Substrate processing method and substrate processing system

Abstract

A substrate processing method for processing a substrate, the method comprising: determining, on the basis of a first thickness of the substrate before etching a first surface and a second surface of the substrate, a first optimal etching condition using an optimization method so that the surface shape of the first surface becomes a target shape after etching, and determining a second optimal etching condition using an optimization method so that the surface shape of the second surface becomes a target shape after etching; etching the first surface on the basis of the first optimal etching condition; and etching the second surface on the basis of the second optimal etching condition.

Description

Substrate processing method and substrate processing system

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

[0002] Patent Document 1 discloses a substrate processing method including a grinding step of grinding the surface of a substrate, a measurement step of measuring the thickness of the ground substrate, a condition determination step of determining processing conditions for a wet etching process to be performed on the substrate based on the measured thickness of the substrate, and a damaged layer removal step of supplying a processing liquid to the ground substrate based on the determined processing conditions to perform a wet etching process and remove a damaged layer formed on the surface of the substrate.

[0003] Japanese Patent Application Laid-Open No. 2018-147908

[0004] The technology according to the present disclosure appropriately controls the surface shapes of both surfaces of a substrate after etching the surfaces.

[0005] One aspect of the present disclosure is a substrate processing method for processing a substrate, the method including: determining first optimal etching conditions using an optimization method based on a first thickness of the substrate before etching the first and second surfaces of the substrate so that the surface shape of the first surface after etching will be a target shape; determining second optimal etching conditions using the optimization method so that the surface shape of the second surface after etching will be the target shape; etching the first surface based on the first optimal etching conditions; and etching the second surface based on the second optimal etching conditions.

[0006] According to the present disclosure, it is possible to appropriately control the surface shapes of both surfaces of a substrate after etching the surfaces.

[0007] Fig. 1 is a plan view showing an outline of the configuration of a wafer processing system; Fig. 2 is a side view showing an outline of the configuration of an etching apparatus; Fig. 3 is an explanatory diagram showing how a nozzle moves in a radial direction; Fig. 4 is a flow diagram showing main steps of wafer processing; Fig. 5 is an explanatory diagram showing main steps of wafer processing; Fig. 6 is a flow diagram showing main steps of a method for determining first and second optimum etching conditions for a first pattern; Fig. 7 is a flow diagram showing main steps of a method for determining first and second optimum etching conditions for a second pattern.

[0008] In the manufacturing process of semiconductor devices, the cut surface of a disk-shaped silicon wafer (hereinafter referred to as "wafer") obtained by cutting a single crystal silicon ingot using a wire saw or the like is flattened and further smoothed to make the wafer thickness uniform. The flattening of the cut surface is performed, for example, by surface grinding or lapping. The smoothing is performed, for example, by spin etching, in which an etching solution is supplied from above the cut surface of the wafer while the wafer is rotating.

[0009] The aforementioned Patent Document 1 discloses that a ground wafer is subjected to a wet etching process to remove a damaged layer formed on the wafer surface by the grinding process. In the condition determination process described in Patent Document 1, the process conditions for the wet etching process, such as the operation of the nozzle supplying the process liquid, the wafer rotation speed, the supply amount of the process liquid, the supply time of the process liquid, and the type of the process liquid, are determined based on the wafer thickness obtained in the measurement process. Then, in the damaged layer removal process, the wafer is subjected to a wet etching process based on the determined process conditions, thereby improving the flatness of the wafer surface.

[0010] However, for example, when the target etching amount in an etching process is small, the supply time of the etching solution (processing solution) becomes short, which narrows the control range of the etching amount distribution by adjusting the processing conditions, making it difficult to appropriately control the surface shape of the wafer after the etching process.

[0011] The technology disclosed herein appropriately controls the surface shapes of both sides of a substrate after etching the both sides. Hereinafter, a wafer processing system as a substrate processing system and a wafer processing method as a substrate processing method according to the present embodiment will be described with reference to the drawings. Note that in this specification and the drawings, elements having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0012] In the wafer processing system 1 according to this embodiment, a wafer W serving as a substrate obtained by slicing an ingot is subjected to processing to improve the in-plane thickness uniformity. Hereinafter, the slicing surfaces of the wafer W will be referred to as a first surface Wa and a second surface Wb. The first surface Wa is the surface opposite the second surface Wb. The first surface Wa and the second surface Wb may also be collectively referred to as the surfaces of the wafer W.

[0013] 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 cassette C capable of accommodating a plurality of wafers W is loaded and unloaded between the loading / unloading station 2 and the outside. The processing station 3 is equipped with various processing devices that perform desired processing on the wafers W.

[0014] The loading / unloading station 2 is provided with a cassette mounting table 10 on which a plurality of cassettes C, for example, three cassettes C, are mounted. A wafer transfer device 20 is provided adjacent to the cassette mounting table 10 on the negative side of the X-axis of the cassette mounting table 10. The wafer transfer device 20 is configured to be movable on a transfer path 21 extending in the Y-axis direction. The wafer transfer device 20 also has, for example, two transfer arms 22 that hold and transfer wafers W. Each transfer arm 22 is configured to be movable horizontally, vertically, around a horizontal axis, and around a vertical axis. The configuration of the transfer arms 22 is not limited to this embodiment and may have any configuration. The wafer transfer device 20 is configured to be able to transfer wafers W to the cassettes C on the cassette mounting table 10 and to a transition device 30, which will be described later.

[0015] In the loading / unloading station 2 , a transition device 30 for transferring the wafer W to and from the processing station 3 is provided adjacent to the wafer transfer device 20 on the negative side of the X axis of the wafer transfer device 20 .

[0016] For example, three processing blocks G1 to G3 are provided in the processing station 3. The first processing block G1, the second processing block G2, and the third processing block G3 are arranged in this order from the positive side of the X axis (the side of the loading / unloading station 2) to the negative side.

[0017] The first processing block G1 is provided with an etching device 40, a thickness measurement device 50, a reversing device 60, and a wafer transfer device 70. The etching device 40, the thickness measurement device 50, and the reversing device 60 are arranged in a stacked configuration. Note that the number and arrangement of the etching devices 40, the thickness measurement devices 50, and the reversing devices 60 are not limited to this.

[0018] The etching device 40 etches silicon (Si) on the first surface Wa or the second surface Wb after grinding by the grinding device 140 described below. In order to improve the throughput of wafer processing, a plurality of etching devices 40 may be provided.

[0019] As shown in FIG. 2, the etching device 40 includes a wafer holder 41 , a rotating mechanism 42 , a nozzle 43 , and a moving mechanism 44 .

[0020] The wafer holding unit 41 holds the outer edge of the wafer W at multiple points, three points in this embodiment. The configuration of the wafer holding unit 41 is not limited to the example shown in the figure, and for example, the wafer holding unit 41 may include a chuck (not shown) that suction-holds the wafer W from below. The wafer holding unit 41 is configured to be rotatable about a vertical rotation center line 41a by a rotation mechanism 42, thereby allowing the wafer W held on the wafer holding unit 41 to rotate.

[0021] The nozzle 43 supplies the etching liquid E to the first surface Wa or the second surface Wb of the wafer W held by the wafer holder 41. The nozzle 43 is connected to an etching liquid supply source (not shown) that supplies the etching liquid E to the nozzle 43. The nozzle 43 is provided above the wafer holder 41 and configured to be movable in the horizontal and vertical directions by a movement mechanism 44. In one example, the nozzle 43 is configured to be capable of reciprocating movement (scan movement) or swiveling along a rotation center line 41 a of the wafer holder 41, i.e., above the center of the wafer W as shown in FIG. 3 .

[0022] The etching solution E contains hydrofluoric acid (HF), nitric acid (HNO ３ ) and phosphoric acid (H ３ P.O. ４ In one example, the etching solution E is a mixed solution containing hydrofluoric acid, nitric acid, phosphoric acid, and water. The etching target may be, for example, amorphous silicon.

[0023] Further, the nozzle 43 supplies FPM (hydrofluoric acid / hydrogen peroxide solution mixture) to the first surface Wa or the second surface Wb of the wafer W held by the wafer holder 41. The nozzle 43 is connected to an FPM supply source (not shown) that supplies the FPM to the nozzle 43.

[0024] The thickness measurement device 50 shown in FIG. 1 includes, in one example, a measurement unit 51 (see FIG. 5 ) and a calculation unit (not shown). The measurement unit 51 includes a sensor that measures the thickness of the wafer W after etching at multiple points. The calculation unit acquires the thickness distribution of the wafer W from the measurement results (thickness of the wafer W) by the measurement unit 51, and further calculates the flatness (TTV: Total Thickness Variation) of the wafer W. Note that the calculation of the thickness distribution and flatness of the wafer W may be performed by a control device 170 (described later) instead of the calculation unit. In other words, a calculation unit (not shown) may be provided within the control device 170 (described later). Note that the configuration of the thickness measurement device 50 is not limited to this and may be configured arbitrarily.

[0025] The reversing device 60 vertically reverses the first surface Wa and the second surface Wb of the wafer W. The reversing device 60 may have any configuration.

[0026] The wafer transfer device 70 is disposed on the negative side of the transition device 30 in the X-axis direction. The wafer transfer device 70 has, for example, two transfer arms 71 for holding and transferring a wafer W. Each transfer arm 71 is configured to be movable horizontally, vertically, around a horizontal axis, and around a vertical axis. The wafer transfer device 70 is configured to be able to transfer the wafer W to the transition device 30, the etching device 40, the thickness measurement device 50, the inversion device 60, a first cleaning device 80 (described later), a second cleaning device 90 (described later), a thickness measurement device 100 (described later), a buffer device 110 (described later), and an inversion device 120 (described later).

[0027] The second processing block G2 is provided with a first cleaning device 80, a second cleaning device 90, a thickness measurement device 100, a buffer device 110, an inversion device 120, and a wafer transfer device 130. The first cleaning device 80, the second cleaning device 90, the thickness measurement device 100, the buffer device 110, and the inversion device 120 are arranged in a stacked configuration. Note that the number and arrangement of the first cleaning device 80, the second cleaning device 90, the thickness measurement device 100, the buffer device 110, and the inversion device 120 are not limited to this.

[0028] The first cleaning device 80 cleans at least the first surface Wa or the second surface Wb after grinding by the grinding device 140 described below. For example, a cleaning liquid is supplied to the first surface Wa or the second surface Wb from a nozzle 81 (see FIG. 5 ), and a brush 82 (see FIG. 5 ) is brought into contact with the second surface Wb or the first surface Wa, thereby cleaning at least the first surface Wa or the second surface Wb.

[0029] The second cleaning device 90 removes metal components adhering to the first surface Wa or the second surface Wb after cleaning in the first cleaning device 80. For example, FPM is supplied from a nozzle 91 (see FIG. 5 ) to the first surface Wa or the second surface Wb to clean and remove the metal components.

[0030] In one example, the thickness measurement device 100 has the same configuration as the above-described thickness measurement device 50. However, the configuration of the thickness measurement device 100 is not limited to this, and can be configured arbitrarily.

[0031] The buffer apparatus 110 temporarily holds unprocessed wafers W that are transferred from the first processing block G1 to the second processing block G2. The buffer apparatus 110 may have any configuration. The buffer apparatus 110 may also have an alignment mechanism (not shown) that adjusts the center position of the wafer W relative to the chucks 143 a and 143 b (described later) and / or the horizontal orientation of the wafer W.

[0032] The reversing device 120 vertically reverses the first surface Wa and the second surface Wb of the wafer W. The reversing device 120 may have any configuration.

[0033] The wafer transfer device 130 is disposed, for example, on the Y-axis positive side of the first cleaning device 80, the second cleaning device 90, the thickness measurement device 100, the buffer device 110, and the inversion device 120. The wafer transfer device 130 has, for example, two transfer arms 131 that suction-hold and transport the wafer W using a suction-holding surface (not shown). Each transfer arm 131 is supported by an articulated arm member 132 and is configured to be movable horizontally, vertically, around a horizontal axis, and around a vertical axis. The wafer transfer device 130 is configured to be able to transport the wafer W to the etching device 40, the thickness measurement device 50, the inversion device 60, the first cleaning device 80, the second cleaning device 90, the thickness measurement device 100, the buffer device 110, the inversion device 120, and a grinding device 140 (described later).

[0034] The third processing block G3 is provided with a grinding device 140. The grinding device 140 grinds and flattens the first surface Wa or the second surface Wb of the wafer W.

[0035] The grinding device 140 has a rotary table 141. The rotary table 141 is configured to be rotatable about a vertical rotation center line 142 by a rotation mechanism (not shown). Four chucks 143a, 143b for suction-holding a wafer W are provided on the rotary table 141. Of the four chucks 143a, 143b, two first chucks 143a are chucks used for grinding at a first processing position B1 (described later). These two first chucks 143a are arranged in point-symmetric positions with respect to the rotation center line 142. The remaining two second chucks 143b are chucks used for grinding at a second processing position B2 (described later). These two second chucks 143b are also arranged in point-symmetric positions with respect to the rotation center line 142. That is, the first chucks 143a and the second chucks 143b are arranged alternately in the circumferential direction.

[0036] The four chucks 143a, 143b can be moved to the delivery positions A1-A2 and the processing positions B1-B2 by the rotation of the rotary table 141. Furthermore, each of the four chucks 143a, 143b is configured to be rotatable around a vertical axis by a rotation mechanism (not shown).

[0037] The first transfer position A1 is a position on the positive X-axis side and the positive Y-axis side of the rotation center line 142 of the turntable 141, where the wafer W is transferred to the first chuck 143a when the first surface Wa is ground. The second transfer position A2 is a position on the positive X-axis side and the negative Y-axis side of the rotation center line 142 of the turntable 141, where the wafer W is transferred to the second chuck 143b when the second surface Wb is ground.

[0038] First processing position B1 is a position on the negative X-axis side and the negative Y-axis side with respect to rotation center line 142 of rotary table 141, and first grinding unit 150 is disposed thereat. First grinding unit 150 has a grinding section 151 equipped with an annular, rotatable grinding wheel (not shown). Grinding section 151 is configured to be movable in the vertical direction along support columns 152. As an example, first grinding unit 150 grinds first surface Wa or second surface Wb of wafer W held by first chuck 143 a.

[0039] The second processing position B2 is a position on the negative X-axis side and the positive Y-axis side with respect to the rotation center line 142 of the rotary table 141, and the second grinding unit 160 is disposed thereat. The second grinding unit 160 has a grinding section 161 equipped with an annular, rotatable grinding wheel (not shown). The grinding section 161 is configured to be movable in the vertical direction along a support column 162. As an example, the second grinding unit 160 grinds the second surface Wb or the first surface Wa of the wafer W held by the second chuck 143b.

[0040] A thickness measuring device (not shown) for measuring the thickness of the wafer W after grinding may be provided at the transfer positions A1, A2 or the processing positions B1, B2.

[0041] The wafer processing system 1 described above is provided with at least one controller 170. The controller 170 processes computer-executable instructions that cause the wafer processing system 1 to perform the various steps described in this disclosure. The controller 170 may be configured to control each element of the wafer processing system 1 to perform the various steps described herein. In one embodiment, some or all of the controller 170 may be included in the wafer processing system 1. The controller 170 may include a processing unit, a storage unit, and a communication interface. The controller 170 may be implemented, for example, by a computer. The processing unit may be configured to read from the storage unit a program that provides logic or routines that enable various control operations to be performed, and to execute the read program to perform various control operations. This program may be stored in the storage unit in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit and read from the storage unit by the processing unit for execution. The medium may be various computer-readable storage media or a communication line connected to the communication interface. The storage medium may be temporary or non-temporary. The processing unit may be a CPU (Central Processing Unit) or one or more circuits. The storage unit may include a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), an 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).

[0042] Next, a description will be given of wafer processing performed using the wafer processing system 1 configured as described above. In this embodiment, processing is performed on wafers W cut from an ingot using a wire saw or the like, or on lapped wafers W, to improve the in-plane thickness uniformity.

[0043] First, a cassette C containing a plurality of wafers W is placed on the cassette mounting table 10 of the carry-in / out station 2. In the cassette C, the wafers W are stored with their first surfaces Wa facing upward and their second surfaces Wb facing downward. Next, the wafer transfer device 20 removes the wafers W from the cassette C and transfers them to the transition device 30. The wafers W transferred to the transition device 30 are then transferred to the buffer device 110 by the wafer transfer device 70.

[0044] Next, the wafer W is transferred to the reversing device 60 by the wafer transfer device 70. In the reversing device 60, the first surface Wa and the second surface Wb of the wafer W are reversed upside down (S1 in FIGS. 4 and 5). That is, the wafer W is reversed so that the second surface Wb faces upward and the first surface Wa faces downward.

[0045] Next, the wafer W is transferred by the wafer transfer device 130 to the grinding device 140 and transferred to the second chuck 143b at the second transfer position A2. The first surface Wa of the wafer W is suction-held by the second chuck 143b. Next, the turntable 141 is rotated to move the wafer W to the second processing position B2. Then, the second surface Wb of the wafer W is ground by the second grinding unit 160 (S2 in FIGS. 4 and 5). Next, the turntable 141 is rotated to move the wafer W to the second transfer position A2.

[0046] Next, the wafer W is transferred by the wafer transfer device 130 to the first cleaning device 80. In the first cleaning device 80, a cleaning liquid is supplied from the nozzle 81 to the second surface Wb to clean the second surface Wb, and the first surface Wa is cleaned by the brush 82 (S3 in FIGS. 4 and 5 ).

[0047] Next, the wafer W is transferred to the reversing device 120 by the wafer transfer device 130. In the reversing device 120, the first surface Wa and the second surface Wb of the wafer W are reversed upside down (S4 in FIGS. 4 and 5). That is, the wafer W is reversed so that the first surface Wa faces upward and the second surface Wb faces downward.

[0048] Next, the wafer W is transferred by the wafer transfer device 130 to the grinding device 140 and transferred to the first chuck 143a at the first transfer position A1. The first chuck 143a suction-holds the second surface Wb of the wafer W. Next, the turntable 141 is rotated to move the wafer W to the first processing position B1. Then, the first grinding unit 150 grinds the first surface Wa of the wafer W (S5 in FIGS. 4 and 5 ). Next, the turntable 141 is rotated to move the wafer W to the first transfer position A1.

[0049] Next, the wafer W is transferred by the wafer transfer device 130 to the thickness measurement device 100. In the thickness measurement device 100, the measurement unit 101 measures the thickness of the wafer W at multiple points after grinding both the first surface Wa and the second surface Wb, thereby obtaining a thickness distribution of the wafer W (S6 in FIGS. 4 and 5 ). The flatness of the wafer W may also be calculated. The obtained thickness distribution of the wafer W is output to, for example, the control device 170, and is used, for example, in processing another wafer W to be processed next in the wafer processing system 1. Note that if the grinding device 140 is provided with a thickness measurement device, the thickness of the wafer W after grinding may be measured by the thickness measurement device of the grinding device 140.

[0050] Next, the wafer W is transferred by the wafer transfer device 130 to the first cleaning device 80. In the first cleaning device 80, a cleaning liquid is supplied from the nozzle 81 to the first surface Wa to clean the first surface Wa, and the second surface Wb is cleaned by the brush 82 (S7 in FIGS. 4 and 5 ).

[0051] Next, the wafer W is transferred to the reversing device 120 by the wafer transfer device 130. In the reversing device 120, the first surface Wa and the second surface Wb of the wafer W are reversed upside down (S8 in FIGS. 4 and 5). That is, the wafer W is reversed so that the second surface Wb faces upward and the first surface Wa faces downward.

[0052] Next, the wafer W is transferred by the wafer transfer device 130 to the second cleaning device 90. In the second cleaning device 90, the FPM is supplied from the nozzle 91 to the second surface Wb to clean the second surface Wb and remove metal components adhering to the second surface Wb (S9 in FIGS. 4 and 5 ).

[0053] Next, the wafer W is transferred to the reversing device 120 by the wafer transfer device 130. In the reversing device 120, the first surface Wa and the second surface Wb of the wafer W are reversed upside down (S10 in FIGS. 4 and 5). That is, the wafer W is reversed so that the first surface Wa faces upward and the second surface Wb faces downward.

[0054] Next, the wafer W is transferred to the thickness measurement device 50 by the wafer transfer device 130 or the wafer transfer device 70. In the thickness measurement device 50, the measurement unit 51 measures the thickness of the wafer W at multiple points after grinding both the first surface Wa and the second surface Wb, thereby obtaining the thickness distribution of the wafer W and further calculating the flatness of the wafer W (S11 in FIGS. 4 and 5 ). In the thickness measurement device 50, the measurement unit 51 measures the thickness of the wafer W, for example, while the second surface Wb is held by a chuck (not shown). At this time, since metal components have been removed from the second surface Wb in S9, contamination of the chuck can be suppressed, and subsequent thickness measurements of the wafer W can be performed appropriately. The thickness distribution and flatness of the wafer W obtained in S11 are output to, for example, the control device 170. Note that the thickness of the wafer W measured in S11 corresponds to the first thickness in this disclosure.

[0055] The control device 170 determines first optimal etching conditions for the etching process of the first surface Wa and second optimal etching conditions for the etching process of the second surface Wb from the output thickness distribution and flatness of the wafer W (S12 in FIG. 4). The first optimal etching conditions are conditions for optimizing the etching amount distribution when etching the first surface Wa in S13, which will be described later. The second optimal etching conditions are conditions for optimizing the etching amount distribution when etching the second surface Wb in S15, which will be described later. The method of determining the first optimal etching conditions and the second optimal etching conditions in the control device 170 will be described later.

[0056] Next, the wafer W is transferred by the wafer transfer device 70 to the etching device 40. In the etching device 40, the first surface Wa of the wafer W is etched under the first optimal etching conditions determined in S12 (S13 in FIGS. 4 and 5). In S13, the wafer W held by the wafer holder 41 is rotated, and the nozzle 43 is moved back and forth while the etching solution E is supplied from the nozzle 43 to the first surface Wa, thereby etching the first surface Wa. Then, by etching the first surface Wa under the first optimal etching conditions, the etching amount distribution is optimized, and the first surface Wa is processed into a target shape.

[0057] In addition, in S13, after the first surface Wa is etched with the etching solution E, FPM is supplied from the nozzle 43 to the first surface Wa to clean the first surface Wa and remove metal components from the first surface Wa.

[0058] Next, the wafer W is transferred to the reversing device 60 by the wafer transfer device 70. In the reversing device 60, the first surface Wa and the second surface Wb of the wafer W are reversed upside down (S14 in FIGS. 4 and 5). That is, the wafer W is reversed so that the second surface Wb faces upward and the first surface Wa faces downward.

[0059] Next, the wafer W is transferred by the wafer transfer device 70 to the etching device 40. In the etching device 40, the second surface Wb of the wafer W is etched under the second optimal etching conditions determined in S12 (S15 in FIGS. 4 and 5). In S13, the wafer W held by the wafer holder 41 is rotated and the nozzle 43 is moved back and forth while the etching solution E is supplied from the nozzle 43 to the second surface Wb, thereby etching the second surface Wb. Then, by etching the second surface Wb under the second optimal etching conditions, the etching amount distribution is optimized and the second surface Wb is processed into a target shape.

[0060] In S15, the second surface Wb is etched with the etching liquid E, and then FPM is supplied from the nozzle 43 to the second surface Wb to clean the second surface Wb.

[0061] Next, the wafer W is transferred to the reversing device 60 by the wafer transfer device 70. In the reversing device 60, the first surface Wa and the second surface Wb of the wafer W are reversed upside down (S16 in FIGS. 4 and 5). That is, the wafer W is reversed so that the first surface Wa faces upward and the second surface Wb faces downward.

[0062] Next, the wafer W is transferred by the wafer transfer device 70 to the thickness measurement device 50. In the thickness measurement device 50, the measurement unit 51 measures the thickness of the wafer W at multiple points on both the first surface Wa and the second surface Wb after etching, thereby obtaining a thickness distribution of the wafer W (S17 in FIGS. 4 and 5 ). Furthermore, the flatness of the wafer W may be calculated. The obtained thickness distribution of the wafer W is output to, for example, the control device 170, and is used, for example, in processing another wafer W to be processed next in the wafer processing system 1.

[0063] Thereafter, the wafer W that has been subjected to all the processes is transferred to the cassette C on the cassette mounting table 10 via the transition device 30. In this way, a series of wafer processes in the wafer processing system 1 is completed.

[0064] Next, the method for determining the first and second optimal etching conditions (S12 in FIG. 4) will be described. There are, for example, two patterns for determining the first and second optimal etching conditions. The first pattern will be described below using the flowchart in FIG. 6, and the second pattern will be described below using the flowchart in FIG. 7.

[0065] In the first pattern, first, a plurality of learning data to be used in the optimization process described below is acquired (S120 in FIG. 6 ) before processing is performed on the wafer W in the wafer processing system 1. The learning data is an etching amount distribution (etching profile) of the wafer W under certain etching conditions.

[0066] In S120, etching is performed on the dummy wafer under, for example, a plurality of different etching conditions. Similar to the etching processes in S13 and S15, etching of each dummy wafer is performed by rotating the dummy wafer and supplying etching solution E to the dummy wafer from the nozzle 43 while the nozzle 43 is moved back and forth (scanning movement). In the following description, the reciprocating movement of the nozzle 43 between both ends of the dummy wafer is defined as one loop. Specifically, in S120, the dummy wafer is etched by changing, for example, the rotation speed (also referred to as the number of rotations) of the dummy wafer during etching, the scanning speed (also referred to as the swing speed) of the nozzle 43, the scanning width (see the scanning width L in FIG. 3 , also referred to as the swing radius) of the nozzle 43, or the number of loops of the nozzle 43. In this case, the etching processing time for each dummy wafer is the same.

[0067] An etching amount distribution is acquired for etching of the dummy wafer under each etching condition, and the etching amount distribution is output to the control device 170. Furthermore, the control device 170 compresses the output etching amount distribution under each etching condition into an etching amount distribution per unit time (unit number of loops), and stores each compressed etching amount distribution as the learning data.

[0068] Next, a first target etching amount distribution and a second target etching amount distribution are obtained based on the thickness distribution in the target shape of the wafer W after etching and the thickness distribution in the surface shape of the wafer W after grinding (hereinafter referred to as the "measured shape") obtained in S11 (S121 in FIG. 6). The first target etching amount distribution is the target etching amount distribution when etching the first surface Wa in S13. The second target etching amount distribution is the target etching amount distribution when etching the second surface Wb in S15. The first target etching amount distribution and the second target etching amount distribution may be obtained by any method. For example, a predetermined value, such as a minimum etching amount, may be set as a constraint for the first target etching amount distribution and the second target etching amount distribution. Then, the difference between the thickness distribution in the target shape of the wafer W and the thickness distribution in the measured shape is calculated, and the first target etching amount distribution and the second target etching amount distribution are obtained based on the constraint. For example, if the first target etching amount distribution is 1.5 μm and the second target etching amount distribution is 1.5 μm, the target etching amount distribution (the difference) is 3.0 μm. Note that the constraint may be other than the etching amount distribution, and may be, for example, the flatness of the target shape of the wafer W.

[0069] Next, the learning data to be used for the superposition and the number of times the learning data is superposed are optimized using an optimization method so that the multiple learning data are superposed to obtain the first target etching amount distribution and the second target etching amount distribution obtained in S121 (S122 in FIG. 6).

[0070] In S122, for example, the control of the etching amount distribution is applied to a knapsack problem to optimize the number of overlaps of the learning data with the learning data. For example, the etching amount distribution is the knapsack in the knapsack problem, and the learning data are the items in the knapsack problem. Then, the number of overlaps of the learning data with the learning data is optimized so that the difference between the overlapped etching amount distribution and the first and second target etching amount distributions is minimized.

[0071] Next, the etching conditions corresponding to the learning data optimized in S122 are integrated to determine first and second optimum etching conditions (S123 in FIG. 6). Specifically, the selected etching conditions are integrated so that the optimized number of overlaps is used to determine the first and second optimum etching conditions.

[0072] In the second pattern, a plurality of learning data to be used in the optimization process described below is also acquired (S220 in FIG. 7 ) before processing the wafer W in the wafer processing system 1. The method for acquiring the learning data in S220 is the same as the method for acquiring the learning data in S120 in the first pattern.

[0073] Next, in S13, a first target etching amount distribution for etching the first surface Wa is obtained based on the thickness distribution in the target shape of the wafer W after etching and the thickness distribution in the measured shape of the wafer W after grinding obtained in S11 (S221 in FIG. 7 ). The method for obtaining the first target etching amount distribution in S221 is the same as the method for obtaining the first target etching amount distribution in S121 for the first pattern. For example, if the first target etching amount distribution is 1.5 μm and the second target etching amount distribution is 1.5 μm, the target etching amount distribution (the difference) is 3.0 μm.

[0074] Next, the learning data to be used for superimposition and the number of times the learning data are superimposed are optimized using an optimization method so that the multiple learning data are superimposed to obtain the first target etching amount distribution obtained in S221 (S222 in FIG. 7). In S222, similar to S122 in the first pattern, the learning data and the number of times the learning data are superimposed are optimized using, for example, the knapsack problem.

[0075] Next, the etching conditions corresponding to the learning data optimized in S222 are integrated to determine first optimum etching conditions (S223 in FIG. 7). The method for determining the first optimum etching conditions in S223 is the same as the method for determining the first optimum etching conditions in S123 of the first pattern.

[0076] Next, based on the first optimal etching conditions determined in S223, the thickness distribution of the wafer W when the first surface Wa is etched is estimated (S224 in FIG. 7). In S224, for example, the thickness distribution of the wafer W is estimated by subtracting the etching amount distribution of the first surface Wa optimized in S221 to S223 from the thickness distribution of the wafer W acquired in S11. Note that the thickness of the wafer W estimated in S224 corresponds to the second thickness in the present disclosure.

[0077] Next, in S15, a second target etching amount distribution for etching the second surface Wb is obtained based on the thickness distribution in the target shape of the wafer W after etching and the thickness distribution of the wafer W estimated in S224 (S225 in FIG. 7 ). The method for obtaining the second target etching amount distribution in S225 is the same as the method for obtaining the second target etching amount distribution in S121 for the first pattern.

[0078] Next, the learning data to be used for superimposition and the number of times the learning data are superimposed are optimized using an optimization method so that the multiple learning data are superimposed to obtain the second target etching amount distribution obtained in S225 (S226 in FIG. 7). In S226, similar to S122 in the first pattern, the learning data and the number of times the learning data are superimposed are optimized using, for example, the knapsack problem.

[0079] Next, the etching conditions corresponding to the learning data optimized in S226 are integrated to determine second optimum etching conditions (S227 in FIG. 7). The method for determining the second optimum etching conditions in S227 is the same as the method for determining the second optimum etching conditions in S123 of the first pattern.

[0080] Here, when the first target etching amount distribution and the second target etching amount distribution are small, the supply time of the etching solution E is shortened, and therefore the control range of the etching amount distribution by adjusting the etching conditions becomes small. For example, when the knapsack problem is used as the optimization method, the capacity of the knapsack (etching amount distribution) becomes small.

[0081] In this regard, in both the first pattern and the second pattern of this embodiment, the first and second optimal etching conditions are determined based on the thickness distribution of the wafer W acquired in S11. That is, both the etching conditions for the first surface Wa and the etching conditions for the second surface Wb are optimized. Furthermore, when double-sided etching is performed as in this embodiment, the etching amount is doubled compared to single-sided etching. In this case, even if the first target etching amount distribution and the second target etching amount distribution are small, the etching amount distribution for the first surface Wa and the etching amount distribution for the second surface Wb can be optimized, respectively. As a result, the surface shape of the wafer W after etching can be appropriately controlled.

[0082] In the first pattern, the first and second optimum etching conditions are simultaneously determined based on the thickness distribution of the wafer W obtained in S11. In this case, since a calculation is performed in one optimization calculation taking into account both the etching of the first surface Wa and the etching of the second surface Wb, the first and second optimum etching conditions can be determined with high accuracy.

[0083] In the second pattern, first optimal etching conditions are determined based on the thickness distribution of the wafer W acquired in S11, and then second optimal etching conditions are determined based on the optimized etching amount distribution of the first surface Wa. That is, in the second pattern, optimization calculations are performed twice: one to determine the first optimal etching conditions, and the other to determine the second optimal etching conditions. In this case, the number of optimal etching conditions determined in each optimization calculation is small, so that the calculations can be completed in a short time.

[0084] In the second pattern, after determining the first optimum etching conditions in steps S221 to S223, etching the first surface Wa under the first optimum etching conditions in step S13 and determining the second optimum etching conditions in steps S224 to S227 may be performed in parallel, thereby improving the throughput of wafer processing.

[0085] In the above embodiment, the etching amount distribution is used as the etching index distribution (learning data) for controlling the etching process of the wafer W. However, an etching amount deviation distribution may also be used. The etching amount deviation distribution is a distribution of values ​​obtained by subtracting the average value of the etching amount from the etching amount within the wafer surface. In such a case, when determining the first optimal etching condition and the second optimal etching condition, the etching amount deviation distribution is used instead of the etching amount distribution.

[0086] In the above embodiment, the acquisition of the plurality of learning data in S120 and S220 is performed in the wafer processing system 1, but it may be performed outside the wafer processing system 1. In such a case, the control device 170 determines the first optimum etching condition and the second optimum etching condition based on the plurality of learning data acquired outside the wafer processing system 1.

[0087] In the above embodiments, the order of the wafer processing sequence is not limited to the above. For example, the grinding (S2) and cleaning (S3) of the second surface Wb are performed first, followed by the grinding (S5) and cleaning (S7) of the first surface Wa. However, the grinding and cleaning of the first surface Wa may be performed first, followed by the grinding and cleaning of the second surface Wb. Furthermore, the etching of the first surface Wa (S13) is performed first, followed by the etching of the second surface Wb (S15). However, the etching of the second surface Wb may be performed first, followed by the etching of the first surface Wa. In such a case, in S9, FPM is supplied to the first surface Wa to clean the first surface Wa and remove metal components adhering to the first surface Wa. Furthermore, in S9, both the removal of metal components from the first surface Wa and the removal of metal components from the second surface Wb may be performed.

[0088] In the above embodiments, the target shape of the wafer W after etching is not limited. For example, the technology of the present disclosure can be applied to any one of a flat type, a convex type, a concave type, a W-shape, an M-shape, or a combination of any two of these. The flat type is a shape in which the entire surface of the wafer W is adjusted to a desired flatness (TTV) or less, preferably a shape in which the thickness is controlled to be uniform over the entire surface. The convex type is a shape in which the thickness at the center of the wafer W is greater than the thickness at the outer periphery. The concave type is a shape in which the thickness at the concave portion of the wafer W is smaller than the thickness at the outer periphery. The W-shape is a shape in which the thickness at the center of the radius of the wafer W is smaller than the thickness at the center and outer periphery. The M-shape is a shape in which the thickness at the center of the radius of the wafer W is greater than the thickness at the center and outer periphery.

[0089] In the wafer processing system 1 of the above embodiment, the metal components are removed by supplying FPM to at least one of the first surface Wa or the second surface Wb in the second cleaning apparatus 90, but such removal of the metal components may also be performed in the etching apparatus 40. In such a case, the second cleaning apparatus 90 is omitted.

[0090] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. For example, the components of the above-described embodiments may be arbitrarily combined. Such an arbitrary combination naturally provides the functions and effects of each of the components involved in the combination, and also provides other functions and effects that are apparent to those skilled in the art from the description of this specification.

[0091] Furthermore, the effects described herein are merely descriptive or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that are apparent to those skilled in the art from the description of this specification, in addition to or in place of the above-described effects.

[0092] 1 Wafer processing system 40 Etching device 170 Control device W Wafer Wa First surface Wb Second surface

Claims

1. A substrate processing method for processing a substrate, comprising: determining first optimum etching conditions using an optimization method based on a first thickness of a substrate before etching a first surface and a second surface of the substrate, so that the surface shape of the first surface after etching will be a target shape, and determining second optimum etching conditions using an optimization method so that the surface shape of the second surface after etching will be the target shape; etching the first surface based on the first optimum etching conditions; and etching the second surface based on the second optimum etching conditions.

2. The substrate processing method according to claim 1, further comprising the steps of: determining the first optimum etching conditions and the second optimum etching conditions simultaneously using an optimization technique based on the first thickness.

3. The substrate processing method of claim 1, comprising: determining the first optimum etching conditions using an optimization technique based on the first thickness; estimating a second thickness of the substrate after etching the first surface based on the first optimum etching conditions; and determining the second optimum etching conditions using an optimization technique based on the second thickness.

4. The substrate processing method according to claim 3, wherein etching of said first surface based on said first optimum etching conditions and determining of said second optimum etching conditions are carried out in parallel.

5. The substrate processing method according to claim 1, wherein when determining said first optimum etching conditions and said second optimum etching conditions, a target etching amount of said first surface and a target etching amount of said second surface are set as constraints.

6. The substrate processing method according to claim 1, comprising: grinding the first surface and the second surface; cleaning at least one of the first surface and the second surface of the substrate after grinding to remove metal components; and measuring the first thickness of the substrate after cleaning.

7. A substrate processing system for processing a substrate, comprising: an etching apparatus for etching a surface of a substrate; and a control apparatus, wherein the control apparatus performs the following control: determining first optimum etching conditions using an optimization method based on a first thickness of a substrate before etching a first surface and a second surface of the substrate, so that a surface shape of the first surface after etching will become a target shape, and determining second optimum etching conditions using the optimization method so that a surface shape of the second surface after etching will become a target shape; controlling, in the etching apparatus, etching the first surface based on the first optimum etching conditions; and controlling, in the etching apparatus, etching the second surface based on the second optimum etching conditions.

8. The substrate processing system according to claim 7, wherein the control device executes control to simultaneously determine the first optimum etching conditions and the second optimum etching conditions using an optimization technique based on the first thickness.

9. The substrate processing system of claim 7, wherein the control device executes the following controls: determining the first optimal etching conditions using an optimization method based on the first thickness; estimating a second thickness of the substrate after etching the first surface based on the first optimal etching conditions; and determining the second optimal etching conditions using an optimization method based on the second thickness.

10. The substrate processing system of claim 9, wherein the control device executes control in the etching device to etch the first surface based on the first optimal etching conditions and to determine the second optimal etching conditions in parallel.

11. The substrate processing system of claim 7, wherein the control device performs control in which the target etching amount of the first surface and the target etching amount of the second surface are constraints when determining the first optimal etching conditions and the second optimal etching conditions.

12. A substrate processing system as described in claim 7, comprising: a grinding device that grinds a surface of a substrate; a cleaning device that cleans the surface of the substrate after grinding to remove metal components; and a thickness measuring device that measures the thickness of the substrate after cleaning, wherein the control device executes the following controls: control in the grinding device to grind the first surface and the second surface; control in the cleaning device to clean at least one of the first surface and the second surface of the substrate after grinding to remove metal components; and control in the thickness measuring device to measure the first thickness of the substrate after cleaning.

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