Patent Application
20250146167
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, even 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, even 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 detecting a film thickness of a plating film formed on a substrate during a plating process.
According to an embodiment, a plating apparatus is proposed, and the plating apparatus includes a plating tank, a substrate holder configured to hold a substrate, an anode disposed in the plating tank to oppose the substrate held by the substrate holder, a resistor disposed between the substrate and the anode to adjust an electric field, a first detection electrode disposed in a region between a surface to be plated of the substrate and the anode and having an electrode end disposed at a first position inside the resistor, a second detection electrode disposed at a second position where there is less change in potential as compared with the first position in the plating tank, and a controller that measures a potential difference between the first detection electrode and the second detection electrode, to estimate a thickness of a plating film on the substrate based on the potential difference during a plating process.
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.
The load port 100 is a module for loading a substrate that is housed in a cassette, such as a FOUP, (not illustrated) to the plating apparatus 1000 and is a target to be plated 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, the pre-wet module 200, and the spin rinse dryer 600. 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 controller 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 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 robot 110 receives the substrate from the spin rinse dryer 600 and transfers the substrate on which the drying process has been performed to the cassette at the load port 100. Finally, the cassette housing the substrate is unloaded from the load port 100.
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 configured to hold a substrate Wf with a surface Wf-a to be plated 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 plating tank 410 in the vertical direction. The inside of the plating tank 410 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 anode region 424 of the plating tank 410, an anode 430 is provided. In an example, the anode 430 is a member with a circular shape having a plate surface with a dimension that is substantially equal to that of the plate surface of the substrate Wf. 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 controller 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.
The plating module 400 includes a resistor 450 disposed between the substrate Wf and the anode 430. The resistor 450 is disposed in the cathode region 422 to face the membrane 420. The resistor 450 is a member made of a dielectric material (for example, polyvinyl chloride) and is a member for uniformizing the plating process in the surface Wf-a to be plated of the substrate Wf by adjusting an electric field. In the present embodiment, the resistor 450 is configured to be movable in the up-down direction in the plating tank 410 by a drive mechanism 458, and the position of the resistor 450 is adjusted by the controller 800. However, the present application is not limited to such an example, and in an example, the resistor 450 may be fixed to the plating tank 410 such that the resistor 450 cannot move inside the plating tank 410.
The resistor 450 affects plating film thickness distribution at the outer edge portion of the surface Wf-a to be plated of the substrate Wf, in particular. The resistance value between the anode 430 and the substrate Wf is increased by the resistor 450, and the electric field becomes less likely to spread. Therefore, if the distance between the substrate Wf and the resistor 450 increases, a space where the electric field can spread between the substrate Wf and the resistor 450 increases in size. Here, since the power supply contact point of the substrate holder 440 is in contact with the outer edge portion of the substrate Wf, the electric field is relatively likely to concentrate on the outer edge portion of the substrate Wf, and the plating film thickness at the outer edge portion increases. Therefore, the resistor 450 is preferably disposed in the vicinity of the surface Wf-a to be plated of the substrate Wf.
Also, the plating module 400 include a paddle 480 disposed between the substrate Wf held by the substrate holder 440 and the resistor 450 and a paddle stirring mechanism 482 that is for stirring the plating solution by moving he paddle 480 inside the plating solution. Although the paddle 480 can be configured of a plate member having a plurality of rod-shaped members disposed in a grid shape, for example, the present application is not limited thereto, and the paddle 480 can also be configured of a plate member with many holes with honey comb shapes formed therein. The paddle stirring mechanism can be realized by a known mechanism such as a motor, for example. The paddle stirring mechanism 482 is configured to stir the plating solution in the vicinity of the surface Wf-a to be plated of the substrate Wf by causing the paddle 480 to reciprocate along the surface Wf-a to be plated of the substrate Wf. However, the present application is not limited to such an example, and the paddle stirring mechanism 482 may be configured to cause the paddle 480 to reciprocate perpendicularly to the surface Wf-a to be plated in an example. Also, although the example in which the paddle 480 and the paddle stirring mechanism 482 are provided has been described in the present embodiment, the paddle 480 and the paddle stirring mechanism 482 may not be provided.
In addition, the plating module 400 includes a first detection electrode 460 for detecting the potential in the plating tank 410. The potential detected by the first detection electrode 460 can be used to estimate the film thickness of the plating film formed on the surface Wf-a to be plated. The first detection electrode 460 has an electrode end disposed at a first position inside the resistor 450. In the present embodiment, the resistor 450 is configured in a plate shape including a substrate-side facing surface 450-a facing the surface Wf-a to be plated of the substrate Wf and the anode-side facing surface 450-b facing the anode 430. Also, “inside the resistor 450” means the region between the substrate-side facing surface 450-a and the anode-side facing surface 450-b in the present embodiment. In other words, the first detection electrode 460 is disposed on the same plane of the resistor 450 as that of the substrate-side facing surface 450-a or at a position that is further from the surface Wf-a to be plated of the substrate Wf than the substrate-side facing surface 450-a. Note that in a case where the resistor 450 is configured of a porous material or the like, the substrate-side facing surface 450-a and the anode-side facing surface 450-b can be virtual planes. In addition, the electrode end of the first detection electrode 460 is not covered with the resistor 450 and is configured to face the surface Wf-a to be plated of the substrate Wf, and the substrate-side facing surface 450-a means a surface in the region except for the region where the first detection electrode 460 is provided in the present embodiment.
In addition, the plating module 400 includes the paddle 480, and the paddle 480 is disposed between the resistor 450 and the substrate Wf, in the present embodiment. The paddle 480 is configured to be caused to reciprocate in the direction along the surface Wf-a to be plated by the paddle stirring mechanism 482. Note that in the example illustrated in
On the contrary, the first detection electrode 460 in the present embodiment is disposed inside the resistor 450 as illustrated in
It is possible to shorten the distance between the resistor 450 and the surface Wf-a to be plated of the substrate Wf by the first detection electrode 460 being disposed inside the resistor 450 in this manner, and it is thus possible to improve uniformity of the plating film thickness distribution. Also, the first detection electrode 460 and the paddle 480 do not interfere with each other by the first detection electrode 460 being disposed inside the resistor 450 in this manner, and it is thus possible to suitably stir the plating solution with the paddle 480. In the present embodiment, the first detection electrode 460 is disposed in a region which overlaps the paddle 480 caused to reciprocate by the paddle stirring mechanism 482 (the region where the paddle 480 reciprocates when the surface Wf-a to be plated is seen from the anode 430; see the one-dotted dashed line in
In addition, the plating module 400 includes a second detection electrode 462 for detecting the potential inside the plating tank 410 along with the first detection electrode 460. The second detection electrode 462 is disposed at a location where there is relatively no change in potential inside the plating tank 410. Specifically, the second detection electrode 462 is disposed at a second position outside the region between the substrate Wf and the anode 430. In other words, the second detection electrode 462 is disposed at a location where the second detection electrode 462 does not overlap the substrate Wf when seen in the direction perpendicular to the plate surface of the substrate Wf as illustrated in
Each of the first detection electrode 460 and the second detection electrode 462 may be configured as an electrode with the same material and/or the same shape in an example. As the electrode material, at least one of platinum (Pt), gold (Au), carbon (C), and copper (Cu) can be employed.
Detection signals obtained by the first detection electrode 460 and the second detection electrode 462 are input to the controller 800. In the present embodiment, the controller 800 measures the potential difference between the first detection electrode 460 and the second detection electrode 462 and estimates the film thickness of the plating film formed on the surface Wf-a to be plated of the substrate Wf on the basis of the potential difference. This is based on the plating current and the potential being correlated in the plating process. It is possible to estimate the current plating film thickness on the basis of a temporal change in plating formation speed calculated from the start of the plating. For the estimation of the plating film thickness based on the potential difference between the first detection electrode 460 and the second detection electrode 462, a known method can be used. In an example, the controller 800 can estimate plating current distribution in the substrate during the plating process on the basis of the detection signals and can estimate the film thickness distribution of the plating film inside the substrate on the basis of the estimated plating current distribution. The estimation of the film thickness of the plating film on the substrate Wf achieved by the controller 800 during the plating process will be described later in detail.
Return to the description of the configuration of the plating module 400. In an embodiment, a shielding body 470 for shielding the current flowing from the anode 430 through the substrate Wf is provided in the cathode region 422 (see
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 Wf-a to be plated 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 Wf-a to be plated of the substrate Wf. In the present embodiment, a potential difference between the first detection electrode 460 and the second detection electrode 462 is detected in real time during the plating process. Also, the controller 800 estimates the film thickness of the plating film on the basis of the potential difference between the first detection electrode 460 and the second detection electrode 462. Thereby, the change in film thickness of the plating film formed on the surface Wf-a to be plated of the substrate Wf in the plating process can be measured in real time.
In addition, in the plating module 400 in the present embodiment, the result of measuring the potential difference between the first detection electrode 460 and the second detection electrode 462 includes noise in accordance with a reciprocation cycle of the paddle 480 as illustrated in
Furthermore, the controller 800 preferably adjusts the reciprocation cycle (first cycle) of the paddle 480 and the rotation cycle (second cycle) of the substrate holder 440 to prevent them from being in a relationship of an integer multiple during the plating process. In other words, it is preferable that the reciprocation cycle of the paddle 480 do not become an integer multiple of the rotation cycle of the substrate holder 440 and the rotation cycle of the substrate holder 440 do not become an integer multiple of the reciprocation cycle of the paddle 480. This is for preventing the same influence from being constantly provided by the paddle 480 when the specific position of the surface Wf-a to be plated is detected due to overlapping of the reciprocation cycle of the paddle 480 and the rotation cycle of the substrate holder 440. Therefore, it is possible to suitably estimate the plating film formed on the surface Wf-a to be plated through such control.
In this manner, according to the plating apparatus 1000 of the present embodiment, it is possible to detect the potential in the plating tank 410 during the plating process by using the first detection electrode 460 disposed inside the resistor 450 and to estimate and detect a change in film thickness of the plating film. It is possible to adjust the plating conditions including at least one of the plating current value, the plating time, the position of the resistor 450, the opening dimension of the anode mask 426, and the position of the shielding body 470 during the plating process and/or in the next plating process, with reference to the thus estimated (detected) change in film thickness of the plating film. Note that the adjustment of the plating conditions may be performed by a user of the plating apparatus 1000 or may be performed by the controller 800. In an example, the adjustment of the plating conditions achieved by the controller 800 is preferably performed on the basis of a conditional expression defined in advance through experiments or the like, a program, or the like.
The plating module 400 in the above-described embodiment is adapted such that the surface Wf-a to be plated of the substrate Wf is oriented downward during the plating process. However, the present application is not limited to such an example, and the substrate Wf may be held such that the substrate Wf extends in the vertical direction in the plating tank, that is, the plate surface is oriented in the horizontal direction. Note that in such a case, the substrate Wf may be a rectangular substrate or may be a circular substrate similarly to the above-described embodiment.
The present invention can also be described as following aspects.
[Aspect 1] According to Aspect 1, a plating apparatus is proposed, 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 resistor disposed between the substrate and the anode to adjust an electric field, a first detection electrode disposed in a region between a surface to be plated of the substrate and the anode and having an electrode end disposed at a first position inside the resistor, a second detection electrode disposed at a second position where there is less change in potential as compared with the first position in the plating tank, and a controller that measures a potential difference between the first detection electrode and the second detection electrode, to estimate a thickness of a plating film on the substrate based on the potential difference during a plating process. According to Aspect 1, it is possible to shorten the distance between the resistor and the substrate and to estimate and detect the film thickness of the plating film during the plating process.
[Aspect 2] According to Aspect 2, in Aspect 1, the resistor has a facing surface that faces the surface to be plated of the substrate, and the first detection electrode is disposed in a groove portion formed in the facing surface.
[Aspect 3] According to Aspect 3, in Aspects 1 or 2, a rotation mechanism that rotates the substrate holder is further included, the first detection electrode is provided in a region of not more than 1.7% at a circumference of a circle passing through the first detection electrode around a rotation axis of the rotation mechanism, and the controller is configured to estimate a film thickness of the plating film with rotation of the substrate achieved by the rotation mechanism. According to Aspect 3, it is possible to suitably adjust the electric field by the resistor.
[Aspect 4] According to Aspect 4, in Aspects 1 to 3, a paddle disposed between the resistor and the substrate and a paddle stirring mechanism configured to cause the paddle to reciprocate in a direction along the surface to be plated of the substrate are included, and the first detection electrode is disposed in a region where the paddle reciprocates when the surface to be plated is viewed from the anode. According to Aspect 4, it is possible to suitably stir a plating solution with the paddle.
[Aspect 5] According to Aspect 5, in Aspect 4, the paddle stirring mechanism is configured to cause the paddle to reciprocate at a predetermined cycle, and the controller estimates the thickness of the plating film on the substrate by removing a vibration component having a frequency corresponding to the predetermined cycle from the potential difference. According to Aspect 5, it is possible to more suitably estimate the film thickness of the plating film formed on the substrate.
[Aspect 6] According to Aspect 6, in Aspect 4 or 5, the plating apparatus further includes a rotation mechanism that rotates the substrate holder, the paddle stirring mechanism is configured to cause the paddle to reciprocate at a first cycle, the controller is configured to estimate the film thickness of the plating film with rotation of the substrate at a second cycle achieved by the rotation mechanism, and the first cycle and the second cycle are adjusted such that the first cycle and the second cycle are not in a relationship of an integer multiple. According to Aspect 6, it is possible to curb overlapping of the cycles of the reciprocation of the paddle and the rotation of the substrate and to more suitably estimate the film thickness of the plating film formed on the substrate.
[Aspect 7] According to Aspect 7, in Aspects 1 to 6, the substrate holder is configured to hold the substrate with a surface to be plated being oriented downward in the plating tank.
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.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/046435 | 12/16/2022 | WO |
