Substrate Processing Method and Substrate Processing System

Abstract

This substrate processing method comprises determining an optimum etching condition, and supplying an etchant to a surface to be etched of a substrate on the basis of the optimum etching condition to etch the surface. Determining the optimum etching condition comprises: acquiring an etching indicator distribution radially of the object to be etched when the surface to be etched is etched under a plurality of different etching conditions; using an optimization scheme and superposing the etching indicator distributions corresponding to a plurality of etching conditions to optimize a combination of the etching indicator distributions used for the superposition and the number of times the etching indicator distributions are superposed, such that the shape of the surface to be etched becomes a target shape; and determining an optimum etching condition by integrating the etching conditions corresponding to the optimized combination.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a substrate processing method including a grinding step of grinding the surface of a substrate, a measuring step of measuring the thickness of the ground substrate, a condition determining step of determining the processing conditions of wet etching treatment 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 wet etching treatment based on the determined processing conditions.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The technology according to the present disclosure appropriately controls the surface shape of an object to be etched after the etching treatment.

Means for Solving the Problems

[0005] One aspect of the present disclosure is a substrate processing method for processing a substrate, including determining optimal etching conditions, and based on the optimal etching conditions, supplying an etching solution to the surface of the object to be etched on the substrate to etch the surface. Determining the optimal etching conditions includes obtaining the etching index distribution in the radial direction of the object to be etched when etching the surface of the object to be etched under a plurality of different etching conditions, and using an optimization method to overlap the etching index distributions corresponding to the plurality of etching conditions so that the shape of the surface of the object to be etched becomes a target shape, optimizing the combination of the etching index distribution used for the overlapping and the number of times of overlapping the etching index distributions, and integrating the etching conditions corresponding to the optimized combination to determine the optimal etching conditions.

Advantages of the Invention

[0006] According to the present disclosure, the surface shape of the object to be etched after the etching process can be appropriately controlled.

Brief Description of the Drawings

[0007]

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Mode for Carrying Out the Invention

[0008] In the manufacturing process of semiconductor devices, a semiconductor substrate (hereinafter referred to as "wafer") on which devices such as a plurality of electronic circuits are formed on the surface is ground and thinned, and further, the ground surface of the wafer is 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 rotating the wafer.

[0009] Patent Document 1 described above discloses performing a wet etching process on a wafer after grinding to remove a damaged layer formed on the surface of the wafer by the grinding process. In the condition determination step described in Patent Document 1, based on the thickness of the wafer obtained in the measurement step, as conditions for the wet etching process, the operation of the nozzle for supplying the processing liquid, the rotation speed of the wafer, the supply amount of the processing liquid, the supply time of the processing liquid, the type of the processing liquid, etc. are determined.

[0010] However, when performing spin etching in which the processing liquid is supplied while rotating the wafer as in the method disclosed in Patent Document 1, it has been difficult to perform precise etching control because the processing liquid supplied to the wafer surface flows radially outward due to centrifugal force. More specifically, it has been difficult to appropriately control the surface shape of the wafer after the etching process, particularly at the center of the wafer.

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

[0012] In this etching process, while rotating the wafer, the etching liquid is supplied from the nozzle while moving the nozzle in the radial direction passing through the center of the wafer. The nozzle is reciprocated a plurality of times between both ends of the wafer. In the following description, one reciprocation of the nozzle between both ends of the wafer is defined as one loop.

[0013] FIG. 1 is a graph showing the distribution of etching amount deviation for each case where a wafer is etched under a plurality of different etching conditions. The horizontal axis in FIG. 1 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.

[0014] Comparative Example 1 (dashed line) in FIG. 1 shows the distribution of etching amount deviation when only the etching process under Condition A where the rotation speed of the wafer is 200 rpm is performed. Comparative Example 2 (dotted line) shows the distribution of etching amount deviation when only the etching process under Condition B where the rotation speed of the wafer is 1000 rpm is performed. In contrast, Example 1 (thick solid line) shows the distribution of etching amount deviation when Conditions A and B are performed at a time (number of loop times) 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 half of the etching amount deviation distribution of Comparative Example 1 and half of the etching amount deviation distribution of Comparative Example 2. Example 2 (thick dashed line) shows the distribution of etching amount deviation when Conditions A and B are 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. Note that in all of Comparative Examples 1 and 2 and Examples 1 and 2, the etching conditions other than the rotation speed of the wafer were the same.

[0015] In such a case, as shown in FIG. 1, it was confirmed that the measured value of the etching amount deviation distribution of Example 1 where Conditions A and B were performed at a time ratio of 1:1 substantially coincides with the average value (calculated value) of the etching amount deviation distribution of Comparative Example 1 and the etching amount deviation distribution of Comparative Example 2. Also, it was confirmed that the measured value of the etching amount deviation distribution of Example 2 where Conditions A and B were performed at a time ratio of 5:1 substantially coincides with the proportional distribution value (calculated value) obtained by prorating the etching amount deviation distribution of Comparative Example 1 and the etching amount deviation distribution of Comparative Example 2 by the time ratio. Thus, since the measured value and the calculated value substantially coincide, it was found that the etching amount deviation distribution after superposition is accurate.

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

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

[0018] The technology according to the present disclosure has been made in view of the above findings, and appropriately controls the surface shape of the object to be etched after the etching process. Hereinafter, a wafer processing system as a substrate processing system according to the present embodiment and a wafer processing method as a substrate processing method will be described with reference to the drawings. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

[0019] In the wafer processing system 1 according to the present embodiment described later, as shown in FIG. 2, processing is performed on a polymerized wafer T as a substrate in which a first wafer W and a second wafer S are joined. Hereinafter, in the first wafer W, the surface on the side joined to the second wafer S is referred to as a front surface Wa, and the surface on the side opposite to the front surface Wa is referred to as a back surface Wb. Similarly, in the second wafer S, the surface on the side joined to the first wafer W is referred to as a front surface Sa, and the surface on the side opposite to the front surface Sa is referred to as a back surface Sb.

[0020] The first wafer W is a semiconductor wafer such as a silicon substrate, and a device layer Dw including a plurality of devices is formed on the surface Wa side. Further, a bonding film Fw is formed on the device layer Dw, and the first wafer W is bonded to the second wafer S through the bonding film Fw. As the bonding film Fw, for example, an oxide film (THOX film, SiO2 film, TEOS film), SiC film, SiCN film, or an adhesive is used.

[0021] The second wafer S has, for example, the same configuration as the first wafer W, and a device layer Ds and a bonding film Fs are formed on the surface Sa. Note that the second wafer S does not necessarily have 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] As shown in FIG. 3, 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 stacked wafers T is loaded / unloaded to / from the outside. The processing station 3 is provided with various processing apparatuses that perform desired processing on the stacked wafers T.

[0023] The loading / unloading station 2 is provided with a cassette mounting table 10 on which a plurality of, for example, three cassettes C are placed. Further, on the negative X-axis side of the cassette mounting table 10, a wafer transfer device 20 is provided adjacent to 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. Further, the wafer transfer device 20 has, for example, two transfer arms 22, 22 that hold and transfer the stacked wafers T. Each transfer arm 22 is configured to be movable in the horizontal direction, vertical direction, around the horizontal axis, and around the vertical axis. Note that the configuration of the transfer arm 22 is not limited to this embodiment and can take any configuration. Then, the wafer transfer device 20 is configured to be able to transfer the stacked wafers T to / from the cassette C on the cassette mounting table 10 and a transition device 30 described later.

[0024] On the negative X-axis side of the wafer transfer device 20, adjacent to the wafer transfer device 20, a transition device 30 for transferring the stacked wafer T between the processing station 3 is provided in the loading / unloading station 2.

[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 X-axis side (the loading / unloading station 2 side) to the negative direction side.

[0026] An etching device 40, a thickness measuring device 41, and a wafer transfer device 50 are provided in the first processing block B1. The etching device 40 and the thickness measuring device 41 are arranged in a stacked manner. Note that the number and arrangement of the etching device 40 and the thickness measuring device 41 are not limited to this.

[0027] The etching device 40 etches the back surface Wb (grinding surface) of the first wafer W after grinding in the processing device 80 described later, further thins the first wafer W (stacked wafer T) after grinding, and smoothes the grinding surface by removing the grinding marks generated by the grinding process. The detailed configuration of the etching device 40 will be described later.

[0028] The thickness measuring device 41 includes a measuring unit (not shown) and a calculating unit (not shown) in one example. The measuring unit includes a sensor that measures the thickness of the first wafer W after etching at a plurality of points. The calculating unit obtains the thickness distribution of the first wafer W from the measurement results (the thickness of the first wafer W) by the measuring 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 the control device 90 described later instead of the calculating unit. In other words, a calculating unit (not shown) may be provided in the control device 90 described later. Note that the configuration of the thickness measuring device 41 is not limited to this and can be arbitrarily configured.

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

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

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

[0032] The thickness measurement device 61 includes, in one example, 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 grinding at a plurality of points. The calculation unit obtains 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) of the first wafer W. Note that the calculation of the thickness distribution and flatness of such a first wafer W may be performed by the control device 90 described later instead of the calculation unit. In other words, a calculation unit (not shown) may be provided in the control device 90 described later. Note that the configuration of the thickness measurement device 61 is not limited to this and can be arbitrarily configured.

[0033] The buffer device 62 temporarily holds the pre - processed polymerized 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. Note that the buffer device 62 may have an alignment mechanism (not shown) that adjusts the center position of the polymerized wafer T with respect to the chuck 83 described later and / or the horizontal orientation of the polymerized wafer T.

[0034] The wafer transfer device 70 is arranged, for example, on the positive Y - axis side of 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 polymerized wafer T by an adsorption holding surface (not shown) and transfer it. Each transfer arm 71 is supported by an articulated arm member 72 and is configured to be movable in the horizontal direction, the vertical direction, around the horizontal axis, and around the vertical axis. And the wafer transfer device 70 is configured to be able to transfer the polymerized 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 the processing device 80 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 about a vertical rotation center line 82 by a rotation mechanism (not shown). On the rotary table 81, two chucks 83 for adsorbing and holding the polymerized wafer T are provided. 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 when the rotary table 81 rotates. Also, each of the two chucks 83 is configured to be rotatable about the vertical axis by a rotation mechanism (not shown).

[0037] At the delivery position A0, the polymerized wafer T is delivered. At the processing position A1, a grinding unit 84 is arranged, and the first wafer W is ground while the second wafer S is sucked and held by a chuck 83. The grinding unit 84 has a grinding part 85 provided with a grinding wheel (not shown) that is annular and rotatable. Further, the grinding part 85 is configured to be movable in the vertical direction along a support column 86.

[0038] Note that the configuration of the processing apparatus 80 is not limited to this. For example, four chucks 83 may be provided on the rotary table 81, and the four chucks 83 may be configured to be movable between the delivery position of the polymerized wafer T, a rough grinding part (not shown) for performing rough grinding of the first wafer W, a semi-finishing grinding part (not shown) for performing semi-finishing grinding of the first wafer W, and a finish grinding part (not shown) for performing finish grinding of the first wafer W. Also, for example, the processing apparatus 80 may be provided with a thickness measuring device (not shown) for measuring the thickness of the first wafer W after grinding at a plurality of points.

[0039] The above wafer processing system 1 is provided with a control device 90. The control device 90 is a computer including, for example, a CPU and a memory, and has a program storage part (not shown). A program for controlling the processing of the polymerized wafer T in the wafer processing system 1 is stored in the program storage part. Note that the above program may be recorded on a computer-readable storage medium H and installed from the storage medium H to the control device 90. Also, the above storage medium H may be temporary or non-temporary.

[0040] Next, the configuration of the etching apparatus 40 described above will be explained. As shown in FIG. 4, the etching apparatus 40 has a wafer holding part 100 as a substrate holding part, a rotation mechanism 101, and a nozzle 102 as an etching liquid supply part.

[0041] The wafer holding part 100 holds the outer edge part of the polymerized wafer T at a plurality of points, three points in this embodiment. Note that the configuration of the wafer holding part 100 is not limited to the illustrated example. For example, the wafer holding part 100 may include a chuck that adsorbs and holds the polymerized wafer T from below. The rotation mechanism 101 rotates the polymerized wafer T (first wafer W) held by the wafer holding part 100 about the 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 is configured to be movable in the horizontal and vertical directions by a moving mechanism 103. In one example, the nozzle 102 is configured to be reciprocally movable (scan movable) through the rotation center line 100a of the wafer holding part 100, that is, through the center part above the first wafer W as shown in FIG. 5.

[0043] The etching liquid E contains at least hydrofluoric acid or nitric acid in order to appropriately etch the silicon of the first wafer W that can be an etching target. Further, the etching liquid E may contain phosphoric acid or sulfuric acid. Note that the etching target is not limited to the first wafer W, and may be, for example, amorphous silicon. Also, the etching target in this embodiment is not limited to the back surface Wb of the first wafer W. For example, it can also be applied to the case of processing a wafer on which processing by the processing apparatus 80 is not performed. For example, when a film is formed on the back surface Wb, the film also becomes an etching target.

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

[0045] First, a cassette C containing a plurality of polymerized wafers T is placed on the cassette mounting table 10 of the loading / unloading station 2. Next, the polymerized wafer T in the cassette C is taken out by the wafer transfer device 20 and transferred to the transition device 30. The polymerized wafer T transferred to the transition device 30 is transferred to the buffer device 62 by the wafer transfer device 50. Note that in the buffer device 62, the center position of the polymerized wafer T with respect to the chuck 83 and / or the horizontal direction of the polymerized wafer T may be adjusted.

[0046] Next, the polymerized wafer T is transferred to the processing device 80 by the wafer transfer device 70 and delivered to the chuck 83 at the delivery position A0. At the chuck 83, the back surface Sb of the second wafer S is adsorbed and held. 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. By such grinding treatment, the thickness of the first wafer W (polymerized wafer T) is reduced to a desired grinding target thickness (step S1 in FIG. 6).

[0047] Next, the polymerized wafer T is transferred to the thickness measuring device 61 by the wafer transfer device 70. In the thickness measuring device 61, the thickness distribution of the first wafer W after grinding is obtained by measuring the thickness of the first wafer W (polymerized wafer T) at a plurality of points after grinding, and further the flatness of the first wafer W is calculated (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 when a thickness measuring device is provided in the processing device 80, the thickness of the first wafer W after grinding may be measured by the thickness measuring device of the processing device 80.

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

[0049] The measured thickness of the polymerized wafer T of the first wafer W is then transported to the cleaning device 60 by the wafer transport device 70 or the wafer transport device 50. In the cleaning device 60, the back surface Wb, which is the ground surface of the first wafer W after grinding, is cleaned (step S4 in FIG. 6). Also, in the cleaning device 60, the back surface Sb of the second wafer S may be cleaned as described above. When measuring the thickness after grinding with the thickness measuring device 61 as in the present embodiment, the order of step S2 and step S3 and step S4 may be reversed. That is, after cleaning the back surface Wb of the first wafer W with the cleaning device 60, the thickness of the first wafer W may be measured with the thickness measuring device 61, and the optimum etching conditions in the etching process may be determined.

[0050] Next, the polymerized wafer T is transported to the etching device 40 by the wafer transport 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 the optimum etching conditions (step S5 in FIG. 6).

[0051] When etching the first wafer W, first, the wafer holding part 100 (the first wafer W) is rotated around the vertical rotation center line 100a, and the supply (discharge) of the etching solution E from the nozzle 102 is started to start etching the back surface Wb.

[0052] When etching the first wafer W, while continuing to supply the etching solution E from the nozzle 102, as shown in FIG. 5, the nozzle 102 is reciprocally moved (scanned) with the rotation center line 100a as the intermediate point above the rotation center of the first wafer W, that is, passing through the rotation center line 100a. Details of the method 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 reciprocally moving the nozzle 102 will be described later.

[0053] When the etching of the back surface Wb under the optimum etching conditions is completed, the supply of the etching liquid E from the nozzle 102 is stopped, the back surface Wb of the first wafer W is rinsed with pure water, and then spin-dried. Then, the rotation of the wafer holding unit 100 (the first wafer W) is stopped, and the etching of the first wafer W is completed.

[0054] Here, the optimum 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 optimum etching conditions are determined based on the difference between the actually measured values of the thickness distribution and flatness of the first wafer W in the thickness measuring device 61 and the thickness distribution and flatness in the target surface shape (hereinafter referred to as the "target shape") of the first wafer W after etching. In step S5, by etching the first wafer W under the optimum etching conditions, the difference between the actually measured value and the target value of the thickness of the first wafer W is removed by etching, and the surface of the first wafer W is processed into the target shape. 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 polymerized wafer T is transported by the wafer transport device 50 to the thickness measuring device 41. In the thickness measuring device 41, the thickness distribution of the first wafer W after etching is obtained by measuring the thickness of the first wafer W (polymerized wafer T) after etching at a plurality of points (step S6 in FIG. 6). Further, the flatness of the first wafer W may be calculated. The calculated thickness distribution of the first wafer W is output to, for example, the control device 90 and is used, as an example, for the processing of other polymerized wafers T to be processed in the wafer processing system 1 next. When the thickness of the first wafer W after grinding is measured by the thickness measuring device of the processing device 80, the thickness of the first wafer W after etching may be measured in the thickness measuring device 61.

[0056] Thereafter, the polymerized wafer T that has been subjected to all the processes is transported to the cassette C on the cassette mounting table 10 via the transition device 30. Thus, a series of wafer processes in the wafer processing system 1 is completed.

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

[0058] First, when determining the optimum etching conditions, prior to the treatment of the polymer wafer T in the wafer processing system 1, a plurality of parts used in the optimization process described later are acquired (step S3-0 in FIG. 7). Note that the parts are the etching amount deviation distribution of the first wafer W with respect to a certain etching condition.

[0059] In step S3-0, for example, etching is performed on a dummy wafer under a plurality of different etching conditions. Specifically, for example, the rotation speed of the dummy wafer during etching, the scan speed of the nozzle 102, or the scan width of the nozzle 102 (see the scan width L in FIG. 5) is changed to etch the dummy wafer. At this time, the processing time for etching each dummy wafer is the same. The etching of the dummy wafer is performed in the same manner as the etching in step S5, while rotating the dummy wafer and reciprocating the nozzle 102, and supplying the etching solution E from the nozzle 102 to the dummy wafer. In the following description, one reciprocation of the nozzle 102 between both ends of the dummy wafer is defined as one loop.

[0060] The etching of the dummy wafer under each etching condition is performed for a predetermined desired time (desired number of loop repetitions). Then, the etching amount deviation distribution of the dummy wafer is acquired, and the etching amount deviation distribution is output to the control device 90. Further, in the control device 90, the etching amount deviation distribution under each output etching condition is compressed into an etching amount deviation distribution per unit time (per unit number of loop repetitions), and each compressed etching amount deviation distribution is stored as the above-described parts.

[0061] FIG. 8 shows an example of a plurality of parts. The horizontal axis in 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 the case where a total of 36 types of parts are stored in the control device 90. In other words, it is an example of obtaining the etching amount deviation distribution under a total of 36 different etching conditions.

[0062] Note that the above unit time (unit loop count) can be arbitrarily set according to the purpose. However, in order to appropriately obtain the target etching amount deviation distribution in the superposition of the parts described later, it is desirable that the unit time (unit loop count) be short. In one example, the unit time of the parts stored in the control device 90 can be the time for 1 loop (one round trip of the scan width L shown in FIG. 5), preferably the time for 0.5 loop (half round trip of the scan width L shown in FIG. 5).

[0063] Note that in the above, the case of obtaining the above parts by etching the dummy wafer has been described as an example. However, the etching target when obtaining the parts is not limited to the 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 parts. Also, for example, when 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 parts.

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

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

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

[0067] Next, a plurality of parts are overlapped, and using an optimization method, the parts used for overlapping and the number of times of overlapping of the parts are optimized so as to obtain the target etching amount deviation distribution obtained in step S3-1 above (step S3-2 in FIG. 7).

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

[0069] As this optimization method, for example, a genetic algorithm or a dynamic programming method can be used. Then, by performing the optimization calculation, one or more parts to be used for superposition are selected from the plurality of parts shown in FIG. 8 as shown in FIG. 10, and further 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] Also, in this optimization calculation, the number of superposition times of parts is optimized so that the supply time of the etching liquid E from the nozzle 102 to the first wafer W in the etching process is minimized. As described above, in this embodiment, so-called multi-objective optimization is performed to optimize both the etching amount deviation distribution, that is, the etching accuracy, and the supply time of the etching liquid E. Specifically, it is optimized using the following formula (1). Note that the etching accuracy is the accuracy within the wafer surface of the etching amount deviation distribution.

[0071]

Equation

[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, for example, when the coefficient α is 1, it becomes an algorithm that emphasizes flatness, and when the coefficient α is 0 (zero), it becomes an algorithm that emphasizes the variation in the thickness distribution.

[0073] In step S3-2, when optimizing the number of superposition times of the parts, the number of superposition times may be optimized in units of 0.5 loops. In such a case, for example, the supply of the etching solution E can start from the center of the first wafer W and end at the center.

[0074] When the number of superposition times of the parts and the parts is optimized as described above, next, the etching conditions corresponding to the parts optimized in step S3-2 are integrated to determine the optimum etching conditions (step S3-3 in FIG. 7). Specifically, a plurality of selected etching conditions are integrated so as to be performed with the optimized number of superposition times, and the optimum etching conditions are determined. In other words, the optimum etching conditions for optimizing the etching amount deviation distribution are determined.

[0075] Thereafter, in step S4, after cleaning the back surface Wb of the first wafer W, in step S5, the back surface Wb of the first wafer W is etched under the optimum etching conditions. That is, in the etching apparatus 40, the polymerization wafer T (the first wafer W) is rotated at the rotation speed determined by the optimum etching conditions, and while moving the nozzle 102 at the determined scan speed and scan width, the etching solution E is supplied to the first wafer W.

[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 performed as described above.

[0077] According to the above embodiments, in step S3, an optimization method is used to optimize the parts to be overlapped and the number of overlaps of the parts, and the optimal etching conditions are determined. Then, in step S5, the first wafer W can be etched under the optimal etching conditions. As a result, the deviation distribution of the etching amount in the etching process can be optimized to approach the target etching amount deviation distribution. As a result, the surface shape of the first wafer W after etching can be made into the target shape. In other words, the optimal etching conditions can be determined from the indefinite etching conditions, and the surface shape of the first wafer W after etching can be appropriately controlled.

[0078] When the inventors actually performed simulations, in any case where the target etching amount deviation distribution was V-shaped, A-shaped, M-shaped, or W-shaped, the variation in the thickness distribution of the first wafer W after etching could be kept within the allowable range. Also, the flatness (TTV) of the first wafer W after etching was improved compared to the prior art.

[0079] In addition, since steps S1 to S6 are performed for each stacked wafer T, the surface shape of the first wafer W after etching can be controlled for each sheet.

[0080] In the above embodiments, 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 variables for the etching conditions. However, the variables for the etching conditions are not limited to these. For example, the type, viscosity, temperature, supply amount, etc. of the etching solution E may be used as variables for the etching conditions. In such a case, in step S3-0, a plurality of parts with the type, viscosity, temperature, supply amount, etc. of the etching solution E changed are obtained. Then, steps S3-1 to S3-3 are executed to determine the optimal etching conditions.

[0081] In the above embodiment, in the bonded wafer T in which the first wafer W and the second wafer S are bonded, the case where various processes are performed on the back surface Wb of the first wafer W has been described as an example, but the processing target is not limited to this. For example, a single wafer may be subjected to thinning processing or etching processing. 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 be arbitrarily switchable to supply different types of etching liquid E according to the etching target. Further, for example, when a film formed on the wafer surface is the etching target, the etching processing result of the film may be stored as the above parts. In the thickness measuring device 61, the thickness of the film is measured. Further, when a protective tape is attached to the device surface of the wafer, thinning processing or etching processing may be performed on the surface opposite to the protective tape. Furthermore, thinning processing or etching processing may be performed on a wafer cut out from an ingot by a wire saw or the like and lapped. Regardless of the processing target, the etching processing can be performed under the optimum etching conditions of the above embodiment.

[0082] Further, for example, when 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. In step S2, instead of the thickness of the first wafer W, the thickness of the film is measured, and further the thickness distribution and flatness of the film are calculated. Then, in step S3, the optimum etching conditions are determined based on the calculated thickness distribution and flatness of the film.

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

[0084] In the above embodiments, the first wafer W is thinned by the processing apparatus 80, but the thinning method is not limited thereto. For example, the thinning process of the first wafer W includes polishing the back surface Wb of the first wafer W. Alternatively, for example, the first wafer W may be thinned by separation based on a modified layer (not shown) formed by laser processing inside the first wafer W. In such a case, instead of the processing apparatus 80, a laser processing apparatus (not shown) for forming the modified layer (not shown) is provided in the wafer processing system 1.

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

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

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

[0088] In step S3-2, the plurality of parts are superimposed, and using an optimization method, the parts used for superimposition and the number of times of superimposition of the parts are optimized so as to obtain the target etching amount distribution obtained in step S3-1. At this time, an example of the parts used for superimposition is a part with the vertical axis in FIG. 10 being the etching amount. And an example of the superimposed etching amount distribution is the solid line with the vertical axis in FIG. 11 being 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. That is, the optimal etching conditions for optimizing the etching amount distribution on the back surface Wb are determined.

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

[0091] Here, when optimizing the etching amount deviation distribution as in the above embodiment, the shape (profile) of the back surface Wb of the first wafer W after etching can be precisely controlled. On the other hand, when optimizing the etching amount as in this embodiment, the shape of the back surface Wb of the first wafer W after etching can be precisely controlled, and the thickness of the first wafer W can also be precisely controlled.

[0092] FIG. 12 shows an example of the thickness deviation distribution (distribution of the value obtained by subtracting the average value of the thickness from the thickness within the wafer surface) of the first wafer W after grinding and after etching. The horizontal axis in 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 in this embodiment (solid line in FIG. 12), 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 in 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. The thickness distribution of the first wafer W after grinding (the broken line in FIG. 13) and the thickness distribution of the first wafer W after etching in this embodiment (the solid line in FIG. 13 When compared with the solid line in FIG.), it can be made uniform to the average value of the thickness of the first wafer W (the value obtained by averaging the thickness within the wafer surface) after etching. Therefore, according to this embodiment, the thickness can also be precisely controlled by etching. On the first wafer W The thickness can be precisely controlled.

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

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

[0096] In this embodiment, using the wafer processing system 200 shown in FIG. 14, a process for improving the in-plane uniformity of the thickness is performed on the wafer W as a substrate cut out from an ingot with a wire saw or the like and lapped. Hereinafter, the cut surface 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 on the opposite side of the second surface Wb. Also, the first surface Wa and the second surface Wb may be collectively referred to as the surface of the wafer W in some cases.

[0097] The wafer processing system 200 further includes inversion devices 210 and 211 in the wafer processing system 1 of the above embodiment, and has a configuration in which a processing device 220 is provided instead of the processing device 80. Note that since other configurations of the wafer processing system 200 are the same as those of the wafer processing system 1, the description thereof is omitted.

[0098] The etching device 40 etches silicon (Si) on the first surface Wa or the second surface Wb after grinding by the processing device 220. A plurality of etching devices 40 may be provided to improve the throughput of wafer processing. The cleaning device 60 cleans at least the first surface Wa or the second surface Wb after grinding by the processing device 220.

[0099] The inversion device 210 is stacked and arranged on the etching device 40 and the thickness measurement device 41. The inversion device 211 is stacked and arranged on the cleaning device 60, the thickness measurement device 61, and the buffer device 62. These inversion devices 210 and 211 invert the first surface Wa and the second surface Wb of the wafer W in the vertical direction. The configurations of the inversion devices 210 and 211 are arbitrary.

[0100] The processing device 220 includes 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 sucking and holding the wafer W are provided on the rotary table 221. Among the four chucks 223, two first chucks 223a are chucks used for grinding at the first processing position C1. These two first chucks 223a are arranged at positions that are point-symmetrical with respect to the rotation center line 222. The remaining two second chucks 223b are chucks used for grinding at the second processing position C2. These two second chucks 223b are also arranged at positions that are point-symmetrical with respect to the rotation center line 222. That is, the first chucks 223a and the second chucks 223b are alternately arranged in the circumferential direction.

[0101] The four chucks 223 can be moved to the delivery position D1 ~ D2 and the machining positions C1 to C2 as the rotary table 221 rotates. Also, each of the four chucks 223 is configured to be rotatable about a vertical axis by a rotation mechanism (not shown).

[0102] The first delivery position D1 is a position on the X-axis Positive direction side and the positive Y-axis side of the rotary table 221, and the wafer W is transferred to the first chuck 223a when grinding the first surface Wa. The second delivery position D2 is a position on the X-axis Positive direction side and the negative Y-axis side of the rotary table 221, and the wafer W is transferred to the second chuck 223b when grinding the second surface Wb.

[0103] The first machining position C1 is a position on the X-axis Negative direction side and the negative Y-axis side of the rotary table 221, and the first grinding unit 230 is arranged. The first grinding unit 230 has a grinding portion 231 provided with a grinding wheel (not shown) that is annular and rotatable. Also, the grinding portion 231 is configured to be movable in the vertical direction along the support column 232. The first grinding unit 230 grinds, for example, the first surface Wa or the second surface Wb of the wafer W held by the first chuck 223a.

[0104] The second machining position C2 is a position on the X-axis Negative direction side and the positive Y-axis side of the rotary table 221, and the second grinding unit 240 is arranged. The second grinding unit 240 has a grinding portion 241 provided with a grinding wheel (not shown) that is annular and rotatable. Also, the grinding portion 241 is configured to be movable in the vertical direction along the support column 242. The second grinding unit 240 grinds, for example, the second surface Wb or the first surface Wa of the wafer W held by the second chuck 223b.

[0105] Incidentally, the delivery position D1 , D2 or at the processing positions C1 and C2, a thickness measuring device (not shown) for measuring the thickness of the wafer W after grinding may be provided.

[0106] Next, the wafer processing (double-sided processing) performed using the wafer processing system 200 configured as described above will be described. Hereinafter, wafer processing in three patterns will be described.

[0107] In the wafer processing of the first pattern, first, a cassette C containing a plurality of wafers W is placed on the cassette mounting table 10 of the loading / unloading station 2. In the cassette C, the wafers W are stored with the first surface Wa facing upward and the second surface Wb facing downward. Next, the wafer W in the cassette C is taken out by the wafer transfer device 20 and transferred to the transition device 30. The wafer W transferred to the transition device 30 is transferred to the buffer device 62 by the wafer transfer device 50. Incidentally, in the buffer device 62, the center position of the wafer W with respect to the chuck 223 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 delivered to the first chuck 223a at the first delivery position D1 . At the first chuck 223a, the second surface Wb of the wafer W is sucked and held.

[0109] Next, the rotary table 221 is rotated to move the wafer W to the first processing position C1. Then, the first surface Wa of the wafer W is ground by the first grinding unit 230 (step S101 in FIG. 15). In step S101, the control device 90 controls the processing device 220 to grind the first surface Wa in a V shape so as to form a concave portion War in which the central portion is recessed from the outer peripheral portion on the first surface Wa after grinding as shown in FIG. 16(a).

[0110] Next, rotate the rotary table 221 to move the wafer W to the first delivery position. D1 At the first delivery position D1 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 transported to the cleaning device 60 by the wafer transfer device 70. 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 transported 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 in the vertical direction (step S103 in FIG. 15). That is, the wafer W is reversed such that the first surface Wa faces downward and the second surface Wb faces upward.

[0113] Next, the wafer W is transported to the processing device 220 by the wafer transfer device 70 and delivered to the second chuck 223b at the second delivery position. D2 At the second chuck 223b, the first surface Wa of the wafer W is sucked and held.

[0114] Next, rotate the rotary table 221 to move the wafer W to the second processing position C2. Then, the second surface Wb of the wafer W is ground by the second grinding unit 240 (step S104 in FIG. 15). In step S104, the control device 90 controls the processing device 220 to grind the second surface Wb in a V shape so as to form a concave portion Wbr in which the central portion is recessed from the outer peripheral portion on the second surface Wb after grinding as shown in FIG. 16(b).

[0115] Next, rotate the rotary table 221 to move the wafer W to the second delivery position. D2 At the second delivery position D2 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 transported to the cleaning device 60 by the wafer transfer device 70. 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 transfer device 70 or the wafer transfer device 50. In the thickness measuring device 61, the thickness distribution of the ground wafer W is obtained by measuring the thickness of the wafer W at a plurality of points on both the first surface Wa and the second surface Wb, and further the flatness of the wafer W is calculated (step S106 in FIG. 15). The calculated thickness distribution and flatness of the wafer W are output to, for example, the control device 90. When the processing device 220 is provided with a thickness measuring device, the thickness of the ground wafer W may be measured by the thickness measuring device of the processing device 220.

[0118] In the control device 90, the optimum etching conditions for the second surface Wb are determined by optimizing the etching amount deviation distribution in the etching process of the second surface Wb from the output thickness distribution and flatness of the wafer W (step S107 in FIG. 15). This step S107 is the same as step S3 in the above embodiment.

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

[0120] Next, the wafer W is transported to the inversion device 210 by the wafer transfer device 50. In the inversion device 210, the first surface Wa and the second surface Wb of the wafer W are inverted in the vertical direction (step S109 in FIG. 15). That is, the wafer W is inverted such that the first surface Wa faces upward and the second surface Wb faces downward.

[0121] Next, the wafer W is transported to the thickness measuring device 41 by the wafer transfer device 50. In the thickness measuring device 41, the thickness distribution of the wafer W after grinding is obtained by measuring the thickness of the wafer W at a plurality of points, and further the flatness of the wafer W is calculated (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] In the control device 90, the optimum etching conditions for the first surface Wa are determined to optimize the etching amount distribution in the etching process of the first surface Wa from the output thickness distribution and flatness of the wafer W (step S111 in FIG. 15). This step S111 is the same as step S3 in the above embodiment.

[0123] Next, the wafer W is transported to the etching device 40 by the wafer transfer device 50. In the etching device 40, the first surface Wa of the wafer W is etched with the etching solution E under the optimum etching conditions determined in step S111 (step S112 in FIG. 15). In step S112, by etching the first surface Wa under the optimum etching conditions, the etching amount distribution is optimized, 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 to the thickness measuring device 41 by the wafer transfer device 50. In the thickness measuring device 41, the thickness distribution of the wafer W after grinding is obtained by measuring the thickness of the wafer W at a plurality of points on both the first surface Wa and the second surface Wb after etching (step S113 in FIG. 15). The flatness of the wafer W may be further calculated. This step S111 is the same as step S6 in the above embodiment.

[0125] Thereafter, the wafer W on which all the processes have been performed is transported to the cassette C on the cassette mounting table 10 via the transition device 30. Thus, a series of wafer processes in the wafer processing system 200 are completed. Note that the wafer W processed in the wafer processing system 200 may be polished outside the wafer processing system 200.

[0126] Even in the above embodiments, the same effects as those of the above embodiments can be enjoyed. That is, the etching amount deviation distribution of the second surface Wb in step S108 is optimized, and the etching amount distribution of the first surface Wa in step S112 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 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) has a tendency that the etching amount deviation (etching amount) near the center of the wafer W becomes small and forms a downwardly concave V-shaped shape. In other words, the surface of the wafer after etching tends to have an A-shaped shape protruding upward. Therefore, it is preferable to form the shape of the surface of the wafer after grinding into a V-shaped shape.

[0128] By grinding the first surface Wa and the second surface Wb into shapes that are easy to control by etching in this way, the accuracy of optimizing the etching amount deviation distribution of the first surface Wa and the second surface Wb in step S108 S112 can be improved.

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

[0130] The wafer processing of the second pattern is different in steps S107 and S108 from the wafer processing of the first pattern. 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. 16.

[0131] First, as shown in FIG. 17, steps S201 to S206 are performed to sequentially perform double-sided grinding of the wafer W, double-sided cleaning of the wafer W, and thickness measurement 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, based on the thickness distribution and flatness of the wafer W obtained in step S206, the optimal etching conditions for the second surface Wb are determined to optimize the etching amount distribution in the etching process of the second surface Wb. That is, in step S107 of the above embodiment, the etching amount deviation distribution was optimized, but in step S207, the etching amount distribution is optimized.

[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 perform etching of the first surface Wa and thickness measurement of the wafer W. These steps S209 to S213 are the same as steps S109 to S113 of the first pattern. Also in step S211, similar to step S111 of the first pattern, the optimal etching conditions for optimizing the etching amount distribution of the first surface Wa are determined.

[0135] In the above embodiments as well, the same effects as the above embodiments can be enjoyed. 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 be appropriately controlled.

[0136] The wafer processing of the third pattern is different from steps S106 and S206 and later of the wafer processing of the first pattern and the second pattern.

[0137] First, as shown in FIG. 18, steps S301 to S305 are performed to sequentially perform double-sided grinding and double-sided cleaning of the wafer W. These steps S301 to S305 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 in a V shape so as to form a concave portion War in which the central portion is recessed from the outer peripheral portion. In step S304, as shown in FIG. 19(b), the second surface Wb is ground. As an example, the second surface Wb is ground in a V shape so as to form a concave portion Wbr in which the central portion is recessed from the outer peripheral portion.

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

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

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

[0141] Even in the above embodiments, the same effects as those of the above embodiment can be enjoyed. That is, even if the etching amount deviation of the second surface Wb in step S306 is uniform within the wafer surface, the etching amount distribution of 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 be appropriately controlled.

[0142] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The above embodiments may be omitted, replaced, or changed in various forms without departing from the scope and gist of the appended claims.

Explanation of Reference Numerals

[0143] 1 Wafer processing system 40 Etching apparatus 90 Control apparatus E 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; and supplying an etching solution to the surface of the object to be etched on the substrate based on the optimal etching conditions and etching the surface, wherein determining the optimal etching conditions includes: acquiring the etching index distribution in the radial direction of the object to be etched when etching the surface of the object to be etched under a plurality of different etching conditions; and using an optimization method to superimpose the etching index distributions corresponding to the plurality of etching conditions so as to optimize the combination of the etching index distribution used for the superimposition and the number of times of superimposing the etching index distributions such that the shape of the surface of the object to be etched becomes a target shape; and integrating the etching conditions corresponding to the optimized combination to determine the optimal etching conditions.

2. When determining the optimal etching conditions, etching the surface of the object to be etched under the plurality of different etching conditions is performed for each substrate, and the etching processing time for the object to be etched on each substrate is the same. The substrate processing method according to claim 1.

3. In the optimization method, the etching accuracy of the surface of the object to be etched and the supply time of the etching solution to the surface of the object to be etched are simultaneously optimized. The substrate processing method according to claim 1 or 2.

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

5. When etching the surface of the object to be etched, the substrate is rotated and the etching solution is supplied from the etching solution supply unit while moving the etching solution supply unit in the radial direction passing through the center of the object to be etched, when the reciprocating movement of the etching solution supply unit between both ends of the object to be etched is defined as one loop, in the optimization method, the number of times of superimposing the etching index distributions is optimized in units of 0.5 loop. The substrate processing method according to claim 1 or 2.

6. Before etching the surface of the object to be etched, measuring the thickness of the object to be etched to obtain the thickness distribution of the object to be etched. The substrate processing method according to claim 1 or 2, wherein the optimal etching conditions are determined based on the obtained thickness distribution of the etching target.

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

8. The substrate processing method according to claim 1 or 2, wherein the etching index distribution is at least one of an etching amount deviation distribution obtained by subtracting an average value of the etching amount from the etching amount within the substrate surface, or an etching amount distribution of the etching amount within the substrate surface.

9. Grinding the first surface and the 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 for optimizing the etching amount deviation distribution from the thickness distribution; Etching the first surface based on the optimal etching conditions for optimizing the etching amount distribution from the thickness distribution, the substrate processing method according to claim 8.

10. Grinding the first surface and the 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 for optimizing the etching amount distribution from the thickness distribution; Etching the first surface based on the optimal etching conditions for optimizing the etching amount distribution from the thickness distribution, the substrate processing method according to claim 8.

11. Grinding the first surface and the 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; Etching the first surface based on the optimal etching conditions for optimizing the etching amount distribution from the thickness distribution, the substrate processing method according to claim 8.

12. A substrate processing system for processing a substrate, comprising: An etching device that supplies an etching solution to a surface of the substrate to be etched and etches the surface; A control device that controls the etching of the etching target in the etching device based on optimal etching conditions, and The control device Obtaining the etching index distribution in the radial direction of the object to be etched when etching the surface of the object to be 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 the combination of the etching index distribution used for the superimposition and the number of times of superimposing the etching index distributions so that the shape of the surface of the object to be etched becomes the target shape; Integrating the etching conditions corresponding to the optimized combination to determine the optimal etching conditions, and a substrate processing system that executes the above.

13. When determining the optimal etching conditions, the control device etches the surface of the object to be etched under the plurality of different etching conditions for each substrate, and controls the etching processing time for the object to be etched on each substrate to be the same. The substrate processing system according to claim 12.

14. In the optimization method, the control device simultaneously optimizes the etching accuracy of the surface of the object to be etched and the supply time of the etching solution to the surface of the object to be etched. The substrate processing system according to claim 12 or 13.

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

16. The etching device includes: A substrate holding part for holding the substrate; A rotation mechanism for rotating the substrate holding part; An etching solution supply part for supplying an etching solution from above the surface of the object to be etched on the substrate held by the substrate holding part; A moving mechanism for moving the etching solution supply part in the horizontal direction, and has When the reciprocating movement of the etching solution supply part between both ends of the object to be etched is taken as one loop, in the optimization method, the control device optimizes the number of times of superimposing the etching index distributions in units of 0.5 loops. The substrate processing system according to claim 12 or 13.

17. It has a thickness measuring device for measuring the thickness of the object to be etched before etching. The substrate processing system according to claim 12 or 13, wherein the control device determines the optimum etching conditions based on the thickness distribution of the etching target obtained from the thickness of the etching target measured by the thickness measuring device.

18. comprising a thinning device for thinning the substrate, The substrate processing system according to claim 17, wherein the thickness measuring device measures the thickness of the etching target in the substrate after thinning.

19. The substrate processing system according to claim 12 or 13, wherein the etching index distribution is at least one of an etching amount deviation distribution obtained by subtracting an average value of the etching amount from the etching amount in the substrate plane or an etching amount distribution of the etching amount in the substrate plane.

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