Substrate processing method and substrate processing system

Abstract

The present invention provides a substrate processing method and a substrate processing system for appropriately etching the target material on a substrate. [Solution] A substrate processing method comprising: determining etching conditions from a predetermined target etching amount distribution, including etching solution supply conditions when supplying an etching solution to the target to be etched on the substrate, and pure water supply conditions when supplying pure water to the target to be etched simultaneously with the etching solution; and etching the target to be etched based on the etching conditions. In determining the etching conditions, the etching conditions include optimal etching solution supply conditions, and the optimal etching solution supply conditions are determined by an optimization method from the target etching amount distribution using a plurality of previously acquired learning data that include the radial etching amount distribution of the target to be etched when the target to be etched with a plurality of different learning etching conditions including the etching solution supply conditions.

Description

Technical Field

[0001] The present disclosure relates to a substrate processing method and a substrate processing system.

Background Art

[0002] Patent Document 1 discloses a substrate processing method including supplying an etching solution containing hydrofluoric acid and phosphoric acid to the surface of a substrate to etch the surface, recovering the etching solution after etching, and selecting and adding at least hydrofluoric acid or phosphoric acid to the etching solution recovered after etching to adjust the composition ratio of the etching solution.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technology according to the present disclosure appropriately etches an etching target of a substrate.

Means for Solving the Problems

[0005] One aspect of the present disclosure is a substrate processing method comprising: determining etching conditions from a predetermined target etching amount distribution, including etching solution supply conditions for supplying an etching solution to an etching target on a substrate, and pure water supply conditions for supplying pure water simultaneously with the etching solution to the etching target; and etching the etching target by simultaneously supplying the etching solution and the pure water to the etching target based on the etching conditions, wherein the etching conditions include optimal etching solution supply conditions, and the optimal etching solution supply conditions are determined by an optimization method from the target etching amount distribution using a plurality of learning data acquired in advance, which include the radial etching amount distribution of the etching target when the etching target is etched with a plurality of different learning etching conditions including the etching solution supply conditions. [Effects of the Invention]

[0006] According to this disclosure, the target of etching on the substrate can be appropriately etched. [Brief explanation of the drawing]

[0007] [Figure 1] This is a plan view showing the schematic configuration of the wafer processing system. [Figure 2] This is a side view showing a schematic configuration of the etching apparatus. [Figure 3] This is an explanatory diagram showing how the nozzle moves in the radial direction. [Figure 4] This is an explanatory diagram showing the general configuration of the back rinse nozzle and an example of one state when pure water is supplied. [Figure 5] This is an explanatory diagram illustrating a schematic example of the configuration of an etching solution supply device. [Figure 6] This is a flowchart showing the main steps in wafer processing. [Figure 7] This is a flowchart showing the main steps in determining the optimal etching conditions. [Figure 8]This is an explanatory diagram illustrating the general etching process based on an example of combined supply conditions. [Figure 9] This is an explanatory diagram illustrating the general etching process based on an example of combined supply conditions. [Figure 10] This is an explanatory diagram illustrating the etching process based on another example of combined supply conditions. [Figure 11] This is an explanatory diagram illustrating the etching process based on another example of combined supply conditions. [Figure 12] This is an explanatory diagram showing an example of the thickness distribution of the target shape or a feasible shape. [Figure 13] This flowchart shows the main steps involved in the recovery and reuse of etching solutions and diluted etching solutions. [Figure 14] This is an explanatory diagram illustrating the general route for the recovery and reuse of etching solution. [Figure 15] This is a flowchart showing the main steps in the recovery and reuse process of etching solution. [Figure 16] This is a flowchart showing the main steps in the recovery and reuse process of diluted etching solution. [Figure 17] This is an explanatory diagram showing an example of the condition of the inner cup during the recovery and reuse process of diluted etching solution. [Figure 18] This is an explanatory diagram illustrating the general route for one step in the recovery and reuse process of diluted etching solution. [Figure 19] This is an explanatory diagram illustrating the general route of another step in the recovery and reuse process of diluted etching solution. [Modes for carrying out the invention]

[0008] Hereinafter, the wafer processing system as a substrate processing system and the wafer processing method as a substrate processing method according to this embodiment will be described with reference to the drawings. In this specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant explanations will be omitted.

[0009] In the wafer processing system 1 according to this embodiment, a process for improving the in-plane uniformity of the thickness is performed on a wafer W as a substrate obtained by cutting out from an ingot. Hereinafter, the cut surface of the wafer W is referred to as a first surface Wa and a second surface Wb. The first surface Wa is the surface on the opposite side of the second surface Wb. Also, the first surface Wa and the second surface Wb may be collectively referred to as the surface of the wafer W.

[0010] As shown in FIG. 1, the wafer processing system 1 has a configuration in which a loading / unloading station 2 and a processing station 3 are integrally connected. In the loading / unloading station 2, for example, a hoop F capable of accommodating a plurality of wafers W is loaded / unloaded to / from the outside. The processing station 3 includes various processing apparatuses for performing desired processing on the wafer W.

[0011] The loading / unloading station 2 is provided with a hoop mounting table 10 for mounting a plurality of, for example, three hoops F. Further, on the negative X-axis side of the hoop mounting table 10, a wafer transfer device 20 is provided adjacent to the hoop mounting table 10. The wafer transfer device 20 is configured to be movable on a transfer path 21 extending in the Y-axis direction. Also, the wafer transfer device 20 has, for example, two transfer arms 22 for holding and transferring the wafer W. Each transfer arm 22 is configured to be movable in the horizontal direction, the vertical direction, around the horizontal axis, and around the vertical axis. Note that the configuration of the transfer arm 22 is not limited to this embodiment and can take any configuration. And the wafer transfer device 20 is configured to be able to transfer the wafer W to / from the hoop F on the hoop mounting table 10 and a transition device 30 described later.

[0012] In the loading / unloading station 2, on the negative X-axis side of the wafer transfer device 20, a transition device 30 for transferring the wafer W to / from the processing station 3 is provided adjacent to the wafer transfer device 20.

[0013] Processing station 3 is provided with, for example, three processing blocks G1 to G3. The first processing block G1, the second processing block G2, and the third processing block G3 are arranged in this order from the positive X-axis side (towards the loading / unloading station 2) to the negative X-axis side.

[0014] The first processing block G1 is equipped with an etching apparatus 40, a thickness measuring device 50, an inversion device 51, and a wafer transport device 60. The etching apparatus 40, the thickness measuring device 50, and the inversion device 51 are arranged in a stacked configuration. However, the number and arrangement of the etching apparatus 40, the thickness measuring device 50, and the inversion device 51 are not limited to this.

[0015] The etching apparatus 40 etches the silicon (Si) on the first surface Wa or the second surface Wb after grinding by the grinding apparatus 90 described later. Multiple etching apparatuses 40 may be provided to improve the throughput of wafer processing. The configuration of the etching apparatus 40 will be described later.

[0016] The thickness measuring device 50, in one example, comprises a measuring unit (not shown) and a calculation unit (not shown). The measuring unit includes sensors that measure the thickness of the wafer W after etching at multiple points. The measuring unit can measure the thickness of the wafer W at any reference point on the wafer W. The calculation unit obtains the thickness distribution of the wafer W from the measurement results (thickness of the wafer W) obtained by the measuring unit, and further calculates the thickness deviation (TTV: Total Thickness Variation) of the wafer W. The thickness deviation of the wafer W is the maximum value of the difference between the thickness of the target shape and the measured thickness. Note that the calculation of the thickness distribution and thickness deviation of the wafer W may be performed by the control device 130 described later instead of the calculation unit. In other words, the calculation unit (not shown) may be provided within the control device 130 described later. Note that the configuration of the thickness measuring device 50 is not limited to this and can be configured arbitrarily.

[0017] The inversion device 51 inverts the first surface Wa and the second surface Wb of the wafer W in the vertical direction. The configuration of the inversion device 51 is arbitrary.

[0018] The wafer transfer device 60 is located on the negative X-axis side of the transition device 30. The wafer transfer device 60 has, for example, two transfer arms 61 that hold and transfer the wafer W. Each transfer arm 61 is configured to be movable in the horizontal direction, vertical direction, around the horizontal axis, and around the vertical axis. The wafer transfer device 60 is configured to transfer the wafer W to the transition device 30, etching device 40, thickness measuring device 50, inversion device 51, cleaning device 70 (described later), thickness measuring device 71 (described later), buffer device 72 (described later), and inversion device 73 (described later).

[0019] The second processing block G2 is equipped with a cleaning device 70, a thickness measuring device 71, a buffer device 72, an inversion device 73, and a wafer transport device 80. The cleaning device 70, the thickness measuring device 71, the buffer device 72, and the inversion device 73 are arranged in a stacked configuration. However, the number and arrangement of the cleaning device 70, the thickness measuring device 71, the buffer device 72, and the inversion device 73 are not limited to this.

[0020] The cleaning device 70 cleans at least the first surface Wa or the second surface Wb after grinding in the grinding device 90 described later.

[0021] In one example, the thickness measuring device 71 has the same configuration as the thickness measuring device 50 described above. However, the configuration of the thickness measuring device 71 is not limited to this and can be configured arbitrarily.

[0022] The buffer device 72 temporarily holds the wafer W before processing, which is being transferred from the first processing block G1 to the second processing block G2. The configuration of the buffer device 72 is arbitrary. The buffer device 72 may also have an alignment mechanism (not shown) that adjusts at least one of the central position of the wafer W relative to the chucks 93a and 93b described later, or the horizontal orientation of the wafer W.

[0023] The inversion device 73 inverts the first surface Wa and the second surface Wb of the wafer W in the vertical direction. The configuration of the inversion device 73 is arbitrary.

[0024] The wafer transport device 80 is positioned, for example, on the positive Y-axis side of the cleaning device 70, thickness measuring device 71, buffer device 72, and inversion device 73. The wafer transport device 80 has, for example, two transport arms 81 that transport wafers W by adsorption and holding them with an adsorption holding surface (not shown). Each transport arm 81 is supported by a multi-joint arm member 82 and is configured to be movable in the horizontal direction, vertical direction, around the horizontal axis, and around the vertical axis. The wafer transport device 80 is configured to transport wafers W to the etching device 40, thickness measuring device 50, inversion device 51, cleaning device 70, thickness measuring device 71, buffer device 72, inversion device 73, and the grinding device 90 described later.

[0025] The third processing block G3 is equipped with a grinding device 90. The grinding device 90 grinds and flattens the first surface Wa or the second surface Wb of the wafer W.

[0026] The grinding apparatus 90 has a rotary table 91. The rotary table 91 is configured to rotate freely around a vertical rotation centerline 92 by a rotation mechanism (not shown). A total of four chucks 93a and 93b for adsorbing and holding wafers W are provided on the rotary table 91. Porous chucks, for example, are used for the chucks 93a and 93b. The surfaces of the chucks 93a and 93b, i.e., the wafer holding surfaces, have a convex shape in which the central part protrudes more than the outer periphery when viewed from the side.

[0027] Of the four chucks 93a and 93b, the two first chucks 93a are used for grinding at the first machining position B1, which will be described later. These two first chucks 93a are positioned symmetrically with respect to the rotation centerline 92. The remaining two second chucks 93b are used for grinding at the second machining position B2, which will be described later. These two second chucks 93b are also positioned symmetrically with respect to the rotation centerline 92. In other words, the first chucks 93a and the second chucks 93b are arranged alternately in the circumferential direction.

[0028] The four chucks 93a and 93b are movable to the transfer positions A1-A2 and the machining positions B1-B2 as the rotary table 91 rotates. In addition, each of the four chucks 93a and 93b is configured to rotate around a vertical axis by a rotation mechanism (not shown). Furthermore, each of the four chucks 93a and 94b is configured to adjust the relative inclination between the grinding surfaces of the grinding sections 101 and 111 at the machining positions B1-B2 (described later) and the upper surfaces of the chucks 93a and 93b by an inclination adjustment mechanism (not shown).

[0029] The first transfer position A1 is located on the positive X-axis and positive Y-axis side with respect to the rotation centerline 92 of the rotary table 91, and the wafer W is transferred to the first chuck 93a when grinding the first surface Wa.

[0030] The second transfer position A2 is located on the positive X-axis side and the negative Y-axis side with respect to the rotation centerline 92 of the rotary table 91, and the wafer W is transferred to the second chuck 93b when grinding the second surface Wb.

[0031] The first processing position B1 is located on the negative X-axis and negative Y-axis side with respect to the rotation centerline 92 of the rotary table 91, and the first grinding unit 100 is positioned there. The first grinding unit 100 has a grinding section 101 equipped with an annular, rotatable grinding wheel (not shown). The grinding section 101 is also configured to move vertically along the support column 102. As an example, the first grinding unit 100 grinds the first surface Wa or the second surface Wb of a wafer W held in the first chuck 93a.

[0032] The second processing position B2 is located on the negative X-axis side and positive Y-axis side with respect to the rotation centerline 92 of the rotary table 91. The second grinding unit 110 is positioned at this location and has a grinding section 111 equipped with an annular, rotatable grinding wheel (not shown). The grinding section 111 is also configured to move vertically along the support column 112. As an example, the second grinding unit 110 grinds the second surface Wb or the first surface Wa of the wafer W held in the second chuck 93b.

[0033] As described above, the holding surfaces of the chucks 93a and 93b have a convex shape. Therefore, in the wafer grinding process using the grinding units 100 and 110, the annularly arranged grinding wheels contact the wafer W from the center to the outer edge in an arc shape. By rotating the chucks 93a and 93b and the grinding wheels respectively in this state, the entire surface of the wafer W is ground.

[0034] Furthermore, in the grinding units 100 and 110, the shape of the wafer W after grinding can be controlled to be flat, convex (convex or A-shaped), concave (concave or V-shaped), W-shaped, M-shaped, or a combination of any two of these shapes by adjusting the relative angle (inclination) between the holding surfaces of the chucks 93a and 93b and the grinding surface of the grinding wheel. The flat shape is a shape in which the entire surface of the wafer W is adjusted to be below a desired thickness deviation (TTV), preferably a shape in which the thickness is uniformly controlled across the entire surface. The convex shape is a shape in which the thickness in the center of the wafer W is greater than the thickness in the outer periphery. The concave shape is a shape in which the thickness in the concave part of the wafer W is smaller than the thickness in the outer periphery. The W-shaped shape is a shape in which the thickness at the center of the radius is smaller than the thickness in the center and outer periphery of the wafer W. The M-shaped shape is a shape in which the thickness at the center of the radius is larger than the thickness in the center and outer periphery of the wafer W.

[0035] Furthermore, thickness measuring devices (not shown) for measuring the thickness of the wafer W after grinding may be provided at the handover positions A1, A2 or processing positions B1, B2.

[0036] The wafer processing system 1 described above is equipped with a display panel 120. The display panel 120 may be, for example, a monitor or a touch panel, and may be directly attached to the wafer processing system 1 or it may be accessible remotely. The display panel 120 displays screens for operating each process performed by the wafer processing system 1. Signals of the operation results on the display panel 120 are output to the control device 130, which will be described later.

[0037] The wafer processing system 1 described above is provided with at least one control device 130. The control device 130 processes computer-executable instructions that cause the wafer processing system 1 to perform the various processes described herein. The control device 130 may be configured to control each element of the wafer processing system 1 to perform the various processes described herein. In one embodiment, some or all of the control device 130 may be included in the wafer processing system 1. The control device 130 may include a processing unit, a storage unit, and a communication interface. The control device 130 is implemented, for example, by a computer. The processing unit may be configured to read a program from the storage unit that provides logic or routines that enable various control operations, and to perform various control operations by executing the read program. This program may be stored in the storage unit in advance, or it may be retrieved via a medium when needed. The retrieved program is stored in the storage unit and read from the storage unit and executed by the processing unit. The medium may be various storage media readable by a computer, or it may be a communication line connected to a communication interface. The storage medium may be temporary or non-temporary. The processing unit may be a CPU (Central Processing Unit), or it may be one or more circuits. The storage unit may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface may communicate with the wafer processing system 1 via a communication line such as a LAN (Local Area Network).

[0038] Next, the configuration of the etching apparatus 40 described above will be explained. For convenience, the following explanation will describe the case where the etching target is the first surface Wa and the non-etching target is the second surface Wb. However, the same applies when the etching target is the second surface Wb and the non-etching target is the first surface Wa, or when the etching target is a film formed on the first surface Wa or the second surface Wb.

[0039] As shown in Figure 2, the etching apparatus 40 has a wafer holding section 200 for holding a wafer W. The wafer holding section 200 holds the outer edge of the wafer W at multiple points, for example, three points, such that the first surface Wa of the wafer W, which is to be etched, faces upward. Note that the configuration of the wafer holding section 200 is not limited to the illustrated example, and for example, the wafer holding section 200 may include a chuck (not shown) for adsorbing and holding the wafer W from below. The wafer holding section 200 is configured to be rotatable about a vertical rotation center line 200a by a rotation mechanism 201, thereby enabling the wafer W held on the wafer holding section 200 to rotate.

[0040] Above the wafer holding section 200, an etching solution nozzle 210 is provided as an etching solution supply section, and a pure water nozzle 211 is provided as a pure water supply section. The etching solution nozzle 210 and the pure water nozzle 211 are configured to be movable in the horizontal and vertical directions by moving mechanisms 213 and 214, respectively.

[0041] The etching solution nozzle 210 supplies etching solution E to the first surface Wa of the wafer W held in the wafer holding section 200, which is the target of etching. The etching solution nozzle 210 is configured to be movable in the horizontal and vertical directions by a moving mechanism 213. In one example, as shown in Figure 3, the etching solution nozzle 210 is configured to be able to reciprocate (scan) or pivot, passing above the center of the wafer W through the rotation centerline 200a of the wafer holding section 200.

[0042] The etching solution E according to this embodiment contains at least one of hydrofluoric acid (HF), phosphoric acid (H3PO4), and nitric acid (HNO3) to appropriately etch the silicon of the wafer W that may be etched. In one example, the etching solution E contains hydrofluoric acid, phosphoric acid, nitric acid, and water as processing solutions, i.e., it is a mixture of multiple processing solutions. The material to be etched may be amorphous silicon, for example. Furthermore, the etching method of this embodiment is also applicable to wafers that are not ground by the grinding device 90. For example, if a film is formed on the first surface Wa or the second surface Wb, that film will also be etched.

[0043] A first liquid supply line 221 is connected to the etching solution nozzle 210, and the first liquid supply line 221 is connected to a first tank 310, which will be described later. As will be described in detail later, the first tank 310 constitutes the supply source of etching solution E in the etching solution supply device 300. In other words, the etching solution supply device 300 supplies etching solution E from the first tank 310 to the etching solution nozzle 210 via the first liquid supply line 221. The first liquid supply line 221 is provided with a valve 222 that controls the supply of etching solution E. The valve 222 controls the supply of etching solution E according to a control signal from the control device 130. The first liquid supply line 221 is equipped with a pump (not shown) between the first tank 310 and the valve 222 for transporting the etching solution E.

[0044] The pure water nozzle 211 supplies pure water to the first surface Wa of the wafer W held in the wafer holding section 200, which is the target of etching. A second liquid supply line 250 is connected to the pure water nozzle 211, and the second liquid supply line 250 is connected to a pure water supply source 251. The pure water supply source 251 stores pure water internally. The second liquid supply line 250 is provided with a valve 252 that controls the supply of pure water.

[0045] Pure water includes, for example, deionized water. Furthermore, pure water may contain impurities to an acceptable degree for production purposes.

[0046] As will be described later, the supply of pure water from the pure water nozzle 211 may occur simultaneously with the supply of etching solution E from the etching solution nozzle 210. The etching solution E supplied from the etching solution nozzle 210 and the pure water supplied from the pure water nozzle 211 are mixed to produce a diluted etching solution M. The diluted etching solution M is collected in the outer cup 411, which will be described later.

[0047] In one embodiment, the pure water nozzle 211 may be configured to supply pure water P as rinsing water used for rinsing the etched object after etching.

[0048] As shown in Figure 4, a back rinse nozzle 260 is provided below the wafer holding section 200. The back rinse nozzle 260 supplies pure water P to the second surface Wb of the wafer W held by the wafer holding section 200, which is not to be etched. A third liquid supply line 261 is connected to the back rinse nozzle, and the third liquid supply line 261 is connected to, for example, a pure water supply source 251. The third liquid supply line 261 is provided with a valve 262 that controls the supply of pure water P.

[0049] The supply of pure water P from the back rinse nozzle 260 can be performed simultaneously with the supply of etching solution E from the etching solution nozzle 210. That is, as shown in Figure 4, the supply of pure water P from the back rinse nozzle 260 can prevent the etching solution E from flowing around the peripheral edge We of the wafer W and being supplied from the first surface Wa to the second surface Wb. This protects the second surface Wb, which is not to be etched.

[0050] The etching solution E supplied from the etching solution nozzle 210 and the pure water P supplied from the back rinse nozzle 260 are mixed to produce a diluted etching solution M. The diluted etching solution M is collected in the outer cup 411, which will be described later.

[0051] In one embodiment, the etching apparatus 40 may be equipped with a nozzle (not shown) for supplying a cleaning solution. The nozzle for supplying the cleaning solution supplies the cleaning solution to the first surface Wa or second surface Wb of the wafer W held in the wafer holding section 200, and removes metal adhering to the first surface Wa or second surface Wb. The cleaning solution used is one that can remove metal from the first surface Wa or second surface Wb of the wafer W, such as hydrofluoric acid or a mixture of hydrofluoric acid and hydrogen peroxide (FPM). The cleaning solution used to clean the wafer W may be collected in an outer cup 411 (described later) and drained through a drain line 413.

[0052] As shown in Figure 5, the etching solution supply device 300 has a first tank 310 for storing etching solution E inside. The first liquid supply line 221 described above is connected to the first tank 310.

[0053] The first tank 310 is connected to a hydrofluoric acid supply line 340, a phosphoric acid supply line 350, and a nitric acid supply line 360.

[0054] A hydrofluoric acid supply source 341 is connected to the hydrofluoric acid supply line 340, and hydrofluoric acid is supplied from the hydrofluoric acid supply source 341 to the tank 310 via the hydrofluoric acid supply line 340. The hydrofluoric acid supply line 340 is equipped with a valve 342 that controls the supply of hydrofluoric acid.

[0055] A phosphoric acid supply source 351 is connected to the phosphoric acid supply line 350, and phosphoric acid is supplied from the phosphoric acid supply source 351 to the tank 310 via the phosphoric acid supply line 350. The phosphoric acid supply line 350 is equipped with a valve 352 that controls the supply of phosphoric acid.

[0056] A nitric acid supply source 361 is connected to the nitric acid supply line 360, and nitric acid is supplied from the nitric acid supply source 361 to the tank 310 via the nitric acid supply line 360. The nitric acid supply line 360 ​​is equipped with a valve 362 that controls the supply of nitric acid.

[0057] In one embodiment, a pure water supply line (not shown) may be connected to the first tank 310. A pure water supply source (not shown) is connected to the pure water supply line, and pure water P is supplied from the pure water supply source to the first tank 310 via the pure water supply line. The pure water supply line is provided with a valve (not shown) that controls the supply of pure water P.

[0058] Inside the first tank 310, hydrofluoric acid, phosphoric acid, nitric acid, and pure water P are supplied to the etching solution E in desired amounts, and the compositional concentration of the etching solution E is adjusted. The compositional concentration of the etching solution E is adjusted to be equal to the concentration of each component in the etching solution E used to acquire the training data. In this embodiment, the concentration is expressed as mass percentage concentration.

[0059] In this embodiment, the etching solution E and diluted etching solution M are reused for etching multiple wafers W. That is, the etching solution E and diluted etching solution M used on one wafer W are recovered and reused for etching the next wafer W. For this reason, the etching solution supply device 300 is provided with a recovery mechanism.

[0060] As shown in Figures 2 and 5, an inner cup 401 is provided around the wafer holding portion 200. The inner cup 401 is provided so as to surround the wafer holding portion 200 and recovers the etching solution E used for etching the wafer W. A first recovery line 402, which serves as the etching solution recovery line of this disclosure, is connected to the inner cup 401. The inner cup 401 is also configured to be able to move up and down by a lifting mechanism 403.

[0061] The etching solution E recovered in the inner cup 401 is sent to the first tank 310 via the first recovery line 402. The first recovery line 402 is equipped with a pump (not shown) for transporting the recovered etching solution E. By reusing the etching solution E in this way, the amount of etching solution E used can be reduced, thereby lowering costs.

[0062] As shown in Figures 2 and 5, an outer cup 411 is provided outside the inner cup 401. The outer cup 411 is provided so as to surround the wafer holding portion 200 and recovers the diluted etching solution M generated when the etching solution E and pure water P are supplied simultaneously during the etching of the wafer W to be etched. A second recovery line 412 and a drain line 413, which serve as the diluted etching solution recovery line of this disclosure, are connected to the outer cup 411. In the example shown in Figure 5, a collection line for recovery is connected to the outer cup 411, and the second recovery line 412 and the drain line 413 are provided branching off from this collection line. Valves 414 and 415 are also provided at the branching portion to selectively switch the recovery destination so that the etching solution E is recovered in the second recovery line 412 and the rinsing solution is recovered in the drain line 413.

[0063] In one embodiment, the outer cup 411 collects the rinsing liquid used to rinse the wafer W. In another embodiment, the outer cup 411 collects the cleaning liquid, such as FPM, used to clean the wafer W. These rinsing liquids or cleaning liquids are sent to the drain line 413. The rinsing liquids or cleaning liquids sent to the drain line 413 are collected in the drain tank 416 and, after the desired processing, are discarded or reused.

[0064] The etching solution supply device 300 is equipped with a second tank 421 and a third tank 422. The diluted etching solution M recovered in the second recovery line 412 is sent to either the second tank 421 or the third tank 422.

[0065] The second recovery line 412 is provided with valves 423 and 424 for switching the recovery destination of the diluted etching solution M to either the second tank 421 or the third tank 422. In one embodiment, valves 423 and 424 are controlled mutually.

[0066] Furthermore, on the downstream side (first tank 310 side) of the second tank 421 and the third tank 422 in the second recovery line 412, valves 425 and 426, and a pump (not shown) are provided to control the supply of the diluted etching solution M, whose concentration has been adjusted, back from the second tank 421 and the third tank 422 to the first tank 310.

[0067] The second tank 421 and the third tank 422 are connected to the hydrofluoric acid supply line 340, the phosphoric acid supply line 350, the nitric acid supply line 360, and the water supply line 370. Inside the second tank 421 and the third tank 422, hydrofluoric acid, phosphoric acid, nitric acid, and pure water P are supplied to the diluted etching solution M in desired amounts, and the compositional concentration of the diluted etching solution M is adjusted. This adjustment is performed so that the compositional concentration of the diluted etching solution M after concentration adjustment is equal to the compositional concentration of the etching solution E.

[0068] Circulation pumps 431 and 432 are provided in the flow paths before and after the second tank 421 and the third tank 422, respectively, to circulate the diluted etching solution M inside the second tank 421 and the third tank 422, respectively, and to equalize the concentration of the diluted etching solution M.

[0069] In this embodiment, the outer cup 411 does not move up or down, but it may be configured to be able to move up or down by a lifting mechanism (not shown).

[0070] Next, a wafer processing method performed using the wafer processing system 1 configured as described above will be explained. In this embodiment, a wafer W cut from an ingot using a wire saw or the like, or a wrapped wafer W, is subjected to processing to obtain a desired thickness profile for the wafer W.

[0071] First, a hoop F containing multiple wafers W is placed on the hoop mounting table 10 of the loading / unloading station 2. In the hoop F, the wafers W are stored with their first surface Wa facing upwards and their second surface Wb facing downwards. Next, the wafer transport device 20 removes the wafers W from the hoop F and transports them to the transition device 30. The wafers W transported to the transition device 30 are then transported to the buffer device 72 by the wafer transport device 60.

[0072] Next, the wafer W is transported to the grinding device 90 by the wafer transport device 80 and transferred to the first chuck 93a at the first transfer position A1. At the first chuck 93a, the second surface Wb of the wafer W is held by suction.

[0073] Next, the rotary table 91 is rotated to move the wafer W to the first processing position B1. Then, the first grinding unit 100 grinds the first surface Wa of the wafer W (St1 in Figure 6).

[0074] Next, the rotary table 91 is rotated to move the wafer W to the first transfer position A1.

[0075] Next, the wafer W is transported to the cleaning device 70 by the wafer transport device 80. In the cleaning device 70, the first surface Wa of the wafer W is cleaned (St2 in Figure 6). In St2, the second surface Wb of the wafer W may also be cleaned.

[0076] Next, the wafer W is transported to the inversion device 73 by the wafer transport device 80. In the inversion device 73, the first surface Wa and the second surface Wb of the wafer W are inverted vertically (St3 in Figure 6). That is, the wafer W is inverted so that the first surface Wa faces downwards and the second surface Wb faces upwards.

[0077] Next, the wafer W is transported to the grinding device 90 by the wafer transport device 80 and transferred to the second chuck 93b at the second transfer position A2. At the second chuck 93b, the first surface Wa of the wafer W is held by suction.

[0078] Next, the rotary table 91 is rotated to move the wafer W to the second processing position B2. Then, the second grinding unit 110 grinds the second surface Wb of the wafer W (St4 in Figure 6).

[0079] Next, the rotary table 91 is rotated to move the wafer W to the second transfer position A2.

[0080] Next, the wafer W is transported to the cleaning device 70 by the wafer transport device 80. In the cleaning device 70, the second surface Wb of the wafer W is cleaned (St5 in Figure 6). In St5, the first surface Wa of the wafer W may also be cleaned.

[0081] Next, the wafer W is transported to the thickness measuring device 71 by the wafer transport device 80 or wafer transport device 60. The thickness measuring device 71 obtains the thickness distribution of the wafer W by measuring the thickness of the wafer W at multiple points after grinding the second surface Wb, and further calculates the thickness deviation of the wafer W (St6 in Figure 6). The obtained thickness distribution and thickness deviation of the wafer W are output to, for example, the control device 130.

[0082] In the control device 130, the optimal etching conditions for the second surface Wb are determined (St7 in Figure 6) by optimizing the etching amount distribution (etching profile) in the etching process of the second surface Wb from the thickness distribution and thickness deviation of the wafer W acquired in St6 and output to the control device 130. The etching amount is the amount of wafer W removed by etching, and the etching amount distribution is the distribution of etching amount in the radial direction (within the wafer surface) of the wafer W. Furthermore, the optimal etching conditions for the second surface Wb in this embodiment correspond to the set etching conditions in this disclosure. The method for determining the optimal etching conditions for the second surface Wb in the control device 130 will be described later.

[0083] Next, the wafer W is transported to the etching apparatus 40 by the wafer transport device 60. In the etching apparatus 40, the second surface Wb of the wafer W is etched using the optimal etching conditions determined in St7 (St8 in Figure 6). In St8, the etching amount distribution is optimized by etching the second surface Wb using the optimal etching conditions, and the second surface Wb is processed into the target shape.

[0084] As described later, the optimal etching conditions may include the optimal etching solution supply conditions when only etching solution E is supplied to the object to be etched. Furthermore, the optimal etching conditions may include the optimal combination supply conditions when pure water P is supplied to the object to be etched simultaneously with the etching solution E. Therefore, St8 includes the cases in which only etching solution E is supplied to the object to be etched, and the cases in which etching solution E and pure water P are supplied simultaneously. In addition, in either of these cases, pure water P may be supplied as a rinse solution from the back rinse nozzle 260 to the non-etching object.

[0085] In St8, if only etching solution E is supplied to the etching target and pure water P is not supplied from the back rinse nozzle 260, the etching solution E used and recovered for etching the second surface Wb is recovered in the first recovery line 402 and reused. In the first recovery line 402, the recovered etching solution E is sent to the tank 310. Inside the tank 310, hydrofluoric acid, phosphoric acid, nitric acid, and water are supplied to the etching solution E in desired amounts to adjust the composition concentration of the etching solution E. After that, the etching solution E with the adjusted composition concentration is supplied to the etching solution nozzle 210.

[0086] In St8, when etching solution E and pure water P are supplied simultaneously to the etching target, or when pure water P is supplied from the back rinse nozzle 260 to the non-etching target, the pure water P is mixed with the etching solution E and recovered as diluted etching solution M. The diluted etching solution M is recovered in the second recovery line 412 and reused. Details of the reuse process in the second recovery line 412 will be described later.

[0087] Next, the wafer W is transported to the inversion device 51 by the wafer transport device 60. In the inversion device 51, the first surface Wa and the second surface Wb of the wafer W are inverted vertically (St9 in Figure 6). That is, the wafer W is inverted so that the first surface Wa faces upwards and the second surface Wb faces downwards.

[0088] Next, the wafer W is transported to the thickness measuring device 50 by the wafer transport device 60. The thickness measuring device 50 obtains the thickness distribution of the wafer W by measuring the thickness of the wafer W at multiple points after etching the second surface Wb, and further calculates the thickness deviation of the wafer W (St10 in Figure 6). The obtained thickness distribution and thickness deviation of the wafer W are output to, for example, the control device 130.

[0089] The control device 130 determines the optimal etching conditions for the first surface Wa, optimizing the etching amount distribution during the etching process of the first surface Wa, based on the thickness distribution and thickness deviation of the wafer W acquired in St10 and output to the control device 130 (St11 in Figure 6). In this embodiment, the optimal etching conditions for the first surface Wa correspond to the set etching conditions in this disclosure. The method for determining the optimal etching conditions for the first surface Wa in the control device 130 will be described later.

[0090] Next, the wafer W is transported to the etching apparatus 40 by the wafer transport device 60. In the etching apparatus 40, the first surface Wa of the wafer W is etched using the optimal etching conditions determined in St11 (St12 in Figure 6). In St12, the etching amount distribution is optimized by etching the first surface Wa using the optimal etching conditions, and the first surface Wa is processed into the target shape.

[0091] In S12, the etching solution E or diluted etching solution M recovered by etching the first surface Wa is collected in the etching solution supply device 300 and reused. This reuse process is the same as the reuse process in St8 described above, and details will be described later.

[0092] Next, the wafer W is transported to the thickness measuring device 50 by the wafer transport device 60. The thickness measuring device 50 obtains the thickness distribution of the wafer W by measuring the thickness of the wafer W at multiple points on both the first surface Wa and the second surface Wb after etching (St13 in Figure 6). The thickness measuring device 50 may also calculate the thickness deviation of the wafer W.

[0093] The thickness and thickness distribution of multiple wafers W obtained in St13 are output to the control device 130, for example, and can be used to determine the actual etching amount of wafer W and the state of the etching solution supply environment. Furthermore, these thickness and thickness distribution of multiple wafers W may be used for processing other wafers W that are then processed by the wafer processing system 1.

[0094] Subsequently, the wafer W, having undergone all processing, is transported via the transition device 30 to the hoop F on the hoop mounting table 10. This completes the series of wafer processing steps in the wafer processing system 1.

[0095] In the above embodiment, the first surface Wa was ground with St1, and then the second surface Wb was ground with St4, but the order of grinding these surfaces may be reversed. Also, the second surface Wb was etched with St8, and then the first surface Wa was etched with St12, but the order of etching these surfaces may be reversed.

[0096] Next, the method for determining the optimal etching conditions (St7 and St11 in Figure 6) described above will be explained. This determination of the optimal etching conditions is performed by the control device 130. In the following explanation, the method for determining the optimal etching conditions for the first surface Wa in St11 will be described, but the method for determining the optimal etching conditions for the second surface Wb in St7 is the same.

[0097] First, before processing the wafer W in the wafer processing system 1, multiple training data are acquired (St100 in Figure 7). The training data is normal data acquired when etching is performed successfully, as will be described later, and includes the etching amount at multiple reference points on the wafer W and the etching amount distribution of the wafer W. The multiple reference points on the wafer W are reference points for acquiring the etching amount distribution of the wafer W. Furthermore, the multiple reference points on the wafer W are reference points used when determining the actual etching amount state of the wafer W and the state of the etching solution supply environment, as will be described later.

[0098] In St100, etching is performed on a dummy wafer using, for example, multiple different etching conditions (hereinafter referred to as "learning etching conditions"). Specifically, the dummy wafer is etched by changing, for example, the rotation speed R (also called rotational speed) of the dummy wafer during etching, the etching solution supply conditions when only etching solution E is supplied, or the combined supply conditions of etching solution E and pure water P when both are supplied simultaneously.

[0099] The etching solution supply conditions include the scan speed V (also called the swing speed) of the etching solution nozzle 210, the scan width L (see scan width L in Figure 3, also called the swing radius) of the etching solution nozzle 210, or the number of loops N of the etching solution nozzle 210, and the amount of etching solution E supplied.

[0100] The combined supply conditions are a combination of etching solution supply conditions and pure water supply conditions as described above, and the pure water supply conditions include the pure water supply position as the position where the pure water nozzle 211 is located, the amount of pure water P supplied, etc.

[0101] The etching time for each dummy wafer is the same. The etching of the dummy wafer is the same as the etching of the first surface Wa of wafer W in St12.

[0102] As an example of etching, when etching solution E and pure water P are supplied simultaneously, the dummy wafer is rotated and the etching solution nozzle 210 is moved back and forth while the etching solution E is supplied from the etching solution nozzle 210 to the dummy wafer. In addition, a pure water nozzle is placed at the pure water supply position and pure water P is supplied from the pure water nozzle to the dummy wafer. In the following description, the back-and-forth movement of the etching solution nozzle 210 is considered one loop.

[0103] Here, using Figures 8 to 11, we will explain an example of combined supply conditions when etching solution E and pure water P are supplied simultaneously.

[0104] In one example of the conditions shown in Figures 8 and 9, the etching solution nozzle 210 is controlled to supply the etching solution E while reciprocating from a first position (A) near the center Wc of the wafer W to a second position (B) of the etching solution nozzle 210, as shown by the dashed line in Figures 8 and 9. At the same time, the pure water nozzle 211 is controlled to supply pure water P at a third position (C) near the radially outer side of the second position (B) of the etching solution nozzle 210 on the wafer W. In one embodiment, the pure water nozzle may be controlled to supply pure water P while reciprocating from the third position (C) to the peripheral edge We of the wafer W.

[0105] In another example of the conditions shown in Figures 10 and 11, the etching solution nozzle 210 is controlled to supply the etching solution E while reciprocating from a desired fourth position (D) in the radial direction of the wafer W to a fifth position (E) of the etching solution nozzle 210, as shown by the dashed line in Figures 10 and 11. At the same time, the pure water nozzle 211 is controlled to supply pure water P at a sixth position (F) radially outside the fifth position (E) of the etching solution nozzle 210 on the wafer W. In one embodiment, the pure water nozzle may be controlled to supply pure water P while reciprocating from the sixth position (F) to the vicinity of the peripheral edge We of the wafer W.

[0106] The etching of the dummy wafer under each etching condition is performed for a predetermined desired time (desired number of loops). The etching amount distribution of the dummy wafer is then acquired and output to the control device 130. Furthermore, the control device 130 compresses the output etching amount distribution for each etching condition into an etching amount distribution per unit time (unit number of loops), and stores each of these compressed etching amount distributions as the learning data.

[0107] In the above explanation, the case of acquiring the learning data by etching a dummy wafer was used as an example, but the etching target when acquiring the learning data is not limited to a dummy wafer. Specifically, for example, the etching result of a product wafer W processed by the wafer processing system 1 may be stored as the learning data. Also, for example, if a film is formed on the first surface Wa of wafer W, the etching target may be the film, and the etching result of the film may be stored as the learning data.

[0108] Furthermore, although the acquisition of the above-mentioned learning data was performed within the wafer processing system 1, it may also be performed outside of the wafer processing system 1. In such a case, the control device 130 determines the optimal etching conditions based on the multiple learning data acquired outside of the wafer processing system 1.

[0109] Next, the target etching amount distribution in the etching process of St12 is obtained based on the thickness distribution of the target shape of the wafer W after etching and the thickness distribution of the surface shape of the wafer W after etching (hereinafter referred to as the "measured shape") obtained in St10 (St110 in Figure 7). The target etching amount distribution for the etching process can be obtained, for example, by calculating the difference between the thickness distribution of the target shape of the wafer W and the thickness distribution of the measured shape. The target shape of the wafer W can be, for example, a flat shape, a convex shape, a concave shape, a W-shape, an M-shape, or a combination of any two of these shapes.

[0110] Next, multiple training data (etching amount distributions) are superimposed, and an optimization method is used to optimize the training data used for superimposition and the number of times the training data is superimposed so that it matches the target etching amount distribution obtained in St110 (St111 in Figure 7).

[0111] In St111, for example, the control of the etching amount distribution is applied to the knapsack problem, and the number of times the training data is superimposed is optimized. For example, the etching amount distribution is the knapsack in the knapsack problem, and the training data are the items in the knapsack problem. Then, the number of times the training data is superimposed is optimized so that the difference between the superimposed etching amount distribution and the target etching amount distribution in St110 is minimized. In other words, the etching amount distribution when etching the first surface Wa in St12 is optimized.

[0112] Next, the etching conditions corresponding to the training data optimized in St111 are integrated to determine the optimal etching conditions (St112 in Figure 7). Specifically, the multiple etching conditions are integrated so that the selected multiple etching conditions are performed with an optimized number of superpositions, thereby determining the optimal etching conditions. In other words, the optimal etching conditions that optimize the etching amount distribution are determined. The optimal etching conditions thus determined include either or both of the following: the optimal etching solution supply conditions when only etching solution E is supplied, and the optimal combined supply conditions when etching solution E and pure water P are supplied simultaneously.

[0113] As described above, the optimal etching conditions for the first surface Wa in St11 are determined. In this case, by etching the first surface Wa of the wafer W in St12 under the optimal etching conditions, the etching amount distribution can be optimized, and the first surface Wa can be processed into the target shape.

[0114] In this example, a target shape may require a thickness distribution such that the thickness is locally larger at a specific location on the wafer W. For example, as shown by the solid line in Figure 12, a thickness distribution S1 may be desired in which the thickness is locally larger near the peripheral portion We. According to the optimal etching conditions, including the optimal combination supply conditions for simultaneously supplying the etching solution E and pure water P according to this embodiment, it is possible to realize a target shape having such a thickness distribution.

[0115] As a comparative example, consider the case where a surface thickness distribution S2 as shown by the dotted line in Figure 11 can be achieved when only etching solution E is supplied. Through diligent investigation by the inventors, it was found that local control to further increase the thickness from the radial middle part of the wafer W to the vicinity of the peripheral part We is difficult when only etching solution E is supplied. This is thought to be because, when only etching solution E is supplied, the etching solution E spreads from the supply position on the wafer W toward the peripheral part We, and therefore is always in contact with the etching solution E outside the radial middle part of the wafer W, which is the supply position.

[0116] In contrast, with the combined supply of etching solution E and pure water P according to this embodiment, it is possible to supply pure water P in such a way that the etching solution E does not come into contact with the area outside the radial middle portion of the wafer W. This makes it possible to perform localized control to further increase the thickness from the radial middle portion of the wafer W to the vicinity of the peripheral portion We, approximating the thickness distribution S2 shown by the solid line in Figure 11, which is an example of a target shape.

[0117] The optimal etching conditions according to this embodiment include optimal combined supply conditions, which are determined by superimposing learning data related to etching conditions during learning, including combined supply conditions. This enables localized control that more closely approximates the target shape.

[0118] In one embodiment, if the optimal etching conditions include optimal etching solution supply conditions when only etching solution E is supplied, during the etching process under the optimal etching conditions, the supply of pure water P may be controlled to be under predetermined conditions based on the target shape in the vicinity of the radial position where the thickness distribution of the etched object is to be adjusted.

[0119] Next, the recovery and reuse process of etching solution E or diluted etching solution M when etching is performed in St8 or St12 will be explained using Figures 13 to 19.

[0120] First, the etching conditions when etching is performed in St8 or St12 are determined (St201 in Figure 13). The etching conditions include condition A, when only etching solution E is supplied, and condition B, when etching solution E and pure water P are supplied simultaneously. Condition B includes cases where etching solution E and pure water P are supplied simultaneously to the material to be etched, and cases where etching solution E is supplied to the material to be etched and pure water P is supplied to the material not to be etched.

[0121] If condition A is determined in St201, the process proceeds to St202 in Figure 13. In St202, the etching solution E is recovered to the first recovery line 402 via the path shown by the thick solid arrow in Figure 14 and reused. Specifically, the inner cup 401 is first raised (St301 in Figure 15, see Figure 2). This recovers the etching solution E supplied onto the wafer W into the inner cup 401. The etching solution E recovered in the inner cup 401 flows into the first recovery line 402 connected to the inner cup 401. The etching solution E that has flowed into the first recovery line is sent to the first tank 310 (St302 in Figure 15). In the first tank 310, the etching solution E is replenished with various acids from the hydrofluoric acid supply line 340, the phosphoric acid supply line 350, and the nitric acid supply line 360, and adjusted to the same composition concentration as the etching solution E used to acquire the learning data.

[0122] If condition B is determined in St201, the process proceeds to St203 in Figure 13. In St203, the diluted etching solution M is collected in the second recovery line 412 and reused. Specifically, as shown in Figure 17, the inner cup 401 is first lowered (St401 in Figure 16). As a result, the diluted etching solution M, which is produced by mixing the etching solution E and pure water P supplied onto the wafer W, is collected in the outer cup 411. The diluted etching solution M collected in the outer cup 411 flows into the second recovery line 412 connected to the outer cup 411.

[0123] The diluted etching solution M that flows into the second recovery line 412 is first sent to the second tank 421 via the path shown by the thick solid arrow in Figure 18 (St402 in Figure 14). Specifically, valves 414 and 423 are opened, and valves 415, 424, 425, and 426 are closed. During this time, the liquid level in the second tank 421 is monitored by a liquid level sensor (not shown). Then, a determination is made as to whether the liquid level in the second tank 421 has reached the target amount (St403 in Figure 14).

[0124] If the liquid level in the second tank 421 does not reach the planned amount in St403, the process returns to St402, and the supply of diluted etching solution M and monitoring of the liquid level continue. If the liquid level in the second tank 421 reaches the planned amount in St403, the recovery destination of the diluted etching solution M is switched from the second tank 421 to the third tank 422. Specifically, from the state shown in Figure 18, valve 423 is closed and valve 424 is opened (Figure 19). After that, the process proceeds to St411-St414 in the second tank 421 and StSt421-St426 in the third tank 422.

[0125] After St404, in the second tank 421, first, the etching solution supply amount and pure water supply amount for the optimal combination supply condition of etching solution supply conditions and pure water supply conditions included in the optimal etching conditions are read out (St411 in Figure 14). In determining the optimal etching conditions according to this embodiment, the etching solution supply amount and pure water supply amount have already been determined by the optimization method by superimposing the learned data as described above, and are stored in the control device 130, for example. Therefore, in St411, it is sufficient to read out these known etching solution supply amount and pure water supply amount in the control device 130.

[0126] In the second tank 421, the amount of acid to be replenished in etching solution E is then calculated based on the read-out etching solution supply amount and pure water supply amount, so that the acid concentration in diluted etching solution M becomes equal to the acid concentration in etching solution E (St412 in Figure 16).

[0127] In the second tank 421, acid is then added to the diluted etching solution M from one or more of the hydrofluoric acid supply line 340, phosphoric acid supply line 350, and nitric acid supply line 360, based on the calculated replenishment amount. At this time, as shown by the thick solid arrow in Figure 19, the diluted etching solution M inside the second tank 421 is circulated by the circulation pump 431, and the acid is gradually added while the concentration of the diluted etching solution M inside the second tank 421 is made uniform. As a result, the compositional concentration of the diluted etching solution M in the second tank 421 after concentration adjustment becomes equal to the concentration of the etching solution E used to acquire the training data.

[0128] In the second tank 421, after the acid has been replenished with the calculated amount, the diluted etching solution M, after concentration adjustment, is sent to the first tank 310 (St414 in Figure 16).

[0129] Furthermore, after St404, the diluted etching solution M that flowed into the second recovery line 412 is sent to the third tank 422 via the path shown by the thick solid arrow in Figure 19 (St421 in Figure 16). During this time, the liquid level in the third tank 422 is monitored by a liquid level sensor (not shown). Then, a determination is made as to whether or not the liquid level in the third tank 422 has reached the planned amount (St422 in Figure 16).

[0130] If the liquid level in the third tank 422 does not reach the target level at St422, the process returns to St421 and continues to supply the diluted etching solution M and monitor its volume. If the liquid level in the third tank 422 reaches the target level at St422, the process proceeds to StSt423-St426 in the third tank 422. StSt423-St426 in the third tank 422 is the same as St411-St414 in the second tank 421.

[0131] In one embodiment, if the liquid volume in the third tank 422 reaches the planned amount at St422, and the replenishment of acid in the second tank 421 is complete and the second tank 421 is available, the destination for recovering the diluted etching solution M may be switched from the third tank 422 to the second tank 421. In this case, St402 to St414 in the second tank 421 may then be performed in parallel with StSt423 to St426 in the third tank 422.

[0132] In one embodiment, if the liquid volume in the third tank 422 reaches a predetermined amount in St422, and the second tank 421 is unavailable, or if the liquid volume of the etching solution E inside the first tank 310 has reached a predetermined amount, the destination for the recovery of the diluted etching solution M may be switched from the second recovery line 412 to the drainage line 413.

[0133] According to the above embodiments, by simultaneously supplying etching solution E and pure water P to the material to be etched, it is possible to realize a target shape having a thickness distribution such that the thickness at a specific location on the wafer W is locally larger. In particular, with optimal etching conditions including optimal combination supply conditions, it is possible to further increase the thickness from the radial middle portion of the wafer W to the vicinity of the peripheral portion We.

[0134] Furthermore, regarding the recovery of the etching solution and diluted etching solution, if only the etching solution E is supplied to the material to be etched during etching, the etching solution E can be recovered in the first tank 310 using the first recovery line 402. Also, if the etching solution E and pure water P are supplied to the material to be etched during etching, and a diluted etching solution M is generated, the diluted etching solution can be separated from the etching solution E and recovered in the second tank 421 or the third tank 422 using the second recovery line 412.

[0135] The second recovery line 412 in this embodiment is equipped with multiple recovery tanks, such as the second tank 421 and the third tank 422. This allows the recovery destination of the diluted etching solution to be switched to the other recovery tank when one of these recovery tanks reaches a predetermined amount, such as being full. As a result, the amount of recovered solution can be increased without discarding the diluted etching solution when the recovery tank becomes full.

[0136] From this perspective, the number of recovery tanks provided in the second recovery line 412 is not limited to two as in the above embodiment, but may be three or more.

[0137] Furthermore, the supply amounts of etching solution E and pure water P, which are supplied based on the optimal etching conditions, are already determined and stored when the optimal etching conditions are determined. Therefore, in the above embodiment in which the recovery and reuse process of this disclosure is applied in etching using the optimal etching conditions, when calculating the amount of replenishment of acid after the diluted etching solution has been recovered into the second tank 421 and the third tank 422, it is not necessary to refer to the compositional concentration of the acid in the diluted etching solution inside the second tank 421 and the third tank 422. Therefore, even if it is difficult to measure the compositional concentration of the acid in the diluted etching solution inside the second tank 421 and the third tank 422, the concentration of the diluted etching solution can be appropriately adjusted.

[0138] In the embodiments described above, etching of the second surface Wb in St8 was performed under the optimal etching conditions determined in St7, but it may be performed under predetermined etching conditions instead. In this case, St7 in this embodiment is omitted. Similarly, etching of the first surface Wa in St12 was performed under the optimal etching conditions determined in St11, but it may be performed under predetermined etching conditions instead. In this case, St11 in this embodiment is omitted.

[0139] The default etching conditions may be those set so that the surface of the wafer W after etching has the target shape. Alternatively, the default etching conditions may be those selected to correspond to the target shape of the wafer W surface after etching, for example, from the training data acquired in St100.

[0140] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The above embodiments may be omitted, substituted, or modified in various forms without departing from the scope and gist of the appended claims. For example, the constituent elements of the above embodiments can be arbitrarily combined. From such an arbitrary combination, the actions and effects of each constituent element involved in the combination can be naturally obtained, and other actions and other effects that are obvious to those skilled in the art from the description in this specification can also be obtained.

[0141] Also, the effects described in this specification are merely illustrative or exemplary and not limiting. That is, the technology according to the present disclosure may exhibit other effects that are obvious to those skilled in the art from the description in this specification, together with or instead of the above effects.

Description of Reference Numerals

[0142] 1 Wafer Processing System 40 Etching Device 130 Control Device E Etching Solution P Pure Water W Wafer Wa First Surface Wb Second Surface

Claims

1. A substrate processing method, Determining etching conditions, including the etching solution supply conditions when supplying the etching solution to the etching target on the substrate, and the pure water supply conditions when supplying pure water simultaneously with the etching solution to the etching target, based on a predetermined target etching amount distribution, The process includes etching the target to be etched by simultaneously supplying the etching solution and the pure water to the target to be etched based on the etching conditions, In determining the etching conditions, The etching conditions include optimal etching solution supply conditions. The aforementioned optimal etching solution supply conditions are: A substrate processing method determined by an optimization method from the target etching amount distribution, using a plurality of pre-acquired learning data that include the radial etching amount distribution of the etching target when the etching target is etched under a plurality of different learning etching conditions, including the etching solution supply conditions.

2. In determining the etching conditions, The etching conditions include an optimal combination of the etching solution supply conditions and the pure water supply conditions. The aforementioned optimal combination supply conditions are: The substrate processing method according to claim 1, wherein the target etching amount distribution is determined by the optimization method from the target etching amount distribution, using a plurality of learning data acquired in advance, which include the radial etching amount distribution of the etching target when the etching target is etched under a plurality of different learning etching conditions, including a combination supply condition of the etching solution supply conditions and the pure water supply conditions.

3. In determining the etching conditions, The substrate processing method according to claim 1, further comprising optimizing the combination of the learning data used for superposition and the number of times the learning data is superimposed, so that the etching amount distribution of the etching target approximates the target etching amount distribution, using the optimization method described above.

4. The substrate processing method according to claim 2, wherein the aforementioned combined supply conditions and the aforementioned optimal combined supply conditions include a combination of etching solution supply positions and pure water supply positions in the radial direction of the target to be etched.

5. The substrate processing method according to claim 4, wherein the pure water supply position is located on the outer peripheral side in the radial direction of the object to be etched, compared to the etching solution supply position.

6. A substrate processing system, An etching solution supply unit configured to supply etching solution to the substrate to be etched, A pure water supply unit configured to supply pure water to the etching target, Includes a control unit, The control unit, Determining etching conditions, including the etching solution supply conditions when supplying the etching solution to the etching target and the pure water supply conditions when supplying pure water simultaneously with the etching solution to the etching target, based on a predetermined target etching amount distribution, The system is configured to perform control including etching the target object by simultaneously supplying the etching solution and the pure water to the target object based on the etching conditions, In determining the etching conditions, The etching conditions include optimal etching solution supply conditions. The aforementioned optimal etching solution supply conditions are: A substrate processing system determined by an optimization method from the target etching amount distribution, using a plurality of pre-acquired learning data that include the radial etching amount distribution of the etching target when the etching target is etched under a plurality of different learning etching conditions, including the etching solution supply conditions.

7. The etching conditions include an optimal combination of the etching solution supply conditions and the pure water supply conditions. The aforementioned optimal combination supply conditions are: The substrate processing system according to claim 6, wherein the control unit determines the target etching amount distribution by the optimization method from the target etching amount distribution using a plurality of learning data acquired in advance, which include the radial etching amount distribution of the etching target when the etching target is etched under a plurality of different learning etching conditions, including a combination supply condition of the etching solution supply conditions and the pure water supply conditions.

8. The control unit, In determining the etching conditions, The substrate processing system according to claim 6, further comprising the optimization method described above, which includes performing control to optimize the combination of the learning data used for superposition and the number of times the learning data is superimposed, such that the etching amount distribution of the etching target approximates the target etching amount distribution.

9. The substrate processing system according to claim 7, wherein the aforementioned combined supply conditions and the aforementioned optimal combined supply conditions include a combination of etching solution supply positions and pure water supply positions in the radial direction of the etching target.

10. The substrate processing system according to claim 9, wherein the pure water supply position is located on the outer peripheral side in the radial direction of the object to be etched, compared to the etching solution supply position.

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