Substrate processing method, substrate processing system, and program

Abstract

To appropriately control a surface shape of an etching target after etching processing.SOLUTION: A substrate processing method includes: determining an optimum etching condition; and, on the basis of the optimum etching condition, supplying an etching liquid to a surface of an etching target of a substrate to perform etching on the surface. The determining of the optimum etching condition includes: storing a radial etching index distribution of the etching target in performing etching on the surface of the etching target under a plurality of different etching conditions; optimizing, by using an optimization method, a combination of the etching index distributions to be used for superimposition in which etching index distributions corresponding to the plurality of conditions are superimposed so that a shape of the surface of the etching target becomes a target shape, and the number of superimposing the etching index distributions; and integrating etching conditions corresponding to the optimized combination to determine the optimum etching condition.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a substrate processing method, a substrate processing system, and a program. [Background technology]

[0002] Patent Document 1 discloses a substrate processing method including a grinding step of grinding the surface of a substrate, a measuring 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 step of supplying a processing liquid to the ground substrate and performing a wet etching process based on the determined processing conditions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-147908 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology according to the present disclosure appropriately controls the surface shape of an etching target after etching processing. [Means for solving the problem]

[0005] One aspect of the present disclosure is a substrate processing method for processing a substrate, comprising: determining optimal etching conditions; and supplying an etching liquid to a surface of the substrate to be etched based on the optimal etching conditions, thereby etching the surface. Determining the optimal etching conditions includes storing an etching index distribution in a radial direction of the etching target when the surface of the etching target is etched under a plurality of different etching conditions; using an optimization method to superimpose the etching index distributions corresponding to the plurality of etching conditions, and optimizing a combination of the etching index distributions used for the superimposition and the number of times the etching index distributions are superimposed so that a shape of the surface of the etching target becomes a target shape; and integrating the etching conditions corresponding to the optimized combination to determine the optimal etching conditions. [Effects of the Invention]

[0006] According to the present disclosure, the surface shape of an etching target after etching can be appropriately controlled. [Brief explanation of the drawings]

[0007] [Figure 1] 10 is a graph showing the distribution of etching amount deviations when a wafer is etched under a plurality of different etching conditions. [Figure 2] FIG. 2 is a side view illustrating an example of an overlapping wafer being processed in a wafer processing system. [Figure 3] 1 is a plan view schematically showing an outline of the configuration of a wafer processing system according to an embodiment of the present invention; [Figure 4] FIG. 1 is a side view showing an outline of the configuration of an etching apparatus. [Figure 5] FIG. 10 is an explanatory diagram showing a state in which the nozzle moves in the radial direction. [Figure 6] FIG. 1 is a flowchart showing main steps of wafer processing according to the present embodiment. [Figure 7] FIG. 1 is a flowchart showing the main steps of a method for determining optimal etching conditions. [Figure 8] FIG. 10 is an explanatory diagram showing an example of a plurality of parts. [Figure 9] FIG. 10 is an explanatory diagram showing an example of a target etching amount deviation distribution. [Figure 10] FIG. 10 is an explanatory diagram showing an example of parts used for superimposing. [Figure 11] FIG. 10 is an explanatory diagram showing an example of overlapping a plurality of optimized parts. [Figure 12] FIG. 10 is an explanatory diagram showing an example of the thickness deviation distribution of the first wafer after grinding and after etching. [Figure 13] FIG. 4 is an explanatory diagram showing an example of the thickness distribution of the first wafer after grinding and after etching. [Figure 14] FIG. 10 is a plan view schematically illustrating an outline of the configuration of a wafer processing system according to another embodiment. [Figure 15] FIG. 10 is a flowchart showing main steps of wafer processing according to a first pattern of another embodiment. [Figure 16] 10A to 10C are explanatory views showing main steps of wafer processing according to a first pattern of another embodiment. [Figure 17] FIG. 10 is a flowchart showing main steps of wafer processing according to a second pattern of another embodiment. [Figure 18] FIG. 10 is a flowchart showing main steps of wafer processing according to a third pattern of another embodiment. [Figure 19] 10A to 10C are explanatory views showing main steps of wafer processing according to a third pattern of another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] In the manufacturing process of semiconductor devices, a semiconductor substrate (hereinafter referred to as a "wafer") having a plurality of devices such as electronic circuits formed on its surface is ground to thin it, and the ground surface of the wafer is then smoothed. The smoothing of the ground surface is performed, for example, by so-called spin etching, in which an etching solution is supplied from above the ground surface of the wafer while the wafer is rotating.

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

[0010] However, when spin etching is performed by supplying a processing solution to a rotating wafer, as in the method disclosed in Patent Document 1, the processing solution supplied to the wafer surface flows radially outward due to centrifugal force, making it difficult to precisely control the etching. More specifically, it is difficult to appropriately control the surface shape of the wafer after etching, especially at the center of the wafer.

[0011] Here, the inventors have discovered the possibility of controlling the wafer surface shape after etching processing by obtaining an etching amount deviation distribution (etching profile) in the wafer radial direction when etching a wafer under a plurality of different etching conditions (etching recipes) and superimposing the plurality of etching amount deviation distributions. Note that the etching amount deviation indicates a value (deviation) obtained by subtracting the average etching amount from the etching amount within the wafer surface. The average etching amount is a value obtained by averaging the etching amount within the wafer surface. Furthermore, the etching amount deviation distribution is an etching index distribution that serves as an index when controlling the wafer etching processing.

[0012] In this etching process, the wafer is rotated and the nozzle is moved in a radial direction passing through the center of the wafer while supplying the etching solution from the nozzle. The nozzle is moved back and forth between both ends of the wafer multiple times. In the following explanation, the reciprocating movement of the nozzle between both ends of the wafer is considered to be one loop.

[0013] Figure 1 is a graph showing the distribution of etching amount deviations when a wafer is etched under a number of different etching conditions. The horizontal axis of Figure 1 represents the radial position from the center of the wafer (zero on the horizontal axis) to the outer edge (R on the horizontal axis), and the vertical axis represents the etching amount deviation.

[0014] In FIG. 1, Comparative Example 1 (dotted line) shows the etching amount deviation distribution when only the etching process was performed under Condition A, where the wafer rotation speed was 200 rpm. Comparative Example 2 (double-dot chain line) shows the etching amount deviation distribution when only the etching process was performed under Condition B, where the wafer rotation speed was 1000 rpm. In contrast, Example 1 (thick solid line) shows the etching amount deviation distribution when Condition A and Condition B were performed at a time (number of loops) ratio of 1:1. The thin solid line is the calculated value of the etching amount deviation distribution under the etching conditions of Example 1. This calculated value is the sum of 1 / 2 of the etching amount deviation distribution of Comparative Example 1 and 1 / 2 of the etching amount deviation distribution of Comparative Example 2. Example 2 (thick dashed line) shows the etching amount deviation distribution when Condition A and Condition B were performed at a time ratio of 5:1. The thin dashed line is the calculated value of the etching amount deviation distribution under the etching conditions of Example 2. This calculated value is the sum of 5 / 6 of the etching amount deviation distribution of Comparative Example 1 and 1 / 6 of the etching amount deviation distribution of Comparative Example 2. In Comparative Examples 1 and 2 and Examples 1 and 2, the etching conditions other than the wafer rotation speed were the same.

[0015] 1, it was confirmed that the measured value of the etching amount deviation distribution in Example 1, in which Condition A and Condition B were performed at a time ratio of 1:1, was approximately equal to the average value (calculated value) of the etching amount deviation distribution in Comparative Example 1 and Comparative Example 2. It was also confirmed that the measured value of the etching amount deviation distribution in Example 2, in which Condition A and Condition B were performed at a time ratio of 5:1, was approximately equal to the proportionally distributed value (calculated value) obtained by dividing the etching amount deviation distribution in Comparative Example 1 and the etching amount deviation distribution in Comparative Example 2 by the time ratio. Since the measured value and the calculated value were approximately equal, it was confirmed that the etching amount deviation distribution after the superposition was accurate.

[0016] Furthermore, comparing Example 1 and Example 2, the etching amount deviation at the wafer center is smaller than that at the periphery in Example 1, whereas the etching amount deviation distribution is uniform across the wafer surface in Example 2. In other words, it was found that any desired etching amount deviation distribution can be obtained by adjusting the time ratio.

[0017] As described above, by superimposing the etching amount deviation distributions corresponding to a plurality of etching conditions, the wafer surface shape after etching can also be superimposed and controlled.The inventors have found that by adjusting the time ratio (loop number ratio) for a plurality of etching conditions, the etching amount deviation distribution can be controlled, and the wafer surface shape after etching can be controlled.

[0018] The technology disclosed herein has been made in light of the above findings, and appropriately controls the surface shape of an etching target after etching. Hereinafter, a wafer processing system as a substrate processing system and a wafer processing method as a substrate processing method according to this 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.

[0019] In a wafer processing system 1 according to this embodiment, which will be described later, processing is performed on a laminated wafer T, which is a substrate formed by bonding a first wafer W and a second wafer S, as shown in Fig. 2. Hereinafter, the surface of the first wafer W that is bonded to the second wafer S will be referred to as the front surface Wa, and the surface opposite the front surface Wa will be referred to as the back surface Wb. Similarly, the surface of the second wafer S that is bonded to the first wafer W will be referred to as the front surface Sa, and the surface opposite the front surface Sa will be referred to as the back surface Sb.

[0020] The first wafer W is a semiconductor wafer such as a silicon substrate, and has a device layer Dw including a plurality of devices formed on its front surface Wa. A bonding film Fw is further formed on the device layer Dw, and the first wafer W is bonded to the second wafer S via the bonding film Fw. The bonding film Fw may be, for example, an oxide film (THOX film, SiO2 film, TEOS film), a SiC film, a SiCN film, or an adhesive.

[0021] The second wafer S has, for example, the same configuration as the first wafer W, and has a device layer Ds and a bonding film Fs formed on the surface Sa. Note that the second wafer S does not need to be a device wafer on which the device layer Ds is formed, and may be, for example, a support wafer that supports the first wafer W. In such a case, the second wafer S functions as a protective material that protects the device layer Dw of the first wafer W.

[0022] 3, wafer processing system 1 has a configuration in which a loading / unloading station 2 and a processing station 3 are integrally connected. In loading / unloading station 2, for example, a cassette C capable of accommodating a plurality of overlapped wafers T is loaded and unloaded between the loading / unloading station 2 and the outside. Processing station 3 is equipped with various processing devices that perform desired processing on overlapped wafers T.

[0023] The carry-in / out 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, 22 that hold and transfer the overlapped wafer T. 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 arm 22 is not limited to this embodiment and may have any configuration. The wafer transfer device 20 is configured to be able to transfer the overlapped wafer T to the cassette C on the cassette mounting table 10 and to a transition device 30, which will be described later.

[0024] In the loading / unloading station 2, a transition device 30 for transferring the overlapped wafer T 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.

[0025] For example, three processing blocks B1 to B3 are provided in the processing station 3. The first processing block B1, the second processing block B2, and the third processing block B3 are arranged in this order from the positive side of the X axis (the loading / unloading station 2 side) to the negative side.

[0026] The first processing block B1 is provided with an etching device 40, a thickness measuring device 41, and a wafer transfer device 50. The etching device 40 and the thickness measuring device 41 are arranged in a stacked configuration. However, the number and arrangement of the etching devices 40 and the thickness measuring devices 41 are not limited to this.

[0027] The etching device 40 etches the back surface Wb (ground surface) of the first wafer W after grinding in the processing device 80 described below, thereby further thinning the ground first wafer W (overlapping wafer T) and smoothing the ground surface by removing grinding marks caused by the grinding process. The detailed configuration of the etching device 40 will be described later.

[0028] In one example, the thickness measurement device 41 includes a measurement unit (not shown) and a calculation unit (not shown). The measurement unit includes a sensor that measures the thickness of the first wafer W after etching at multiple points. The calculation unit acquires the thickness distribution of the first wafer W from the measurement results (thickness of the first wafer W) by the measurement unit, and further calculates the flatness (TTV: Total Thickness Variation) of the first wafer W. Note that the calculation of the thickness distribution and flatness of the first wafer W may be performed by a control device 90 (described later) instead of the calculation unit. In other words, a calculation unit (not shown) may be provided within the control device 90 (described later). Note that the configuration of the thickness measurement device 41 is not limited to this and may be configured arbitrarily.

[0029] The wafer transfer device 50 is disposed on the negative side of the transition device 30 in the X-axis direction. The wafer transfer device 50 has, for example, two transfer arms 51, 51 that hold and transfer the overlapped wafer T. Each transfer arm 51 is configured to be movable horizontally, vertically, around a horizontal axis, and around a vertical axis. The wafer transfer device 50 is configured to be able to transfer the overlapped wafer T to the transition device 30, the etching device 40, the thickness measurement device 41, the cleaning device 60 described below, the thickness measurement device 61 described below, and the buffer device 62 described below.

[0030] The second processing block B2 is provided with a cleaning device 60, a thickness measuring device 61, a buffer device 62, and a wafer transfer device 70. The cleaning device 60, the thickness measuring device 61, and the buffer device 62 are arranged in a stacked configuration. Note that the number and arrangement of the cleaning devices 60, the thickness measuring devices 61, and the buffer devices 62 are not limited to this.

[0031] The cleaning device 60 cleans the back surface Wb (ground surface) of the first wafer W after grinding in the processing device 80 described below. For example, a brush is brought into contact with the back surface Wb to clean the back surface Wb. Note that a pressurized cleaning liquid may be used to clean the first wafer W. Furthermore, the cleaning device 60 may be configured to be able to simultaneously clean the back surface Sb of the second wafer S when cleaning the first wafer W.

[0032] In one example, the thickness measuring device 61 includes a measuring unit (not shown) and a calculating unit (not shown). The measuring unit includes a sensor that measures the thickness of the first wafer W after grinding at multiple points. The calculating unit acquires the thickness distribution of the first wafer W from the measurement results (thickness of the first wafer W) by the measuring unit, and further calculates the flatness (TTV) of the first wafer W. Note that the calculation of the thickness distribution and flatness of the first wafer W may be performed by a control device 90 (described later) instead of the calculating unit. In other words, a calculating unit (not shown) may be provided within the control device 90 (described later). Note that the configuration of the thickness measuring device 61 is not limited to this and may be configured arbitrarily.

[0033] The buffer device 62 temporarily holds the unprocessed overlapped wafer T that is transferred from the first processing block B1 to the second processing block B2. The configuration of the buffer device 62 is arbitrary. The buffer device 62 may also have an alignment mechanism (not shown) that adjusts the center position of the overlapped wafer T with respect to a chuck 83 (described later) and / or the horizontal orientation of the overlapped wafer T.

[0034] The wafer transfer device 70 is disposed, for example, on the positive side of the Y-axis relative to the cleaning device 60, the thickness measuring device 61, and the buffer device 62. The wafer transfer device 70 has, for example, two transfer arms 71, 71 that adsorb and hold the overlapped wafer T using an adsorption holding surface (not shown) and transport it. Each transfer arm 71 is supported by an articulated arm member 72 and 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 transport the overlapped wafer T to the etching device 40, the thickness measuring device 41, the cleaning device 60, the thickness measuring device 61, the buffer device 62, and a processing device 80, which will be described later.

[0035] The third processing block B3 is provided with a processing device 80. The processing device 80 grinds and thins the first wafer W, and functions as a thinning device in the present disclosure.

[0036] The processing device 80 has a rotary table 81. The rotary table 81 is configured to be rotatable around a vertical rotation center line 82 by a rotation mechanism (not shown). Two chucks 83 that suction-hold the overlapped wafer T are provided on the rotary table 81. The chucks 83 are evenly arranged on the same circumference as the rotary table 81. The two chucks 83 can be moved to a delivery position A0 and a processing position A1 by the rotation of the rotary table 81. Furthermore, each of the two chucks 83 is configured to be rotatable around a vertical axis by a rotation mechanism (not shown).

[0037] At the delivery position A0, the overlapped wafer T is delivered. At the processing position A1, a grinding unit 84 is disposed, which grinds the first wafer W while the second wafer S is held by suction with a chuck 83. The grinding unit 84 has a grinding section 85 equipped with a ring-shaped, rotatable grinding wheel (not shown). The grinding section 85 is configured to be movable in the vertical direction along a support 86.

[0038] It should be noted that the configuration of processing apparatus 80 is not limited to this. For example, four chucks 83 may be provided on rotary table 81, and the four chucks 83 may be configured to be movable among a transfer position for the overlapped wafer T, a rough grinding unit (not shown) that performs rough grinding of the first wafer W, an intermediate grinding unit (not shown) that performs intermediate grinding of the first wafer W, and a finish grinding unit (not shown) that performs finish grinding of the first wafer W. Furthermore, for example, processing apparatus 80 may be provided with a thickness measuring device (not shown) that measures the thickness of the first wafer W at multiple points after grinding.

[0039] The wafer processing system 1 described above is provided with a control device 90. The control device 90 is, for example, a computer equipped with a CPU, a memory, etc., and has a program storage unit (not shown). The program storage unit stores a program for controlling the processing of the overlapped wafer T in the wafer processing system 1. The program may be recorded on a computer-readable storage medium H and installed from the storage medium H into the control device 90. The storage medium H may be temporary or non-temporary.

[0040] Next, a description will be given of the configuration of the etching apparatus 40. As shown in Fig. 4, the etching apparatus 40 has a wafer holder 100 as a substrate holder, a rotation mechanism 101, and a nozzle 102 as an etching liquid supply unit.

[0041] Wafer holding unit 100 holds the outer edge of overlapped wafer T at multiple points, three points in this embodiment. The configuration of wafer holding unit 100 is not limited to the example shown in the figure, and wafer holding unit 100 may include, for example, a chuck that suction-holds overlapped wafer T from below. Rotation mechanism 101 rotates overlapped wafer T (first wafer W) held by wafer holding unit 100 around a vertical rotation center line 100a.

[0042] The nozzle 102 supplies the etching liquid E to the back surface Wb of the first wafer W held by the wafer holding part 100. The nozzle 102 is connected to an etching liquid supply source (not shown) that supplies the etching liquid E to the nozzle 102. The nozzle 102 is provided above the wafer holding part 100 and configured to be movable in the horizontal and vertical directions by a movement mechanism 103. In one example, the nozzle 102 is configured to be capable of reciprocating movement (scan movement) through a rotation center line 100a of the wafer holding part 100, that is, above the center of the first wafer W as shown in FIG. 5 .

[0043] The etching solution E contains at least hydrofluoric acid or nitric acid to properly etch silicon of the first wafer W, which may be the etching target. The etching solution E may also contain phosphoric acid or sulfuric acid. The etching target is not limited to the first wafer W, but may be, for example, amorphous silicon. The etching target of this embodiment is not limited to the back surface Wb of the first wafer W. For example, this embodiment can also be applied to the processing of a wafer that is not processed by the processing device 80. For example, if a film is formed on the back surface Wb, this film will also be the etching target.

[0044] Next, a description will be given of wafer processing performed using the wafer processing system 1 configured as described above. In this embodiment, the overlapped wafer T is formed in advance in a bonding device (not shown) outside the wafer processing system 1. The peripheral edge of the first wafer W, for example, a range of 0.5 mm to 3 mm in the radial direction from the outer edge of the first wafer W, may be removed in advance.

[0045] First, a cassette C containing a plurality of overlapping wafers T is placed on the cassette mounting table 10 of the carry-in / out station 2. Next, the wafer transfer device 20 removes the overlapping wafers T from the cassette C and transfers them to the transition device 30. The overlapping wafers T transferred to the transition device 30 are then transferred to the buffer device 62 by the wafer transfer device 50. Note that in the buffer device 62, the center position of the overlapping wafer T relative to the chuck 83 and / or the horizontal orientation of the overlapping wafer T may be adjusted.

[0046] Next, the overlapped wafer T is transferred to the processing device 80 by the wafer transfer device 70 and transferred to the chuck 83 at the transfer position A0. The back surface Sb of the second wafer S is suction-held by the chuck 83. Next, the chuck 83 is moved to the processing position A1, and the back surface Wb of the first wafer W is ground by the grinding unit 84. Through this grinding process, the thickness of the first wafer W (overlapping wafer T) is reduced to the desired grinding target thickness (step S1 in FIG. 6).

[0047] Next, the overlapped wafer T is transferred to the thickness measuring device 61 by the wafer transfer device 70. The thickness measuring device 61 measures the thickness of the ground first wafer W (overlapping wafer T) at multiple points to obtain the thickness distribution of the ground first wafer W, and further calculates the flatness of the first wafer W (step S2 in FIG. 6). The calculated thickness distribution and flatness of the first wafer W are output to, for example, the control device 90. Note that if the processing device 80 is provided with a thickness measuring device, the thickness of the ground first wafer W may be measured by the thickness measuring device of the processing device 80.

[0048] The control device 90 determines optimal etching conditions for the subsequent etching process from the output thickness distribution and flatness of the first wafer W (step S3 in FIG. 6). A detailed method for determining the optimal etching conditions in the control device 90 will be described later.

[0049] The overlapped wafer T, whose thickness of the first wafer W has been measured, is then transferred to the cleaning apparatus 60 by the wafer transfer apparatus 70 or the wafer transfer apparatus 50. In the cleaning apparatus 60, the back surface Wb, which is the ground surface of the first wafer W after grinding, is cleaned (step S4 in FIG. 6). In addition, in the cleaning apparatus 60, the back surface Sb of the second wafer S may also be cleaned as described above. Note that, when the thickness after grinding is measured by the thickness measuring apparatus 61 as in this embodiment, the order of steps S2 and S3 and step S4 may be reversed. That is, after the back surface Wb of the first wafer W is cleaned by the cleaning apparatus 60, the thickness of the first wafer W may be measured by the thickness measuring apparatus 61, and optimal etching conditions for the etching process may be determined.

[0050] Next, the overlapped wafer T is transferred to the etching device 40 by the wafer transfer device 50. In the etching device 40, the back surface Wb, which is the ground surface of the first wafer W, is etched with the etching solution E under optimal etching conditions (step S5 in FIG. 6).

[0051] When etching the first wafer W, first, the wafer holder 100 (first wafer W) is rotated around the vertical rotation center line 100a, and the supply (discharge) of etching liquid E from the nozzle 102 is started, thereby starting etching of the back surface Wb.

[0052] 5, while continuing to supply the etching solution E from the nozzle 102, the nozzle 102 is moved back and forth (scanned) above the rotation center of the first wafer W, i.e., passing through the rotation center line 100a, with the rotation center line 100a as the midpoint. Note that detailed methods for determining etching conditions such as the rotation speed of the first wafer W, the scan width of the nozzle 102, and the scan speed when the nozzle 102 is moved back and forth will be described later.

[0053] When etching of the back surface Wb under the optimum etching conditions is completed, the supply of etching solution E from nozzle 102 is stopped, and the back surface Wb of first wafer W is rinsed with pure water and then shaken off to dry. Thereafter, rotation of wafer holder 100 (first wafer W) is stopped, and etching of the first wafer W is completed.

[0054] Here, the optimal etching conditions for the first wafer W are determined based on the thickness distribution and flatness of the first wafer W after grinding, as described above. Specifically, the optimal etching conditions are determined based on the difference between the thickness distribution and flatness of the first wafer W measured by the thickness measuring device 61 and the thickness distribution and flatness of the target surface shape of the first wafer W after etching (hereinafter referred to as the "target shape"). Then, in step S5, the first wafer W is etched under the optimal etching conditions, thereby removing the difference between the measured thickness value and the target value of the first wafer W, and processing the surface of the first wafer W into the target shape. As a result, according to this embodiment, the target surface shape of the first wafer W can be appropriately obtained regardless of the surface shape of the first wafer W after grinding.

[0055] Next, the overlapped wafer T is transferred by the wafer transfer device 50 to the thickness measurement device 41. The thickness measurement device 41 measures the thickness of the first wafer W (overlapping wafer T) after etching at multiple points to obtain the thickness distribution of the first wafer W after etching (step S6 in FIG. 6). The flatness of the first wafer W may also be calculated. The calculated thickness distribution of the first wafer W is output to, for example, the control device 90, and is used, for example, in processing another overlapping wafer T that is subsequently processed in the wafer processing system 1. Note that when the thickness of the first wafer W after grinding is measured by the thickness measurement device of the processing device 80, the thickness of the first wafer W after etching may also be measured in the thickness measurement device 61.

[0056] Thereafter, the overlapped wafer T 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.

[0057] Next, a detailed method for determining the above-mentioned optimum etching conditions (step S3 in FIG. 6) will be described.

[0058] First, when determining the optimal etching conditions, a plurality of parts to be used in the optimization process described below are acquired (step S3-0 in FIG. 7) prior to processing the overlapped wafer T in the wafer processing system 1. The parts are the distribution of deviations in the etching amount of the first wafer W under certain etching conditions.

[0059] In step S3-0, the dummy wafer is etched under, for example, a plurality of different etching conditions. Specifically, the dummy wafer is etched by changing, for example, the rotation speed of the dummy wafer during etching, the scanning speed of the nozzle 102, or the scanning width of the nozzle 102 (see scanning width L in FIG. 5). In this case, the etching processing time for each dummy wafer is the same. As with the etching in step S5, the dummy wafer is etched by rotating the dummy wafer and supplying etching solution E from the nozzle 102 to the dummy wafer while the nozzle 102 is moving back and forth. In the following explanation, the reciprocating movement of the nozzle 102 between both ends of the dummy wafer is considered to be one loop.

[0060] Etching of the dummy wafer under each etching condition is carried out for a predetermined desired time (desired number of loops). Then, the etching amount deviation distribution of the dummy wafer is acquired and output to the control device 90. Furthermore, the control device 90 compresses the output etching amount deviation distribution under each etching condition into an etching amount deviation distribution per unit time (unit number of loops), and stores each compressed etching amount deviation distribution as the above-mentioned part.

[0061] FIG. 8 shows an example of a plurality of parts. The horizontal axis of FIG. 8 indicates the radial position from the center of the wafer (0 (zero) on the horizontal axis) to the outer edge (±R on the horizontal axis), and the vertical axis indicates the etching amount deviation. The example shown in FIG. 8 is an example in which a total of 36 types of parts are stored in the control device 90, in other words, an example in which the etching amount deviation distribution is obtained under a total of 36 types of different etching conditions.

[0062] The unit time (number of unit loops) can be set arbitrarily depending on the purpose, but it is desirable that the unit time (number of unit loops) be short in order to appropriately obtain a target etching amount deviation distribution in the part overlay described below. In one example, the unit time for a part stored in the control device 90 may be the time for one loop (one round trip of the scan width L shown in FIG. 5), preferably 0.5 loops (half the round trip of the scan width L shown in FIG. 5).

[0063] Although the above description has been given taking the example of obtaining the parts by etching a dummy wafer as an example, the etching target when obtaining the parts is not limited to a dummy wafer. Specifically, for example, the etching process result of the first wafer W actually processed in the wafer processing system 1 may be stored as the above-mentioned part. Furthermore, for example, if a film is formed on the back surface Wb of the first wafer W, the etching target may be the film, and the etching process result of the film may be stored as the above-mentioned part.

[0064] When processing wafers in the wafer processing system 1 according to the present disclosure, the optimum etching conditions are determined using the plurality of parts thus acquired (FIG. 8).

[0065] First, based on the thickness distribution in the target shape of the first wafer W after etching and the thickness distribution in the surface shape of the first wafer W after grinding acquired in step S2 (hereinafter referred to as the "measured shape"), a target etching amount deviation distribution in the etching process in step S5 is acquired (step S3-1 in FIG. 7). The target etching amount deviation distribution in the etching process can be acquired, for example, by calculating the difference between the thickness distribution in the target shape of the first wafer W and the thickness distribution in the measured shape.

[0066] 9 shows an example of the target etching amount deviation distribution, and in this example, the target etching amount deviation distribution is V-shaped. Note that the shape of the target etching amount deviation distribution is not limited to V-shaped. That is, based on the difference between the thickness distribution of the target shape of the first wafer W and the thickness distribution of the measured shape, the target etching amount deviation distribution can have various shapes such as V-shaped, A-shaped, M-shaped, W-shaped, etc.

[0067] Next, multiple parts are overlapped, and an optimization method is used to optimize the parts to be used for overlapping and the number of overlapping times of the parts so that the target etching amount deviation distribution obtained in step S3-1 above is achieved (step S3-2 in FIG. 7).

[0068] In step S3-2, for example, the control of the etching amount deviation distribution is applied to a knapsack problem to optimize the number of overlapping parts. For example, the etching amount deviation distribution is the knapsack in the knapsack problem, and the parts are the items in the knapsack problem. Then, the number of overlapping parts is optimized so that the difference between the overlapped etching amount deviation distribution and the target etching amount deviation distribution is minimized.

[0069] As this optimization method, for example, a genetic algorithm or dynamic programming can be used. Then, by performing an optimization calculation, one or more parts to be used for superposition are selected from the multiple parts shown in Fig. 8 as shown in Fig. 10, and the selected parts are superposed as shown in Fig. 11. Then, the superposed etching amount deviation distribution (solid line in Fig. 11) approximates the target etching amount deviation distribution (dashed line in Fig. 11).

[0070] Furthermore, in this optimization calculation, the number of overlapping times of parts is optimized so as to minimize the time for supplying etching liquid E from the nozzle 102 to the first wafer W during the etching process. As described above, in this embodiment, so-called multi-objective optimization is performed to optimize both the etching amount deviation distribution, i.e., the etching accuracy, and the supply time for etching liquid E. Specifically, optimization is performed using the following formula (1). Note that the etching accuracy is the accuracy of the etching amount deviation distribution within the wafer surface.

[0071]

number

[0072] In step S3-2, as shown in the above formula (1), the loss function of the etching amount deviation distribution (etching accuracy) is calculated as a weighted linear sum of the flatness of the measured shape and the variation in the thickness distribution of the measured shape. For example, when the coefficient α in the above formula (1) is 0.5, the flatness (TTV) and the variation in the thickness distribution (RMSE) have the same weight. On the other hand, when the coefficient α is 1, the algorithm places emphasis on flatness, and when the coefficient α is 0 (zero), the algorithm places emphasis on the variation in the thickness distribution.

[0073] In step S3-2, when optimizing the number of overlapping times of the parts, the number of overlapping times may be optimized in units of 0.5 loops. In such a case, for example, it becomes possible to start and finish supplying the etching liquid E from the center of the first wafer W.

[0074] Once the number of overlaps between parts has been optimized as described above, the etching conditions corresponding to the parts optimized in step S3-2 are integrated to determine the optimal etching conditions (step S3-3 in FIG. 7). Specifically, the optimal etching conditions are determined by integrating the selected etching conditions so that the optimal number of overlaps is achieved. In other words, the optimal etching conditions are determined to optimize the distribution of etching amount deviation.

[0075] Thereafter, in step S4, the back surface Wb of the first wafer W is cleaned, and then in step S5, the back surface Wb of the first wafer W is etched under optimal etching conditions. That is, in the etching apparatus 40, the overlapped wafer T (first wafer W) is rotated at a rotation speed determined under the optimal etching conditions, and the etching solution E is supplied to the first wafer W while the nozzle 102 is moved at a determined scan speed and scan width.

[0076] The determination of the optimum etching conditions according to this embodiment and the etching process for the first wafer W based on the optimum etching conditions are carried out as described above.

[0077] According to the above embodiment, the optimization method is used in step S3 to optimize the parts to be overlapped and the number of times the parts are overlapped, thereby determining optimal etching conditions. Thereafter, in step S5, the first wafer W can be etched under the optimal etching conditions. This optimizes the etching amount deviation distribution in the etching process and brings it closer to the target etching amount deviation distribution, thereby enabling the surface shape of the first wafer W after etching to be the target shape. In other words, optimal etching conditions can be determined from variable etching conditions, and the surface shape of the first wafer W after etching can be appropriately controlled.

[0078] The inventors actually performed a simulation and found that the variation in thickness distribution of the first wafer W after etching could be kept within an allowable range regardless of whether the target etching amount deviation distribution was V-shaped, A-shaped, M-shaped, or W-shaped. In addition, the flatness (TTV) of the first wafer W after etching was also improved compared to conventional methods.

[0079] Furthermore, since steps S1 to S6 are performed on each overlapped wafer T, the surface shape of the first wafer W after etching can be controlled for each wafer.

[0080] In the above embodiment, the rotation speed of the first wafer W, the scan width of the nozzle 102, and the scan speed of the nozzle 102 are used as the etching condition variables, but the etching condition variables are not limited to these. For example, the type, viscosity, temperature, supply amount, etc. of the etching liquid E may also be used as the etching condition variables. In such a case, in step S3-0, a plurality of parts are obtained in which the type, viscosity, temperature, supply amount, etc. of the etching liquid E are changed. Then, steps S3-1 to S3-3 are performed to determine the optimal etching conditions.

[0081] In the above embodiment, various processes are performed on the back surface Wb of the first wafer W in an overlapped wafer T formed by bonding a first wafer W and a second wafer S. However, the processing target is not limited to this. For example, thinning and etching may be performed on a single wafer. The processing target may be a film formed on the surface of the wafer, such as an oxide film or titanium nitride. In such a case, the nozzle 102 in the etching apparatus 40 may be configured to arbitrarily switch between supplying different types of etching solution E depending on the etching target. Furthermore, for example, when a film formed on the wafer surface is the etching target, the etching process results for the film may be stored as the above-mentioned part. The thickness measuring device 61 measures the film thickness. Furthermore, if a protective tape is attached to the device side of the wafer, thinning and etching may be performed on the side opposite the protective tape. Furthermore, thinning and etching may be performed on wafers cut from an ingot using a wire saw or the like and then lapped. Regardless of the processing target, etching can be performed under the optimal etching conditions of the above embodiment.

[0082] Furthermore, for example, if a film is formed on the back surface Wb of the first wafer, the film may be the etching target. In such a case, for example, the thickness measuring device 61 measures the thickness of the film, and in step S2, the thickness of the film is measured instead of the thickness of the first wafer W, and further, the thickness distribution and flatness of the film are calculated. Then, in step S3, optimal etching conditions are determined based on the calculated thickness distribution and flatness of the film.

[0083] Furthermore, although the wafer processing system 1 includes various devices other than the etching device 40, the device configuration to which the present disclosure is applicable is not limited to this. For example, the processing device 80, which is a thinning device, may be omitted. In such a case, the etching target is not limited to wafers after thinning processing. Furthermore, for example, the technology of the present disclosure can also be applied when etching a wafer in a standalone etching device.

[0084] In the above embodiment, the first wafer W is thinned by the processing device 80, but the thinning method is not limited to this. For example, the thinning process of the first wafer W also includes polishing the back surface Wb of the first wafer W. Alternatively, for example, the first wafer W may be thinned by separation starting from a modified layer (not shown) formed inside the first wafer W by laser processing. In such a case, the wafer processing system 1 is provided with a laser processing device (not shown) for forming the modified layer (not shown) instead of the processing device 80.

[0085] In the above embodiment, the etching amount deviation distribution (the distribution of values obtained by subtracting the average value of the etching amount from the etching amount within the wafer surface) is used as the etching index distribution for controlling the etching process of the back surface Wb of the first wafer W, but a distribution of etching amounts (absolute values) may also be used. Specifically, when determining the optimal etching conditions in step S3, the etching amount distribution is optimized instead of optimizing the etching amount deviation distribution.

[0086] In step S3-0, a plurality of parts of the etching amount distribution are acquired. An example of the plurality of parts is the part in FIG. 8 where the vertical axis represents the etching amount.

[0087] In step S3-1, a target etching amount distribution for the etching process in step S5 is obtained based on the thickness distribution in the target shape of the first wafer W after etching and the thickness distribution in the measured shape of the first wafer W after grinding obtained in step S2. The target etching amount distribution is the etching amount distribution in FIG. 9, with the vertical axis representing the etching amount.

[0088] In step S3-2, multiple parts are overlapped, and an optimization method is used to optimize the parts to be overlapped and the number of times the parts are overlapped, so that the target etching amount distribution obtained in step S3-1 is achieved. An example of the parts to be overlapped is the part in FIG. 10, where the vertical axis represents the etching amount. An example of the overlapped etching amount distribution is the solid line in FIG. 11, where the vertical axis represents the etching amount.

[0089] In step S3-3, the etching conditions corresponding to the parts optimized in step S3-2 are integrated to determine the optimal etching conditions, i.e., the optimal etching conditions that optimize the etching amount distribution on the back surface Wb are determined.

[0090] The detailed method of each of the above steps S3-0 to S3-3 is the same as the method of steps S3-0 to S3-3 in the above embodiment, and only the input data is different. That is, while the input data in the above embodiment was a plurality of parts of the etching amount deviation distribution and the target etching amount deviation distribution, the input data in this embodiment is a plurality of parts of the etching amount distribution and the target etching amount distribution.

[0091] Here, optimizing the etching amount deviation distribution as in the above embodiment makes it possible to precisely control the shape (profile) of the rear surface Wb of the first wafer W after etching. On the other hand, optimizing the etching amount as in the present embodiment makes it possible to precisely control the shape of the rear surface Wb of the first wafer W after etching, and also to precisely control the thickness of the first wafer W.

[0092] FIG. 12 shows an example of the thickness deviation distribution (the distribution of the value obtained by subtracting the average value of the thickness from the wafer thickness) of the first wafer W after grinding and after etching. The horizontal axis of FIG. 12 indicates the radial position from the center of the wafer (0 (zero) on the horizontal axis) to the outer edge (±R on the horizontal axis), and the vertical axis indicates the thickness deviation distribution of the first wafer W. Comparing the thickness deviation distribution of the first wafer W after grinding (dashed line in FIG. 12) with the thickness deviation distribution of the first wafer W after etching of this embodiment (solid line in FIG. 12), it is clear that the flatness (TTV) of the first wafer W is improved after etching. Therefore, according to this embodiment, the flatness (TTV) of the first wafer W can be improved by etching, and the shape of the back surface Wb can be precisely controlled.

[0093] FIG. 13 shows an example of the thickness distribution of the first wafer W after grinding and after etching. The horizontal axis of FIG. 13 indicates the radial position from the center of the wafer (0 (zero) on the horizontal axis) to the outer edge (±R on the horizontal axis), and the vertical axis indicates the thickness distribution of the first wafer W. Comparing the thickness distribution of the first wafer W after grinding (dashed line in FIG. 13) with the thickness distribution of the first wafer W after etching in this embodiment (solid line in FIG. 12), it is clear that the average thickness of the first wafer W (averaged across the wafer surface) can be uniformed after etching. Therefore, according to this embodiment, the thickness of the first wafer W can also be precisely controlled by etching.

[0094] Note that the shape of the back surface Wb of the first wafer W can be controlled more precisely by controlling it based on the etching amount deviation distribution than by controlling it based on the etching amount. Therefore, when more precise control of the shape of the back surface Wb is desired, it is preferable to select control based on the etching amount deviation distribution. When precise control of the thickness of the first wafer W in accordance with the shape of the back surface Wb is desired, it is preferable to control it based on the etching amount.

[0095] In the above embodiment, the case where various processes are performed on the back surface Wb of the first wafer W, i.e., the case where various processes are performed on one side of the wafer, has been described as an example, but the technology of the present disclosure can also be applied to the case where various processes are performed on both sides of the wafer. Below, a case will be described in which the cut surface of a disk-shaped silicon wafer (hereinafter simply referred to as a "wafer") obtained by cutting from a single crystal silicon ingot with a wire saw or the like is flattened and smoothed to make the wafer thickness uniform.

[0096] In this embodiment, a wafer processing system 200 shown in FIG. 14 is used to perform processing to improve the in-plane thickness uniformity on a wafer W, which is a substrate that has been cut from an ingot using a wire saw or the like and then lapped. Hereinafter, the cut surfaces of the wafer W will be referred to as the first surface Wa and the 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 surface of the wafer W.

[0097] The wafer processing system 200 is configured such that, in the wafer processing system 1 of the above embodiment, it further includes reversing devices 210 and 211, and is provided with a processing device 220 instead of the processing device 80. Note that other configurations of the wafer processing system 200 are the same as those of the wafer processing system 1, and therefore description thereof will be omitted.

[0098] The etching apparatus 40 etches silicon (Si) on the first surface Wa or the second surface Wb after grinding by the processing apparatus 220. To improve the throughput of wafer processing, multiple etching apparatuses 40 may be provided. The cleaning apparatus 60 cleans at least the first surface Wa or the second surface Wb after grinding by the processing apparatus 220.

[0099] The reversing device 210 is arranged stacked on the etching device 40 and the thickness measuring device 41. The reversing device 211 is arranged stacked on the cleaning device 60, the thickness measuring device 61, and the buffer device 62. These reversing devices 210 and 211 reverse the first surface Wa and the second surface Wb of the wafer W in the vertical direction. The reversing devices 210 and 211 may have any configuration.

[0100] The processing device 220 has a rotary table 221. The rotary table 221 is configured to be rotatable about a vertical rotation center line 222 by a rotation mechanism (not shown). Four chucks 223 for suction-holding a wafer W are provided on the rotary table 221. Of the four chucks 223, two first chucks 223a are chucks used for grinding at a first processing position C1. These two first chucks 223a are arranged in positions symmetrical with respect to a point across the rotation center line 222. The remaining two second chucks 223b are chucks used for grinding at a second processing position C2. These two second chucks 223b are also arranged in positions symmetrical with respect to a point across the rotation center line 222. That is, the first chucks 223a and the second chucks 223b are arranged alternately in the circumferential direction.

[0101] The four chucks 223 can be moved to delivery positions B1-B2 and processing positions C1-C2 by rotation of the rotary table 221. Furthermore, each of the four chucks 223 is configured to be rotatable around a vertical axis by a rotation mechanism (not shown).

[0102] The first transfer position B1 is a position on the negative X-axis side and the positive Y-axis side of the turntable 221, where the wafer W is transferred to the first chuck 223a when the first surface Wa is ground. The second transfer position B2 is a position on the negative X-axis side and the negative Y-axis side of the turntable 221, where the wafer W is transferred to the second chuck 223b when the second surface Wb is ground.

[0103] The first processing position C1 is a position on the X-axis positive side and the Y-axis negative side of the rotary table 221, and a first grinding unit 230 is disposed thereat. The first grinding unit 230 has a grinding section 231 equipped with an annular, rotatable grinding wheel (not shown). The grinding section 231 is configured to be movable in the vertical direction along a support 232. As an example, the first grinding unit 230 grinds a first surface Wa or a second surface Wb of the wafer W held by the first chuck 223a.

[0104] The second processing position C2 is a position on the X-axis positive side and the Y-axis positive side of the rotary table 221, and a second grinding unit 240 is disposed thereat. The second grinding unit 240 has a grinding section 241 equipped with an annular, rotatable grinding wheel (not shown). The grinding section 241 is configured to be movable in the vertical direction along a support 242. As an example, the second grinding unit 240 grinds the second surface Wb or the first surface Wa of the wafer W held by the second chuck 223b.

[0105] It should be noted that a thickness measuring device (not shown) for measuring the thickness of the wafer W after grinding may be provided at the delivery positions B1, B2 or the processing positions C1, C2.

[0106] Next, a description will be given of wafer processing (double-sided processing) performed using the wafer processing system 200 configured as above. Three patterns of wafer processing will be described below.

[0107] In the first pattern wafer processing, 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. The wafers W are stored in the cassette C with their first surfaces Wa facing upward and their second surfaces Wb facing downward. Next, the wafers W in the cassette C are removed by the wafer transfer device 20 and transferred to the transition device 30. The wafers W transferred to the transition device 30 are then transferred to the buffer device 62 by the wafer transfer device 50. In the buffer device 62, the center position of the wafer W relative to the chuck 83 and / or the horizontal orientation of the wafer W may be adjusted.

[0108] Next, the wafer W is transferred to the processing device 220 by the wafer transfer device 70 and transferred to the first chuck 223a at the first transfer position B1. The second surface Wb of the wafer W is held by suction on the first chuck 223a.

[0109] Next, the turntable 221 is rotated to move the wafer W to the first processing position C1. Then, the first grinding unit 230 grinds the first surface Wa of the wafer W (step S101 in FIG. 15). In step S101, the control device 90 may control the processing device 220 to grind the first surface Wa into a V-shape so that a recess War, the center of which is recessed more than the outer periphery, is formed on the ground first surface Wa, as shown in FIG. 16(a).

[0110] Next, the turntable 221 is rotated to move the wafer W to the first transfer position B1. At the first transfer position B1, the first surface Wa of the wafer W after grinding may be cleaned by a cleaning unit (not shown).

[0111] Next, the wafer W is transferred by the wafer transfer device 70 to the cleaning device 60. In the cleaning device 60, the first surface Wa and the second surface Wb of the wafer W are cleaned (step S102 in FIG. 15).

[0112] Next, the wafer W is transferred to the reversing device 211 by the wafer transfer device 70. In the reversing device 211, the first surface Wa and the second surface Wb of the wafer W are reversed upside down (step S103 in FIG. 15). That is, the wafer W is reversed so that the first surface Wa faces downward and the second surface Wb faces upward.

[0113] Next, the wafer W is transferred to the processing device 220 by the wafer transfer device 70 and transferred to the second chuck 223b at the second transfer position B2. The first surface Wa of the wafer W is held by suction on the second chuck 223b.

[0114] Next, the turntable 221 is rotated to move the wafer W to the second processing position C2. Then, the second grinding unit 240 grinds the second surface Wb of the wafer W (step S104 in FIG. 15). In step S104, the control device 90 may control the processing device 220 to grind the second surface Wb into a V-shape so that a recess Wbr is formed on the ground second surface Wb, the center of which is recessed more than the outer periphery, as shown in FIG. 16(b).

[0115] Next, the turntable 221 is rotated to move the wafer W to the second transfer position B2. At the second transfer position B2, the second surface Wb of the wafer W after grinding may be cleaned by a cleaning unit (not shown).

[0116] Next, the wafer W is transferred by the wafer transfer device 70 to the cleaning device 60. In the cleaning device 60, the second surface Wb and the first surface Wa of the wafer W are cleaned (step S105 in FIG. 15).

[0117] Next, the wafer W is transported to the thickness measuring device 61 by the wafer transport device 70 or the wafer transport device 50. The thickness measuring device 61 measures the thickness of the wafer W after grinding at multiple points on both the first surface Wa and the second surface Wb to obtain the thickness distribution of the wafer W after grinding, and further calculates the flatness of the wafer W (step S106 in FIG. 15). The calculated thickness distribution and flatness of the wafer W are output to, for example, the control device 90. Note that if the processing device 220 is provided with a thickness measuring device, the thickness of the wafer W after grinding may be measured by the thickness measuring device of the processing device 220.

[0118] The control device 90 determines optimal etching conditions for the second surface Wb, which optimize the etching amount deviation distribution in the etching process of the second surface Wb, from the thickness distribution and flatness of the output wafer W (step S107 in FIG. 15). This step S107 is similar to step S3 in the above embodiment.

[0119] Next, the wafer W is transferred to the etching apparatus 40 by the wafer transfer apparatus 50. In the etching apparatus 40, the second surface Wb of the wafer W is etched with the etching solution E under the optimal etching conditions determined in step S107 (step S108 in FIG. 15). In step S108, the second surface Wb is etched under the optimal etching conditions to optimize the etching amount deviation distribution, and the second surface Wb is made to have a target shape, which is flat in this embodiment, as shown in FIG. 16(c).

[0120] Next, the wafer W is transferred to the reversing device 210 by the wafer transfer device 50. In the reversing device 210, the first surface Wa and the second surface Wb of the wafer W are reversed upside down (step S109 in FIG. 15). That is, the wafer W is reversed so that the first surface Wa faces upward and the second surface Wb faces downward.

[0121] Next, the wafer W is transported by the wafer transport device 50 to the thickness measurement device 41. The thickness measurement device 41 measures the thickness of the wafer W at multiple points to obtain the thickness distribution of the wafer W after grinding, and further calculates the flatness of the wafer W (step S110 in FIG. 15). The calculated thickness distribution and flatness of the wafer W are output to, for example, the control device 90.

[0122] The control device 90 determines optimal etching conditions for the first surface Wa, which optimize the etching amount distribution in the etching process on the first surface Wa, from the thickness distribution and flatness of the output wafer W (step S111 in FIG. 15). This step S111 is similar to step S3 in the above embodiment.

[0123] Next, the wafer W is transferred by the wafer transfer device 50 to the etching device 40. In the etching device 40, the first surface Wa of the wafer W is etched with the etching solution E under the optimal etching conditions determined in step S111 (step S112 in FIG. 15). In step S112, the first surface Wa is etched under the optimal etching conditions to optimize the etching amount distribution, and the first surface Wa is processed into a target shape, which is flat in this embodiment, as shown in FIG. 16(d).

[0124] Next, the wafer W is transported by the wafer transport device 50 to the thickness measurement device 41. The thickness measurement device 41 measures the thickness of the wafer W after etching at multiple points on both the first surface Wa and the second surface Wb, thereby obtaining the thickness distribution of the wafer W after grinding (step S113 in FIG. 15). Furthermore, the flatness of the wafer W may be calculated. This step S111 is similar to step S6 in the above embodiment.

[0125] Thereafter, the wafer W that has undergone all the processing is transferred to the cassette C on the cassette mounting table 10 via the transition device 30. This completes the series of wafer processing in the wafer processing system 200. Note that the wafer W that has undergone processing in the wafer processing system 200 may be polished outside the wafer processing system 200.

[0126] The above embodiment can also achieve the same effects as the above embodiment. That is, the etching amount deviation distribution of the second surface Wb is optimized in step S108, and the etching amount distribution of the first surface Wa is optimized in step S112. As a result, the surface shape of the wafer W after etching can be appropriately controlled, and the thickness of the wafer W can also be appropriately controlled.

[0127] Here, in the etching in step S108 (S112), due to the nature of the process, the etching amount deviation distribution (etching amount distribution) tends to have a downwardly depressed V-shape, with the etching amount deviation (etching amount) being smaller near the center of the wafer W. In other words, the wafer surface after etching tends to have an upwardly protruding A-shape. Therefore, it is preferable to form the shape of the wafer surface after grinding into a V-shape.

[0128] In this way, by grinding the first surface Wa and the second surface Wb into a shape that is easy to control by etching, it is possible to improve the accuracy of optimizing the etching amount deviation distribution of the first surface Wa and the second surface Wb in steps S108 and S110.

[0129] In this embodiment, the determination of the optimal etching conditions in steps S107 and S111 is performed based on the thickness distribution and flatness of the wafer W acquired in steps S106 and S110, respectively. In this regard, the optimal etching conditions for the second surface Wb and the first surface Wa may be determined in steps S107 and S111, respectively, based on the thickness distribution and flatness of the wafer W acquired in step S106.

[0130] The wafer processing of the second pattern differs from the wafer processing of the first pattern in steps S107 and S108. Note that the state change of the wafer W processed in the second pattern is the same as that of the first pattern shown in FIG.

[0131] 17, steps S201 to S206 are performed to sequentially grind both sides of the wafer W, clean both sides of the wafer W, and measure the thickness of the wafer W. These steps S201 to S206 are the same as steps S101 to S106 of the first pattern.

[0132] Next, in step S207, optimal etching conditions for the second surface Wb are determined to optimize the etching amount distribution in the etching process on the second surface Wb from the thickness distribution and flatness of the wafer W acquired in step S206. That is, while the etching amount deviation distribution was optimized in step S107 of the above embodiment, the etching amount distribution is optimized in step S207.

[0133] Next, in step S208, the second surface Wb of the wafer W is etched with the etching solution E under the optimal etching conditions determined in step S207. At this time, by etching the second surface Wb under the optimal etching conditions, the etching amount distribution is optimized.

[0134] Next, steps S209 to S213 are performed to sequentially etch the first surface Wa and measure the thickness of the wafer W. These steps S209 to S213 are similar to steps S109 to S113 for the first pattern. In step S211, as in step S111 for the first pattern, optimal etching conditions are determined to optimize the etching amount distribution on the first surface Wa.

[0135] In the above embodiment, the same effects as those of the above embodiment can be obtained. That is, the etching amount distribution of the second surface Wb in step S208 is optimized, and the etching amount distribution of the first surface Wa in step S212 is optimized. As a result, the surface shape of the wafer W after etching can be appropriately controlled, and the thickness of the wafer W can also be appropriately controlled.

[0136] The wafer processing for the third pattern differs from the wafer processing for the first and second patterns in steps S106, S206 and thereafter.

[0137] First, as shown in FIG. 18, steps S301 to S305 are performed to sequentially grind both sides of the wafer W and clean both sides of the wafer W. These steps S301 to S306 are the same as steps S101 to S105 of the first pattern. In step S301, as shown in FIG. 19(a), the first surface Wa is ground. As an example, the first surface Wa is ground into a V-shape so as to form a recess War whose center is recessed more than the outer periphery. In step S304, as shown in FIG. 19(b), the second surface Wb is ground. As an example, the second surface Wb is ground into a V-shape so as to form a recess Wbr whose center is recessed more than the outer periphery.

[0138] Next, in step S306, the second surface Wb is etched as shown in Fig. 19(c). At this time, the etching amount deviation (or etching amount) of the second surface Wb is uniform within the surface, that is, the etching amount deviation distribution (or etching amount distribution) is uniform. In other words, unlike the first pattern and the second pattern, the etching amount deviation distribution or etching amount distribution is not optimized.

[0139] Next, steps S307 to S311 are performed to sequentially measure the thickness of the wafer W and etch the first surface Wa. These steps S307 to S311 are similar to steps S109 to S113 for the first pattern. In step S309, similar to step S111 for the first pattern, optimal etching conditions are determined to optimize the etching amount distribution of the first surface Wa. Then, in step S310, as shown in FIG. 19(d), the first surface Wa is etched under the optimal etching conditions determined in step S309. That is, in this embodiment, the thickness distribution of the wafer W after etching becomes uniform.

[0140] In this embodiment, when steps S301 to S311 are performed consecutively on multiple wafers W, the etching amount deviation (or etching amount) of the second surface Wb is uniform within the surface in step S306. In other words, the second surfaces Wb of the multiple wafers W are etched under the same etching conditions.

[0141] The above embodiment can also achieve the same effects as the above embodiment. That is, even if the etching amount deviation on the second surface Wb in step S306 is uniform across the wafer surface, the etching amount distribution on the first surface Wa in step S310 is optimized. As a result, the surface shape of the wafer W after etching can be appropriately controlled, and the thickness of the wafer W can also be appropriately controlled.

[0142] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0143] 1. Wafer Processing System 40 Etching equipment 90 Control device Etching solution T Polymerized Wafer W First wafer S Second wafer

Claims

1. A substrate processing method for processing a substrate, comprising: Determining optimal etching conditions; supplying an etching solution to a surface of the substrate to be etched based on the optimal etching conditions, and etching the surface; Determining the optimum etching conditions includes: storing an etching index distribution in a radial direction of the etching target when the surface of the etching target is etched under a plurality of different etching conditions; using an optimization method to superimpose the etching index distributions corresponding to the plurality of etching conditions, and optimize a combination of the etching index distributions used for superimposition and the number of times the etching index distributions are superimposed so that the shape of the surface of the etching object becomes a target shape; and determining the optimum etching conditions by integrating the etching conditions corresponding to the optimized combinations.

2. When determining the optimum etching conditions, Etching of the surface of the etching target under the plurality of different etching conditions is performed on each of the substrates, 2. The substrate processing method according to claim 1, wherein the etching processing time for the etching target of each of the substrates is the same.

3. 3. The substrate processing method according to claim 1, wherein the optimization technique simultaneously optimizes the etching accuracy of the surface of the etching target and the supply time of the etching liquid to the surface of the etching target.

4. 4. The substrate processing method according to claim 3, wherein the etching accuracy is calculated as a weighted linear sum of the flatness of the etching target and a variation in thickness distribution of the etching target.

5. When etching the surface of the etching target, the substrate is rotated and the etching liquid is supplied from the etching liquid supply unit while the etching liquid supply unit is moved in a radial direction passing through a center of the etching target; 3. The substrate processing method according to claim 1, wherein when the reciprocating movement of the etching liquid supply part between both ends of the etching target is defined as one loop, the optimization method optimizes the number of times the etching index distributions are superimposed in units of 0.5 loops.

6. measuring a thickness of the etching target before etching the surface of the etching target to obtain a thickness distribution of the etching target; 3. The substrate processing method according to claim 1, wherein the optimum etching conditions are determined based on the obtained thickness distribution of the etching target.

7. The substrate processing method of claim 6 , further comprising thinning the substrate before measuring the thickness of the etching target.

8. 3. The substrate processing method according to claim 1, wherein the etching index distribution is at least one of an etching amount deviation distribution of a value obtained by subtracting an average value of the etching amounts from the etching amounts in the substrate surface, or an etching amount distribution of the etching amounts in the substrate surface.

9. grinding a first surface and a second surface of the substrate; measuring the thickness of the substrate to obtain a thickness distribution of the substrate; Etching the second surface based on the optimal etching conditions that optimize the etching amount deviation distribution from the thickness distribution; 9. The substrate processing method according to claim 8, further comprising: etching the first surface based on the optimum etching conditions that optimize the etching amount distribution from the thickness distribution.

10. grinding a first surface and a second surface of the substrate; measuring the thickness of the substrate to obtain a thickness distribution of the substrate; Etching the second surface based on the optimal etching conditions that optimize the etching amount distribution from the thickness distribution; 9. The substrate processing method according to claim 8, further comprising: etching the first surface based on the optimum etching conditions that optimize the etching amount distribution from the thickness distribution.

11. grinding a first surface and a second surface of the substrate; measuring the thickness of the substrate to obtain a thickness distribution of the substrate; Etching the second surface based on a predetermined etching amount deviation distribution or etching amount distribution; 9. The substrate processing method according to claim 8, further comprising: etching the first surface based on the optimum etching conditions that optimize the etching amount distribution from the thickness distribution.

12. A substrate processing system for processing a substrate, an etching device that supplies an etching solution to a surface of the substrate to be etched and etches the surface; a program storage unit for storing a program; a control device having a computer that reads the program from the program storage unit and runs the program, the control device stores an etching index distribution in a radial direction of the etching target when the surface of the etching target is etched under a plurality of different etching conditions; The program a program that runs on the computer of the control device and controls the substrate processing system to cause the substrate processing system to execute a substrate processing method, The substrate processing method includes: using an optimization method to superimpose the etching index distributions corresponding to the plurality of etching conditions, and optimize a combination of the etching index distributions used for superimposition and the number of times the etching index distributions are superimposed so that the shape of the surface of the etching object becomes a target shape; determining optimal etching conditions by combining the etching conditions corresponding to the optimized combinations; and etching the etching target in the etching device based on the optimum etching conditions.

13. 13. The substrate processing system of claim 12, wherein when determining the optimal etching conditions, the control device etches the surface of the etching target under the plurality of different etching conditions for each substrate, and controls the etching process time for the etching target of each substrate to be the same.

14. 14. The substrate processing system according to claim 12, wherein the control device simultaneously optimizes, in the optimization method, the etching accuracy of the surface of the etching target and a supply time of the etching liquid to the surface of the etching target.

15. 15. The substrate processing system according to claim 14, wherein the control device calculates the etching accuracy as a weighted linear sum of flatness of the etching target and a variation in thickness distribution of the etching target.

16. The etching apparatus includes: a substrate holder for holding the substrate; a rotation mechanism that rotates the substrate holder; an etching liquid supply unit that supplies an etching liquid from above the surface of the substrate to be etched that is held by the substrate holder; a moving mechanism that moves the etching liquid supply unit in a horizontal direction, 14. The substrate processing system according to claim 12, wherein the control device optimizes the number of times the etching index distributions are superimposed in units of 0.5 loops in the optimization method, when the reciprocating movement of the etching liquid supply unit between both ends of the etching target is defined as one loop.

17. a thickness measuring device for measuring the thickness of the etching target before etching; 14. The substrate processing system according to claim 12, wherein the control device determines the optimum etching conditions based on a thickness distribution of the etching target obtained from the thickness of the etching target measured by the thickness measuring device.

18. a thinning device for thinning the substrate; The substrate processing system of claim 17 , wherein the thickness measurement device measures a thickness of the etching target on the substrate after thinning.

19. 14. The substrate processing system according to claim 12, wherein the etching index distribution is at least one of an etching amount deviation distribution of a value obtained by subtracting an average value of the etching amounts from the etching amounts in the substrate surface, or an etching amount distribution of the etching amounts in the substrate surface.

20. A program that runs on a computer of a control device that controls a substrate processing system so as to cause the substrate processing system to execute a substrate processing method for processing a substrate, the substrate processing system, an etching device that supplies an etching solution to a surface of the substrate to be etched and etches the surface; the control device having a program storage unit for storing the program, the control device stores an etching index distribution in a radial direction of the etching target when the surface of the etching target is etched under a plurality of different etching conditions; The substrate processing method includes: using an optimization method to superimpose the etching index distributions corresponding to the plurality of etching conditions, and optimize a combination of the etching index distributions used for superimposition and the number of times the etching index distributions are superimposed so that the shape of the surface of the etching object becomes a target shape; determining optimal etching conditions by combining the etching conditions corresponding to the optimized combinations; and etching the etching target in the etching apparatus based on the optimal etching conditions.

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