be configured such that the bevel polishing device or the notch polishing device is accessible from an exterior of the substrate processing apparatus when the door of the housing and the hatch of the casing are opened.
With the above arrangement, it is possible to conduct maintenance operation such as replacement of the polishing tape of the bevel polishing device or the notch polishing device in the polishing unit directly from the exterior of the substrate processing apparatus. Accordingly, the maintenance operation can efficiently be conducted in a short period of time. As a result, convenience of maintenance for the substrate processing apparatus can be improved.
The substrate processing apparatus may further include a transfer device for transferring the substrate to and from the polishing units. An opening for introducing the substrate into the polishing unit may be formed in a third of the sidewalls of the casing. The opening faces the transfer device. A shutter is provided for opening and closing the opening. With the above arrangement, the substrate can efficiently be transferred so as to improve a throughput of the substrate processing apparatus.
The bevel polishing devices or the notch polishing devices in the polishing units may be arranged so as to be symmetrical with interposing the maintenance space therebetween. Operations of the bevel polishing devices or the notch polishing devices in the polishing units may be configured so as to be symmetrical with interposing the maintenance space therebetween.
When the bevel polishing devices or the notch polishing devices in the polishing units are arranged so as to be symmetrical with interposing the maintenance space therebetween, it is possible to facilitate maintenance operation of the bevel polishing devices or the notch polishing devices in the polishing units. Accordingly, it is possible to efficiently conduct maintenance operation in a short period of time. When operations of the bevel polishing devices or the notch polishing devices in the polishing units are configured so as to be symmetrical with interposing the maintenance space therebetween, operation of the transfer device to transfer the substrate to and from the polishing units and positioning of substrates can be designed so as to be symmetrical with interposing the maintenance space therebetween. Thus, operation of the transfer device to transfer the substrate to and from the polishing units and operations in the polishing units can be performed smoothly. Further, useless spaces for operations of the bevel polishing devices or the notch polishing devices in the polishing units can be eliminated so as to operate the polishing units efficiently.
The polishing unit may include a substrate holding table for holding the substrate to be polished by the bevel polishing device and/or the notch polishing device. The polishing unit may further include a swing mechanism for swinging the substrate holding table on a horizontal plane and/or a horizontal movement mechanism for linearly moving the substrate holding table on a horizontal plane.
With the above arrangement, the substrate held by the substrate holding table can be swung or linearly moved by the substrate holding table swing mechanism or the substrate holding table horizontal movement mechanism while the substrate is polished by the bevel polishing device and/or the notch polishing device. Accordingly, desired polishing can be conducted on the peripheral portion of the substrate. Further, the substrate can be moved from the bevel polishing device to the notch polishing device by moving the substrate holding table. Accordingly, it is possible to facilitate polishing by the bevel polishing device and the notch polishing device.
The bevel polishing device and/or the notch polishing device may be configured so as to bring a surface of a polishing tape into sliding contact with the peripheral portion or a notch of the substrate to polish the substrate. The polishing tape may have a polishing layer in which a chemically inactive resin material into which abrasive particles are dispersed is applied to a surface of a tape base.
With the above arrangement, it is possible to prevent chemical reaction with the polishing liquid. Accordingly, it is possible to prevent abrasive particles from being attached to the substrate so as to contaminate the substrate and from scattering and being attached to the components of the polishing units so as to contaminate the components. Thus, it is possible to reduce loads of maintenance operation such as cleaning of the polishing units and the substrate processing apparatus. Further, it is possible to prevent degradation of quality of the substrate.
The polishing unit may include a substrate holding device for horizontally holding the substrate to be polished by the bevel polishing device and/or the notch polishing device. The polishing unit may further include a first supply nozzle for supplying at least one of pure water, ultrapure water, and deionized water toward a polishing area of the substrate held by the substrate holding device and a second supply nozzle for supplying at least one of pure water, ultrapure water, and deionized water toward a central portion on an upper surface of the substrate.
With the above arrangement, pure water supplied from the second supply nozzle spreads over an upper surface of the substrate held horizontally to form a film of pure water on the upper surface of the substrate. Thus, the substrate is prevented from being contaminated by an atmosphere or polishing wastes in the polishing units. Further, it is also possible to prevent secondary contamination in a unit to which the contaminated substrate is to be transferred. Accordingly, it is possible to reduce loads of maintenance operation such as cleaning of the substrate processing apparatus. Further, while pure water is supplied near the polishing area of the substrate from the first supply nozzle, pure water supplied from the second supply nozzle spreads over the upper surface of the substrate to reach the vicinity of the polishing area. Accordingly, polishing wastes are prevented from scattering from the polishing area, and frictional heat can be removed during polishing. Since pure water is supplied to the substrate from the first and second supply nozzles, it is possible to maintain a cleanliness of the substrate and the components in the polishing units. Further, since pure water is supplied from the first and second supply nozzles, frictional heat can be removed between the polishing layer and the substrate. Accordingly, it is possible to prevent the resin material from being softened so as to cause abrasive particles to be separated from the polishing tape.
According to a second aspect of the present invention, there is provided a substrate polishing method which can improve a process efficiency of polishing a substrate, allows maintenance operation to be efficiently conducted in a short time of period, and can reduce loads of maintenance operation. According to this method, abrasive particles are dispersed into a chemically inactive resin material. The chemically inactive resin material is applied to a surface of a tape base to form a polishing tape having a polishing layer. A surface of the polishing layer of the polishing tape is brought into sliding contact with a peripheral portion of the substrate to polish the substrate.
According to the above method, it is possible to prevent abrasive particles from being separated from the polishing tape due to a chemical reaction with the polishing liquid during polishing. Accordingly, it is possible to prevent abrasive particles from being attached to the substrate so as to contaminate the substrate and from scattering and being attached to the components of the polishing units so as to contaminate the components. Thus, it is possible to reduce loads of maintenance operation such as cleaning of the polishing units and the substrate processing apparatus. Further, it is possible to prevent degradation of quality of the substrate.
The substrate may have semiconductor devices formed on a surface thereof and a number of recesses formed in the surface thereof. In this case, since it is possible to prevent abrasive particles from being separated from the polishing tape due to a chemical reaction with the polishing liquid during polishing, abrasive particles are not introduced into the recesses in the substrate. Accordingly, it is possible to prevent degradation of quality of the substrate.
Only pure water may be supplied to the substrate during the polishing. In this case, it is possible to maintain a cleanliness of the substrate and the units in the apparatus and to prevent secondary contamination in a unit to which the contaminated substrate is to be transferred. Further, since the resin material of the tape base is not reformed by a chemical reaction, abrasive particles are prevented from being separated. Accordingly, it is possible to prevent abrasive particles from being attached to the substrate so as to contaminate the substrate and from scattering and being attached to the units of the apparatus so as to contaminate the components. Thus, it is possible to reduce loads of maintenance operation such as cleaning of the substrate processing apparatus. Further, since pure water is supplied during polishing, frictional heat can be removed between the polishing layer and the substrate. Accordingly, it is possible to prevent the resin material from being softened so as to cause abrasive particles to be separated from the polishing tape.
According to a third aspect of the present invention, there is provided a substrate polishing method which can improve a process efficiency of polishing a substrate, allows maintenance operation to be efficiently conducted in a short time of period, and can reduce loads of maintenance operation. According to this method, a substrate is moved to one of a bevel polishing device for polishing a peripheral portion of the substrate and a notch polishing device for polishing a notch of the substrate by a movement mechanism. The peripheral portion of the substrate or the notch of the substrate is first polished by the one of the bevel polishing device and the notch polishing device. Only pure water is supplied to the substrate to form a water film covering a surface of the substrate after the polishing. The substrate is moved to another of the bevel polishing device and the notch polishing device by the movement mechanism in a state such that the water film is formed on the surface of the substrate. The peripheral portion of the substrate or the notch of the substrate is second polished by the other of the bevel polishing device and the notch polishing device.
According to the above method, the substrate is prevented from being contaminated by an atmosphere or polishing wastes in the polishing units. It is possible to maintain a cleanliness of the substrate. Further, it is possible to prevent secondary contamination of the bevel polishing device or the notch polishing device where the substrate is to be transferred. Therefore, polishing can be conducted without hindrance in the bevel polishing device or the notch polishing device. Since it is also possible to maintain a cleanliness of the components in the polishing units, loads of maintenance operation such as cleaning can be reduced.
According to a fourth aspect of the present invention, there is provided a substrate processing method which can improve a process efficiency of polishing a substrate, allows maintenance operation to be efficiently conducted in a short time of period, and can reduce loads of maintenance operation. This method employs a substrate processing apparatus having at least two polishing units and a transfer device for transferring the substrate into the polishing units. Each of the polishing units includes at least one of a bevel polishing device for polishing a peripheral portion of the substrate and a notch polishing device for polishing a notch of the substrate. Bevel polishing devices or notch polishing devices are arranged in the polishing units so as to be symmetrical as seen from the transfer device. Different substrates are transferred into the polishing units by the transfer device. The different substrates are polished in parallel in the polishing units to remove contaminants and/or surface roughness of peripheral portions of the different substrates. In this case, the bevel polishing devices or the notch polishing devices may be operated in the polishing units so as to be symmetrical as seen from the transfer device.
According to the above method, a plurality of substrates are simultaneously polished so as to increase the number of substrates processed per unit time. Thus, a throughput of the substrate processing apparatus 1 can be improved. Further, with the above arrangement, even if different substrates are transferred into the respective polishing units by the transfer device and polished in parallel in the respective polishing units, the substrates can smoothly be transferred to the respective polishing units, and bevel polishing or notch polishing can smoothly be conducted in the polishing units. Further, useless spaces for operation of the bevel polishing device or the notch polishing device can be eliminated in the polishing units to operate the polishing units efficiently.
According to a fifth aspect of the present invention, there is provided a substrate processing method which can improve a process efficiency of polishing a substrate, allows maintenance operation to be efficiently conducted in a short time of period, and can reduce loads of maintenance operation. This method employs a substrate processing apparatus having at least two polishing units and a transfer device for transferring the substrate into the polishing units. Each of the polishing units includes at least one of a bevel polishing device for polishing a peripheral portion of the substrate and a notch polishing device for polishing a notch of the substrate. Bevel polishing devices or notch polishing devices are arranged in the polishing units so as to be symmetrical as seen from the transfer device. A substrate is transferred sequentially into the polishing units by the transfer device. The substrate is sequentially polished in the polishing units to remove contaminants and/or surface roughness of peripheral portions of the substrate. In this case, the bevel polishing devices or the notch polishing devices may be operated in the polishing units so as to be symmetrical as seen from the transfer device.
According to the above method, the respective polishing units can perform different polishing processes, e.g., rough polishing and finish polishing. Thus, the polishing units can be used for the respective purposes. Therefore, the substrate can effectively be finished into a desired shape. Further, with the above arrangement, even if the same substrate is transferred sequentially into the polishing units and polished in the polishing units, the substrate can smoothly be transferred to the respective polishing units, and bevel polishing or notch polishing can smoothly be conducted in the polishing units. Further, useless spaces for operation of the bevel polishing device or the notch polishing device can be eliminated in the polishing units to operate the polishing units efficiently.
According to a sixth aspect of the present invention, there is provided a substrate processing method which can improve a process efficiency of polishing a substrate, allows maintenance operation to be efficiently conducted in a short time of period, and can reduce loads of maintenance operation. This method employs a substrate processing apparatus having at least two polishing units and a transfer device for transferring the substrate into the polishing units. Each of the polishing units includes at least one of a bevel polishing device for polishing a peripheral portion of the substrate and a notch polishing device for polishing a notch of the substrate. Bevel polishing devices or notch polishing devices are arranged in the polishing units so as to be symmetrical as seen from the transfer device. One of the following two polishing processes is selectively performed. In a first polishing process, different substrates are transferred into the polishing units by the transfer device and polished in parallel in the polishing units to remove contaminants and/or surface roughness of peripheral portions of the different substrates. In a second polishing process, a substrate is transferred sequentially into the polishing units by the transfer device and polished sequentially in the polishing units to remove contaminants and/or surface roughness of peripheral portions of the substrate. In this case, the bevel polishing devices or the notch polishing devices may be operated in the polishing units so as to be symmetrical as seen from the transfer device.
According to purposes of substrate processing, the number of substrates processed per unit time can be increased to improve a throughput of the substrate processing apparatus. Alternatively, the polishing units can be used for the respective purposes so that the substrate can effectively be finished into a desired shape. When one of these processes is selectively performed, it is not necessary to rearrange the units and operations of the substrate processing apparatus so as to correspond to the selected process. Thus, the above processes can be switched with a simple procedure to improve an efficiency of the substrate. Further, in each process, the substrate can smoothly be transferred to the respective polishing units, and bevel polishing or notch polishing can smoothly be conducted in the polishing units.
The above and other objects, features, and advantages of the present invention will be apparent, from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.
A substrate processing apparatus according to embodiments of the present invention will be described below with reference to
The units of the substrate processing apparatus 1 are housed in a housing 3 disposed in a clean room 2. An inner space of the substrate processing apparatus 1 is partitioned from an inner space of the clean room 2 by walls of the housing 3. Further, the substrate processing apparatus 1 has a transfer region F in which the first transfer robot 200A is disposed and a process region G in which the other units are disposed. Clean air is introduced into the internal space of the substrate processing apparatus 1 through a fan unit (not shown) having an air supply fan, a chemical filter, a HEPA filter, and a ULPA filter provided at an upper portion of the housing 3. The fan unit is configured to draw air through an air duct (not shown) from an upper portion of the substrate processing apparatus 1 and supply clean air that has passed through the filters in a downward direction. Air inside the housing 3 is discharged to the exterior of the substrate processing apparatus 1 through a discharge section (not shown) provided at a lower portion of the housing 3. Thus, a downflow of clean air is formed in the housing 3. Accordingly, a downflow of clean air is formed onto a surface of a wafer transferred within the substrate processing apparatus 1 to prevent contamination of the wafer.
An arrangement of the loading/unloading port 100 will be described. In the substrate processing apparatus 1 shown in
When substrate processing is completed, the shutter 5 is closed. The SMIF pod or FOUP 101 is automatically or manually separately from the substrate processing apparatus 1 and transferred to another process. Accordingly, contaminated air should not be introduced into an inner space of the SMIF pod or FOUP 101. For this purpose, a chemical filter (not shown) is provided above the transfer region F, through which the wafers have passed before they are returned to the wafer cassette 102. A downflow of clean air is formed through the chemical filter. In order to maintain clean wafers in the wafer cassette 102, the SMIF pod or FOUP 101 of a hermetically sealed container may have a chemical filter or a fan to maintain the cleanliness of the container.
Since the two SMIF pods or FOUPs 101 are provided in parallel in the substrate processing apparatus 1, wafers can be transferred in parallel from and to these two SMIF pods or FOUPs 101. Thus, it is possible to improve a rate of operation in the substrate processing apparatus 1. Specifically, a wafer in the wafer cassette 102 mounted on one of the SMIF pods or FOUPs 101 is transferred into the substrate processing apparatus 1, and then a wafer in the wafer cassette 102 mounted on the other of the SMIF pods or FOUPs 101 is transferred into the substrate processing apparatus 1. At that time, the wafer cassette 102 mounted on the one of the SMIF pods or FOUPs 101, which becomes empty, can be replaced so that wafers are continuously introduced into the substrate processing apparatus 1.
Dummy wafer stations 107 are disposed below the respective loading/unloading stages 104. The dummy wafer station 107 receives at least one wafer including a dummy wafer used for stabilizing conditions in the first and second polishing units 400A and 400B before product wafers are processed or a quality control (QC) wafer for confirming conditions of the substrate processing apparatus 1. The dummy wafer station 107 has a sensor 108 for detecting a wafer to confirm the presence of the wafer. The dummy wafer station 107 may have a sensor for detecting any wafer projecting from the dummy wafer station 107. Alternatively, the dummy wafer station 107 may employ the aforementioned wafer projection detecting mechanism of the transmission optical sensors 106. A wafer is placed onto the dummy wafer station 107 as follows. The wafer cassette 103 housing wafers is placed on the loading/unloading stage 104, and then wafers are searched to determine a wafer to be transferred to the dummy wafer station 107. Commands are sent from the control panel 6 (see
As shown in
A wafer searching operation is performed as follows. The wafer searching mechanism 109 moves up from a position below the dummy wafer station 107 to a position above the uppermost slot in the wafer cassette 103 and then moves down to the position below the dummy wafer station 107. During this movement, the pair of the search sensors 112 counts the number of times that the light is interrupted by a wafer, thereby counting the number of wafers in the wafer cassette 103. At that time, the wafer searching mechanism 109 determines the positions of the wafers based on the pulses of the pulse motor in the driving source 110, thereby determining which slots in the wafer cassette 103 the wafers are inserted into. The wafer searching mechanism 109 also has an oblique wafer detecting function, which detects an obliquely inserted wafer when the light between the search sensors 112 is interrupted for a period of time corresponding to the number of pulses that is greater than the number of pulses corresponding to a spacing between the slots in the wafer cassette 103. The spacing between the slots in the wafer cassette 103 is preset in advance.
As shown in
The following two methods may be used in order to place a wafer cassette 103 on one of the loading/unloading stages 104.
(1) A wafer cassette 103 having wafers therein is placed directly on one of the loading/unloading stages 104. This process is employed when a space in the clean room 2 facing the loading/unloading port 100 is relatively clean, e.g., it has a cleanliness of class 100 or lower. In this case, a filter fan unit 116 should be mounted above the loading/unloading port 100 (100-2) to maintain a clean atmosphere around the loading/unloading stages 104 in the loading/unloading port 100.
(2) When the space in the clean room 2 facing the loading/unloading port 100 is relatively dirty, e.g., it has a cleanliness of class 1000 or higher, a wafer cassette 103 is placed in a box, which is controlled at a cleanliness of about class 100, delivered in the clean room 2, and placed on one of the loading/unloading stages 104.
The above transfer operation (2) of a wafer from the loading/unloading port 100 will be described below.
The placement plate 125a is attached to a vertical movement mechanism 126. Thus, the placement plate 125a is vertically movable in a state such that the base plate 124a and the wafer cassette 123 are placed on the placement plate 125a. When it is confirmed that the placement plate 125a and the base plate 124a are locked, the placement plate 125a is lowered to introduce the wafer cassette 123 into the lower space 122. The upper space 121 is an atmosphere that is contaminated to a degree equal to a space outside of the substrate processing apparatus 1. The lower space 122 is maintained in a state as clean as the interior of the substrate processing apparatus 1. Accordingly, wafers in the wafer cassette 123 can be transferred into the substrate processing apparatus 1 without exposure to the dirty atmosphere of the upper space 121. In this case, a hand of the first transfer robot 200A is moved to a height of a wafer in the lower space 122 to introduce the wafer into the substrate processing apparatus 1.
Next, the first transfer robot 200A will be described below.
Each of the upper hand 203a and the lower hand 203b has a vacuum line (not shown). Thus, both of the upper hand 203a and the lower hand 203b can be used as a vacuum suction hand. Alternatively, the lower hand 203b may be used as an attraction-type hand to attract a wafer under vacuum, and the upper hand 203a may be used as a recess-type hand to hold a peripheral portion of a wafer. The attraction-type hand can transfer a wafer with accuracy irrespective of displacement of the wafer in the wafer cassette 102. The recess-type hand can transfer a wafer while maintaining a cleanliness of a rear face of the wafer because the recess-type hand does not collect dust unlike the attraction-type hand. It is desirable to use a recess-type hand for wafers that have been subjected to a cleaning process. In this case, the upper hand 203a should comprise a recess-type thin hand made of ceramics. The recess-type thin hand made of ceramics is used for a transfer process from receiving a wafer from the secondary cleaning and drying unit 610 to returning the wafer to the wafer cassette 102. The lower hand 203b may comprise a forked vacuum suction hand made of ceramics, which has a vacuum line. The lower hand 203b is used for a transfer process from receiving a wafer from the wafer cassette 102 to delivering the wafer to the wafer stage 300 or the measurement unit 310. Thus, since the upper hand 203a and the lower hand 203b are used for separate purposes, clean wafers that have been subjected to a cleaning process can be transferred without contamination due to attachment of a cleaning liquid or foreign matter.
Next, the second transfer robot 200B will be described below.
The second transfer robot 200B has an upper hand 203a and a lower hand 203b, each of which comprises a recess-type hand to hold a peripheral portion of a wafer. The upper hand 203a is used to hold a wafer W that is not wet. Specifically, the upper hand 203a is used to transfer a wafer from the wafer stage 300 or the measurement unit 310 to the first polishing unit 400A, the second polishing unit 400B, and the primary cleaning unit 600 and to transfer a wafer from the secondary cleaning and drying unit 610 to the wafer stage 300 or the measurement unit 310. The lower hand 203b is used to hold a wet wafer W. Specifically, the lower hand 203b is used to transfer a wafer in transfer processes other than the transfer processes of the upper hand 203a. Thus, a wet wafer W is located below a wafer W that is not wet. Accordingly, the wafer W that is not wet is prevented from being contaminated by a dropping cleaning liquid or the like.
As shown in
Instead of the wafer stage 300, the measurement unit 310 may be provided at the position of the wafer stage 300. The measurement unit 310 has a function to measure a shape of a peripheral portion of a wafer before and after processing. A measurement unit having a diameter measurement mechanism for measuring a diameter of a wafer will be described as an example of the measurement unit 310.
The substrate holding and rotating mechanism 361 shown in
Operation of the substrate holding and rotating mechanism 361 will be described below with reference to
The measurement unit 310 shown in
As shown in
Further, rotational angles of the upper chuck 362 and the lower chuck 363 in the substrate holding and rotating mechanism 361 are indexed to measure the diameter at a plurality of points on the peripheral portion of the wafer W. In this manner, it is possible to obtain information that cannot be obtained from one point measurement, such as variations of the polishing amount over the entire peripheral portion of the wafer W. Furthermore, the diameter of the wafer can continuously be measured while the wafer is rotated by the substrate holding and rotating mechanism 361. According to this method, the diameter of the wafer can be obtained as continuous data. Thus, it is possible to calculate the circularity of the wafer.
The measurement unit may have a cross-sectional shape measurement mechanism for measuring a cross-sectional shape of a peripheral portion of a wafer, a surface condition measurement mechanism for measuring surface conditions of a peripheral portion of a wafer, or a defect detection mechanism for detecting defective portions on a peripheral portion of a wafer. Further, the measurement unit may have a plurality of these mechanisms.
Thus, since the wafer stage 300 is provided above the measurement unit 310, both of the measurement unit 310 and the wafer stage 300 can be disposed in a common space. Accordingly, it is possible to reduce a space required for the substrate processing apparatus 1. Further, a wafer can be transferred efficiently in an optimized route as will be described in processing patterns of the substrate processing apparatus 1. Thus, it is possible to improve a throughput of the substrate processing apparatus 1.
Next, structures of the first polishing unit 400A and the second polishing unit 400B will be described below. The first and second polishing units 400A and 400B have common structures. As shown in
As shown in
In the polishing unit 400-1, the sidewall 404 near the bevel polishing head 460 has a maintenance hatch (door) 407, and the sidewall 406 near the notch polishing head 49 has a maintenance hatch (door) 408. The maintenance hatches 407 and 408 face the bevel polishing head 460 and the notch polishing head 490, respectively. When the maintenance hatch 407 is opened, an operator is accessible to the bevel polishing head 460 from the exterior of the polishing unit 400-1. When the maintenance hatch 408 is opened, an operator is accessible to the notch polishing head 490. The sidewall 409 of the polishing unit 400-1 has an opening 405 for allowing a wafer W to be introduced into and discharged from the polishing chamber 401. The polishing unit 400-1 has a shutter 405a for covering the opening 405 and an air cylinder 405b for actuating the shutter 405a. In the polishing unit 400-1 shown in
As shown in
The lower rotational shaft 412b is rotatably supported by bearings 414b fixed onto an inner circumferential surface of a support member 413b. A pulley 415b is fixed to the lower rotational shaft 412b. A motor 419 is fixed onto the support member 413b. A pulley 420 is attached to a rotational shaft of the motor 419. The pulley 415b is connected to the pulley 420 via a timing belt 421. Thus, when the motor 419 is driven, the lower rotational shaft 412b is rotated via the pulley 420 and the timing belt 421. The upper rotational shaft 412a can be swung about the lower rotational shaft 412b by rotating the motor 419 through a predetermined angle. In this manner, the motor 419 and the lower rotational shaft 412b form a substrate holding table swing mechanism 439 for swinging the substrate holding table 411, which is connected to the upper rotational shaft 412a, on the horizontal plane. In order to prevent a treatment liquid from being attached to mechanical components of the substrate holding and rotating mechanism 410, a cover 438 is provided so as to cover the rotational shaft 412, the support member 413, and the like.
The support member 413a and the support member 413b are connected to each other by a plate member 422. The support member 413b is attached via a horizontal movement mechanism (substrate holding table horizontal movement mechanism) 423 to a base plate 403a, which is provided at an interface between the polishing chamber 401 and the machine chamber 402. The horizontal movement mechanism 423 includes an upper plate 425 attached to the base plate 403a, linear guides 424 for sliding the upper plate 425 in a first direction with respect to the base plate 403a, a lower plate 427 attached to the upper plate 425, and linear guides 426 for sliding the lower plate 427 in a second direction, which is perpendicular to the first direction, with respect to the upper plate 425. The horizontal movement mechanism 423 allows the support member 413 (413a and 413b) to linearly move in two directions (X-Y directions), which are perpendicular to each other on the horizontal plane, with respect to the base plate 403a. Thus, the horizontal movement mechanism 423 serves as an X-Y stage. Servomotors 428 and 429 and ball screws 430 and 431 are fixed to the upper plate 425 and the lower plate 427, respectively. When the servomotors 428 and 429 are driven, the upper plate 425 and the lower plate 427 are linearly moved along the linear guides 424 and 426, respectively.
A polishing pad 435 is attached to an upper surface of the substrate holding table 411. The polishing pad 435 has an upper surface with grooves 435a formed therein. The polishing pad 435 is made of elastic material such as urethane. Thus, the polishing pad 435 is adopted to hold a wafer W without damaging a rear face of the wafer W and to hermetically seal a contact portion with the wafer W. The grooves 435a communicate via the substrate holding table 411 with a communication passage 432a formed within the upper rotational shaft 412a. The communication passage 432a in the upper rotational shaft 412a is connected via a rotary joint 433 to a pipe 434, which is connected to a communication passage 432b in the lower rotational shaft 412b. The communication passage 432b in the lower rotational shaft 412b is connected to a vacuum line 436 and a compressed air supply line 437. Accordingly, vacuum is supplied via the vacuum line 436 to form a vacuum in the grooves 435a of the polishing pad 435. Thus, a wafer W placed on the substrate holding table 411 is attracted onto the upper surface of the polishing pad 435 under vacuum.
Further, a substrate transfer mechanism 440 is disposed above the substrate holding and rotating mechanism 410. The substrate transfer mechanism 440 has a pair of arms 441 and 441, which have holding portions 441a and 441a corresponding to a bevel portion of the wafer W. The arms 441 and 441 are capable of opening and closing in directions indicated by arrows shown in
The polishing unit 400-1 includes supply pipes (not shown) for supplying liquid or gas (e.g., pure water or gas) to the respective components, such as the substrate holding and rotating mechanism 410, the bevel polishing device 450, and the notch polishing device 480, and various pipes (not shown) such as a drainage pipe for a waste liquid discharged from the respective components. As shown in
The polishing unit 400-1 also includes electric cables (not shown) for supplying power to motors or the like and wiring (not shown) such as control signal lines for supplying control signals to various sensors. These cables are aggregated at the spacing section 495 and connected to power supply/signal connectors 496 provided at the spacing section 495. The space 12 at the base portion 11 houses electric cables and control signal lines (not shown) connected to power sources and the controller 4 in the substrate processing apparatus 1. Branched lines from these lines are connected to the power supply/signal connectors 496. Thus, connection of pipes to the polishing unit 400-1 is conducted via the spacing section 495 provided on the sidewall 404 in the substrate processing apparatus 1.
As shown in
The swing mechanism 470 is coupled to a reciprocation movement mechanism 476 for reciprocating the bevel polishing head 460 along the tangential direction of the wafer W. An air cylinder may suitably be used as the reciprocation movement mechanism 476. The reciprocation movement mechanism 476 reciprocates the swing mechanism 470 and the crank member 471 along the direction in which the crank axis 471a extends. Thus, the bevel polishing head 460 connected to the crank member 471 is reciprocated (oscillated) along the tangential direction of the wafer. Since the bevel polishing device 450 has the swing mechanism 470 and the reciprocation movement mechanism 476, the bevel polishing head 460 can be swung about the peripheral portion of the wafer W and reciprocated along the tangential direction of the wafer W.
Referring back to
A maintenance hatch 457 is provided over the machine chamber 456 so as to extend upward from the sidewall 404. When the maintenance hatch 457 is opened, an operator is accessible to the polishing tape supply/recovery mechanism 452 from the exterior of the polishing unit 400-1. Thus, the operator can replace the polishing tape 451 with the feed reel 453a and the takeup reel 453b or conduct maintenance operation of the polishing tape supply/recovery mechanism 452.
Resin material in which abrasive particles are dispersed is applied to a surface of a tape base and solidified to form the polishing surface 451a of the polishing tape 451. Examples of the abrasive particles include diamond and SiC. Types and grain size of abrasive particles are selected according to the type of wafer to be polished or a required degree of polishing. For example, diamond having a grain size of #4000 to #11000 or SiC having a grain size of #4000 to #10000 can be used as abrasive particles. Further, a beltlike polishing cloth having no particles attached to its surface may be used instead of the polishing tape 451.
When a side surface of the bevel portion is polished with a polishing tape 451 having a small grain size, the wafer can be formed so as to have a desired diameter. In a case where a rough polishing process and a finish polishing process are performed in different polishing units 400-1, a polishing material having a low count (i.e., a rough polishing material of abrasive particles having a large particle diameter) is applied to a polishing tape 451, and the polishing tape 451 is mounted to the bevel polishing device 450 in a polishing unit 400 for rough polishing. At that time, a polishing material having a high count (i.e., a fine polishing material of abrasive particles having a small particle diameter) is applied to a polishing tape 451, and the polishing tape 451 is mounted to the bevel polishing device 450 in another polishing unit 400 for finish polishing. Thus, a plurality of polishing unit 400 are separately used for their purposes.
Examples of a polishing material having a low count include a polishing material of abrasive particles having an average particle diameter of 5 μm and a grain size of about #3000. Examples of a polishing material having a high count include a polishing material of abrasive particles having an average particle diameter of 0.2 μm and a grain size of about #20000. Generally, a polishing material of abrasive particles having a grain size larger than about #6000 is used for shaping, and a polishing material of abrasive particles having a grain size smaller than about #6000 is used for adjustment of the surface conditions.
More specifically, the tape base of the polishing tape 451 is formed by a beltlike polyethylene terephthalate (PET) resin having a thickness of about several tens of micrometers. A polishing layer to polish a wafer is formed on one surface of the tape base. Resin material in which abrasive particles such as diamond are dispersed is applied to the tape base, dried, and solidified to form the polishing layer. The polishing layer is a uniform layer having a thickness of about several micrometers and has a polishing surface 451a thereon. Fine irregularities are formed in the polishing surface 451a by the dispersed abrasive particles.
The resin material in which abrasive particles are dispersed includes composite resin material into which various resin components are mixed. Properties of resin materials vary depending on manufacturers of polishing tapes. The hardened resin material should be water-insoluble. The hardened resin material should have a strength such that abrasive particles are not removed by frictional forces between the polishing surface and the wafer, which are produced during polishing. Further, the hardened resin material should not be softened due to frictional heat produced during polishing to a degree such that abrasive particles are separated. Furthermore, the hardened resin material is required to be chemically inactive. Particularly, the hardened resin material should be chemically inactive even if it gets wet with water (polishing water) supplied during polishing. Specifically, it is desirable that the resin material of the polishing tape has no chemical polishing effect. When a wafer W is polished with a polishing tape in which abrasive particles are fixed by resin material that meets the above requirements, it is possible to prevent abrasive particles from being readily separated during polishing. Chemical inactiveness of resin material means that the resin material does not chemically react with a wafer to be polished, abrasive particles, or water at polishing temperatures with mechanical sliding contact.
The swing mechanism 510 includes a motor 511, a rotational shaft 512 to which rotation of the motor 511 is transmitted, and a first support plate 514 fixed to an end of the rotational shaft 512. The first support plate 514 can be swung (rotated) about the rotational shaft 512. Specifically, the first support plate 514 is fixed to the end of the rotational shaft 512 via an attachment plate 513 and connected to a second support plate 515 and the notch polishing head 490. A gear 517 is provided on another end of the rotational shaft 512. The gear 517 engages with a worm 518, which has an axis 519 extending in a direction perpendicular to the rotational shaft 512. The axis 519 has an end coupled to a rotational shaft of the motor 511. Accordingly, when the motor 511 is driven, rotation of the motor 511 is converted into rotation of the rotational shaft 512 via the axis 519, the worm 518, and the gear 517. By rotating the motor 511 in opposite directions through a predetermined angle, the rotational shaft 512 is rotated in opposite directions to thereby swing the first support plate 514 about the rotational shaft 512. The notch polishing head 490 has a polishing area positioned on an extension of an axis of the rotational shaft 512. Thus, the notch polishing head 490 can be swung about the polishing area in a vertical direction.
The vertical movement mechanism 500 includes the second support plate 515 and linear guides 516 for moving the second support plate 515 in the vertical direction with respect to the first support plate 514. The notch polishing head 490 is fixed to the second support plate 515. As shown in
Referring back to
The polishing tape 481 is made of the same material as the polishing tape 451 used in the bevel polishing device 450. Since the material and details of the polishing tape 481 are the same as those of the polishing tape 451, details of the polishing tape 481 will not be described repetitively. The polishing tape 481 has a width corresponding to the shape of the notch of the wafer W. The polishing tape 481 has a width smaller than that of the polishing tape 451. The polishing tape 481 is wound around a cylindrical core member 484. The core member 484 is attached to the feed reel 483a. The polishing tape 481 extends between the pair of the feed rollers 491 and 491 in the notch polishing head 490 in a state such that the polishing surface 481a faces outward. Then, the polishing tape 481 is attached to the takeup reel 483b. The takeup reel 483b is coupled to a rotation drive mechanism (not shown) such as a motor. The polishing tape 481 can be wound up and recovered with a predetermined tension applied thereto.
A maintenance hatch 459 is provided over the machine chamber 458 so as to extend upward from the sidewall 406. When the maintenance hatch 459 is opened, an operator is accessible to the polishing tape supply/recovery mechanism 482 from the exterior of the polishing unit 400-1. Thus, the operator can replace the polishing tape 481 with the feed reel 483a and the takeup reel 483b or conduct maintenance operation of the polishing tape supply/recovery mechanism 482.
When the notch polishing head 490 is reciprocated in a vertical direction by the vertical movement mechanism 500, the polishing surface 481a of the polishing tape 481 can be brought into sliding contact with the notch of the wafer W to thereby polish the notch of the wafer W. At that time, the notch polishing head 490 may be swung by the swing mechanism 510 so as to be inclined in the vertical direction at a predetermined angle with respect to the wafer surface. The notch of the wafer W can also be polished in such a state.
The polishing unit 400 includes a notch sensor (not shown). For example, the notch sensor may comprise a straight-beam retro-reflective sensor, which includes laser sensor having a light-emitting portion, a light-receiving portion provided at the same portion as the light-emitting portion, and a reflection portion disposed away from the light-emitting portion. If a laser emitted from the light-emitting portion passes through a notch of a wafer, it reaches the reflection portion, reflects from the reflection portion, and returns to the light-receiving portion. Only when the notch passes right below the light-emitting portion, the laser reflects from the reflection portion and returns to the light-receiving portion. Thus, the notch can be detected. If a notch of a wafer W is detected by the notch sensor in a state such that the substrate holding table 411 having the wafer W attracted thereto is rotated, the rotation of the substrate holding table 411 is stopped to align the notch of the wafer W with the polishing tape 481 of the notch polishing device 480.
As shown in
The polishing water supplied from the polishing water supply nozzles 523 and 524 serves not only to prevent contamination on the upper and lower surfaces of the wafer W due to polishing wastes but also to remove heat produced by friction during polishing so as to cool the wafer W. Thus, by adjusting the temperature of the polishing water to be supplied, heat can be removed from the polished areas of the wafer W to achieve a stable polishing process.
An endpoint of a polishing process for the peripheral portion of the wafer W by the bevel polishing device 450 may be managed by the polishing time. Alternatively, a temperature variation of the peripheral portion of the wafer W may be monitored, and an endpoint of a polishing process may be detected based on the measured temperature variation. The polishing unit 400 may have a polishing endpoint detection device for detecting an endpoint of the polishing process. Examples of such a polishing endpoint detection device will be described below.
In the polishing endpoint detection device 530-1, a peripheral portion of a wafer W is lit by the lighting ring 532 during polishing the peripheral portion of the wafer W. The controller 533 captures images from the image sensor 531 and monitors a variation of colors of the peripheral portion of the wafer W to detect a polishing endpoint. When the controller 533 detects a polishing endpoint, the controller 533 sends an endpoint signal to a polishing controller (not shown), which moves the substrate holding table 411 in a horizontal direction to separate the peripheral portion of the wafer W from the polishing tape 481 and stops the rotation of the substrate holding table 411. Before the polishing process, an initial shape of the peripheral portion of the wafer W may be stored in the controller 533 via the image sensor 531. The peripheral portion of the wafer W may be polished so as to maintain the initial shape of the peripheral portion of the wafer W. Factors to determine the initial shape include an inclination angle, a curvature, and a dimension of the peripheral portion of the wafer W. Further, an image of a peripheral portion of a reference wafer that has been polished may previously be stored as a reference image in the controller 533 via the image sensor 531. In this case, images obtained during polishing by the image sensor 531 may be compared with the reference image to detect a polishing endpoint.
In the polishing endpoint detection device 530-2, a signal from the motor 416 (e.g., a motor current) rotating the substrate holding table 411, which attracts a wafer under vacuum, at a predetermined speed is amplified by the motor amplifier 534 during polishing a peripheral portion of the wafer W. The amplified signal is sent to the controller 535. The controller 535 calculates a torque required for rotation of the motor 416 based on the signal from the motor amplifier 534. Then, the controller 535 analyzes a variation of the torque to detect a polishing endpoint. When the controller 535 detects a polishing endpoint, the controller 535 sends an endpoint signal to a polishing controller (not shown), which moves the substrate holding table 411 in a horizontal direction to separate the peripheral portion of the wafer W from the polishing tape 481 and stops the rotation of the substrate holding table 411. A torque gauge (not shown) may be provided on the rotational shaft 412 of the substrate holding table 411. A rotation torque of the substrate holding table 411 can directly be detected, and a variation of the rotation torque can be analyzed so as to detect a polishing endpoint. In this case, a varied amount of rotation torque at a polishing endpoint may previously be measured and stored in the controller 535. Measured values can be compared with the stored value to detect a polishing endpoint. Further, a polishing endpoint may be detected by analyzing current variations of the servomotors 428 and 429, which horizontally move the substrate holding table 411.
In the polishing endpoint detection device 530-3, a peripheral portion of a wafer W is lit by the light-emitting portion 536a of the photosensor 536 during polishing the peripheral portion of the wafer W. Scattered light reflected from the peripheral portion is received by the light-receiving portion 536b of the photosensor 536, measured, and amplified by the measurement amplifier 537. The amplified signal is sent to the controller 538. The controller 538 analyzes the scattered light from the signal of the measurement amplifier 537 to evaluate roughness of the polishing state of the peripheral portion of the wafer W. Thus, a polishing endpoint is detected.
The aforementioned polishing endpoint detection device which optically detects a polishing endpoint can also be employed to detect an endpoint of a polishing process of a notch of a wafer W by the notch polishing device 480.
Next, a processing process of a peripheral portion of a wafer in the polishing unit 400 will be described below. A semiconductor wafer W to be polished in the polishing unit 400 has semiconductor devices formed thereon. The wafer W has a diameter of 200 mm or 300 mm. When the air cylinder 405b is actuated, the shutter 405a is lifted to open the opening 405. The wafer W is introduced through the opening 405 into the polishing chamber 401 by the second transfer robot 200B and transferred to above the substrate holding table 411. At that state, when the arms 441 and 441 come close to each other, the holding portions 441a and 441a of the arms 441 and 441 are brought into contact with the peripheral portion of the wafer W. Thus, the holding portions 441a and 441a of the arms 441 and 441 hold the wafer W therebetween and center the wafer W with respect to the substrate holding table 411. Then, the arms 441 and 441 holding the wafer W are lowered to place the wafer. W on the upper surface of the substrate holding table 411. Vacuum is supplied through the vacuum line 436 to the communication passage 432b to attract the wafer onto the upper surface of the substrate holding table 411 under vacuum. At that state, the arms 441 and 441 are horizontally opened to release the wafer W. The arms 441 and 441 are lifted and held at a standby position. Then, the motor 416 is driven to rotate the wafer W together with the substrate holding table 411.
When bevel polishing of the wafer W is to be conducted, the polishing tape supply/recovery mechanism 452 in the bevel polishing device 450 is operated to feed the polishing tape 451 to the bevel polishing head 460 so as to dispose an unused polishing, surface 451a between the feed rollers 461 and 461. The horizontal movement mechanism 423 of the substrate holding and rotating mechanism 410 moves the wafer W toward the bevel polishing head 460 and locates the wafer W at a polishing position of the bevel polishing device 450. The bevel portion of the rotating wafer W is brought into sliding contact with the polishing tape 451 and thus polished. At the time of polishing, the swing mechanism 470 of the bevel polishing device 450 is driven to swing the bevel polishing head 460 around the polishing position. Thus, it is possible to polish not only the bevel portion but also the edge portion of the wafer W. Further, the reciprocation movement mechanism 476 of the bevel polishing device 450 may be driven to reciprocate the bevel polishing head 460 along the tangential direction of the wafer W during polishing.
Instead of driving the swing mechanism 470 or the reciprocation movement mechanism 476 of the bevel polishing device 450, the wafer W may be swung around the polishing position by the swing mechanism provided on the substrate holding and rotating mechanism 410 or may be reciprocated along the tangential direction of the wafer W. When the wafer W is polished while being rotated by the substrate holding and rotating mechanism 410, the substrate holding and rotating mechanism 410 may not be reciprocated.
When notch polishing of the wafer W is to be conducted, the horizontal movement mechanism 423 is operated to move the wafer W to the polishing position of the notch polishing device 480. While the wafer W held by the substrate holding and rotating mechanism 410 is rotated, the notch of the wafer W is detected by the notch sensor. Then, the notch of the wafer W is aligned with a position facing the polishing tape 481 of the notch polishing device 480. The horizontal movement mechanism 423 of the substrate holding and rotating mechanism 410 moves the notch of the wafer W toward the notch polishing head 490 to bring the notch of the wafer W into contact with the polishing tape 481. At that time, the notch polishing head 490 is repeatedly moved in the vertical direction by the vertical movement mechanism 500 of the notch polishing device 480. Thus, the polishing tape 481 is brought into sliding contact with the notch of the wafer W to polish the notch of the wafer W. The notch polishing head 490 may be swung during polishing by the swing mechanism 510 of the notch polishing device 480. In this case, the notch polishing head 490 can be inclined at a predetermined angle with respect to the wafer surface to thereby polish an upper end or lower end of the notch or polish the notch with a desired angle.
When semiconductor devices are formed on the wafer to be polished, the wafer may have submicronic fine irregularities formed in the surface of the wafer. If abrasive particles are separated from the polishing tape during polishing such a wafer, then the separated abrasive particles enter recesses formed in the surface of the wafer. In such a case, even if the wafer is cleaned in a cleaning process subsequent to the polishing process, the abrasive particles cannot sufficiently be removed from the recesses in the wafer. According to the present embodiment, the aforementioned polishing tapes 451 and 481 are used to bring polishing layers (polishing surfaces 451a and 481a) of the polishing tapes 451 and 481 into sliding contact with the peripheral portion (bevel portion and notch) of the wafer W at the polishing positions in the polishing unit 400-1. Therefore, abrasive particles are prevented from being readily separated and entering recesses formed in the wafer W. Particularly, even if resin material of the polishing tape is exposed to water, abrasive particles are not readily separated. Accordingly, even if the wafer W is polished while polishing water of ultrapure water is supplied onto the surface of the wafer W, the abrasive particles are prevented from being readily separated and entering recesses formed in the wafer W.
In the polishing unit 400-1, the wafer W is polished while polishing water of ultrapure water is supplied onto the surface of the wafer W from the polishing water supply nozzles 523, 524, and 525. As described above, ultrapure water spreads over the surface of the wafer W, which is horizontally held and rotated by the substrate holding and rotating mechanism 410. Thus, ultrapure water serves to cover the entire surface of the wafer W so as to protect the surface of the wafer W and to remove frictional heat produced by friction between the polishing layers of the polishing tapes 451 and 481 and the wafer W. In this case, separate lines may be used for supplying ultrapure water to protect the surface of the wafer W and for supplying ultrapure water to remove heat and cool the wafer W during polishing.
Further, if slurry other than pure water is supplied for polishing the wafer W, the hand of the transfer robot 200B may be contaminated by slurry attached to the wafer W when the wafer W is transferred from the polishing unit 400-1 to the primary cleaning unit 600 by the transfer robot 200B after the polishing. In the present embodiment, if slurry is not used but only ultrapure water is used as polishing water supplied for polishing in the polishing unit 400-1, then the hand of the transfer robot 200B and other units are prevented from being contaminated by the polished wafer W.
Further, when the slurry is supplied during polishing in the polishing unit 400-1, the slurry contaminates the bevel polishing head 480 and the notch polishing head 490 in the polishing unit 400-1 and the respective components in the polishing unit 400-1. In such a case, an operator should be accessible to the polishing unit 400-1 not only through the maintenance hatches 407 and 408 but also in other directions at the time of cleaning of the polishing unit 400-1, i.e., at the time of maintenance of the polishing unit 400-1. Thus, maintenance operation becomes a heavy load on an operator. However, when only ultrapure water is supplied during polishing, the respective components of the polishing unit 400-1 are not contaminated. Accordingly, it becomes unnecessary to clean contaminated portions. The operator can conduct maintenance operation only through the maintenance hatches 407 and 408. Thus, a load on the operator can be reduced.
Further, the wafer W is moved to the position for the bevel polishing device 450, and the peripheral portion of the wafer W is polished by the bevel polishing device 450. Then, the wafer W may be moved from the position for the bevel polishing device 450 to the position for the notch polishing device 480 by the horizontal movement mechanism 423 while ultrapure water is continuously supplied from the polishing water supply nozzle 525 onto the surface of the wafer W. Alternatively, the wafer W may be moved from the position for the notch polishing device 480 to the position for the bevel polishing device 450 while ultrapure water is continuously supplied from the polishing water supply nozzle 525 onto the surface of the wafer W. In this case, the wafer W is moved while the surface of the wafer W is covered with a wafer film. Accordingly, the wafer W is prevented from being contaminated by an atmosphere or polishing wastes in the polishing unit 400-1. Thus, it is possible to maintain a cleanliness of the wafer W. Further, it is possible to prevent secondary contamination of the bevel polishing device 450 or the notch polishing device 480 where the wafer is to be transferred. Therefore, polishing can be conducted without hindrance in the bevel polishing device 450 or the notch polishing device 480. Since it is also possible to maintain a cleanliness of the respective components in the polishing unit 400-1, loads of maintenance operation such as cleaning can be reduced.
During polishing, it is desirable that the polishing chamber 401 is evacuated via a vacuum line (not shown) connected to the polishing chamber 401 so as to reduce an (air) pressure in the polishing chamber 401 to be lower than an (air) pressure outside of the polishing chamber 401. In such a case, polishing powder or particles scattering in the polishing chamber 401 can be discharged into the exterior of the polishing chamber 401. Accordingly, the polishing chamber 401 can be maintained in a clean state. Further, it is possible to prevent polishing powder from flowing into an area that is required to have a high cleanliness. When the polishing endpoint detection device detects a polishing endpoint of the wafer W, polishing is completed in the bevel polishing device 450 or the notch polishing device 480. When all polishing processes are completed, the arms 441 and 441 are lowered from the standby positions to hold the wafer W. The vacuum attraction of the substrate holding and rotating mechanism 410 is released. Then, the arms 441 and 441 holding the wafer W are lifted to predetermined positions, and the shutter 405a is opened. The hand of the second transfer robot 200B is introduced into the polishing chamber 401 to receive the wafer W held by the arms 441 and 441. The second transfer robot 200B transfers the wafer W from the polishing chamber 401.
Another example of the polishing unit 400 will be described below.
The polishing unit 400-2 has a substrate holding and rotating mechanism 550 for holding and rotating a wafer, a substrate transfer mechanism 565 for receiving, centering, and delivering the wafer, a bevel polishing device 560 for polishing a bevel portion of the wafer, a notch polishing device 580 for polishing a notch of the wafer, and a notch sensor (not shown) for detecting the notch of the wafer.
As shown in
The substrate transfer mechanism 565 disposed above the substrate holding and rotating mechanism 550 has a pair of arms 566 and 566. Each of the arms 566 and 566 includes a plurality of chucks 567 having a recessed surface corresponding to a bevel portion of the wafer W. The arms 566 and 566 are capable of opening and closing and can have a close position and a release position. The arms 566 and 566 can sandwich the wafer W between the chucks 567 and 567 at the close position and can release the wafer W at the release position. When the wafer W is clamped by the arms 566 and 566, the wafer W is centered.
The substrate holding and rotating mechanism 550 is lowered to a predetermined position after receiving the wafer W from the substrate transfer mechanism 565. Then, vacuum is supplied via the vacuum line 554 to attract the wafer onto the upper surface of the substrate holding table 551 under vacuum. The rotation drive device 553 is driven to rotate the wafer W at a predetermined rotational speed.
The gear 584 engages with a rack 585, which is fixed to an L-shaped support member 586. The support member 586 is coupled to a rod 587a of an air cylinder 587. The support arm 583 is supported by a support frame 588 so as to be pivotable about a rotational shaft 589. The air cylinder 587 has an upper end fixed to the support frame 588. An air cylinder 590 is fixed to a frame 599 fixed onto a fixed portion such as a base of the apparatus. The support frame 588 is fixed to a rod 590a of the air cylinder 590. The polishing tape 581 is housed in a cassette tape cartridge (not shown). As shown in
As shown in
When the gear 593 is rotated counterclockwise by the servomotor, the gears 594 and 594 rotate clockwise while the support lever 595 is swung counterclockwise about the axis 592. Thus, the polishing tape 581 is drawn toward the takeup reel RA. When the gear 593 is rotated clockwise by the servomotor, the gears 594 and 594 rotate counterclockwise while the support lever 595 is swung clockwise about the axis 592. Thus, the polishing tape 581 is drawn toward the feed reel RB. A reciprocation stroke of the polishing tape 581 is absorbed by idle rollers 597a and 597b provided at an upper portion and a lower portion, respectively. The idle rollers 597a and 597b are movable in directions of arrows. The upper and lower idle rollers 597a and 597b are biased by an upper tension 598a and a lower tension 598b of extension coil springs, respectively. When the polishing tape 581 is vertically reciprocated by the servomotor, the takeup reel RA and the feed reel RB are locked by a lock mechanism. Since the polishing tape 581 is vertically reciprocated by the servomotor, a relative speed can be adjusted between a surface to be polished and the polishing tape 581. Thus, a polishing rate can readily be adjusted.
The notch of the wafer is polished by the notch polishing device 580 as follows. When the notch of the wafer W is detected by the notch sensor and aligned with the elastic roller 582 of the notch polishing device 580, operation of the notch polishing device 580 is started. In the notch polishing device 580, when the air cylinder 587 is operated to move the rod 587a upward, the rack 585 fixed to the support member 586 is also moved upward to rotate the gear 584 counterclockwise. As a result, the support arm 583 is pivoted downward about the rotational shaft 589 to move the elastic roller 582 to a lower position. When the air cylinder 587 is operated to move the rod 587a downward, the rack 585 fixed to the support member 586 is also moved upward to rotate the gear 584 clockwise. As a result, the support arm 583 is pivoted upward about the rotational shaft 589 to move the elastic roller 582 to an upper position. The air cylinder 587 can move the rod 587a to three positions including an upper position, a lower position, and an intermediate position. The air cylinder 590 is operated to move the support frame 588 forward so that the elastic roller 582 is moved toward the wafer W. Thus, the polishing tape 581 is pressed against the notch N of the wafer W by the elastic roller 582.
At that time, the wafer W is attracted onto the substrate holding table 551 under vacuum, and rotation of the substrate holding table 551 is stopped in a stationary state. The servomotor is driven to swing the support lever 595 of the tape drive mechanism 591, so that the polishing tape 581 is vertically reciprocated. Accordingly, the polishing tape 581 is brought into sliding contact with the notch of the wafer W to polish the notch of the wafer W. A pressure to press the polishing tape 581 against the notch can be adjusted by properly adjusting a pressure of compressed air to be supplied to the air cylinder 590. Further, polishing water is supplied to the notch of the wafer W and a contacting portion of the polishing tape 581 from polishing water supply nozzles 523 and 524. Thus, the notch of the wafer W is polished in a wet state. A worn polishing tape 581 is wound up before a polishing rate of the tape is lowered, so that a new polishing tape 581 is brought into contact with the wafer W.
When the side surface of the notch of the wafer W is to be polished, the air cylinder 587 is operated to move the rod 587a to the intermediate position. At that time, the support arm 583 is held substantially in a horizontal state. The air cylinder 590 is operated to move the support frame 588 forward (see
When a lower edge portion of the notch N of the wafer W is to be polished, the air cylinder 587 is operated to move the rod 587a to the upper position. At that time, the gear 584 is rotated counterclockwise, and the support arm 583 is pivoted downward about the rotational shaft 589 to move the elastic roller 582 to the lower position. Then, the air cylinder 590 is operated to move the support frame 588 forward (see
Thus, according to the notch polishing device 580, it is possible to polish the upper edge portion, the outer periphery, and the lower edge portion of the notch N of the wafer. Thus, ideal polishing corresponding to the shape of the notch can be conducted.
Arrangements of the first and second polishing units 400A and 400B in the substrate processing apparatus 1 will be described below. As shown in
The first and second polishing units 400A and 400B are provided so as to surround a central area of the substrate processing apparatus 1, in which the second transfer robot 200B is disposed. Openings 405A and 405B for transfer of wafers in the first and second polishing units 400A and 400B face the second transfer robot 200B, respectively. With such an arrangement, the second transfer robot 200B is accessible to both of the first and second polishing units 400A and 400B. Further, the second transfer robot 200B is disposed substantially on an extension of the center line L. Accordingly, the arrangements of the first and second polishing units 400A and 400B are symmetric as seen from the second transfer robot 200B. Specifically, as seen from the second transfer robot 200B, the bevel polishing device 450A is disposed on the left side of the opening 405A in the first polishing unit 400A, and the bevel polishing device 450B is disposed on the right side of the opening 405B in the second polishing unit 400B.
A maintenance space 7 is formed in front of the corner portion 3e of the substrate processing apparatus 1, which is interposed between the first and second polishing units 400A and 400B. An operator can enter the maintenance space 7 from the exterior of the substrate processing apparatus 1. The maintenance space 7 is substantially rectangular in a plan view. The maintenance space 7 is surrounded by two sides facing a sidewall 404A, near which the bevel polishing device 450A is disposed in the first polishing unit 400A, and a sidewall 404B, near which the bevel polishing device 450B is disposed in the second polishing unit 400B, and by two sides facing sidewalls 3b and 3c, which interpose the corner portion 3e of the substrate processing apparatus 1. An entrance 8 is provided on the sidewall 3b at a position facing the maintenance space 7. The operator can enter the maintenance space 7 through the entrance 8 from the exterior of the substrate processing apparatus 1.
Specifically, the maintenance space 7 faces the maintenance hatches 407A and 407B, which are provided in the sidewalls 404A and 404B of the first and second polishing units 400A and 400B, respectively. After an operator enters the maintenance space 7, the operator can open the maintenance hatch 407A or 407B so as to replace a polishing tape or a polishing pad in the bevel polishing device 450A or 450B. Thus, since the operator is accessible to the bevel polishing devices 450A and 450B in the first and second polishing units 400A and 400B from the same maintenance space 7, polishing tapes or the like can be replaced all at once in both of the bevel polishing devices 450A and 450B.
Further, the maintenance space 7 faces the maintenance hatch 457 for the machine chamber 456 (see
Further, the spacing sections 495 of the first polishing unit 400A and the second polishing unit 400B are collectively disposed at positions facing the maintenance space 7. Accordingly, it is possible to shorten pipes branched from pipes of the substrate processing apparatus 1 into the polishing units 400A and 400B. Thus, it is possible to reduce pressure loss of liquid or gas flowing through the pipes. As a result, the branched pipes can have a small diameter and thus achieve good management of piping connection.
The notch polishing device 480A is disposed near the sidewall 406A, which faces the sidewall 3c of the substrate processing apparatus 1, in the first polishing unit 400A. The maintenance hatch 408A is provided in the sidewall 406A. The maintenance hatch 10 is also provided in the sidewall 3c at a position facing the sidewall 406A. Thus, when an operator opens the maintenance hatch 10 of the substrate processing apparatus 1 from the exterior of the substrate processing apparatus 1 and the maintenance hatch 408A of the first polishing unit 400A, the operator becomes accessible to the notch polishing device 480A and can conduct maintenance operation of the notch polishing device 480A.
The notch polishing device 480B is disposed near the sidewall 406B, which faces the sidewall 3b of the substrate processing apparatus 1, in the second polishing unit 400B. The maintenance hatch 408B is provided in the sidewall 406B. The maintenance hatch 9 is also provided in the sidewall 3b at a position facing the sidewall 406B. Thus, when an operator opens the maintenance hatch 9 of the substrate processing apparatus 1 from the exterior of the substrate processing apparatus 1 and the maintenance hatch 408B of the second polishing unit 400B, the operator becomes accessible to the notch polishing device 480B and can conduct maintenance operation of the notch polishing device 480B.
The maintenance hatches 459 of the machine chambers 458 (see
Next, an arrangement of the primary cleaning unit 600 will be described below.
The cleaning members 602a and 602b are attached to the drive mechanisms 603a and 603b, respectively. The cleaning members 602a and 602b can be rotated about their axes and moved in a vertical direction by the drive mechanisms 603a and 603b, respectively. The cleaning members 602a and 602b can be moved downward and upward so as to be brought into contact with the upper and lower surfaces of the wafer W to be cleaned, respectively. When the wafer W is transferred into and from the primary cleaning unit 600, the cleaning members 602a and 602b can be retracted upward and downward, respectively. The primary cleaning unit 600 includes a chemical liquid supply nozzle 604 for supplying an etching liquid (chemical liquid) onto the upper surface (front face) of the wafer W, a cleaning liquid supply nozzle 605 for supplying a cleaning liquid (pure water) onto the upper surface (front face) of the wafer W, a chemical liquid supply nozzle 606 for supplying an etching liquid (chemical liquid) onto the lower surface (rear face) of the wafer W, and a cleaning liquid supply nozzle 607 for supplying a cleaning liquid onto the lower surface (rear face) of the wafer W.
A cleaning process of the primary cleaning unit 600 will be described. When a wafer W is transferred to the primary cleaning unit 600, the wafer W is held and rotated by the spindles 601. Simultaneously, the cleaning members 602a and 602b are moved downward and upward so that they are brought into contact with the upper and lower surfaces of the wafer W. At that state, while the cleaning members 602a and 602b are rotated, they are brought into sliding contact with the upper and lower surfaces of the wafer W. The cleaning liquid supply nozzles 605 and 607 supply cleaning liquids onto the upper and lower surfaces of the wafer W to scrub and clean the entire areas of the upper and lower surfaces of the wafer W.
After the scrubbing, the cleaning members 602a and 602b are retracted upward and downward. The chemical liquid supply nozzles 604 and 606 supply etching liquids onto the upper and lower surfaces of the wafer W to etch (chemically clean) the upper and lower surfaces of the wafer W. Thus, remaining metal ions are removed. At that time, the rotational speed of the spindles 601 to rotate the wafer W is varied as needed. Then, the cleaning liquid supply nozzles 605 and 607 supply cleaning liquids (pure water) onto the upper and lower surfaces of the wafer W to perform replacement with pure water for a predetermined period of time. Thus, the etching liquids are removed from the upper and lower surfaces of the wafer W. At that time, the rotational speed of the spindles 601 to rotate the wafer W is varied as needed.
Next, an arrangement of the secondary cleaning and drying unit 610 will be described below.
The pencil-type cleaning mechanism 614 has a swing arm 616 supported at an end thereof by a shaft 615, a rotational shaft 617 extending vertically downward from the other end thereof toward an upper surface of the wafer W being cleaned, and a cleaning member 618 attached to a lower end of the rotational shaft 617. For example, the cleaning member 618 may be formed of a porous PVF sponge. Alternatively, the cleaning member 618 may be made of polyurethane foam. The shaft 615 can be vertically moved and rotated by a drive mechanism (not shown). When the shaft 615 is rotated, the swing arm 616 is swung. The cleaning member 618 can be moved between a cleaning position at which the cleaning member 618 is brought into contact with the upper surface of the wafer W and a retracting position at which the cleaning member 618 is spaced from the upper surface of the wafer W. Further, the cleaning member 618 is rotated during cleaning by rotation of the rotational shaft 617. The cleaning liquid supply nozzle 619 is configured to supply a cleaning liquid onto the upper surface of the wafer W. The spin-dry unit 610 may include an additional cleaning liquid supply nozzle (not shown) disposed below the wafer W for supplying a cleaning liquid onto the lower surface of the wafer W.
A cleaning and drying process is performed in the secondary cleaning and drying unit 610 as follows. When a wafer W is introduced into the secondary cleaning and drying unit 610, the substrate holding and rotating mechanism 611 holds the wafer W and rotates the wafer W at a low speed of about 100 to 500 rpm. Then, while a cleaning liquid is supplied from the cleaning liquid supply nozzle 619 onto the upper surface of the wafer W, the swing arm 616 is swung over the entire upper surface of the wafer W. Thus, the rotating cleaning member 618 is brought into contact with the upper surface of the wafer W and moved to scrub and clean the wafer W. After completion of the scrubbing, the swing arm 616 is moved to a standby position. Then, the rotational speed of the substrate holding and rotating mechanism 611 is increased to rotate the wafer W at a high speed of about 1500 to 5000 rpm, thereby spin-drying the wafer W. At that time, a clean inert gas may be supplied from a gas supply nozzle (not shown) during spin-drying as needed. In the present example, the cleaning member 618 is used for scrubbing. However, instead of the above scrubbing process, pure water to which ultrasonic vibration has been applied may be supplied from the cleaning liquid supply nozzle 619 for non-contact cleaning to remove particles attached to the surface of the wafer W.
Next, process patterns of wafers in the substrate processing apparatus 1 will be described below.
The first process pattern is performed for serial processing in which the same wafer is polished sequentially in the first polishing unit 400A and the second polishing unit 400B. According to the serial processing, the first polishing unit 400A and the second polishing unit 400B can be used for respective purposes of polishing. For example, objects attached to a peripheral portion of a wafer or surface roughness of a wafer can be removed in the first polishing unit 400A, and then finish polishing can be conducted on the wafer in the second polishing unit 400B.
In a second process pattern (b), when a wafer cassette 102 is placed on the loading/unloading port 100, the first transfer robot 200A takes a wafer out of the wafer cassette 102 and transfers it to the measurement unit 310 or the wafer stage 300. If the wafer is transferred to the measurement unit 310, necessary data on the diameter of the wafer, the cross-sectional shape of a peripheral portion of the wafer, and the surface conditions of the wafer are measured before polishing. Then, the second transfer robot 200B transfers the wafer from the measurement unit 310 or the wafer stage 300 to the first polishing unit 400A. In the first polishing unit 400A, a peripheral portion (a bevel portion and a notch) of the wafer is polished. The second transfer robot 200B transfers the wafer polished in the first polishing unit 400A to the primary cleaning unit 600, where primary cleaning is conducted on the wafer. The second transfer robot 200B transfers the wafer cleaned in the primary cleaning unit 600 to the secondary cleaning and drying unit 610, where secondary cleaning and drying are conducted on the wafer. The dried wafer is transferred to the measurement unit 310 or the wafer stage 300 by the first or second transfer robot 200A or 200B and then returned to the wafer cassette 102 by the first transfer robot 200A. Alternatively, the dried wafer is returned from the secondary cleaning and drying unit 610 directly to the wafer cassette 102 by the first transfer robot 200A.
In a third process pattern (c), the second transfer robot 200B transfers the wafer to the second polishing unit 400B, instead of transferring the wafer from the measurement unit 310 or the wafer stage 300 to the first polishing unit 400A in the second process pattern (b). At that time, it is possible to conduct parallel processing. Specifically, while a wafer that has previously been transferred can be polished in the first polishing unit 400A according to the second process pattern (b), a next wafer can be transferred and polished in the second polishing unit 400B according to the third process pattern (c). According to parallel processing, in which different wafers are polished in parallel in the first polishing unit 400A and the second polishing unit 400B, the number of wafers processed per unit time can be increased to improve a throughput of the substrate processing apparatus 1. Thus, a rate of operation can be improved. When parallel processing is conducted, the polishing tapes having the same grain size are used in the first and second polishing units 400A and 400B. For example, such polishing tapes include a polishing tape having a grain size of #6000 to #8000.
In a fourth process pattern (d), the first transfer robot 200A takes a wafer out of the wafer cassette 102 and transfers it to the measurement unit 310 or the wafer stage 300. Then, the second transfer robot 200B transfers the wafer from the measurement unit 310 or the wafer stage 300 to the first polishing unit 400A. In the first polishing unit 400A, a peripheral portion (a bevel portion and a notch) of the wafer is polished. The second transfer robot 200B transfers the wafer polished in the first polishing unit 400A to the secondary cleaning and drying unit 610, where secondary cleaning and drying are conducted on the wafer. The dried wafer is transferred to the measurement unit 310 or the wafer stage 300 by the first or second transfer robot 200A or 200B and then returned to the wafer cassette 102 by the first transfer robot 200A. Alternatively, the dried wafer is returned from the secondary cleaning and drying unit 610 directly to the wafer cassette 102 by the first transfer robot 200A.
In a fifth process pattern (e), the second transfer robot 200B transfers the wafer to the second polishing unit 400B, instead of transferring the wafer from the measurement unit 310 or the wafer stage 300 to the first polishing unit 400A in the fourth process pattern (d). At that time, it is possible to conduct parallel processing. Specifically, while a wafer that has previously been transferred can be polished in the first polishing unit 400A according to the fourth process pattern (d), a next wafer can be transferred and polished in the second polishing unit 400B according to the fifth process pattern (e).
In a sixth process pattern (f), the first transfer robot 200A takes a wafer out of the wafer cassette 102 and transfers it to the measurement unit 310 or the wafer stage 300. Then, the second transfer robot 200B transfers the wafer to the primary cleaning unit 600, where primary cleaning is conducted on the wafer. The second transfer robot 200B transfers the wafer cleaned in the primary cleaning unit 600 to the secondary cleaning and drying unit 610, where secondary cleaning and drying are conducted on the wafer. The dried wafer is transferred to the measurement unit 310 or the wafer stage 300 by the first or second transfer robot 200A or 200B and then returned to the wafer cassette 102 by the first transfer robot 200A. Alternatively, the dried wafer is returned from the secondary cleaning and drying unit 610 directly to the wafer cassette 102 by the first transfer robot 200A.
In a seventh process pattern (g), the first transfer robot 200A takes a wafer out of the wafer cassette 102 and transfers it to the measurement unit 310 or the wafer stage 300. Then, the second transfer robot 200B transfers the wafer from the measurement unit 310 or the wafer stage 300 to the secondary cleaning and drying unit 610, where secondary cleaning and drying are conducted on the wafer. The dried wafer is transferred to the measurement unit 310 or the wafer stage 300 by the first or second transfer robot 200A or 200B and then returned to the wafer cassette 102 by the first transfer robot 200A. Alternatively, the dried wafer is returned from the secondary cleaning and drying unit 610 directly to the wafer cassette 102 by the first transfer robot 200A.
The substrate processing apparatus 1 can both conduct parallel processing and serial processing. The first and second polishing units 400A and 400B can be employed for the respective polishing purposes by properly selecting counts of polishing tapes used in the first and second polishing units 400A and 400B and operating conditions in the first and second polishing units 400A and 400B according to purposes of polishing wafers. Thus, optimal polishing processes can be performed on wafers. In the above process patterns, when the measurement unit 310 is occupied by a wafer that has previously been transferred, a next wafer may be placed temporarily on the wafer stage 300 for standby. In such a case, wafers can efficiently be transferred and processed.
When a wafer is measured twice, i.e., before and after polishing, even if the measurement unit 310 is occupied by a wafer measured before polishing, a wafer dried in the secondary cleaning and drying unit 610 can be placed temporarily on the wafer stage 300 for measurement after polishing because the substrate processing apparatus 1 has the wafer stage 300. Accordingly, the secondary cleaning and drying unit 610 can subsequently receive a next wafer and conduct secondary cleaning and drying on the next wafer. Thus, it is possible to improve a throughput of the substrate processing apparatus 1.
In the above process patterns, timing of transferring wafers may be adjusted depending upon required processing periods of time in the measurement unit 310, the first polishing unit 400A, the second polishing unit 400B, the primary cleaning unit 600, and the secondary cleaning and drying unit 610. In such a case, the wafers can smoothly be transferred and processed in the substrate processing apparatus 1 to further improve the throughput of the substrate processing apparatus 1.
Any shapes or materials that have not been directly described in the specification or illustrated in the drawings are encompassed by the scope of the present invention as long as they achieve the advantageous effects of the present invention. For example, in the above embodiments, the polishing unit includes the bevel polishing device and the notch polishing device for polishing a peripheral portion of a wafer. However, the substrate processing apparatus may have a chemical mechanical polishing (CMP) unit for pressing a surface of a wafer against a polishing surface of a polishing table onto which a polishing liquid is supplied. Further, in the above embodiments, the substrate processing apparatus has two polishing units. However, the substrate processing apparatus may have three or more polishing units.
Although certain preferred embodiments of the present invention have been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.
The present invention is suitable for use in a substrate processing apparatus having a polishing unit for polishing a peripheral portion of a substrate such as a semiconductor wafer.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-121680 | Apr 2005 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2006/308493 | 4/18/2006 | WO | 00 | 8/27/2008 |
