The present invention relates to a substrate processing apparatus, a substrate processing method, and a storage medium storing a program causing a computer to perform the method for controlling a substrate processing apparatus.
In recent years, devices such as a memory circuit, a logic circuit and an image sensor (e.g., CMOS sensor) have been more highly integrated. During fabrication of these devices, foreign materials such as particulates and dust may adhere to the device. Foreign materials adhered to the device may cause a short circuit between wires or a failure of the circuit. Therefore, in order to improve reliability of the device, it is required to clean the wafer on which the device is fabricated to remove foreign materials on the wafer.
The above foreign materials such as particulates and dust may also adhere to the back surface (non-device surface) of the wafer. Adhesion of these foreign materials on the back surface of the wafer may cause the wafer to be separated from a reference plane of the stage of an exposure device or may cause the front surface of the wafer to be inclined relative to the reference plane of the stage. This results in a patterning deviation or a deviation of a focal distance. To prevent these problems, foreign materials adhered to the back surface of the wafer need to be removed after a resist is applied to the front surface (device surface) of the wafer and before an exposure process is performed on the front surface.
A patterning device using nano-imprinting technology has recently been developed, besides one using optical exposure technology. The nano-imprinting technology is a technology in which a patterning die is pressed against a resin material applied to the wafer and thereby a wiring pattern is transferred. The nano-imprinting technology requires removal of foreign materials present on the front surface of the wafer in order to prevent dirt from being transferred between the die and the wafer and between the wafers.
PTL 1 discloses a substrate processing apparatus that removes foreign materials adhered to the front surface and/or the back surface of the wafer by sliding a scrubber including abrasive grains, a polishing tape or the like on the rotating wafer.
PTL 1: Japanese Patent Laid-Open No. 2013-172019
However, polishing the substrate with a relatively large polishing head alone may result in local areas of the substrate being insufficiently polished. For example, an outer periphery of the substrate contacts a polishing tool of the polishing head for a shorter time than a central part of the substrate, and thus the outer periphery tends to have a lower polishing rate. This variation in the polishing rate may decrease in-plane uniformity of the substrate and affect an exposure process. An object of the present invention is to solve at least a part of the above problems.
According to an aspect of the present invention, a substrate processing apparatus includes: a first polishing head configured to polish a first surface of a substrate by sliding a polishing tool on the first surface; a second polishing head configured to polish the first surface of the substrate by sliding a polishing tool on the first surface, the second polishing head having a smaller diameter than a diameter of the first polishing head; and a substrate support mechanism configured to support the substrate by a fluid pressure at positions corresponding to the first polishing head and the second polishing head from a second surface of the substrate opposite to the first surface.
According to another aspect of the present invention, a substrate processing apparatus includes: a substrate holding mechanism configured to hold and rotate a substrate, the substrate holding mechanism including plural rollers configured to be able to contact a periphery of the substrate, each roller being configured to be rotatable about an axis thereof; a first polishing head configured to polish a first surface of the substrate by sliding a polishing tool on the first surface; and a second polishing head configured to polish the first surface of the substrate by sliding a polishing tool on the first surface, the second polishing head having a smaller diameter than a diameter of the first polishing head.
Each front load unit 3 is configured to be able to mount one or more wafer cassettes each storing plural wafers. Examples of the wafer cassette include an open cassette, a standard manufacturing interface (SMIF) pod and a front opening unified pod (FOUP). The first transport robot 4 takes a wafer out of the wafer cassette mounted on the front load unit 3 and places the wafer on the wafer station 5.
The wafer station 5 includes a wafer inverter (not shown in the figure) that inverts the wafer placed by the first transport robot 4 upside-down. The second transport robot 6 takes the inverted wafer (in a face-down state) out of the wafer station 5 and transports the wafer to the polishing unit 8 or the polishing unit 9. As will be described later, each of the polishing unit 8 and the polishing unit 9 includes a substrate holding mechanism and a polishing head. The substrate holding mechanism holds and rotates the wafer. The polishing head includes a polishing tool. Each of the polishing unit 8 and the polishing unit 9 is a so-called back surface polishing apparatus, which rotates the wafer by the substrate holding mechanism and polishes the back surface (facing upward) of the water with the polishing tool of the polishing head. Here, explanation will be given of the case where both of the polishing unit 8 and the polishing unit 9 are back surface polishing apparatuses. The wafer taken out of the wafer cassette undergoes a back surface polishing process by either of the two polishing units. Thereafter, the wafer is cleaned, dried and returned to the wafer cassette. In another embodiment, one of the polishing units may be a back surface polishing apparatus and the other of the polishing units may be a bevel polishing apparatus or an apparatus for polishing an outer peripheral area of the wafer. In this case, the wafer undergoes a polishing process by one of the polishing units first and then by the other of the polishing units, and is then cleaned and dried.
The second transport robot 6 places the wafer having undergone the process by the polishing unit 8 or the polishing unit 9 on the wafer station 7. The third transport robot 10 takes the polished wafer out of the wafer station 7 and transports the wafer to the cleaning unit 11. The cleaning unit 11 performs a cleaning process on the polished wafer. In one embodiment, the cleaning unit 11 includes an upper roll sponge and a lower roll sponge arranged so as to sandwich the wafer in-between and cleans both surfaces of the wafer with these sponges while supplying a cleaning liquid to both surfaces of the wafer.
The fourth transport robot 12 takes out the wafer cleaned by the cleaning unit 11 and transports the wafer to the drying unit 13. The drying unit 13 dries the cleaned wafer. In one embodiment, the drying unit 13 spin-dries the wafer by rotating the wafer around an axis of the wafer at a high speed. Then, the dried wafer is taken out by the first transport robot 4 and returned to the wafer cassette.
The controlling device 14 controls operations of each unit of the above-described substrate processing system 1. The controlling device 14 includes a memory storing various setting data and various programs and a CPU executing the programs stored in the memory. A storage medium as the memory may include a volatile storage medium and/or a non-volatile storage medium. The storage medium may include one or more of any storage media such as a ROM, a RAM, a hard disk, a CD-ROM, a DVD-ROM and a flexible disk. The programs stored in the memory may include a program for controlling the transportation by each transport robot, a program for controlling the polishing process by each polishing unit, a program for controlling the cleaning process by the cleaning unit and a program for controlling the drying process by the drying unit. Also, the controlling device 14 is configured to be able to communicate with a host controller (not shown in the figure) that totally controls the substrate processing system 1 and other related apparatuses and to be able to exchange data with a database held by the host controller.
The polishing head 21 has a larger diameter than a radius of the wafer W. One or more polishing tapes each as a polishing tool is attached to a bottom surface (a side contacting the wafer) of the polishing head 21. For example, three polishing tapes are radially arranged on the bottom surface of the polishing head 21. Both ends of the polishing tape is held by two reels (not shown in the figure) disposed in the polishing head 21, and a lower surface of the polishing tape stretching between the two reels can contact the wafer surface. Note that the polishing tool may be any other polishing tool such as a pad containing abrasive grains and fixed abrasive grains. The polishing head 21 is rotatably held by one end of a swing arm 22. The polishing head 21 is rotated by a head rotation mechanism (not shown in the figure) provided at the one end of the swing arm 22. The other end of the swing arm 22 is connected to a swing shaft (not shown in the figure). The swing shaft is rotated by rotation of a shaft rotation mechanism (not shown in the figure), whereby the swing arm 22 is caused to swing (for example, from the state shown in
The polishing head 23 has a smaller diameter than the diameter of the polishing head 21. One or more polishing tapes each as a polishing tool is attached to a bottom surface (a side contact the wafer) of the polishing head 23. For example, three polishing tapes are radially arranged on the bottom surface of the polishing head 23. Both ends of the polishing tape is held by two reels (not shown in the figure) disposed in the polishing head 23, and a lower surface of the polishing tape stretching between the two reels can contact the wafer surface. Note that the polishing tool may be any other polishing tool such as a pad containing abrasive grains and fixed abrasive grains. The polishing head 23 is rotatably held by one end of a swing arm 24. The polishing head 23 is rotated by a head rotation mechanism (not shown in the figure) provided at the one end of the swing arm 24. The other end of the swing arm 24 is connected to a swing shaft (not shown in the figure). The swing shaft is rotated by rotation of a shaft rotation mechanism (not shown in the figure), whereby the swing arm 24 is caused to swing. Swinging of the swing arm 24 causes the polishing head 23 to swing between the retracted position (
Further, a polishing surface (the back surface in the present embodiment) of the wafer W is supplied with a polishing liquid or pure water by a nozzle (not shown in the figure).
One reason for using the polishing head 23 with a relatively smaller diameter in addition to the polishing head 21 with a relatively larger diameter is as follows. The polishing head 21 contacts the outer periphery of the wafer W for a short period of time, which leads to a relatively lower polishing rate of the outer periphery. For this reason, the polishing head 23 with the smaller diameter supplementarily polishes the outer periphery of the wafer W. This additional polishing of the outer periphery of the wafer W by the polishing head 23, which may be made either at the same time as or after the polishing by the polishing head 21, makes the polishing amount of the back surface of the wafer W more uniform. This can improve the in-plane uniformity of the back surface of the wafer W after the polishing process.
The static pressure support mechanism 30 includes a static pressure plate 31 and a static pressure plate 33. The static pressure plate 31 is provided corresponding to the polishing head 21. The static pressure plate 31 is slightly larger than the diameter of the polishing head 21, and configured and disposed so as to be able to cover the entire polishing head 21 in a plan view. The static pressure plate 31 includes a support surface 32 on a side facing the wafer W and is disposed with a slight gap between the support surface 32 and the front surface of the wafer W. The static pressure plate 31 includes a fluid supply passage, which will be described later, and a fluid (either liquid or gas, e.g., pure water) is supplied to the support surface 32 via the fluid supply passage. With this fluid, the static pressure plate 31 supports the front surface of the wafer W in a non-contact manner.
The static pressure plate 33 is provided corresponding to the polishing head 23. The static pressure plate 33 is slightly larger than the diameter of the polishing head 23, and configured and disposed so as to be able to cover the entire polishing head 23 in a plan view. The static pressure plate 33 includes a support surface 34 on a side facing the wafer W and is disposed with a slight gap between the support surface 34 and the front surface of the wafer W. The static pressure plate 33 includes a fluid supply passage, which will be described later, and a fluid (either liquid or gas, e.g., pure water) is supplied to the support surface 34 via the fluid supply passage. With this fluid, the static pressure plate 33 supports the front surface of the wafer W in a non-contact manner.
In the example shown in
As described above, the polishing head 23 is caused to swing by rotation of the swing arm 24 about the swing shaft. Also, the static pressure plate 33 follows the swing of the polishing head 23. That is, along with the movement of the polishing head 23, the static pressure plate 33 moves so as to always cover the polishing head 23 in a plan view.
In the present embodiment, the static pressure plate 31 is movable between a position corresponding to the polishing head 21 and a position corresponding to the polishing head 23. As described above, when at the position corresponding to the polishing head 21, the static pressure plate 31 covers the polishing head 21 in a plan view. Further, when at the position corresponding to the polishing head 23, the static pressure plate 31 covers the polishing head 23 in a plan view. From the size relationship between the polishing head 21 and the polishing head 23, the static pressure plate 31, which corresponds to the polishing head 21 with the larger diameter, is sufficiently larger than the polishing head 23. The moving mechanism of the polishing head 23 may be the same as that explained in the second embodiment for reciprocating the static pressure plate 33. That is, the moving mechanism may be any driving mechanism such as a motor and a ball screw mechanism, a rack-and-pinion mechanism, an air cylinder and a solenoid. In the present embodiment, polishing by the polishing head 23 is made after polishing by the polishing head 21 is finished. Alternatively, this order of polishing may be inverted. At the time of polishing by the polishing head 21, the static pressure plate 31 is situated at the position corresponding to (facing) the polishing head 21. The polishing head 21 performs polishing while the load from the polishing head 21 is received by the static pressure plate 31. Then, at the time of polishing by the polishing head 23, the static pressure plate 31 is moved by the moving mechanism to the position corresponding to (facing) the polishing head 23. The polishing head 23 performs polishing while the load from the polishing head 23 is received by the static pressure plate 31.
The static pressure plate 50 is connected to two fluid supply lines 53, 54, which are respectively provided with flow rate control valves 55, 56. The flow rate is controlled by the flow rate control valves 55, 56 based on signals from the controlling device 14. Further, the fluid supply lines 53, 54 are connected to a fluid supply source 57 and supplied with a pressure fluid (either liquid or gas) by the fluid supply source 57. The liquid is, for example, DIW (pure water).
As shown in
In the case where the polishing head 23 with the smaller diameter is configured to swing, the fluid ejection ports 32c may be formed in plural areas A1, A2 and A3 as shown in
In the case of using the substrate holding mechanism of this configuration, the polishing head and the static pressure plate are set to be shaped and placed so as to avoid the plural rollers 2-11, which are at fixed positions. This keeps the polishing head and the static pressure plate from interfering with the chucks (rollers) during rotation of the wafer W. Accordingly, the polishing head and the static pressure plate can be placed so as to reach the outer periphery of the wafer W or to extend radially outward beyond the outer periphery of the wafer W.
From the above embodiments, at least the following technical ideas can be grasped.
According to a first aspect, a substrate processing apparatus is provided that includes: a first polishing head configured to polish a first surface of a substrate by sliding a first polishing tool on the first surface; a second polishing head configured to polish the first surface of the substrate by sliding a second polishing tool on the first surface, the second polishing head having a smaller diameter than a diameter of the first polishing head; and a substrate support mechanism configured to support the substrate by a fluid pressure at positions corresponding to the first polishing head and the second polishing head from a second surface of the substrate opposite to the first surface.
According to the first aspect, the first polishing head polishes the entire first surface of the substrate, and the second polishing head, which has a smaller diameter than the first polishing head, supplementarily polishes the portions with a lower polishing rate on the first surface of the substrate. This allows the substrate to be uniformly polished. Further, the substrate is supported from the second surface of the substrate at positions corresponding to the first polishing head and the second polishing head. This allows the substrate to be supported from the opposite side of the substrate in an appropriate range according to a pressing force by the first polishing head and the second polishing head. Accordingly, this can prevent an unnecessary supporting force from being applied to the substrate at areas other than those corresponding to the first and the second polishing heads. This can further reduce the amount of fluid used.
According to a second aspect, in the substrate processing apparatus of the first aspect, the substrate support mechanism includes: a first static pressure plate configured to support the substrate at the position corresponding to the first polishing head; and a second static pressure plate configured to support the substrate at the position corresponding to the second polishing head.
According to the second aspect, the first and the second static pressure plates are provided respectively corresponding to the first and the second polishing heads. This allows the substrate to be supported, with a simple configuration, from the opposite side of the substrate in an appropriate range according to the pressing force by the first polishing head and the second polishing head.
According to a third aspect, in the substrate processing apparatus of the second aspect, the second polishing head is configured to polish the substrate while swinging during a polishing process, and the second static pressure plate is configured to be able to move so as to follow the second polishing head. For example, the substrate processing apparatus may further comprise: a second arm configured to move the second polishing head; a movable mechanism provided in the substrate support mechanism and configured to move the second static pressure plate; and a controller configured to control the second arm and the movable mechanism such that the second static pressure plate follows the second polishing head.
According to the third aspect, swinging of the second polishing head with the smaller diameter allows to further improve a polishing rate of the portions on the substrate with a lower polishing rate. As a result, this can shorten the polishing time. Further, the second static pressure plate is configured to move so as to follow the second polishing head, and this allows the second static pressure plate to appropriately support the substrate at the area where the second polishing head is pressed against the substrate.
According to a fourth aspect, in the substrate processing apparatus of the first aspect, the substrate support mechanism includes a static pressure plate configured to be movable between an area corresponding to the first polishing head and an area corresponding to the second polishing head. For example, the substrate support mechanism may include: a static pressure plate; and a movable mechanism configured to move the static pressure plate between an area corresponding to the first polishing head and an area corresponding to the second polishing head.
According to the fourth aspect, use of one common static pressure plate enables to support the substrate at the position corresponding to the first polishing head and at the position corresponding to the second polishing head.
According to a fifth aspect, in the substrate processing apparatus of the first aspect, the substrate support mechanism includes: a static pressure plate configured to support the substrate at the positions corresponding to the first polishing head and the second polishing head; a first fluid line configured to supply a fluid to an area on the static pressure plate corresponding to the first polishing head; and a second fluid line configured to supply a fluid to an area on the static pressure plate corresponding to the second polishing head.
According to the fifth aspect, the fluid is supplied from the first and the second lines to the areas respectively corresponding to the first and the second polishing heads. This allows the substrate to be supported at the position corresponding to the first polishing head and at the position corresponding to the second polishing head in an appropriate range, without moving the common static pressure plate.
According to a sixth aspect, in the substrate processing apparatus of the fifth aspect, the second polishing head is configured to polish the substrate while swinging during a polishing process, and the static pressure plate is configured to allow a position at which the fluid is supplied onto the second surface of the substrate to be changed so as to follow the second polishing head. For example, the substrate processing apparatus may further comprise: a second arm configured to move the second polishing head; a plurality of the second fluid line provided in the substrate support mechanism and connected with a plurality of positions on the static pressure plate within a range in which the second polishing head is moved; and a controller configured to control an amount of the fluid to be supplied through each second fluid line, thereby to change positions on the static pressure plate to which the fluid is supplied follows the second polishing head.
According to the sixth aspect, swinging of the second polishing head with the smaller diameter allows a polishing rate of the portions on the substrate with a lower polishing rate to further improve. As a result, this can shorten the polishing time. Further, the position onto which the fluid is supplied moves so as to follow the second polishing head. This allows the fluid to appropriately support the substrate at the area where the second polishing head is pressed against the substrate.
According to a seventh aspect, in the substrate processing apparatus of any one of the first to the sixth aspects, the second polishing head is arranged to polish the substrate at a position outside of the first polishing head in a radial direction of the substrate.
According to the seventh aspect, the outer periphery of the substrate, which tends to have a lower polishing rate, is supplementarily polished. This can improve the in-plane uniformity of the substrate after polishing.
According to an eighth aspect, in the substrate processing apparatus of any one of the first to the seventh aspects, the substrate processing apparatus includes a back surface polishing apparatus, the first surface of the substrate is a surface on which no device is formed, and the polishing process is performed after a resist is applied to the second surface of the substrate and before an exposure process is performed.
According to the eighth aspect, the in-plane uniformity of the non-device surface is prevented from affecting an exposure process on the device surface, which is performed later.
According to a ninth aspect, a substrate processing apparatus is provided that includes: a substrate holding mechanism configured to hold and rotate a substrate, the substrate holding mechanism including plural rollers configured to be able to contact a periphery of the substrate, each roller being configured to be rotatable about an axis thereof; a first polishing head configured to polish a first surface of the substrate by sliding a first polishing tool on the first surface; and a second polishing head configured to polish the first surface of the substrate by sliding a second polishing tool on the first surface, the second polishing head having a smaller diameter than a diameter of the first polishing head.
According to the ninth aspect, the rollers holding the substrate do not rotate with the substrate. This allows the polishing head to be disposed at the edge portion of the substrate or radially outside of the substrate, which in turn allows the edge portion of the substrate to be polished. Further, the first polishing head polishes the entire substrate, and the second polishing head, which has a smaller diameter than the first polishing head, supplementarily polishes the portions of the substrate with a lower polishing rate. This allows the substrate to be uniformly polished.
According to a tenth aspect, a substrate polishing method is provided that includes: polishing a first surface of a substrate by sliding a first polishing tool of a first polishing head on the first surface of the substrate and by sliding a second polishing tool of a second polishing head on the first surface of the substrate, the second polishing head having a smaller diameter than a diameter of the first polishing head; and supporting the substrate from a second surface of the substrate at positions corresponding to the first polishing head and the second polishing head, the second surface being opposite to the first surface.
The tenth aspect produces the same functions and effects as the first aspect.
According to an eleventh aspect, the substrate processing apparatus method according to tenth aspect, wherein the first surface of the substrate is a surface on which no device is formed, and the polishing process is performed after a resist is applied to the second surface of the substrate and before an exposure process is performed.
According to a twelfth aspect, a substrate polishing method is provided that includes: rotating a substrate by bringing plural rollers into contact with a periphery of the substrate and rotating each roller about an axis thereof; and polishing, during rotation of the substrate, a first surface of the substrate with a first polishing head and a second polishing head, the second polishing head having a smaller diameter than a diameter of the first polishing head.
The twelfth aspect produces the same functions and effects as the ninth aspect.
According to an thirteenth aspect, the substrate processing apparatus method according to twelfth aspect, wherein the first surface of the substrate is a surface on which no device is formed, and the polishing process is performed after a resist is applied to the second surface of the substrate and before an exposure process is performed.
According to a fourteenth aspect, a non-volatile storage medium storing a program causing a computer to perform a method for controlling a substrate processing apparatus is provided, and the method includes: polishing a first surface of a substrate by sliding a first polishing tool of a first polishing head on the first surface of the substrate and by sliding a second polishing tool of a second polishing head on the first surface of the substrate, the second polishing head having a smaller diameter than a diameter of the first polishing head; and supporting, during the polishing, the substrate from a second surface of the substrate at positions corresponding to the first polishing head and the second polishing head, the second surface being opposite to the first surface.
The twelfth aspect produces the same functions and effects as the first aspect.
According to a fifteenth aspect, a non-volatile storage medium storing a program causing a computer to perform a method for controlling a substrate processing apparatus is provided, and the method includes: rotating a substrate by bringing plural rollers into contact with a periphery of the substrate and rotating each roller about an axis thereof; and polishing, during rotation of the substrate, a first surface of the substrate with a first polishing head and a second polishing head, the second polishing head having a smaller diameter than a diameter of the first polishing head.
The thirteenth aspect produces the same functions and effects as the ninth aspect.
The embodiments of the present invention has been explained based on several examples. However, the above embodiments have been given to provide understanding of the present invention and is not intended to restrict the present invention to the embodiments. It will be readily understood that any modifications or improvements may be made to the present invention without departing from the scope of the present invention and that the present invention may include its equivalents. Also, elements disclosed in the claims and the specification may be freely combined or omitted as long as at least some of the above-described problems may be solved or at least some of the above-described advantageous effects may be produced.
The present application claims priority to Japanese Patent Application No. 2017-244060 filed on Dec. 20, 2017. The entire disclosure of Japanese Patent Application No. 2017-244060 filed on Dec. 20, 2017 including specification, claims, drawings and summary is incorporated herein by reference in its entirety.
The entire disclosure of Japanese Patent Publication No. 2013-172019 (Patent Literature 1), including specification, claims, drawings and summary is incorporated herein by reference in its entirety.
Number | Date | Country | Kind |
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2017-244060 | Dec 2017 | JP | national |