Patent Application
20230279579
This application claims priority to Japanese Patent Application No. 2022-030876 filed Mar. 1, 2022, the entire contents of which are hereby incorporated by reference.
The present application relates to a plating apparatus.
As an example of a plating apparatus, a cup type electrolytically plating apparatus is known (see, for example, PTL 1). In the cup type electrolytically plating apparatus, a substrate (for example, a semiconductor wafer) held by a substrate holder with a surface to be plated being oriented downward is immersed into a plating solution, and a voltage is applied between the substrate and an anode, thereby precipitating a conductive film on a substrate surface.
In the plating apparatus, generally, a user sets in advance parameters, such as a plating current value and a plating time, as plating process recipes, based on a target plating film thickness and an actual plating area of a substrate on which a plating process is performed, and the plating process is performed based on the set process recipes (see, for example, PTL 2). Then, the plating process is performed on a plurality of wafers on the same carrier with the same process recipe. Also, to measure the plating film thickness after the plating process, in general, after the plating process of all the wafers in the carrier ends, the carrier containing the wafers is transferred from the plating apparatus to a separate film thickness measuring device, and film thicknesses and wafer in-plane profiles are individually measured.
In a plating apparatus, when a plating process is performed on substrates in the same carrier on the same process conditions, variations might be generated in film thickness of a plating film formed on each substrate, due to dimensional tolerance of the substrate, change in state of a plating solution in a plating tank, or the like. Further, when an average film thickness is adjusted for a plurality of substrates, variations might be generated in plating film thickness depending on a location in the same substrate.
In view of the above-described actual situations, one object of the present application is to provide a plating apparatus capable of improving uniformity of a plating film formed on a substrate.
According to an embodiment, a plating apparatus is provided, and the plating apparatus includes a plating tank, a substrate holder that holds a substrate, an anode disposed in the plating tank to oppose the substrate held by the substrate holder, a conduit having a first portion including an opening end disposed in a region between the substrate held by the substrate holder and the anode, and a second portion apart from the region between the substrate held by the substrate holder and the anode, the conduit having at least a part filled with a plating solution, and a potential sensor that is disposed outside the region of the conduit and that is configured to measure a potential of the plating solution.
According to another embodiment, a plating apparatus is provided, and the plating apparatus includes a plating tank, a substrate holder that holds a substrate, an anode disposed in the plating tank to oppose the substrate held by the substrate holder, a conduit having a first portion including an opening end disposed in a region between the substrate holder and the anode in the plating tank, and a second portion apart from the region between the substrate holder and the anode, the conduit having at least a part filled with a plating solution, and an auxiliary anode disposed in the second portion of the conduit.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the same or corresponding components are denoted with the same reference sign and will not be described in duplicate.
<Overall Configuration of Plating Apparatus>
The load port 100 is a module for loading a substrate housed in a cassette, such as a FOUP, (not illustrated) to the plating apparatus 1000 and unloading the substrate from the plating apparatus 1000 to the cassette. While the four load ports 100 are arranged in the horizontal direction in this embodiment, the number of load ports 100 and arrangement of the load ports 100 are arbitrary. The transfer robot 110 is a robot for transferring the substrate that is configured to grip or release the substrate between the load port 100, the aligner 120, and the transfer device 700. The transfer robot 110 and the transfer device 700 can perform delivery and receipt of the substrate via a temporary placement table (not illustrated) to grip or release the substrate between the transfer robot 110 and the transfer device 700.
The aligner 120 is a module for adjusting a position of an orientation flat, a notch, and the like of the substrate in a predetermined direction. While the two aligners 120 are disposed to be arranged in the horizontal direction in this embodiment, the number of aligners 120 and arrangement of the aligners 120 are arbitrary. The pre-wet module 200 wets a surface to be plated of the substrate before a plating process with a process liquid, such as pure water or deaerated water, to replace air inside a pattern formed on the surface of the substrate with the process liquid. The pre-wet module 200 is configured to perform a pre-wet process to facilitate supplying the plating solution to the inside of the pattern by replacing the process liquid inside the pattern with a plating solution during plating. While the two pre-wet modules 200 are disposed to be arranged in the vertical direction in this embodiment, the number of pre-wet modules 200 and arrangement of the pre-wet modules 200 are arbitrary.
For example, the pre-soak module 300 is configured to remove an oxidized film having a large electrical resistance present on, a surface of a seed layer formed on the surface to be plated of the substrate before the plating process by etching with a process liquid, such as sulfuric acid and hydrochloric acid, and perform a pre-soak process that cleans or activates a surface of a plating base layer. While the two pre-soak modules 300 are disposed to be arranged in the vertical direction in this embodiment, the number of pre-soak modules 300 and arrangement of the pre-soak modules 300 are arbitrary. The plating module 400 performs the plating process on the substrate. There are two sets of the 12 plating modules 400 arranged by three in the vertical direction and by four in the horizontal direction, and the total 24 plating modules 400 are disposed in this embodiment, but the number of plating modules 400 and arrangement of the plating modules 400 are arbitrary.
The cleaning module 500 is configured to perform a cleaning process on the substrate to remove the plating solution or the like left on the substrate after the plating process. While the two cleaning modules 500 are disposed to be arranged in the vertical direction in this embodiment, the number of cleaning modules 500 and arrangement of the cleaning modules 500 are arbitrary. The spin rinse dryer 600 is a module for rotating the substrate after the cleaning process at high speed and drying the substrate. While the two spin rinse dryers are disposed to be arranged in the vertical direction in this embodiment, the number of spin rinse dryers and arrangement of the spin rinse dryers are arbitrary. The transfer device 700 is a device for transferring the substrate between the plurality of modules inside the plating apparatus 1000. The control module 800 is configured to control the plurality of modules in the plating apparatus 1000 and can be configured of, for example, a general computer including input/output interfaces with an operator or a dedicated computer.
An example of a sequence of the plating processes by the plating apparatus 1000 will be described. First, the substrate housed in the cassette is loaded on the load port 100. Subsequently, the transfer robot 110 grips the substrate from the cassette at the load port 100 and transfers the substrate to the aligners 120. The aligner 120 adjusts the position of the orientation flat, the notch, or the like of the substrate in the predetermined direction. The transfer robot 110 grips or releases the substrate whose direction is adjusted with the aligners 120 to the transfer device 700.
The transfer device 700 transfers the substrate received from the transfer robot 110 to the pre-wet module 200. The pre-wet module 200 performs the pre-wet process on the substrate. The transfer device 700 transfers the substrate on which the pre-wet process has been performed to the pre-soak module 300. The pre-soak module 300 performs the pre-soak process on the substrate. The transfer device 700 transfers the substrate on which the pre-soak process has been performed to the plating module 400. The plating module 400 performs the plating process on the substrate.
The transfer device 700 transfers the substrate on which the plating process has been performed to the cleaning module 500. The cleaning module 500 performs the cleaning process on the substrate. The transfer device 700 transfers the substrate on which the cleaning process has been performed to the spin rinse dryer 600. The spin rinse dryer 600 performs the drying process on the substrate. The transfer device 700 grips or releases the substrate on which the drying process has been performed to the transfer robot 110. The transfer robot 110 transfers the substrate received from the transfer device 700 to the cassette at the load port 100. Finally, the cassette housing the substrate is unloaded from the load port 100.
Note that the configuration of the plating apparatus 1000 described with reference to
<Configuration of Plating Module>
Next, a configuration of the plating module 400 will be described. Since 24 plating modules 400 in the present embodiment have the same configuration, one plating module 400 alone will be described.
The plating module 400 includes a substrate holder 440 that holds a substrate Wf with a surface to be plated Wf-a being oriented downward. The substrate holder 440 includes a power supply contact point to supply power from an unillustrated power supply to the substrate Wf. The plating module 400 includes an elevating/lowering mechanism 442 that elevates and lowers the substrate holder 440. Further, in one embodiment, the plating module 400 includes a rotation mechanism 448 that rotates the substrate holder 440 about a vertical axis. The elevating/lowering mechanism 442 and the rotation mechanism 448 can be achieved by a known mechanism such as a motor.
The plating module 400 includes a membrane 420 that separates an inside of the inner tank 412 in the vertical direction. The inside of the inner tank 412 is divided into a cathode region 422 and an anode region 424 by the membrane 420. The cathode region 422 and the anode region 424 are each filled with the plating solution. In the present embodiment, an example where the membrane 420 is provided is described, and alternatively, the membrane 420 need not be provided.
On a bottom surface of the inner tank 412 of the anode region 424, an anode 430 is provided. Also, in the anode region 424, an anode mask 426 for adjusting electrolysis between the anode 430 and the substrate Wf is disposed. The anode mask 426 is, for example, a substantially plate-shaped member made of a dielectric material and provided on a front surface of (above) the anode 430. The anode mask 426 has an opening through which a current flowing between the anode 430 and the substrate Wf passes. In the present embodiment, the anode mask 426 is configured to have a changeable opening dimension and the opening dimension is adjusted by the control module 800. Here, the opening dimension means a diameter when the opening is circular, and a length of a side or longest opening width when the opening is polygonal. To change the opening dimension in the anode mask 426, a known mechanism can be adopted. In the present embodiment, an example where the anode mask 426 is provided is described, and alternatively, the anode mask 426 need not be provided. Furthermore, the membrane 420 described above may be provided in the opening of the anode mask 426.
In the cathode region 422, a resistor 450 opposing the membrane 420 is disposed. The resistor 450 is a member for uniformly performing the plating process in the surface to be plated Wf-a of the substrate Wf. In the present embodiment, the resistor 450 is configured to be movable in an up-down direction in the plating tank 410 by a drive mechanism 452, and a position of the resistor 450 is adjusted by the control module 800. Alternatively, the plating module 400 need not include the resistor 450. While a specific material of the resistor 450 is not particularly limited, in a modification of the present embodiment, for example, a porous resin such as polyether ether ketone is used.
In a vicinity of the surface of the substrate Wf in the cathode region 422, a paddle 456 for stirring the plating solution is provided. The paddle 456 is made of, for example, titanium (Ti) or a resin. The paddle 456 reciprocally moves parallel to the surface of the substrate Wf, to stir the plating solution so that sufficient metal ions are uniformly supplied to the surface of the substrate Wf during the plating of the substrate Wf. The present invention is not limited to such an example, and the paddle 456 may be configured, for example, to move perpendicularly to the surface of the substrate Wf. Alternatively, the plating module 400 need not include the paddle 456.
The cathode region 422 is provided with a conduit 462. The conduit 462 is a hollow tube and can be made of a resin such as polypropylene (PP) or polyvinyl chloride (PVC) as an example. When the resistor 450 is provided in the cathode region 422, the conduit 462 may be provided between the substrate Wf and the resistor 450. Further, when the paddle 456 is provided, the conduit 462 may be disposed so as not to interfere with the paddle 456, and as an example, it is preferable that the conduit has the same height as the paddle 456 and is disposed on an outer peripheral side of the paddle 456 (in
The inside of the conduit 462 is filled with the plating solution in the same manner as in the cathode region 422. The conduit 462 may be provided with a filling mechanism 468 for filling the inside of the conduit 462 with the plating solution. As the filling mechanism 468, various known mechanisms can be adopted, and as an example, an air vent valve, a mechanism for supplying the plating solution, or the like can be adopted. The filling mechanism 468 is provided in the second portion 462b of the conduit 462 as an example.
While
In the second portion 462b of the conduit 462, a potential sensor 470 is provided. While the potential sensor 470 is disposed outside the plating tank 410 in
Additionally, in the plating module 400, it is preferable to provide a potential sensor for reference (not illustrated) in a place of the plating tank 410 where there is relatively no change in potential, and to acquire a difference between a detected potential by the potential sensor for reference and a detected potential by the potential sensor 470. Since a change in potential difference measured by the potential sensor 470 is exceedingly small, the measurement is susceptible to noise. For reducing noise, it is preferable to install an independent electrode in the plating solution and connect the electrode directly to ground. In this case, it is further preferable to install at least five electrodes in the plating tank 410, that is, electrodes for a plating substrate (cathode), for an anode 430, for two potential sensors (the potential sensor 470 and the potential sensor for reference) and for grounding.
The control module 800 can calculate a plating formation rate of the surface to be plated Wf-a based on a detection value by the potential sensor 470. This is based on correlation between a plating current and potential in the plating process. A current plating film thickness can be estimated based on change, over time, in plating formation rate calculated from the start of plating. The estimation of a plating film thickness based on the potential detected by the potential sensor 470 can adopt a known technique. As an example, the control module 800 can estimate a distribution of the plating current in the substrate during the plating process based on the detection signal and estimate a film thickness distribution of the plating film in the substrate based on the estimated plating current distribution.
<End Point Detection and End Point Prediction>
The control module 800 may detect an end point of the plating process or may predict a time until the end point of the plating process, based on the detection value by the potential sensor 470. As an example, the control module 800 may end the plating process when the film thickness of the plating film reaches a desired thickness based on the detection value by the potential sensor 470. As an example, a film thickness measurement module may calculate a film thickness increase rate of the plating film and may predict a time until the desired thickness is reached, that is, the time until the end point of the plating process based on the detection value by the sensor 470.
<Shielding Body>
Return to the description of the configuration of the plating module 400. As illustrated in
<Plating Process>
Next, the plating process in the plating module 400 of the present embodiment will be described in more detail. By immersing the substrate Wf in the plating solution of the cathode region 422 by use of the elevating/lowering mechanism 442, the substrate Wf is exposed to the plating solution. By applying a voltage between the anode 430 and the substrate Wf in this state, the plating module 400 can perform the plating process on the surface to be plated Wf-a of the substrate Wf. In one embodiment, the plating process is performed while rotating the substrate holder 440 by use of the rotation mechanism 448. Through the plating process, a conductive film (plating film) is precipitated on the surface to be plated Wf-a of the substrate Wf. In the present embodiment, real-time detection is made by the potential sensor 470 provided in the conduit 462 during the plating process. The control module 800 then measures the film thickness of the plating film based on the detection value by the potential sensor 470. Thereby, the change in film thickness of the plating film formed on the surface to be plated Wf-a of the substrate Wf in the plating process can be measured in real time.
Further, by performing the detection by the potential sensor 470 with the rotation of the substrate holder 440 (substrate Wf), the detection position by the sensor 470 can be changed, and film thicknesses at a plurality of points of the substrate Wf in the circumferential direction, or in the entire circumferential direction can be measured.
The plating module 400 may change a rotation speed of the substrate Wf by the rotation mechanism 448 during the plating process. As an example, the plating module 400 may slowly rotate the substrate Wf for the estimation of the plating film thickness by the film thickness estimation module. As an example, the plating module 400 may rotate the substrate Wf at a first rotation speed Rs1 during the plating process and rotate the substrate Wf at a second rotation speed Rs2 slower than the first rotation speed Rs1 while the substrate Wf rotates once or several times every predetermined period (for example, every few seconds). In this way, the plating film thickness of the substrate Wf can be estimated with high accuracy even when a sampling period by the potential sensor 470 is small with respect to the rotation speed of the substrate Wf. Here, the second rotation speed Rs2 may be set, for example, to a speed of one-tenth of the first rotation speed Rs1.
Thus, according to the plating apparatus 1000 of the present embodiment, by detecting the potential by the potential sensor 470 through the conduit 462 provided in the plating tank 410, the change in film thickness of the plating film during the plating process can be measured. With reference to the change in film thickness of the plating film thus measured, plating conditions can be adjusted including at least one selected from a plating current value, a plating time, the opening dimension of the anode mask 426, and the position of the shielding body 480 in and after the next plating process. The plating conditions may be adjusted by a user of the plating apparatus 1000 or by the control module 800. As an example, the adjustment of the plating conditions by the control module 800 may be performed, for example, based on a conditional expression or a program predetermined by experiments or the like.
The adjustment of the plating conditions may be performed when plating another substrate Wf, or the plating conditions in the current plating process may be adjusted in real time. As an example, the control module 800 may adjust the position of the shielding body 480.
The control module 800 may adjust a distance between the substrate Wf and the resistor 450 as a real-time adjustment of the plating conditions. According to research by the present inventors, it has been found that the distance between the substrate Wf and the resistor 450 comparatively noticeably affects the amount of plating formed near the outer periphery of the substrate Wf and that the distance does not comparatively affect the amount of plating formed in a central region of the substrate Wf. For this reason, as an example, when the film thickness of the plating film near the outer periphery is larger than a target, the control module 800 can reduce the distance between the substrate Wf and the resistor 450, and when the film thickness of the plating film near the outer periphery is smaller than the target, the control module can increase the distance between the substrate Wf and the resistor 450. The longer the shielding body 480 is in the shielding position, the control module 800 may increase the distance between the substrate Wf and the resistor 450, and the shorter the shielding body 480 is in the shielding position, the control module may reduce the distance between the substrate Wf and the resistor 450. In this way, the amount of plating formed near the outer periphery of the substrate Wf can be adjusted, to improve the uniformity of the plating film formed on the substrate Wf. As an example, the control module 800 can drive the elevating/lowering mechanism 442, to adjust the distance between the substrate Wf and the resistor 450. However, without being limited to such examples, the control module 800 may adjust the distance between the substrate Wf and the resistor 450 by moving the resistor 450 with the drive mechanism 452.
Further, the control module 800 may adjust the opening dimension of the anode mask 426 as the real-time adjustment of the plating conditions. As an example, when the film thickness of the plating film near the outer periphery is larger than the target, the control module 800 may reduce the opening dimension of the anode mask 426, and when the film thickness of the plating film near the outer periphery is smaller than the target, the control module may increase the opening dimension of the anode mask 426.
The auxiliary anode 472 is configured to apply a voltage between the anode and the substrate Wf through a plating solution in the conduit 462. Here, when the voltage is applied between the auxiliary anode 472 and the substrate Wf, a current flows mainly through a surface to be plated Wf-a in the vicinity of an opening end 464 of the conduit 462. Therefore, by using the auxiliary anode 472, precipitation of a conductive film (plating film) can be promoted in a local region in the vicinity of the opening end 464. In particular, by using the auxiliary anode 472 with rotation of a substrate holder 440 (substrate Wf), the control module 800 can promote the precipitation of the plating film locally in a region where the plating film is slowly formed (film thickness is small), and uniformity of the plating film formed on the substrate Wf can be improved.
<Modification>
The anode 430A is disposed to oppose the plate surface of the substrate Wf in the plating tank. The anode 430A is connected to a positive electrode of a power supply 90, and the substrate Wf is connected to a negative electrode of the power supply 90 via the substrate holder 440A. When a voltage is applied between the anode 430A and the substrate Wf, a current flows through the substrate Wf, and a metal film is formed on the surface of the substrate Wf in the presence of the plating solution.
The plating tank 410A includes an inner tank 412A in which the substrate Wf and the anode 430A are arranged, and an overflow tank 414A adjacent to the inner tank 412A. The plating solution in the inner tank 412A overflows a side wall of the inner tank 412A to flow into the overflow tank 414A.
One end of a plating solution circulation line 58a is connected to a bottom of the overflow tank 414A, and the other end of the plating solution circulation line 58a is connected to a bottom of the inner tank 412A. To the plating solution circulation line 58a, a circulation pump 58b, a constant temperature unit 58c and a filter 58d are attached. The plating solution overflows the side wall of the inner tank 412A to flow into the overflow tank 414A and is further returned to a plating solution storage tank 52 through the plating solution circulation line 58a from the overflow tank 414A. Thus, the plating solution circulates between the inner tank 412A and the overflow tank 414A through the plating solution circulation line 58a.
The plating module 400A further includes a regulation plate 454 that regulates a potential distribution on the substrate Wf. The regulation plate 454 is disposed between the substrate Wf and the anode 430A and has an opening 454a for limiting an electric field in the plating solution.
The plating module 400A is provided with a conduit 462A in the plating tank 410A. The conduit 462A can be, as an example, made of a resin such as polypropylene (PP) or polyvinyl chloride (PVC). The conduit 462A, in the same manner as the conduit 462 of the above embodiments, includes a first portion 462Aa including an opening end 464A disposed in a region between the substrate Wf and the anode 430A, and a second portion 462Ab disposed in a region apart from the region between the substrate Wf and the anode 430A. Further, a potential sensor 470A is provided in the second portion 462Ab of the conduit 462A. A detection signal by the potential sensor 470A is inputted into a control module 800A.
In the plating module 400A in this third embodiment, real-time detection by the potential sensor 470A can be performed during a plating process in the same manner as in the plating module 400 of the first embodiment. Then, the control module 800A measures a film thickness of a plating film based on a detection value by the potential sensor 470A. Thereby, a change in film thickness of the plating film formed on a surface to be plated of the substrate Wf can be measured in real time in the plating process. The control module 800A can also adjust plating conditions based on the film thickness of the plating film, in the same manner as in the first embodiment.
Also, in the plating module 400A of the third embodiment, an auxiliary anode 472 may be provided in the conduit 462A in place of the potential sensor 470A. Thereby, the plating conditions can be adjusted using the auxiliary anode 472 in the same manner as in the second embodiment. The plating module 400A may include one or more sets, each set including a first conduit 462A provided with the auxiliary anode 472 and a second conduit 462A provided with the potential sensor 470A. Furthermore, the conduit 462 may be configured to be movable by the drive mechanism 466.
This application is based on and claims the benefit of priority of Japanese Patent Application No. 2022-30876 filed on Mar. 1, 2022, and all disclosures, including a description, claims, drawings and an abstract of Japanese Patent Application No. 2022-30876 are incorporated herein by reference as a whole. All disclosures, including descriptions, claims, drawings and abstracts of Japanese Patent Laid-Open No. 2008-19496 (PTL 1) and Japanese Patent Laid-Open No. 2002-105695 (PTL 2) are incorporated herein by reference as a whole.
The present invention can be described in the following aspects.
According to Aspect 1, the potential of the plating solution in the plating tank during a plating process can be measured. This can improve uniformity of a plating film formed on the substrate.
According to Aspect 2, uniformity of a plating film formed on the substrate can be improved using the auxiliary anode disposed in the conduit.
The embodiments of the present invention have been described above, and the above embodiments of the present invention are described to facilitate understanding of the present invention and are not intended to limit the present invention. Needless to say, the present invention may be changed or modified without departing from the spirit, and the present invention includes equivalents to the invention. Also, in a range in which at least some of the above-described problems can be solved or a range in which at least some of effects are exhibited, any arbitrary combination of the embodiment and the modification is possible, and arbitrary combination or omission of respective constituent components described in claims and description is possible.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-030876 | Mar 2022 | JP | national |
