Plating apparatus and plating method

Abstract

To improve uniformity of plating thickness in a plating apparatus.SOLUTION: A plating apparatus is provided for plating a substrate by passing an electric current from an anode to the substrate. The plating apparatus comprises a plurality of anode-side electrical wires electrically connected to the anode via a plurality of electrical contacts on the anode, a plurality of substrate-side electrical wires electrically connected to the substrate via a plurality of electrical contacts on the substrate, and on at least either one of the anode side or the substrate side, a plurality of variable resistors located in the middle of the plurality of anode-side electrical wires or the plurality of substrate-side electrical wires, and a controller configured to adjust the respective resistance values of the plurality of variable resistors.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a plating apparatus and a plating method.

Background Art

[0002] In a plating apparatus that performs plating by passing an electric current through a substrate immersed in a plating solution, the current is supplied to the substrate through a plurality of electrical contacts provided at the peripheral edge of the substrate (see, for example, Patent Document 1 (particularly FIG. 9)). In a plating apparatus having such a configuration, in order to make the film thickness of the plating film formed on the substrate uniform over the substrate surface, it is important that substantially equal currents flow through the plurality of electrical contacts at the peripheral edge of the substrate. For such a purpose, it is known to connect variable resistors to the plurality of electrical contacts at the peripheral edge of the substrate and adjust the resistance values of the variable resistors to cause a uniform current to flow through the plurality of electrical contacts (see, for example, Patent Document 1 (particularly paragraph 0059)).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, it is not easy to determine what resistance values should be set for each of the plurality of variable resistors. For example, the contact resistance at each electrical contact may vary, and the film thickness distribution within the substrate surface may show a distribution specific to the plating apparatus.

Means for Solving the Problems

[0005] [Embodiment 1] According to Embodiment 1, a plating apparatus is provided for plating a substrate by passing an electric current from an anode to the substrate, comprising: a plurality of anode-side electrical wirings electrically connected to the anode via a plurality of electrical contacts on the anode; a plurality of substrate-side electrical wirings electrically connected to the substrate via a plurality of electrical contacts on the substrate; a plurality of variable resistors arranged in the middle of the plurality of anode-side electrical wirings or the plurality of substrate-side electrical wirings on at least one of the anode side and the substrate side; and a control unit configured to adjust the resistance value of each of the plurality of variable resistors.

[0006] [Form 2] According to Form 2, in the plating apparatus of Form 1, the control unit is configured to determine the resistance value of each of the multiple variable resistors using a machine learning model that takes the plating thickness at each point on the substrate as input and the resistance value of each of the multiple variable resistors as output, set the determined resistance value of each of the multiple variable resistors and cause the plating apparatus to perform the plating process.

[0007] [Form 3] According to Form 3, in the plating apparatus of Form 2, the machine learning model further includes as input one or more of the following: a current value supplied between the anode and the substrate, a voltage value applied between the anode and the substrate, the energizing time for which current is passed between the anode and the substrate, information regarding the shape of the substrate, and information regarding the characteristics of the plating solution used for plating the substrate.

[0008] [Embodiment 4] According to Embodiment 4, in the plating apparatus of Embodiment 3, the information relating to the shape of the substrate includes one or more of the following: the aperture area of ​​the substrate, the aperture ratio of the substrate, and the thickness of the seed layer formed on the surface of the substrate.

[0009] [Form 5] According to Form 5, in any one of Forms 2 to 4, the machine learning model further includes, as an output, the size value of a mask placed between the anode and the substrate to adjust the electric field between the anode and the substrate.

[0010] [Form 6] According to Form 6, in any one of Forms 2 to 4, the control unit is configured to use the machine learning model to calculate the resistance value of each variable resistor based at least on the target value of the plating film thickness at each point on the substrate, set the calculated resistance value to each of the plurality of variable resistors, perform a plating process in the plating apparatus in which each resistance value has been set to each of the plurality of variable resistors, obtain measured values ​​of the plating film thickness at each point on the substrate after the plating process, use the machine learning model to calculate the resistance value of each variable resistor based at least on the obtained measured values ​​of the plating film thickness at each point on the substrate, and update the machine learning model based on the difference between the resistance value of each variable resistor obtained in the former calculation process and the resistance value of each variable resistor obtained in the latter calculation process.

[0011] [Form 7] According to Form 7, in any one of Forms 1 to 6, the control unit adjusts the resistance values ​​of the plurality of variable resistors such that the sum of the resistance values ​​on each path of the plurality of anode-side electrical wiring or the plurality of substrate-side electrical wiring is substantially equal, regardless of the contact resistance value at each of the plurality of electrical contacts.

[0012] [Embodiment 8] According to Embodiment 8, in the plating apparatus of Embodiment 7, the control unit adjusts the resistance values ​​of the plurality of variable resistors so that substantially equal current flows through each path of the plurality of anode-side electrical wiring or the plurality of substrate-side electrical wiring.

[0013] [Form 9] According to Form 9, in any one of Forms 1 to 8, the control unit adjusts the resistance values ​​of the plurality of variable resistors such that the resistance value of the variable resistor connected to the electrical contact near the central part of the anode is relatively small, and the resistance value of the variable resistor connected to the electrical contact near the peripheral part of the anode is relatively large.

[0014] [Form 10] According to Form 10, in any one of the plating apparatuses from Form 1 to Form 9, the resistance value of each variable resistor is greater than the contact resistance value of the electrical contact.

[0015] [Form 11] According to Form 11, in the plating apparatus of Form 10, the resistance value of each variable resistor is 10 times or more greater than the contact resistance value of the electrical contact.

[0016] [Embodiment 12] According to embodiment 12, there is a method for plating a substrate by passing an electric current from an anode to the substrate in a plating apparatus, wherein the plating apparatus comprises a plurality of anode-side electrical wirings electrically connected to the anode via a plurality of electrical contacts on the anode, a plurality of substrate-side electrical wirings electrically connected to the substrate via a plurality of electrical contacts on the substrate, and a plurality of variable resistors arranged in the middle of the plurality of anode-side electrical wirings or the plurality of substrate-side electrical wirings on at least one of the anode side and the substrate side, and the method is provided, comprising the steps of determining the resistance value of each of the plurality of variable resistors using a machine learning model that takes the plating thickness at each point on the substrate as input and the resistance value of each of the plurality of variable resistors as output, and setting each of the determined resistance values ​​to each of the plurality of variable resistors and causing the plating apparatus to perform a plating process. [Brief explanation of the drawing]

[0017] [Figure 1] This is an overall layout diagram of a plating apparatus according to one embodiment of the present invention. [Figure 2] This is a schematic side cross-sectional view of a plating module in a plating apparatus. [Figure 3] This circuit diagram shows in more detail how the anode and substrate are electrically connected to the rectifier in a plating module. [Figure 4] This diagram shows a control unit for controlling the resistance values ​​of multiple variable resistors. [Figure 5] This figure shows an example implementation of a machine learning model included in a control unit. [Figure 6] It is a flowchart showing the learning phase and the operation phase of a machine learning model. [Figure 7] It is a flowchart showing a method that enables more efficient training of a machine learning model.

Embodiments for Carrying Out the Invention

[0018] 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 by the same reference numerals, and redundant descriptions are omitted.

[0019] FIG. 1 is an overall layout diagram of a plating apparatus 10 according to an embodiment of the present invention. The plating apparatus 10 includes two cassette tables 102, an aligner 104 that aligns the positions of the substrate's orifla (orientation flat) and notch in a predetermined direction, and a spin rinse dryer 106 that dries the substrate after plating by rotating it at high speed. The cassette table 102 mounts a cassette 100 containing a substrate such as a semiconductor wafer. Near the spin rinse dryer 106, a load / unload station 120 for mounting a substrate holder 30 and attaching / detaching the substrate is provided. A transfer robot 122 for transferring the substrate between these units is arranged at the center of these units 100, 104, 106, 120.

[0020] The load / unload station 120 includes a flat mounting plate 152 that is slidable horizontally along a rail 150. Two substrate holders 30 are mounted in parallel on this mounting plate 152 in a horizontal state. After the substrate is transferred between one substrate holder 30 and the transfer robot 122, the mounting plate 152 is slid horizontally, and the substrate is transferred between the other substrate holder 30 and the transfer robot 122.

[0021] The plating apparatus 10 further includes a stocker 124, a pre-wet module 126, a pre-soak module 128, a first rinse module 130a, a blow module 132, a second rinse module 130b, and a plating module 110. In the stocker 124, the substrate holders 30 are stored and temporarily placed. In the pre-wet module 126, the substrate is immersed in pure water. In the pre-soak module 128, the oxide film on the surface of the conductive layer such as the seed layer formed on the surface of the substrate is etched and removed. In the first rinse module 130a, the substrate after pre-soaking is cleaned with a cleaning liquid (such as pure water) together with the substrate holder 30. In the blow module 132, the liquid on the cleaned substrate is drained. In the second rinse module 130b, the substrate after plating is cleaned with a cleaning liquid together with the substrate holder 30. The load / unload station 120, the stocker 124, the pre-wet module 126, the pre-soak module 128, the first rinse module 130a, the blow module 132, the second rinse module 130b, and the plating module 110 are arranged in this order.

[0022] The plating module 110 is configured, for example, by housing a plurality of plating tanks 114 inside an overflow tank 136. In the example of FIG. 1, the plating module 110 has eight plating tanks 114. Each plating tank 114 is configured to house one substrate inside and immerse the substrate in the plating solution held inside to apply plating such as copper plating on the substrate surface.

[0023] The plating apparatus 10 is located on the side of each of these devices and transfers the substrate holder The plating apparatus 10 has a transport device 140 that transports the substrate 30 together with the substrate, for example, employing a linear motor system. This transport device 140 has a first transport device 142 and a second transport device 144. The first transport device 142 is configured to transport the substrate between the load / unload station 120, the stocker 124, the pre-wet module 126, the pre-soak module 128, the first rinse module 130a, and the blow module 132. The second transport device 144 is configured to transport the substrate between the first rinse module 130a, the second rinse module 130b, the blow module 132, and the plating module 110. The plating apparatus 10 may also consist only of the first transport device 142 without the second transport device 144.

[0024] On both sides of the overflow tank 136 are a paddle drive unit 160 and a paddle driven unit 162, which are located inside each plating tank 114 and drive paddles that act as stirring rods to agitate the plating solution inside the plating tank 114.

[0025] An example of a series of plating processes using this plating apparatus 10 will be described. First, a transport robot 122 takes one substrate from a cassette 100 mounted on a cassette table 102 and transports the substrate to an aligner 104. The aligner 104 aligns the positions of orientation flats, notches, etc., to a predetermined direction. The substrate, whose orientation has been aligned by the aligner 104, is then transported by the transport robot 122 to the load / unload station 120.

[0026] At the load / unload station 120, the two substrate holders 30 that were housed in the stocker 124 are simultaneously grasped by the first transport device 142 of the transport device 140 and transported to the load / unload station 120. The two substrate holders 30 are then simultaneously placed horizontally on the mounting plate 152 of the load / unload station 120. In this state, the transport robot 122 transports substrates to each substrate holder 30 and holds the transported substrates in the substrate holders 30.

[0027] Next, the substrate holders 30 holding the substrates are simultaneously gripped by the first transport device 142 of the transport device 140 and stored in the pre-wet module 126. Then, the substrate holders 30 holding the substrates processed in the pre-wet module 126 are transported by the first transport device 142 to the pre-soak module 128, where the oxide film on the substrates is etched. Subsequently, the substrate holders 30 holding these substrates are transported to the first rinse module 130a, where the surface of the substrates is washed with pure water stored in the first rinse module 130a.

[0028] The substrate holder 30, which holds the substrate after rinsing, is transported from the first rinsing module 130a to the plating module 110 by the second transport device 144 and placed in the plating tank 114 filled with plating solution. The second transport device 144 repeats the above procedure sequentially, placing the substrate holders 30 holding the substrates into each of the plating tanks 114 of the plating module 110 one after another.

[0029] In each plating tank 114, a plating voltage is applied between the anode (not shown) inside the plating tank 114 and the substrate, and at the same time, the paddles are moved back and forth parallel to the surface of the substrate by the paddle drive unit 160 and the paddle driven unit 162, thereby plating the surface of the substrate.

[0030] After the plating is complete, the substrate holders 30 holding the plated substrates are simultaneously grasped by the second transport device 144 and transported to the second rinse module 130b, where they are immersed in the pure water contained in the second rinse module 130b to wash the surface of the substrates with pure water. Next, the substrate holders 30 are transported to the blow module 132 by the second transport device 144, where any water droplets adhering to the substrate holders 30 are removed by blowing air or the like. After that, the substrate holders 30 are transported to the load / unload station 120 by the first transport device 142.

[0031] At the load / unload station 120, the processed substrates are removed from the substrate holder 30 by the transport robot 122 and transported to the spin rinse dryer 106. The spin rinse dryer 106 dries the plated substrates by rotating them at high speed. The dried substrates are returned to the cassette 100 by the transport robot 122.

[0032] Figure 2 is a schematic side cross-sectional view of the plating module 110 described above. As shown in the figure, the plating module 110 includes an anode holder 220 configured to hold an anode 221, a substrate holder 30 configured to hold a substrate W, a plating tank 114 containing a plating solution Q containing additives, and an overflow tank 136 that receives and discharges the plating solution Q that overflows from the plating tank 114. The plating tank 114 and the overflow tank 136 are separated by a partition wall 255. The anode holder 220 and the substrate holder 30 are housed inside the plating tank 114. As previously mentioned, the substrate holder 30 holding the substrate W is transported by the second transport device 144 (see Figure 1) and housed in the plating tank 114.

[0033] Although only one plating tank 114 is shown in Figure 2, as mentioned above, the plating module 110 may have multiple plating tanks 114 with the same configuration as shown in Figure 2.

[0034] The anode 221 is electrically connected to the positive terminal 271 of the rectifier 270 via an electrical contact (not shown) on the anode 221 and an electrical terminal 223 provided on the anode holder 220. The substrate W is electrically connected to the negative terminal 272 of the rectifier 270 via an electrical contact 242 on the substrate W and an electrical terminal 243 provided on the substrate holder 30. The rectifier 270 is configured to supply a plating current between the anode 221 connected to the positive terminal 271 and the substrate W connected to the negative terminal 272, and to measure the applied voltage between the positive terminal 271 and the negative terminal 272.

[0035] The anode holder 220, which holds the anode 221, and the substrate holder 30, which holds the substrate W, are immersed in the plating solution Q in the plating tank 114, and are positioned opposite each other so that the anode 221 and the plated surface W1 of the substrate W are substantially parallel. While the anode 221 and the substrate W are immersed in the plating solution Q in the plating tank 114, a plating current is supplied from the rectifier 270. As a result, metal ions in the plating solution Q are reduced on the plated surface W1 of the substrate W, and a film is formed on the plated surface W1.

[0036] The anode holder 220 has an anode mask 225 for adjusting the electric field between the anode 221 and the substrate W. The anode mask 225 is a substantially plate-shaped member made of, for example, a dielectric material, and is provided on the front surface of the anode holder 220 (the surface facing the substrate holder 30). That is, the anode mask 225 is positioned between the anode 221 and the substrate holder 30. The anode mask 225 has a first opening 225a in its approximate center through which the current flowing between the anode 221 and the substrate W passes. The diameter of the opening 225a is preferably smaller than the diameter of the anode 221. The anode mask 225 may be configured to allow adjustment of the diameter of the opening 225a.

[0037] The plating module 110 further includes a regulation plate 230 for adjusting the electric field between the anode 221 and the substrate W. The regulation plate 230 is a substantially plate-shaped member made of, for example, a dielectric material, and is placed between the anode mask 225 and the substrate holder 30 (substrate W). The regulation plate 230 has a second opening 230a through which the current flowing between the anode 221 and the substrate W passes. The diameter of the opening 230a is preferably smaller than the diameter of the substrate W. The regulation plate 230 has an opening 23 The diameter of 0a may be configured to be adjustable. Furthermore, a paddle (not shown) is placed between the regulation plate 230 and the substrate holder 30 (substrate W) to serve as a stirring rod for agitating the plating solution Q in the plating tank 114.

[0038] The plating tank 114 has a plating solution supply port 256 for supplying the plating solution Q into the tank. The overflow tank 136 has a plating solution outlet 257 for discharging the plating solution Q that has overflowed from the plating tank 114. The plating solution supply port 256 is located at the bottom of the plating tank 114, and the plating solution outlet 257 is located at the bottom of the overflow tank 136.

[0039] When the plating solution Q is supplied to the plating tank 114 from the plating solution supply port 256, the plating solution Q overflows from the plating tank 114, passes over the partition wall 255, and flows into the overflow tank 136. The plating solution Q that flows into the overflow tank 136 is discharged from the plating solution outlet 257, and impurities are removed by a filter or the like in the plating solution circulation device 258. The plating solution Q from which impurities have been removed is supplied to the plating tank 114 via the plating solution supply port 256 by the plating solution circulation device 258.

[0040] Figure 3 is a circuit diagram showing in more detail how the anode 221 and the substrate W are electrically connected to the rectifier 270 in the plating module 110. The anode 221 has a plurality of electrical contacts 222 on its back surface (the surface opposite to the surface facing the substrate W). The plurality of electrical contacts 222 may be arranged over the entire back surface of the anode 221, from the center to the periphery. Alternatively, the plurality of electrical contacts 222 may be arranged only on a portion of the back surface of the anode 221 (e.g., the periphery). In addition to the back surface of the anode 221, or instead of the back surface of the anode 221, electrical contacts 222 may be arranged on the periphery of the front surface of the anode 221 (the surface facing the substrate W). Similarly, the substrate W has a plurality of electrical contacts 242 on its back surface (the surface opposite to the surface facing the anode 221). The plurality of electrical contacts 242 may be arranged over the entire back surface of the substrate W, from the center to the periphery. The back surface of the substrate W may be covered with an insulating material such as an oxide film, except for the peripheral edges. In such cases, the multiple electrical contacts 242 may be arranged only on the peripheral edges of the back surface of the substrate W, or, if possible, the electrical contacts 242 may be arranged on the peripheral edges of the front surface of the substrate W (the surface facing the anode 221).

[0041] Each of the multiple electrical contacts 222 on the anode 221 is connected to the positive terminal 271 of the rectifier 270 by an electrical wire (hereinafter referred to as anode-side electrical wire) 226. Similarly, each of the multiple electrical contacts 242 on the substrate W is connected to the negative terminal 272 of the rectifier 270 by an electrical wire (hereinafter referred to as substrate-side electrical wire) 246. In this way, the anode 221 is electrically connected to the rectifier 270 via the multiple electrical contacts 222 and the multiple anode-side electrical wires 226, and the substrate W is electrically connected to the rectifier 270 via the multiple electrical contacts 242 and the multiple substrate-side electrical wires 246. As a result, the supply current from the rectifier 270 flows to the anode 221 and the substrate W via the multiple electrical contacts 222 and 242. Alternatively, multiple rectifiers 270 may be installed to supply plating current from each rectifier 270 to each individual electrical contact 222 and 242, or to each group of several electrical contacts 222 and 242 located in close proximity.

[0042] A variable resistor 228 is inserted in the middle of each anode-side electrical wire 226 connecting one electrical contact 222 on anode 221 to the positive terminal 271 of rectifier 270. Each variable resistor 228 allows for individual adjustment of the electrical resistance between rectifier 270 and each electrical contact 222 on anode 221. Similarly, a variable resistor 248 is inserted in the middle of each board-side electrical wire 246 connecting one electrical contact 242 on board W to the negative terminal 272 of rectifier 270. Each variable resistor 248 allows for individual adjustment of the electrical resistance between rectifier 270 and each electrical contact 242 on board W. Note that in Figure 3, for the sake of simplification of the diagram, multiple a Only a portion of the node-side electrical wiring 226 and variable resistor 228, as well as some of the multiple board-side electrical wiring 246 and variable resistor 248, are shown; the rest are omitted from the illustration.

[0043] Here, the contact resistance at each electrical contact 242 on the substrate W (the contact resistance between the electrode provided at the tip of the substrate-side electrical wiring 246 and the substrate surface) may differ for each electrical contact 242. Similarly, the contact resistance at each electrical contact 222 on the anode 221 may not be uniform between contacts. In these cases, the current flowing through each substrate-side electrical wiring 246 will vary between multiple current paths, resulting in an uneven current distribution within the plane of the substrate W, which may reduce the uniformity of the plating film thickness formed on the substrate W. In addition, if the current flowing through each anode-side electrical wiring 226 varies between current paths, the electric field distribution in the plating solution Q between the anode 221 and the substrate W will become uneven, which also affects the potential on the plating surface of the substrate W and, consequently, the uniformity of the plating film thickness.

[0044] By individually setting the resistance values ​​of the variable resistors 228 and 248, it is possible to control the film thickness distribution of the plating film formed on the substrate W. For example, by setting the resistance value of the variable resistor 248 to compensate for the difference in contact resistance at each electrical contact 242 on the substrate W, the electrical resistance value from the rectifier 270 to each electrical contact 242 can be made equal in all current paths on the substrate W side. Similarly, by setting the resistance value of the variable resistor 228 to compensate for the difference in contact resistance at each electrical contact 222 on the anode 221, the electrical resistance value from the rectifier 270 to each electrical contact 222 can be made equal in all current paths on the anode 221 side. As a result, the current flowing through each substrate-side electrical wiring 246 and / or each anode-side electrical wiring 226 becomes uniform between the wirings, and consequently, the uniformity of the film thickness of the plating film formed on the substrate W can be improved.

[0045] The setting of the resistance values ​​of the variable resistors 228 and 248 is not limited to making the current flowing through each substrate-side electrical wiring 246 and / or each anode-side electrical wiring 226 uniform. For example, in a configuration where the electrical contacts 242 are located only at the periphery of the substrate W, current does not flow easily near the center of the substrate W due to the resistance of the substrate W itself or the resistance of the seed layer on the substrate W between the center and the periphery of the substrate W. Therefore, in such a configuration, the plating film thickness in the center of the substrate W tends to be thinner than at the periphery. By setting the variable resistor 228 on the anode 221 side such that the resistance value decreases as the variable resistor 228 is closer to the center of the anode 221, the decrease in current flowing into the center of the substrate W can be suppressed, and the current distribution within the substrate surface can be made uniform, thereby improving the uniformity of the plating film thickness formed on the substrate W.

[0046] Furthermore, it is preferable that the resistance values ​​of the variable resistors 228 and 248 are greater than the contact resistance of the electrical contacts 222 and 242. For example, the resistance value of each variable resistor 228 and 248 may be about 10 times or more the contact resistance of the electrical contacts 222 and 242 (for example, the average value of all contact resistances). This reduces the influence of variations in the contact resistance of the electrical contacts 222 and 242, making it easier to control the balance of the current flowing through each electrical contact 222 and 242. However, the resistance values ​​of the variable resistors 228 and 248 must be smaller than a predetermined upper limit so that the output voltage of the rectifier 270 does not exceed the rated value for the set output current of the rectifier 270.

[0047] Furthermore, since multiple variable resistors 228 and 248 are connected in parallel to the rectifier 270, under the condition of constant plating current (i.e., assuming that the combined resistance between the rectifier 270 and the anode 221 and between the rectifier 270 and the substrate W is constant), the more variable resistors 228 and 248 there are, the larger the resistance value of each individual variable resistor 228 and 248 becomes. Therefore, the more variable resistors 228 and 248 there are, the smaller the influence of variations in the contact resistance of electrical contacts 222 and 242 on the resistance values ​​of the variable resistors 228 and 248 becomes, and as a result This makes it easier to control the balance of the current values ​​flowing through each electrical contact 222, 242.

[0048] Figure 4 shows a control unit for controlling the resistance values ​​of multiple variable resistors 228, 248. The control unit 400 may be a computer equipped with a processor and memory (not shown). In one embodiment, the control unit 400 is configured to control the resistance values ​​of the multiple variable resistors 228, 248 using a machine learning model 420. For example, the machine learning model 420 may be implemented in the control unit 400 by the processor reading and executing a program (computer executable instruction) stored in the memory of the control unit (computer) 400. The machine learning model 420 is trained using a large amount of training data and is configured to determine the resistance values ​​of each variable resistor 228, 248 necessary to achieve the optimal or desired film thickness distribution of the plating film formed on the substrate W. The control unit 400 is configured to set the respective resistance values ​​determined by the machine learning model 420 to each variable resistor 228, 248.

[0049] Figure 5 shows an example implementation of the machine learning model 420. The machine learning model 420 is composed of a neural network 421 comprising an input layer 422 having multiple input nodes 423, an intermediate layer 424 consisting of one or more layers, each having multiple nodes 425, and an output layer 426 having multiple output nodes 427. Each node is connected to multiple nodes in the layer to which it belongs, with an intensity characterized by weighting parameters. In the learning (training) phase, a trained machine learning model 420 is created by updating the weighting parameters between each node using a large amount of training data. In the operation (inference / prediction) phase, the resistance values ​​of each variable resistor 228, 248 are determined using the trained machine learning model 420.

[0050] As shown in Figure 5, the input node 423 of the machine learning model 420 is associated with the plating film thickness values ​​at multiple coordinates 1 to M on the substrate W, and the output node 427 of the machine learning model 420 is associated with the resistance values ​​of the variable resistors 248 connected to each electrical contact 1 to N1 (electrical contact 242) on the substrate W and the resistance values ​​of the variable resistors 228 connected to each electrical contact 1 to N2 (electrical contact 222) on the anode 221. Note that the positions of the multiple coordinates 1 to M are independent of the positions of each electrical contact 222, 242, and the number M may be different from the number of electrical contacts N1, N2. As mentioned above, the resistance values ​​of each variable resistor 228, 248 affect the film thickness distribution of the plating film formed on the substrate W. Therefore, by configuring the machine learning model 420 to have the film thickness distribution (i.e., the film thickness value at each coordinate) as input and the resistance values ​​of each variable resistor 228, 248 as output, it is possible to infer and determine the resistance values ​​of each variable resistor 228, 248 necessary to achieve the desired film thickness distribution. Then, by setting the variable resistors 228 and 248 to the resistance values ​​determined in this way and performing the plating process, a plating film with a uniform thickness distribution can be formed on the substrate W.

[0051] Other data besides the plating film thickness value may be associated with the input node 423 of the machine learning model 420. For example, when a constant current is output from the rectifier 270, the output voltage of the rectifier 270 changes when the resistance values ​​of the variable resistors 228 and 248 change, and the output voltage of the rectifier 270 also changes depending on the magnitude of the constant current output from the rectifier 270. Furthermore, the output current value and output voltage value from the rectifier 270 as design values ​​are related to the combined resistance value between the positive terminal 271 and the negative terminal 272 of the rectifier 270 (including the resistance values ​​of the variable resistors 228 and 248, as well as the contact resistance at the electrical contacts 222 and 242, the wiring resistance of the anode-side electrical wiring 226 and the substrate-side electrical wiring 246, the chemical resistance of the plating solution Q, and the polarization resistance on the surface of the substrate W and anode 221). Furthermore, the film thickness values ​​at each point on the substrate surface of the plating film formed on the substrate W, and the average film thickness value on the substrate surface are determined by the magnitude of the constant current supplied from the rectifier 270, the distribution of current flowing through each electrical contact 222, 242, the energizing time for outputting the constant current from the rectifier 270, and the substrate W The results vary depending on the shape of the substrate (aperture area of ​​the substrate W, aperture ratio of the substrate W, thickness of the seed layer formed on the surface of the substrate W, etc.) and the characteristics of the plating solution Q (concentration, temperature, chemical components, etc.). The aperture area of ​​the substrate W refers to the area of ​​the front surface of the substrate W that is not covered by an insulating film such as an oxide film or resist (i.e., the area where the plating film is actually formed), and the aperture ratio of the substrate W is defined as the ratio of the aperture area to the area of ​​the front surface of the substrate W.

[0052] Therefore, as shown in the machine learning model 420 in Figure 5, it is advantageous to further associate one or more of the following with the input node 423: (1) the current value supplied between the anode 221 and the substrate W, (2) the voltage value applied between the anode 221 and the substrate W, (3) the energizing time for which current is passed between the anode 221 and the substrate W, (4) information regarding the shape of the substrate W (aperture area of ​​the substrate W, aperture ratio of the substrate W, thickness of the seed layer formed on the surface of the substrate W, etc.), and (5) information regarding the characteristics of the plating solution Q (concentration, temperature, chemical components of the plating solution Q, etc.). This allows for more accurate inference and determination of the resistance values ​​of each variable resistor 228, 248.

[0053] The resistance values ​​of the variable resistors 228 and 248 associated with the output node 427 of the machine learning model 420 are controlled by the control unit 400. That is, the control unit 400 operates to determine the optimal resistance values ​​of each variable resistor 228 and 248 according to the given conditions (i.e., the input values ​​to the input node 423). In addition to the resistance values ​​of the variable resistors 228 and 248, the control unit 400 may also control other elements. For example, the anode mask 225 and regulation plate 230 (see Figure 2) placed between the anode 221 and the substrate W affect the electric field distribution in the plating solution Q between the anode 221 and the substrate W, and consequently, the uniformity of the plating film thickness formed on the substrate W. Therefore, as in the machine learning model 420 in Figure 5, it is possible to further associate the output node 427 with one or both of the size (aperture diameter) of the opening 225a of the anode mask 225 and the size of the opening 230a of the regulation plate 230. By applying the aperture diameter determined using such a machine learning model 420 to the anode mask 225 and / or regulation plate 230, the uniformity of the film thickness of the plating film formed on the substrate W can be further improved.

[0054] Note that the sizes of the opening 225a of the anode mask 225 and the opening 230a of the regulation plate 230 may be associated with the input node 423 instead of the output node 427. If the machine learning model 420 is configured in this way, the optimal resistance values ​​of each variable resistor 228, 248 can be determined by the machine learning model, not only according to each of the input parameters (1) to (5) above, but also according to the sizes of the opening 225a of the anode mask 225 and the opening 230a of the regulation plate 230.

[0055] Figure 6 is a flowchart showing the learning and operation phases of the machine learning model 420. In the learning phase, a large amount of training data is required to train the machine learning model 420. This training data can be prepared by performing plating processes under various conditions in the plating module 110 (step 602). For example, the resistance values ​​of each variable resistor 228, 248, the aperture size of the electric field adjustment mask (anode mask 225 and regulation plate 230), the output current value from the rectifier 270 and the energizing time for which the current is passed, the shape of the substrate W, and the characteristics of the plating solution Q are each set to certain conditions, and the plating process is performed. Then, the output voltage value of the rectifier 270 is measured during the plating process, and after the plating process, the plating film thickness values ​​at coordinates 1 to M on the substrate W are measured. Each of these set values ​​and measured values ​​constitutes one set of training data. By setting multiple different conditions in the plating module 110 and performing plating processes and measurements in the same way, a large number of sets of training data can be created.

[0056] Next, one set of the created training data is provided to the input node 423 and output node 427 of the machine learning model 420 (step 604), and the weighting parameters between each node are updated (step 606). Steps 604 and 606 are repeated for many sets of training data, thereby training the machine learning model 420. Once the training has progressed to a predetermined stage, the machine learning model 420 can be used in the operational phase.

[0057] In the operational phase, the target plating film thickness distribution (i.e., the plating film thickness at coordinates 1 to M on the substrate W) and the settings of the plating module 110 (such as the output current value of the rectifier 270) are input to the input node 423 of the machine learning model 420 (step 608). For example, these inputs may be made by the operator of the plating apparatus 10 via the user interface of the control unit (computer) 400. Then, in response to the data input to the input node 423, the machine learning model 420 can output from the output node 427 the resistance values ​​of each variable resistor 228, 248 and the aperture sizes of the anode mask 225 and regulation plate 230 required to achieve the target plating film thickness distribution (step 610). The resistance values ​​determined in this way by the machine learning model 420 are set to each variable resistor 228, 248 by the control unit 400 (and, if necessary, the determined aperture sizes are set to the anode mask 225 and regulation plate 230) (step 612).

[0058] Next, in the plating module 110, where each variable resistor 228, 248 (and the aperture size of the anode mask 225 and regulation plate 230) is set to the optimal value, plating is performed on the substrate W. This makes it possible to form a plating film with a target film thickness distribution on the substrate W. If it is possible to measure the plating film thickness at each coordinate 1 to M on the substrate W in real time during the plating process, the above learning phase and operation phase can be repeated using the film thickness data measured at each time point, thereby allowing for more precise control of the film thickness distribution of the plating film formed on the substrate W.

[0059] Figure 7 is a flowchart illustrating a method for more efficiently training the machine learning model 420 by performing training and operation of the machine learning model 420 in parallel. First, in step 702, a machine learning model 420 is prepared in which the weighting parameters between each node are set to their initial values. The machine learning model 420 in which the weighting parameters are set to their initial values ​​may be, for example, a machine learning model 420 that has been trained to some extent according to the training phase of the flowchart in Figure 6 described above. Alternatively, the resistance values ​​of each variable resistor 228, 248 may be calculated from the target film thickness distribution, current value, voltage value, energizing time, etc., by predetermined theoretical calculations or simulations, and the machine learning model 420 may be pre-trained using this data to obtain a machine learning model 420 in which the weighting parameters are set to their initial values.

[0060] Next, in step 704, the target plating film thickness distribution (i.e., the plating film thickness at coordinates 1 to M on the substrate W) and the settings of the plating module 110 (output current value of the rectifier 270, output voltage value, energizing time, shape of the substrate W, and characteristics of the plating solution Q) are input to the input node 423 of the machine learning model 420. In step 706, the machine learning model 420 outputs the resistance values ​​of each variable resistor 228 and 248, and the aperture sizes of the anode mask 225 and regulation plate 230, from the output node 427, according to the data input to the input node 423. In step 708, the control unit 400 sets the resistance values ​​determined in step 706 to each variable resistor 228 and 248, and sets the aperture sizes to the anode mask 225 and regulation plate 230. These steps 704 to 708 correspond to steps 608 to 612 in the flowchart of Figure 6 mentioned above.

[0061] Next, in step 710, a plating process is performed on the plating module 110 to which the settings described above have been applied. In step 712, the output current value, output voltage value, energizing time of the rectifier 270 during the plating process, and the film thickness values ​​of the plating film formed on the substrate W by this plating process at coordinates 1 to M on the substrate W are measured. Then, in step 714, each measurement value measured in step 712 is input to the input node 423 of the machine learning model 420. In step 716, the machine learning model 420 outputs the resistance values ​​of each variable resistor 228, 248 from the output node 427 according to the data input to the input node 423.

[0062] In step 706, the resistance values ​​of each variable resistor 228 and 248 calculated by the machine learning model 420 correspond to the target plating film thickness distribution in the plating process, while the resistance values ​​of each variable resistor 228 and 248 calculated in step 716 correspond to the plating film thickness distribution actually obtained by performing the plating process. In step 718, the control unit 400 calculates the difference between the resistance values ​​of each variable resistor 228 and 248 calculated in step 706 and the resistance values ​​of each variable resistor 228 and 248 calculated in step 716, and updates the weighting parameters between each node of the machine learning model 420 based on this difference. For example, backpropagation can be used to update these weighting parameters. This improves the weighting parameters between each node of the machine learning model 420 to match the actually obtained plating film thickness distribution, and as a result, the machine learning model 420 can calculate more accurate resistance values ​​for each variable resistor 228 and 248.

[0063] The cycle of steps 704-718 can be repeated any number of times, and the machine learning model 420 can be further optimized with each iteration.

[0064] While embodiments of the present invention have been described above based on several examples, the embodiments described above are for the purpose of facilitating understanding of the present invention and do not limit it. For example, the plating apparatus 10 described with reference to Figures 1 and 2 is a so-called dip-type plating apparatus, but the present invention can also be applied to a so-called cup-type plating apparatus in which a substrate such as a semiconductor wafer is placed horizontally with the surface to be plated facing downwards (face down), and the plating solution is sprayed up from below to plate the substrate. The present invention can be modified and improved without departing from its spirit, and of course, the present invention includes its equivalents. Furthermore, any combination or omission of each component described in the claims and specification is possible to the extent that at least a part of the above-mentioned problems can be solved, or at least a part of the effects can be achieved. [Explanation of Symbols]

[0065] 10 Plating equipment 30 PCB holders 100 cassettes 102 Cassette Table 104 Alaina 106 Spin Rinse Dryer 110 Plating Module 114 Plating tank 120 Load / Unload Stations 122 Transport robots 124 Stocker 126 Pre-wet module 128 Pre-soak Modules 130a First Rinse Module 130b Second rinse module 132 Blow Module 136 Overflow tank 140 Conveyor equipment 142 First Conveyor Device 144 Second conveying device 150 rails 152 Mounting plate 160 Paddle Drive Unit 162 Paddle Driven Section 220 Anode Holder 221 Anodes 222 Electrical contacts 223 Electrical terminals 225 Anode Mask 225a First opening 226 Anode-side electrical wiring 228 Variable resistor 230 Regulation Plate 230a Second opening 242 Electrical contacts 243 Electrical terminals 246 Circuit board side electrical wiring 248 Variable resistor 255 Partition wall 256 Plating solution supply port 257 Plating solution outlet 258 Plating solution circulation device 270 Rectifier 271 Positive terminal 272 negative terminal 400 control units 420 Machine Learning Models 421 Neural Networks 422 Input Layer 423 Input Nodes 424 Middle layer 425 nodes 426 Output Layer 427 Output Nodes Q Plating solution W board W1 Plating surface

Claims

1. A plating apparatus for plating a substrate by passing an electric current from the anode to the substrate, Multiple anode-side electrical wirings electrically connected to the anode via multiple electrical contacts on the anode, Multiple electrical wirings on the substrate that are electrically connected to the substrate via multiple electrical contacts on the substrate, A rectifier connected to the plurality of anode-side electrical wirings and the plurality of substrate-side electrical wirings, which supplies plating current between the anode and the substrate, Multiple variable resistors are placed in the middle of the multiple anode-side electrical wirings, A control unit configured to adjust the resistance value of each of the plurality of variable resistors, A plating apparatus equipped with the following features.

2. The plating apparatus according to claim 1, wherein the control unit adjusts the resistance value of each of the plurality of variable resistors such that the sum of the resistance values ​​along each path of the plurality of anode-side electrical wiring or the plurality of substrate-side electrical wiring is substantially equal, regardless of the contact resistance value at each of the plurality of electrical contacts.

3. The plating apparatus according to claim 2, wherein the control unit adjusts the resistance value of each of the plurality of variable resistors so that substantially equal current flows through each of the plurality of anode-side electrical wirings or the plurality of substrate-side electrical wirings.

4. The plating apparatus according to any one of claims 1 to 3, wherein the control unit adjusts the resistance values ​​of the plurality of variable resistors such that the resistance value of the variable resistor connected to the electrical contact near the central part of the anode is relatively small, and the resistance value of the variable resistor connected to the electrical contact near the peripheral part of the anode is relatively large.

5. The plating apparatus according to any one of claims 1 to 4, wherein the resistance value of each of the variable resistors is greater than the contact resistance value of the electrical contacts.

6. The plating apparatus according to claim 5, wherein the resistance value of each of the variable resistors is 10 times or more greater than the contact resistance value of the electrical contacts.

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