Patent Application
20050236268
1. Field of the Invention
The present invention relates to a substrate processing apparatus having a plating apparatus for plating a substrate, and more particularly to a substrate processing apparatus having a plating apparatus for plating a substrate, such as a semiconductor wafer, a glass substrate, or an interposer, to form interconnections, such as large scale integrated circuits (LSI) or plugs, in a surface of the substrate. The present invention is particularly effective in reducing defects in interconnections which would be caused by a plating process.
2. Description of the Related Art
Materials for interconnections such as LSI have changed from aluminum-based materials to copper-based materials. Accordingly, there has been a growing tendency to employ a plating process to form interconnections instead of a dry process such as chemical vapor deposition (CVD) or physical vapor deposition (PVD). Thus, plating apparatuses for performing such a plating process have increasingly been required to have various additional functions. Specifically, plating apparatuses have been required to perform additional processes including an annealing process for heating a plated film to grow grains (crystal grains) and promote stabilization, an etching process for reducing steps on a surface of a plated film, a polishing process for grinding or polishing a surface of a plated film, an inspection process for measuring the film thickness of a plated film or detecting defects of a plated film, and the like. Particularly, an annealing process immediately after deposition of a copper plated film has been widely employed to uniformly grow and stabilize grains of the copper plated film so as to uniformize the size of the grains and reduce the resistivity of the plated film.
In the conventional substrate processing apparatus, substrate storage containers 806 are moved between the plating apparatus 810 and the annealing apparatus 800 to transfer substrates between the plating apparatus 810 and the annealing apparatus 800. Accordingly, it is difficult to maintain a constant standby time of substrates between the plating apparatus 810 and the annealing apparatus 800. Changes of the standby time may cause variations in size of resultant grains over surfaces of substrates and thus inhibit homogeneity of a plated film. Further, in the conventional substrate processing apparatus, the annealing apparatus 800 needs to be provided separately from the plating apparatus 810.
Recently, as shown in
Unlike the substrate processing apparatus shown in
Recently, porous organic materials such as a low-k material have been employed for interlayer dielectrics. Accordingly, technical issues that cannot be solved by the integration of the apparatus have newly arisen. When a low-k material is subjected to heating or application of an electron beam, bonding between molecules is strengthened so as to reduce its volume. Specifically, the low-k material is cured. Thus, stress concentration may be caused at an interface between a plated film and an underlying layer so as to greatly reduce the reliability of the plated film.
Further, when a plating process is employed to form LSI interconnections at 65 nm node or smaller node (interconnection width of 100 nm or less), thermal hysteresis (thermal budget) applied to interconnections may be reduced so that grains further grow even after compulsory annealing. This phenomenon is considered to be affected by the fact that a low-k material has a thermal conductivity lower than conventional materials for insulating films.
In order to avoid the above problems, an annealing process should be performed for a longer period of time. Accordingly, a throughput of the plating apparatus is considerably lowered by the annealing process. Thus, there has been desired a substrate processing apparatus which can perform an additional process such as an annealing process in addition to a plating process without lowering a throughput of the apparatus.
Further, there have been pointed out other problems such as formation of native oxides or organic contamination on a surface of a plating feed layer (seed layer). These problems depend on standby times from a pre-plating process to a plating process or conditions under which substrates are stored.
The substrate transfer device 842 takes out a substrate (e.g., semiconductor wafer) from one of the substrate storage containers 806 and sequentially introduces it into each plating unit 812 to perform a plating process on the substrate. Then, the substrate transfer device 842 takes out the substrate having a plated film formed thereon from the plating unit 812 and transfers it to the etching and cleaning unit 814. In the etching and cleaning unit 814, an etching process, a cleaning process, and a drying process are performed on the substrate. The substrate transfer device 842 takes out the dried substrate from the etching and cleaning unit 814 and returns it to the other of the substrate storage containers 806.
As shown in
In a conventional copper plating process, a copper seed layer is formed by sputtering, chemical vapor deposition (CVD), atomic layer deposition (ALD), or electroless plating. A copper seed layer becomes thinner year by year as the size of interconnections becomes smaller. The thickness of a copper seed layer to form a device of 65-nm generation is around 600 angstroms in a substrate field. The thickness of a copper seed layer to form a device of 45-nm generation is expected to be less than 500 angstroms.
As a method of forming copper interconnections, there is employed a method of plating a substrate with copper sulfate to form copper interconnections on a thin copper seed layer. Then, copper crystal is grown and stabilized by heating. An excessive copper film is polished and removed by chemical mechanical polishing (CMP). Generally, copper interconnections thus formed are multilayered so as to have at least 10 layers for the purpose of manufacturing LSI.
As interconnections become finer, defects of copper interconnections become more problematic. For example, the term “defects” means a state in which portions of copper interconnections lacks, a state in which abnormal plating deposition is caused at portions of copper interconnections so as to produce irregularities on surfaces of the copper interconnections, or singular points at which voids are likely to be generated by a heating process after a plating process. Some defects may be produced by deficiency of processes other than a plating process. However, defects resulting from a plating process tend to increase according to progress of scaledown of interconnections. Such defects considerably inhibit improvement of a yield of products.
It is considered that one of reasons why defects are produced is adsorption of volatile substances (e.g., organic solvent such as benzene, toluene, xylene, or amine, alkali such as ammonia, and lower organic acid) on a surface of a substrate.
Further, an LSI fabrication process is performed in a clean room, which is extremely cleaned. However, recent progress of local cleaning technology including front opening unified pods (FOUP), standard manufacturing interface pods (SMIF), and E-cube allows cleanliness of a clean room to be lower than ten years ago. This is because a clean room requires a large amount of investment. Such a change of specification has an influence on increase of defects.
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 can perform an additional process in addition to a plating process without lowering a throughput of the apparatus and can upgrade the additional process at a low cost.
A second object of the present invention is to provide a substrate processing apparatus which can effectively reduce interconnection defects caused by plating.
According to a first aspect of the present invention, there is provided a substrate processing apparatus which can perform an additional process in addition to a plating process without lowering a throughput of the apparatus and can upgrade the additional process at a low cost. The substrate processing apparatus has a plating apparatus configured to plate a substrate so as to deposit a metal on a surface of the substrate and an additional process apparatus configured to perform an additional process on the substrate. The plating apparatus has a substrate placement stage on which the substrate to be transferred to the additional process apparatus is placed. The additional process apparatus has an additional process unit configured to perform the additional process on the substrate and a substrate transfer device operable to transfer the substrate between the substrate placement stage of the plating apparatus and the additional process unit.
According to a second aspect of the present invention, there is provided a substrate processing apparatus which can perform an additional process in addition to a plating process without lowering a throughput of the apparatus and can upgrade the additional process at a low cost. The substrate processing apparatus has a plating apparatus configured to plate a substrate and an additional process apparatus configured to perform an additional process on the substrate. The additional process apparatus is disposed adjacent to the plating apparatus. The plating apparatus has a plating unit configured to plate the substrate so as to deposit a metal on a surface of the substrate, a first substrate transfer device operable to transfer the substrate in the plating apparatus, and a substrate placement stage on which the substrate to be transferred to the additional process apparatus is placed. The additional process apparatus has an additional process unit configured to perform the additional process on the substrate and a second substrate transfer device operable to transfer the substrate between the substrate placement stage of the plating apparatus and the additional process unit.
The plating apparatus and the additional process apparatus may be disposed independently of each other. The additional process unit may comprise an annealing unit configured to heat the substrate, a cleaning unit configured to clean the substrate, an etching unit configured to etch the substrate, a polishing unit configured to polish the substrate, or a film thickness measurement unit configured to measure a film thickness of the metal film formed on the surface of the substrate. The plating apparatus may be configured to fill fine recesses formed in the substrate with the metal. The metal may contain at least one of copper, cobalt, nickel, gold, and tin.
According to a third aspect of the present invention, there is provided a substrate processing apparatus which can perform an additional process in addition to a plating process without lowering a throughput of the apparatus and can upgrade the additional process at a low cost. The substrate processing apparatus has a main process apparatus configured to perform a main process on a substrate and an additional process apparatus configured to perform an additional process on the substrate. The main process apparatus has a substrate placement stage on which the substrate to be transferred to the additional process apparatus is placed. The additional process apparatus has an additional process unit configured to perform the additional process on the substrate and a substrate transfer device operable to transfer the substrate between the substrate placement stage of the main process apparatus and the additional process unit.
Since the substrate is transferred between the plating apparatus and the additional process apparatus by the second substrate transfer device of the additional process apparatus, the substrate processing apparatus can perform an additional process in addition to a plating process without lowering a throughput of the apparatus. Further, when the plating apparatus and the additional process apparatus are disposed independently of each other, the additional process apparatus can be upgraded at low cost as needed. For example, with regard to an annealing process, only an annealing unit as the additional process apparatus can be retrofitted or upgraded as needed. Further, when a heating mechanism in the annealing unit is to be changed from a hot plate to other mechanisms such as a lamp, an induction heater, an infrared heater, or an electron beam applicator, a conventional substrate processing apparatus should be modified as a whole. However, according to the present invention, only an annealing unit can be replaced. Thus, it is possible to remarkably reduce cost and labor for upgrade.
According to a fourth aspect of the present invention, there is provided a substrate processing apparatus which can effectively reduce interconnection defects caused by plating. The substrate processing apparatus has a plating unit configured to plate a substrate so as to deposit a metal on a surface of the substrate, a cleaning and drying unit configured to clean and dry the substrate, and a substrate transfer device operable to transfer the substrate between the plating unit and the cleaning and drying unit. The substrate processing apparatus also has an air supply system configured to supply at least one of intake air and circulation air into the substrate processing apparatus and a volatile substance removal mechanism configured to remove a volatile substance contained in the at least one of intake air and circulation air to be supplied by the air supply system.
Since the volatile substance contained in the at least one of intake air and circulation air is removed, the volatile substance is prevented from being adsorbed on the surface of the substrate in the substrate processing apparatus. Thus, defects are prevented from being caused by plating. Accordingly, it is possible to reduce defects resulting from a plating process with a small amount of investment. Further, a yield of LSI products can be improved so as to contribute to a low-cost production.
The volatile substance removal mechanism may comprise a chemical filter capable of removing the volatile substance contained in the at least one of intake air and circulation air. When the volatile substance removal mechanism comprises such a chemical filter, the volatile substance can effectively be captured and removed by the chemical filter. Accordingly, defects can be reduced more effectively.
In this case, the chemical filter may be provided at an upper portion of the substrate processing apparatus. When the chemical filter is provided at an upper portion of the substrate processing apparatus, air from which the volatile substance has been removed flows into the substrate processing apparatus to form a downflow. Thus, it is possible to suitably form the downflow, which is required in the substrate processing apparatus.
It is desirable that the chemical filter comprises at least one of activated carbon, zeolite, a polymer membrane, polymer fiber, and non-woven fabric, or a member chemically modified by at least one of activated carbon, zeolite, a polymer membrane, polymer fiber, and non-woven fabric. In this case, the chemical filter can efficiently capture and remove a volatile substance including basic gases such as ammonia and trimethylamine, acid gases such as SOx, NOx, and chlorine, and organic gases such as xylene, toluene, benzene, and siloxane. Particularly, it is possible to capture and remove organic gases such as toluene and xylene that are considered to be likely to cause and promote plating defects.
The volatile substance removal mechanism may comprise a combination filter including a chemical filter capable of removing the volatile substance contained in the at least one of intake air and circulation air and a particulate removal filter capable of removing fine particles in the at least one of intake air and circulation air. In this case, the volatile substance removal mechanism has functions of removing not only volatile substances but also fine particles in the intake air and/or the circulation air. Accordingly, it is possible to reduce defects more effectively.
Alternatively, the volatile substance removal mechanism may comprise a scrubber operable to clean the at least one of intake air and circulation air. For example, when air to be introduced into the substrate processing apparatus is supplied to the scrubber, a volatile substance in the air is adsorbed in an adsorbing solution. Thus, since air containing no volatile substances is introduced into the substrate processing apparatus, defects are prevented from being produced on the substrate.
The volatile substance removal mechanism may comprise a heating furnace operable to pyrolyze the volatile substance contained in the at least one of intake air and circulation air. For example, when air to be introduced into the substrate processing apparatus is supplied to the heating furnace, a volatile substance in the air is pyrolyzed in the heating furnace. Thus, since air containing no volatile substances is introduced into the substrate processing apparatus, defects are prevented from being produced on the substrate.
According to a fifth aspect of the present invention, there is provided a substrate processing apparatus which can effectively reduce interconnection defects caused by plating. The substrate processing apparatus has a plating unit configured to plate a substrate so as to deposit a metal on a surface of the substrate, a cleaning and drying unit configured to clean and dry the substrate, and a substrate transfer device operable to transfer the substrate between the plating unit and the cleaning and drying unit. The substrate processing apparatus also has a pressure controller operable to control a pressure of an interior of the substrate processing apparatus so as to be lower than a pressure of an exterior of the substrate processing apparatus and control pressures of interiors of the plating unit and the cleaning and drying unit so as to be lower than the pressure of the interior of the substrate processing apparatus.
Thus, the pressure of the interior of the substrate processing apparatus is set to be lower than the pressure of the exterior of the substrate processing apparatus. The pressures of the interiors of the plating unit and the cleaning and drying unit are set to be lower than the pressure of the interior of the substrate processing apparatus. Accordingly, air contaminated by chemical mist used in the substrate processing apparatus is prevented from leaking out of the substrate processing apparatus. Thus, even if the substrate processing apparatus is installed in a clean room, the clean room is prevented from being contaminated by the chemical mist used in the substrate processing apparatus.
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 plating apparatus 2 includes five plating units 20 each for plating a substrate to deposit metal on a surface of the substrate, two etching and cleaning units (cleaning and drying units) 22 each for etching, cleaning, and drying the plated substrate, a substrate placement stage 24 having a monitoring function, a substrate placement stage 26 disposed adjacent to the additional process apparatus 3, and a substrate transfer device 28 movable along a longitudinal direction of the plating apparatus 2. The substrate placement stage 24, the two plating units 20, the etching and cleaning unit 22, and the substrate placement stage 26 are disposed on one side of the substrate transfer device 28. The three plating units 20 and the etching and cleaning unit 22 are disposed on the other side of the substrate transfer device 28.
Substrate storage containers 4 such as standard manufacturing interface pods (SMIF) or front opening unified pods (FOUP), which can receive a number of substrates, are detachably mounted to a longitudinal end of the plating apparatus 2. The substrate transfer device 28 transfers a substrate between the plating units 20, the etching and cleaning units 22, the substrate placement stages 24 and 26, and the substrate storage containers 4.
As shown in
A substrate is introduced from the substrate storage container 4 into the plating apparatus 2 and transferred to the plating unit 20 by the substrate transfer device 28. Thus, the substrate is plated in the plating unit 20. The plated substrate is transferred to the etching and cleaning unit 22 by the substrate transfer device 28. In the etching and cleaning unit 22, a plated film attached to an edge portion (bevel portion) of the substrate is etched, and then the substrate is cleaned and dried.
After completion of the processes in the plating apparatus 2, the substrate is placed on the substrate placement stage 26 by the substrate transfer device 28 and introduced into the additional process unit 30 of the additional process apparatus 3 by the substrate transfer device 32. An additional process including an annealing process, an etching process, and a polishing process is performed in the additional process unit 30. The substrate that has been subjected to the additional process is returned to the substrate placement stage 26 of the plating apparatus 2 by the substrate transfer device 32. The substrate on the substrate placement stage 26 is returned to the substrate storage container 4 by the substrate transfer device 28. The substrate storage containers 4 may be provided not only on the plating apparatus 2, but also on the additional process apparatus 3. In this case, the substrate that has been subjected to the additional process is returned directly to a substrate storage container (not shown) provided on the additional process apparatus 3 by the substrate transfer device 32.
As described above, the substrate processing apparatus 1 in the present embodiment can perform or upgrade a diversified additional process after the plating process at low cost and becomes multifunctional without any influence on a standby time of a substrate before or after the plating process or on a throughput of the apparatus.
In the example shown in
The substrate stage 604 has a vacuum passage 604a defined within the substrate stage 604 and an annular vacuum attraction groove 604b defined at a peripheral portion of an upper surface of the substrate stage 604. The vacuum attraction groove 604b communicates with the vacuum passage 604a. Seal rings 608 and 610 are provided on inward and outward sides of the vacuum attraction groove 604b, respectively. The substrate W is placed on the upper surface of the substrate stage 604, and the vacuum attraction groove 604b is evacuated through the vacuum passage 604a to attract the peripheral portion of the substrate W. Thus, the substrate W is held on the substrate stage 604.
The swing arm 600 is moved vertically by a servomotor and a ball screw (not shown) and pivoted (swung) by a swing motor (not shown). Pneumatic actuators may be used instead of the motors.
The cathode unit 606 has six divided cathode electrodes 612 and an annular seal member 614 disposed above the cathode electrodes 612 so as to cover upper surfaces of the cathode electrodes 612. The seal member 614 has an inner circumferential portion inclined inward and downward. The thickness of the inner circumferential portion is gradually reduced. The seal member 614 has an inner circumferential edge portion extending downward. When the substrate stage 604 is moved upward, the peripheral portion of the substrate W held by the substrate stage 604 is pressed against the cathode electrodes 612 so as to flow a current to the substrate W At the same time, the inner circumferential edge portion of the seal member 614 is brought into pressure contact with an upper surface of the peripheral portion of the substrate W so as to hermetically seal the contact portion. Accordingly, a plating solution that has been supplied onto the upper surface (surface to be plated) of the substrate W is prevented from leaking out of an edge portion of the substrate W, and the cathode electrodes 612 are thus prevented from being contaminated by the plating solution. In this embodiment, the cathode unit 606 is not movable in the vertical direction but is rotatable together with the substrate stage 604. However, the cathode unit 606 may be designed to be movable in the vertical direction so that the seal member 614 is brought into pressure contact with the surface of the substrate W when the cathode unit 606 is moved downward.
The electrode head 602 includes a rotatable housing 622 and a vertically movable housing 620 which are concentrically disposed. Each of the rotatable housing 622 and the vertically movable housing 620 has a bottomed cylindrical shape with a downwardly open end. The rotatable housing 622 is fixed to a lower surface of a rotating member 624 attached to a free end of the swing arm 600 so that the rotatable housing 622 is rotated together with the rotating member 624. The vertically movable housing 620 has an upper portion positioned inside the rotatable housing 622. The vertically movable housing 620 is rotated together with the rotatable housing 622 and moved relative to the rotatable housing 622 in a vertical direction. The lower open end of the vertically movable housing 620 is closed with a porous member 628 so as to define an anode chamber 630 in the vertically movable housing 620. The anode chamber 630 has a circular anode 626 dipped in a plating solution Q which is introduced to the anode chamber 630.
In this example, the porous member 628 has a multilayered structure having three laminated layers of porous materials. Specifically, the porous member 628 includes a plating solution impregnated material 632 which mainly serves to hold a plating solution, and a porous pad 634 attached to a lower surface of the plating solution impregnated material 632. The porous pad 634 includes a lower pad 634a adapted to be brought into direct contact with the substrate W and an upper pad 634b disposed between the lower pad 634a and the plating solution impregnated material 632. The plating solution impregnated material 632 and the upper pad 634b are positioned in the vertically movable housing 620, and the lower open end of the vertically movable housing 620 is closed by the lower pad 634a. Thus, since the porous member 628 has a multilayered structure, the porous pad 634 (the lower pad 634a) which is brought into contact with the substrate W can have flatness enough to flatten irregularities on the surface of the substrate W to be plated.
The contact surface of the lower pad 634 which is brought into contact with the surface of the substrate is required to have a certain degree of flatness. Further, the lower pad 634 should have fine through-holes therein for allowing a plating solution to pass therethrough. Furthermore, at least the contact surface of the lower pad 634a should be made of an insulator or a material having high insulating properties. The surface of the lower pad 634a is required to have a maximum roughness (RMS) of about several tens of micrometers or less.
It is desirable that the fine through-holes of the lower pad 634a have a circular cross section in order to maintain flatness of the contact surface. Optimum diameters of the fine through-holes and an optimum number of the fine through-holes per unit area vary depending on the kind of a plated film and an interconnect pattern. However, it is desirable that both of the diameters and number of the fine through-holes are as small as possible in view of improving the selectivity of a plated film growing in the fine through-holes. Specifically, the diameter of each fine through-hole may be not more than 30 μm, preferably in the range of 5 to 20 μm. The number of the fine through-holes may be set so that the lower pad 634a has a porosity of not more than 50%. Further, it is desirable that the lower pad 634a has a certain degree of hardness. For example, the lower pad 634a may have a tensile strength ranging from about 5 to 100 kg/cm2 and a bend elastic constant ranging from about 200 to 10000 kg/cm2.
Furthermore, it is desirable that the lower pad 634a is made of hydrophilic material. For example, the following materials may be subjected to hydrophilic treatment or polymerized with a hydrophilic group. Examples of such materials include porous polyethylene (PE), porous polypropylene (PP), porous polyamide, porous polycarbonate, and porous polyimide. The porous polyethylene, the porous polypropylene, the porous polyamide, and the like are produced as follows. Fine powder of ultrahigh-molecular polyethylene, polypropylene, and polyamide, or the like is used as a material, squeezed, and sintered. These materials are commercially available by the name of Firudasu™ (by Mitsubishi Plastics, Inc.), Sunfine™ UF and Sunfine™ AQ (by Asahi Kasei Corporation), Spacy™ (by Spacy Chemical Corporation), and the like. Porous polycarbonate may be produced by passing a high-energy heavy metal such as copper, which has been accelerated by an accelerator, through a polycarbonate film to form straight tracks, and then selectively etching the tracks. The lower pad 634a may be produced by pressing or machining the surface of the lower pad 634a which is brought into contact with the surface of the substrate W to a flat finish. In this case, high-preferential deposition is expected to be carried out in fine recesses or grooves.
The plating solution impregnated material 632 is formed of porous ceramics such as alumina, SiC, mullite, zirconia, titania, or cordierite, a hard porous member such as a sintered compact of polypropylene or polyethylene, a composite material including these materials, woven fabric, or non-woven fabric. For example, alumina-based ceramics have a pore diameter of 30 to 200 μm. Further, SiC has a pore diameter of not more than 30 μm, a porosity of 20 to 95%, and a thickness of 1 to 20 mm, preferably 5 to 20 mm, more preferably 8 to 15 mm. In this embodiment, the plating solution impregnated material 632 is formed of porous alumina ceramics having a porosity of 30% and an average pore diameter of 100 μm. Although the porous ceramic plate per se is an insulator, the porous ceramic plate is constructed such that a plating solution is introduced into complicated passages in the porous ceramic which are considerably long in the thickness direction so as to have a smaller conductivity than the plating solution.
In this manner, the plating solution impregnated material 632 is disposed in the anode chamber 630 so as to provide a high resistance. Accordingly, influence of a resistance of a copper film layer (plated film) can be reduced to a negligible degree. Thus, a difference in current density over the surface of the substrate W due to electrical resistance on the surface of the substrate W can be made small so as to improve the uniformity of the plated film over the surface of the substrate.
The electrode head 602 has a pressing mechanism such as an air bag 640 for pressing the lower pad 634a against the surface of the substrate W held by the substrate stage 604 under a desired pressure. Specifically, in this embodiment, the annular air bag (pressing mechanism) 640 is provided between a lower surface of a top wall of the rotatable housing 622 and an upper surface of a top wall of the vertically movable housing 620 and connected to a pressurized fluid source (not shown) through a fluid introduction pipe 642.
The swing arm 600 is fixed at a predetermined position (process position) so as not to move in the vertical direction, and then the interior of the air bag 640 is pressurized under a pressure P. Thus, the lower pad 634a is uniformly pressed against the surface of the substrate W held by the substrate stage 604 under a desired pressure. Thereafter, the pressure P is restored to an atmospheric pressure so as to release pressing of the lower pad 634a against the substrate W
A plating solution introduction pipe 644 is connected to the vertically movable housing 620 to introduce the plating solution into the interior of the vertically movable housing 620. A pressurized fluid introduction pipe (not shown) is connected to the vertically movable housing 620 to introduce a pressurized fluid into the interior of the vertically movable housing 620. The anode 626 has a number of pores 626a formed therein. A plating solution Q is introduced through the plating solution introduction pipe 644 into the anode chamber 630. The interior of the anode chamber 630 is pressurized. Thus, the plating solution Q reaches the upper surface of the plating solution impregnated material 632 through the pores 626a of the anode 626. The plating solution Q passes through the plating solution impregnated material 632 and the porous pad 634 (the upper pad 634b and the lower pad 634a). As a result, the plating solution reaches an upper surface of the substrate W held by the substrate stage 604.
The anode chamber 630 includes gases generated by chemical reaction therein. Accordingly, the pressure in the anode chamber 630 may be varied. Therefore, the pressure in the anode chamber 630 is controlled to a predetermined set value by a feedback control during the plating process.
For example, in the case of performing a copper plating process, the anode 626 is made of copper containing 0.03 to 0.05% of phosphorus (phosphorus-containing copper) in order to prevent slime formation. The anode 626 may comprise an insoluble metal such as platinum or titanium, or an insoluble electrode of a metal on which platinum or the like is plated. The insoluble metal or the insoluble electrode is preferable because replacement is unnecessary. Further, the anode 626 may be a meshed anode which allows a plating solution to readily pass therethrough.
The cathode electrodes 612 are electrically connected to a cathode of a plating power source 650, and the anode 626 is electrically connected to an anode of the plating power source 650.
Next, operation of performing a plating process in the plating unit 20 will be described below. First, a substrate W is attracted to and held on the upper surface of the substrate stage 604. The substrate stage 604 is raised so as to bring a peripheral portion of the substrate W into contact with the cathode electrodes 612. Thus, a current can be supplied to the substrate W Then, the substrate stage 604 presses the seal member 614 against the upper surface of the peripheral portion of the substrate W so as to hermetically seal the peripheral portion of the substrate W
The electrode head 602 is moved from a position (idling position) where replacement of the plating solution, removal of bubbles, and the like are conducted during idling to a predetermined position (process position) in a state such that the plating solution Q is held inside the electrode head 602. Specifically, the swing arm 600 is raised and further pivoted to locate the electrode head 602 right above the substrate stage 604. Thereafter, the electrode head 602 is lowered. When the electrode head 602 reaches the predetermined position (process position), the electrode head 602 is stopped. Then, the anode chamber 630 is pressurized, and the plating solution Q held by the electrode head 602 is discharged from the lower surface of the porous pad 634. Next, pressurized air is introduced into the air bag 640 to press the lower pad 634a downward. Thus, the lower pad 634a is pressed against the upper surface (surface to be plated) of the substrate W held by the substrate stage 604 under a desired pressure.
The lower pad 634a makes two revolutions, for example, at a speed of 1 revolution/second in a state such that the lower pad 634a is brought into contact with the surface of the substrate W Then, rotation of the lower pad 634a is stopped. Thus, the lower pad 634a is rubbed against the surface of the substrate W. Alternatively, the lower pad 634a may be stationary while the substrate W may be rotated. The cathode electrodes 612 are electrically connected to the cathode of the plating power source 650 and the anode 626 is electrically connected to the anode of the plating power source 650 preferably within two seconds after rotation of the lower pad 634a is stopped. Thus, a plating process on the surface of the substrate W to be plated is started.
The plating process is performed for a certain period of time. Then, the cathode electrodes 612 and the anode 626 are disconnected from the plating power source 650. The anode chamber 630 is restored to an atmospheric pressure. Further, the air bag 640 is restored to an atmospheric pressure to release pressing of the lower pad 634a against the substrate W. Then, the electrode head 602 is raised.
The above operation is repeated a predetermined number of times, if necessary. Thus, the copper layer (plated film) having a sufficient film thickness enough to fill fine interconnection recesses is formed on the surface of the substrate W. Then, the electrode head 602 is pivoted and returned to its original position (idling position). In the present embodiment, copper is filled into interconnection recesses of a substrate. However, cobalt, nickel, gold, or tin may be filled into interconnection recesses of a substrate.
Next, there will be described an example in which an annealing unit for heating a substrate is provided as the additional process unit 30.
Each of the annealing chambers 700 includes a heating chamber 702 for heating a substrate and a cooling chamber 704 for cooling the substrate. The cooling chamber 704 has shutters 706 and 708. The heating chamber 702 has a hot plate 710 for heating the substrate, for example, to 400° C. and a plurality of vertically movable pins 712 extending through the hot plate 710 in the vertical direction. The vertically movable pins 712 are used to hold a substrate placed on upper ends of the vertically movable pins 712. The cooling chamber 704 has a cool plate 714 for cooling the substrate, for example, by cooling water flowing through the cool plate 714 and a plurality of vertically movable pins 716 extending through the cool plate 714 in the vertical direction. The vertically movable pins 716 are used to hold a substrate placed on upper ends of the vertically movable pins 716.
A substrate is introduced through the shutters 706 and 708 into the heating chamber 702 and held by the vertically movable pins 712 in the heating chamber 702. Then, the vertically movable pins 712 are lowered until a distance between the substrate and the hot plate 710 becomes about 0.1 to 1.0 mm. At that state, the substrate is heated, for example, to 400° C. by the hot plate 710. At that time, a gas for preventing oxidation is introduced into the heating chamber 702 to prevent the substrate from being oxidized. Thus, the substrate is annealed. The annealing process is continued for several tens of seconds to about 60 seconds. The heating temperature of the substrate is set to be in a range of 100 to 600° C.
After completion of the annealing process, the substrate is moved to the cooling chamber 704 and held by the vertically movable pins 716 in the cooling chamber 704. Then, the vertically movable pins 716 are lowered until a distance between the substrate and the cool plate 714 becomes about 0 to 0.5 mm. At that state, cooling water is introduced into the cool plate 714 to cool the substrate, for example, to 100° C. or less for about 10 to 60 seconds. The cooled substrate is transferred to the substrate storage container 4 by the substrate transfer device 32 in the additional process apparatus 3.
Next, there will be described an example in which an etching and cleaning unit for etching and cleaning a substrate is provided as the additional process unit 30.
In the etching and cleaning unit 30b, ultrapure water 726, nitrogen or dry air 728, and etching chemical liquid or pre-treatment liquid 730 are jetted to upper and lower surfaces of the substrate W Thus, the substrate W is subjected to pre-treatment, cleaning, and etching. For example, it is possible to etch excessive metal at a peripheral portion of the substrate W or etch the substrate W for the purpose of reducing steps formed on a surface of the substrate W during plating. Further, after the etching process and the cleaning process, the substrate stage 720 may be rotated at a high speed to dry the substrate W. Alternatively, a rinser drier or a spin-drier employing a dry gas may be used in the etching and cleaning unit 30b to dry the substrate W.
Next, there will be described an example in which a polishing unit for polishing a substrate is provided as the additional process unit 30.
The polishing table 742 is coupled to a scroll motor 746 disposed below the polishing table 742. Thus, when the scroll motor 746 is driven, the polishing table 742 makes a translational rotation movement. The top ring 744 is coupled through a top ring shaft 748 to a rotation motor 750. Thus, when the rotation motor 750 is driven, the top ring 744 is rotated about the top ring shaft 748.
In the polishing unit 30c, a polishing liquid (e.g., slurry 752 or ultrapure water 754) is supplied to an upper surface of the polishing pad 740. The substrate W is pressed against the polishing table 742 by the top ring 744 to polish a surface of the substrate W to a flat mirror finish. The purpose of the polishing unit 30c is not limited to such chemical mechanical polishing. For example, the polishing unit 30c may perform a process to reduce steps on a surface of a plated substrate, such as high-speed grinding by a fixed abrasive, rough polishing by electrolytic etching, or normal grinding.
Next, there will be described an example in which an inspection unit for measuring the film thickness of a plated film formed on a surface of a substrate is provided as the additional process unit 30.
The substrate W is chucked by the X-Y stage 760. The sensor 762 is brought close to the plated surface of the substrate W Then, the X-Y stage 760 is moved on the horizontal plane. Thus, the surface of the substrate W can be inspected at desired points. The sensor 762 may comprise a film thickness sensor, a particle counter, a surface roughness sensor, a reflectometer, an image recognition sensor, or the like. Thus, the sensor 762 can detect the film thickness of a plated film, an underlying film, or a native oxide, the surface contamination, or the reflectance, the surface roughness, or irregularities of the plated film. Further, defects in interconnections formed on the substrate W (e.g., metal lack or pits) can be detected based on changes of an image at a specific area of the substrate or comparison of relative scatter intensity.
In the above embodiments, the substrate processing apparatus has a plating apparatus and at least one additional process apparatus. However, the present invention is not limited to a combination of a plating apparatus and an additional process apparatus. The present invention is applicable to any combination of a main process apparatus for performing a main process on a substrate (e.g., a CMP apparatus or a cleaning apparatus) and an additional process apparatus for performing an additional process on the substrate.
A portion of internal air in the plating apparatus 502a is discharged as exhaust air 552 through a duct 554 to an exterior of the plating apparatus 502a. Another portion of the internal air in the plating apparatus 502a is circulated as circulation air 556 through the combination filter 530. Further, external air is introduced as intake air 558 through the combination filter 530. Specifically, the plating apparatus 502a has an air supply system for supplying the intake air 558 and the circulation air 556 to the interior of the plating apparatus 502a. Air in each of the plating units 20 is discharged as exhaust air 562 through a dedicated exhaust duct 560 to the exterior of the plating apparatus 502a. Further, air 563 flows into the chemical liquid management unit 529 from a region in which the plating units 20 and the etching and cleaning units 22 are installed. Air in the chemical liquid management unit 529 is discharged as exhaust air 566 through an exhaust duct 564 to the exterior of the plating apparatus 502a. As shown in
The chemical filter 540 may employ activated carbon, activated carbon to which chemicals are added, porous members, plastic fiber having various functional groups, films having various functional groups, non-woven fabric having various functional groups, zeolite, a polymer membrane, polymer fiber, and the like. The chemical filter 540 may be chemically modified by these substances. The chemical filter 540 can remove volatile substances including basic gases such as ammonia and trimethylamine, acid gases such as SOx, NOx, and chlorine, and organic gases such as xylene, toluene, benzene, and siloxane. Volatile substances removed by the chemical filter 540 are not limited to these substances. It has been revealed that organic gases such as toluene and xylene are likely to cause and promote plating defects.
These volatile organic substances may be adsorbed on a surface of a substrate (a surface of a Cu seed layer or a barrier metal). The volatile organic substances are not mixed into a plating solution. Thus, the volatile organic substances repel a plating solution so as to produce plating defects. While the particulate removal filter 550 such as a HEPA filter or an ULPA filter removes these volatile organic substances at a low removal rate, the chemical filter 540 such as activated carbon can remove the volatile organic substances at a remarkably high removal rate. According to experimental results, the density of plating defects was reduced from 5.5 points per substrate to 0.1 point per substrate by the chemical filter 540 in the plating apparatus 502a.
Locations at which the chemical filter 540 is provided are not limited to the illustrated examples. Nevertheless, it is desirable to provide a chemical filter 540 inside of a plating apparatus at an upper portion thereof or outside of a plating apparatus on an upper wall thereof as shown in
The scrubber 570 includes a pump 571, a pipe 572, a spray pipe 573, an induced draft fan 575, and a lower tank 576. The lower tank 576 stores an absorbing solution 574 therein. The absorbing solution 574 is supplied through the pipe 572 to the spray pipe 573 by the pump 571. Thus, the absorbing solution 574 is sprayed downward from the spray pipe 573. The intake air 559 is forced to flow upward through the pipe 572 by the induced draft fan 575. At that time, volatile substances contained in the intake air 559 are brought into contact with the absorbing solution 574 and absorbed in the absorbing solution 574. Thus, the volatile substances are removed from the intake air 559. Intake air 558 from which volatile substances have been removed is supplied through the particulate removal filter 550 into the plating apparatus 502d. The scrubber 570 may employ water as the absorbing solution 574. However, any solvent can be employed as the absorbing solution 574 as long as it can remove organic substances.
When the thermal cracking furnace 580 comprises a heating furnace combined with a catalyst, palladium, platinum, zirconium, or the like is generally employed as a catalyst. However, the catalyst is not limited to these examples. The heating temperature of the thermal cracking furnace 580 is determined based on pyrolysis properties of volatile organic substances to be removed.
The region in which the plating units 20 and the etching and cleaning units 22 are installed in the plating apparatus 502f may contain hydrogen chloride or sulfuric acid mist which is produced from a plating solution, or an alkali liquid (TMAH) or a reducing agent (formalin) which is contained in an electroless plating solution. Accordingly, it is necessary to maintain the pressure of the interior of the plating apparatus 502f so as to be lower than the pressure of the external space (clean room). However, because a recent clean room has a cleanliness of about class 1000, it is necessary to provide a particulate removal filter 550 such as a HEPA filter or an ULPA filter for intake air 558 to be introduced from the external space (clean room). Since chemical liquids are used in the plating units 20 and the etching and cleaning units 22, air is forced to be discharged from the units. Thus, the pressure in the units is maintained so as to be lowest in the substrate processing apparatus. The relationship of the pressures inside and outside of the plating apparatus 502f as shown in
In the above embodiments, the etching and cleaning units 22 may comprise a cleaning and drying chamber for cleaning and drying a substrate. The substrate processing apparatus may include a substrate loading/unloading unit.
According to the present invention, volatile substances, which would cause plating defects, are prevented from entering the plating apparatus. Accordingly, it is possible to forestall adsorption of the volatile substances on a surface of a seed layer of a substrate. Thus, defects caused by plating can remarkably be reduced at low cost. The present invention is applicable not only to a plating apparatus but also to other deposition apparatuses, polishing apparatuses, cleaning apparatuses, and etching apparatuses.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-125920 | Apr 2004 | JP | national |
| 2004-143375 | May 2004 | JP | national |
