TW202326836A - Substrate processing method and substrate processing system - Google Patents

Abstract

An object of the invention is to appropriately control the surface shape of an etching target following etching processing. Determining optimal etching conditions includes a step of acquiring learning data that includes an etching quantity distribution in the radial direction of an etching target obtained by etching the surfaces of etching targets under a plurality of different etching conditions, and a step of using the least squares method to optimize first etching conditions in the first etching quantity distribution so as to minimize a first residual distribution between a first etching quantity distribution predicted from formulas (1) to (6) below using the learning data and a first target etching quantity distribution. ER _scan(R)=ER _ref(R)×Ratio _scan(R)・・・(1) Ratio _scan(R)=b ₀×exp(b ₁×T+b ₂)+C・・・(2) b ₀=f(S,V)・・・(3) b ₁=f(S,V)・・・(4) b ₂=f(S,V)・・・(5) T=(L-R)/V・・・(6)

Description

Substrate processing method and substrate processing system

The invention relates to a substrate processing method and a substrate processing system.

In Patent Document 1, a substrate processing method is disclosed, which includes the following steps: a grinding step of grinding the surface of the substrate, a measuring step of measuring the thickness of the substrate after grinding, and determining the wetness of the substrate based on the measured thickness of the substrate. The step of determining the processing conditions of the conventional etching process, and the step of supplying the processing liquid to the polished substrate based on the determined processing conditions to perform wet etching processing. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2018-147908

[Problem to be solved by the invention]

According to the technology of the present invention, the surface shape of the etching object after etching can be properly controlled. [Means to solve the problem]

One aspect of the present invention is a substrate processing method for processing a substrate, which includes the steps of: determining optimum etching conditions; and, based on the optimum etching conditions, supplying an etching solution while rotating an object to be etched on the substrate The part passes above the center of rotation of the etching object and moves back and forth in the radial direction, while supplying the etching liquid from the etching liquid supply part to the surface of the etching object to etch the surface; the step of determining the optimum etching conditions includes the following Steps: Obtain learning data that includes etching amount distribution in the radial direction of the etching object after etching the surface of the etching object with a plurality of different etching conditions; and use the learning data to pass the following formula (1)～( 6) In such a way that the first residual distribution between the predicted first etching amount distribution and the first target etching amount distribution becomes the smallest, the first etching condition of the first etching amount distribution is optimized by the least square method. ER _scan (R)=ER _ref (R)×Ratio _scan (R)・・・(1) Ratio _scan (R)=b ₀ ×exp(b ₁ ×T+b ₂ )+C・・・(2) b ₀ =f(S,V)・・・(3) b ₁ =f(S,V)・・・(4) b ₂ =f(S,V)・・・(5) T=(LR) /V・・・(6) Among them, ER _scan : the etching amount when the etching liquid supply part is moved back and forth; ER _ref : the etching amount when the etching liquid supply part is not moved back and forth; Ratio _scan : scanning ratio; R : The position from the center of the etching object; T: The non-spraying time when the etching liquid is not supplied; C: Constant; S: The rotation speed when the etching object is rotated; V: The time when the etching liquid supply part is moved back and forth Scanning speed; L: scanning width when the etching liquid supply part is moved back and forth. [Invention effect]

Through the present invention, the surface shape of the etching object after etching treatment can be properly controlled.

In the manufacturing process of semiconductor elements, a semiconductor substrate (hereinafter referred to as "wafer") on which a plurality of electronic circuits and other elements are formed on the surface is ground and thinned, and the polished surface of the wafer is smoothed. For smoothing the polished surface, for example, while rotating the wafer, an etchant is supplied from above the polished surface of the wafer, that is, spin etching is performed.

In the aforementioned Patent Document 1, it is disclosed that wet etching is performed on the polished wafer to remove the damaged layer formed on the surface of the wafer due to the polishing treatment. In the condition determination step described in Patent Document 1, the operation of the nozzle supplying the processing liquid, the rotation speed of the wafer, the supply amount of the processing liquid, the supply time of the processing liquid, and the like are determined based on the thickness of the wafer obtained in the measurement step. The type of processing liquid, etc., are used as conditions for wet etching processing.

However, in the method disclosed in Patent Document 1, when performing spin etching in which the processing liquid is supplied while the wafer is rotated, the processing liquid supplied to the wafer surface flows outward in the radial direction due to the centrifugal force, and it is difficult to perform precise etching. Etching control. More specifically, it is difficult to properly control the surface shape of the wafer after the etching process, especially at the central portion of the wafer.

Therefore, the present invention proposes a method in which while rotating the wafer, the nozzle is moved (scanned) back and forth in the radial direction passing through the center of the wafer, and an etching solution is supplied from the nozzle to the surface of the wafer to etch the surface. . Hereinafter, such etching is referred to as "scanning etching". In scanning etching, while supplying an etchant to the center of the wafer, the flow of the etchant is generated on the surface of the wafer at the center, thereby controlling the surface shape of the wafer.

Here, in order to control the surface shape of the wafer after etching, it is important to properly control the distribution of etching amount in the radial direction of the wafer (etching profile). The control of etching amount distribution is to obtain the target etching amount distribution by adjusting the etching conditions (etching formula) such as the rotation speed (rotational speed) of the wafer, the scanning speed and the scanning width when the nozzle moves back and forth.

However, the control of etching amount distribution in the past is mainly carried out by engineers to predict the change of etching amount distribution, and obtain the information about etching amount distribution one by one to correspond to the target etching amount distribution, that is, it is carried out by trial and error. In this case, the control of etching amount distribution depends on the ability of the engineer, and individual differences may arise in the operating time required for control and the degree of completion of control.

According to the technique of the present invention, the etching amount distribution in the radial direction of the etching object is appropriately predicted in scanning etching. Hereinafter, a wafer processing system and a wafer processing method according to this embodiment will be described with reference to the drawings. In addition, in this specification and drawings, the same code|symbol is attached|subjected to the element which has substantially the same functional structure, and repeated description is abbreviate|omitted.

In the wafer processing system 1 described later according to this embodiment, as shown in FIG. 1 , a superimposed wafer T as a substrate formed by bonding a first wafer W and a second wafer S is processed. Hereinafter, in the first wafer W, the surface on the side bonded to the second wafer S is referred to as a surface Wa, and the surface opposite to the surface Wa is referred to as a rear surface Wb. Similarly, in the second wafer S, the surface on the side bonded to the first wafer W is called a surface Sa, and the surface opposite to the surface Sa is called a back surface Sb.

The first wafer W is, for example, a semiconductor wafer such as a silicon substrate, and an element layer Dw including a plurality of elements is formed on the surface Wa side. Furthermore, a bonding film Fw is further formed on the element layer Dw, and the second wafer S is bonded via the bonding film Fw. As the bonding film Fw, for example, an oxide film (THOX film, SiO ₂ film, TEOS film), SiC film, SiCN film, or an adhesive is used.

The second wafer S has, for example, the same configuration as that of the first wafer W, and the element layer Ds and the bonding film Fs are formed on the surface Sa. Also, the second wafer S does not need to be an element wafer on which the element layer Ds is formed, and may be, for example, a support wafer that supports the first wafer W. In this case, the second wafer S functions as a protective material for protecting the element layer Dw of the first wafer W.

As shown in FIG. 2 , the wafer processing system 1 has a structure 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 superimposed wafers T is loaded and unloaded to and from the outside. The processing station 3 includes various processing devices for performing desired processing on the superposed wafer T. As shown in FIG.

The loading/unloading station 2 is provided with a cassette loading table 10 on which a plurality of, for example, three cassettes C are mounted. Further, a wafer transfer device 20 is provided adjacent to the cassette mounting table 10 on the X-axis negative direction side of the cassette mounting table 10 . The wafer transfer device 20 can move freely on a transfer path 21 extending in the Y-axis direction. Moreover, the wafer transfer apparatus 20 has, for example, two transfer arms 22 and 22 for holding and transferring the overlapped wafer T. As shown in FIG. Each transfer arm 22 is free to move horizontally, vertically, or around a horizontal axis and a vertical axis. Also, the configuration of the transfer arm 22 is not limited to this embodiment, and any configuration can be adopted. Furthermore, the wafer transfer device 20 can transfer the overlapped wafer T to the cassette C of the cassette mounting table 10 and the transfer device 30 described later.

In the loading/unloading station 2 , a transfer device 30 for transferring the overlapped wafer T between the processing station 3 and the processing station 3 is provided adjacent to the wafer transfer device 20 on the X-axis negative direction side of the wafer transfer device 20 .

For example, three processing blocks B1 to B3 are provided in the processing station 3 . The 1st processing block B1, the 2nd processing block B2, and the 3rd processing block B3 are arrange|positioned in order from the X-axis positive direction side (the side of loading and unloading station 2) to the negative direction side.

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 stacked and disposed. In addition, the number and arrangement of the etching device 40 and the thickness measuring device 41 are not limited thereto.

The etching device 40 etches the rear surface Wb (polished surface) of the first wafer W polished by the processing device 80 described later, and further thins the polished first wafer W (overlapped wafer T). At the same time, it removes the grinding marks produced by the grinding process and smoothes the grinding surface. In addition, the detailed structure of the etching device 40 will be described in detail later.

The thickness measurement device 41 includes a measurement unit (not shown) and a calculation unit (not shown) in one example. The measurement section includes sensors for measuring the thickness of the etched first wafer W at plural positions. The calculation unit obtains the thickness distribution of the first wafer W from the measurement result (thickness of the first wafer W) of the measurement unit, and calculates the flatness (TTV: Total Thickness Variation) of the first wafer W. In addition, 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 calculation unit. In other words, a calculation unit (not shown) may be provided in the control device 90 described later. In addition, the configuration of the thickness measuring device 41 is not limited to this, and may be configured arbitrarily.

The wafer transfer device 50 is disposed on the negative X-axis side of the transfer device 30 . The wafer transfer device 50 has, for example, two transfer arms 51 , 51 for holding and transferring the overlapped wafer T. Each transfer arm 51 is free to move in the horizontal direction, the vertical direction, or around the horizontal axis and the vertical axis. Furthermore, the wafer transfer device 50 can transfer the overlapped wafer T to the transfer 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.

A cleaning device 60 , a thickness measuring device 61 , a buffer device 62 and a wafer transfer device 70 are provided in the second processing block B2 . The cleaning device 60, the thickness measuring device 61, and the buffer device 62 are arranged in layers. In addition, the number and arrangement of the cleaning device 60, the thickness measuring device 61, and the buffer device 62 are not limited thereto.

The cleaning device 60 cleans the back surface Wb (polished surface) of the first wafer W polished by the processing device 80 described later. For example, a brush is brought into contact with the back surface Wb, and the back surface Wb is brushed and cleaned. In addition, a pressurized cleaning solution may be used for cleaning the first wafer W. In addition, the cleaning device 60 may be configured to clean the back surface Sb of the second wafer S at the same time as cleaning the first wafer W.

The thickness measurement device 61 includes a measurement unit (not shown) and a calculation unit (not shown) in one example. The measuring section includes sensors for measuring the thickness of the polished first wafer W at plural positions. The calculation unit obtains the thickness distribution of the first wafer W from the measurement result (thickness of the first wafer W) of the measurement unit, and calculates the flatness (TTV) of the first wafer W. In addition, 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 calculation unit. In other words, a calculation unit (not shown) may be provided in the control device 90 described later. In addition, the configuration of the thickness measuring device 61 is not limited to this, and may be configured arbitrarily.

The buffer device 62 temporarily holds the pre-processed superimposed wafer T transferred from the first processing block B1 to the second processing block B2. The configuration of the buffer device 62 is arbitrary. In addition, the buffer device 62 may have a positioning mechanism (not shown) for adjusting the center position of the overlapping wafer T and/or the horizontal orientation of the overlapping wafer T with respect to the chuck 83 described later.

The wafer transfer device 70 is arranged, for example, on the positive side of the Y-axis 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 for sucking and holding the stacked wafer T on a suction-holding surface (not shown) and transferring it. Each transfer arm 71 is supported by a multi-joint arm member 72, and moves freely in the horizontal direction, the vertical direction, or around the horizontal axis and the vertical axis. Furthermore, the wafer transfer device 70 can transfer 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 the processing device 80 described later.

A processing device 80 is installed in the third processing block B3. The processing device 80 grinds and thins the first wafer W, and functions as the thinning device of the present invention.

The processing device 80 has a rotary table 81 . The rotating table 81 can freely rotate around the vertical rotation center line 82 through a rotating mechanism (not shown). The rotary table 81 is provided with two suction cups 83 for absorbing and holding the overlapped wafer T. The suction cups 83 are equally arranged on the same circumference as the turntable 81 . The two suction pads 83 can be rotated by the turntable 81 and moved to the transfer position A0 and the processing position A1. In addition, the two suction pads 83 are each rotatable around a vertical axis by a rotation mechanism (not shown).

In the transfer position A0, transfer of the overlapped wafer T is performed. A polishing unit 84 for polishing the first wafer W while the second wafer S is sucked and held by the chuck 83 is disposed in the processing position A1. The grinding unit 84 has a grinding part 85 having a ring-shaped and freely rotatable grinding stone (not shown). Moreover, the grinding part 85 is movable in the vertical direction along the pillar 86 .

In addition, the structure of the processing apparatus 80 is not limited to this. For example, four suction cups 83 can be provided on the turntable 81, and the four suction cups 83 can perform the rough grinding part (not shown) of the rough grinding of the first wafer W at the transfer position of the overlapped wafer T, and the second rough grinding of the wafer W. A wafer W is moved between a polishing section (not shown) during grinding and a finishing section (not shown) for finishing polishing of the first wafer W. In addition, for example, a thickness measuring device (not shown) for measuring the thickness of the polished first wafer W at plural positions may be provided in the processing device 80 .

The above wafer processing system 1 is provided with a control device 90 . The control device 90 is, for example, a computer including a CPU, a memory, and the like, and has a program storage unit (not shown). The program storage unit stores programs for controlling the processing of the overlapped wafers T in the wafer processing system 1 . In addition, the above-mentioned program may be recorded on a computer-readable recording medium H and installed from the recording medium H to the control device 90 . In addition, the above-mentioned recording medium H may be temporary or non-transitory.

Next, the configuration of the etching apparatus 40 described above will be described. As shown in FIG. 3 , the etching apparatus 40 has a wafer holding unit 100 as a substrate holding unit, a rotation mechanism 101 , and an etchant supply unit 102 .

The wafer holding unit 100 holds the outer edge of the overlapped wafer T at a plurality of positions (three in this embodiment). In addition, the configuration of the wafer holding unit 100 is not limited to the example shown in the figure. For example, the wafer holding unit 100 may include a suction cup that absorbs and holds the overlapped wafer T from below. The rotation mechanism 101 rotates the overlapping wafer T (first wafer W) held by the wafer holding unit 100 around the vertical rotation center line 100a.

The etchant supply unit 102 has, for example, a nozzle for supplying the etchant E to the rear surface Wb of the first wafer W held by the wafer holding unit 100 . The etchant supply part 102 is disposed above the wafer holding part 100 and can move in the horizontal direction and the vertical direction through the moving mechanism 103 . In one example, the etchant supply unit 102 can move back and forth (scanning movement) through the center of rotation 100 a of the wafer holding unit 100 , that is, above the center of the first wafer W as shown in FIG. 4 . In addition, in the following description, the back-and-forth movement of the etchant supply unit 102 is assumed to be one cycle.

The etchant E contains at least hydrofluoric acid, nitric acid, or a mixed acid in order to properly etch the silicon of the first wafer W to be etched. In addition, phosphoric acid or sulfuric acid may be contained in etching liquid E. Also, the etching target is not limited to the first wafer W, and may be amorphous silicon, for example. In addition, the etching target of this embodiment is not limited to the back surface Wb of the first wafer W. For example, it can also be applied to the processing of wafers that have not been processed by the processing device 80 . For example, when a film is formed on the back surface Wb, this film can also be used as an etching target.

In the etching apparatus 40 described above, while the first wafer W is rotated, the etchant supply unit 102 is moved back and forth, and the etchant is supplied from the etchant supply unit 102 to the back surface Wb of the first wafer W. etch. In this embodiment, a predictive model is used to predict the etching amount distribution of scanning etching.

The prediction model of etching amount distribution is shown in Fig. 5, which is the model when scanning etching is carried out under the etching conditions of fixed scanning speed and left-right symmetrical scanning. That is, the scanning speed V when the etchant supply unit 102 is moved back and forth is constant. In addition, the scan width L of the etchant supply unit 102 is left-right symmetrical from the center of the first wafer W, and the etchant supply unit 102 moves back and forth between one scanning end “+L” and the other scanning end “-L”. . Hereinafter, the sequence of scanning etching is called "scanning sequence at constant speed", and the derived predictive model is called "scanning at constant speed model".

The constant velocity sweep model is constituted by the following equations (1) to (6). ER _scan (R)=ER _ref (R)×Ratio _scan (R)・・・(1) Ratio _scan (R)=b ₀ ×exp(b ₁ ×T+b ₂ )+C・・・(2) b ₀ =f(S,V)・・・(3) b ₁ =f(S,V)・・・(4) b ₂ =f(S,V)・・・(5) T=(LR) /V・・・(6) Among them, ER _scan : the etching amount when the etching liquid supply part 102 is moved back and forth; ER _ref : the etching amount when the etching liquid supply part 102 is not moved back and forth; Ratio _scan : the scanning ratio; R : the position from the center of the first wafer W; T: the non-discharge time when the etching solution E is not supplied; C: a constant; S: the rotation speed when the first wafer W is rotated; V: the etching solution supply unit 102 Scanning speed when moving back and forth; L: scanning width when the etchant supply part 102 is moved back and forth.

The functions in the above formulas (3)-(5) are determined by analyzing the learning data. For example, a test wafer is etched in a constant-speed scanning sequence with a plurality of different etching conditions, and learning materials about the distribution of etching amount are obtained. Specifically, the test wafer is etched by changing the rotation speed S of the test wafer, the scan speed V when the etchant supply unit 102 is moved back and forth, and the scan width L of the etchant supply unit 102 . At this time, the etching processing time for each test wafer was the same.

The etching of the test wafer under each etching condition was performed at a predetermined desired time. And, the etching amount distribution of the test wafer is obtained, and the etching amount distribution is output to the control device 90 . Furthermore, in the control device 90, the output etching amount distribution under each etching condition is compressed into an etching amount distribution (etching rate) in a unit time or a unit cycle, and the compressed etching amount distribution is stored as learning data. .

Figure 6 is an example of the acquired learning materials. The rotation speed S of the test wafer is changed from S1 to S5. The scanning speed V of the etchant supply unit 102 is changed from V1 to V3. The scanning width L of the etchant supply unit 102 is changed from L1 to L4. In this manner, the etching amount distribution is obtained for plural (60 types in this example) etching conditions. In the graphs of each learning material, the horizontal axis represents the radial position from the center of the test wafer (0 (zero) on the horizontal axis) to an outer end, and the vertical axis represents the etching amount (etching rate).

In addition, the example in which the above-mentioned learning data is obtained by etching the test wafer has been described above, but the etching target when obtaining the learning data is not limited to the test wafer. Specifically, for example, the results of the etching process of the first wafer W actually processed in the wafer processing system 1 may be stored as the above-mentioned learning data. Also, for example, when a film is formed on the back surface Wb of the first wafer W, the etching target may be set as the film, and the etching process result of the film may be stored as the above-mentioned learning data.

Next, a detailed derivation method of the above-mentioned constant speed sweep model will be described.

First, the inventors of the present case have grasped the etching amount distribution of scanning etching. In addition, it was found that the etching amount distribution when the etchant supply unit 102 is fixed and does not move back and forth (hereinafter referred to as "unscanned") becomes the reference etching amount distribution of the etching amount distribution predicted by the constant-speed scanning model.

7 shows the etching amount distribution when the rotation speed S is S5, the scanning speed V is V3, and the scanning width L is changed from L1 to L4 among the learning materials shown in FIG. 6 above. In addition, FIG. 7 also shows the distribution of the standard etching amount when no scanning is performed. Referring to FIG. 7 , in scanning etching, with the scanning width L as the starting point, only the etching amount distribution on the inner peripheral side changes, and the etching amount distribution on the outer peripheral side does not change. In other words, in scanning etching, only the etching amount distribution on the inner peripheral side of the scanning width L varies from the unscanned reference etching amount distribution, and the etching amount distribution on the outer peripheral side of the scanning width L exhibits the same distribution as the reference etching amount distribution. Therefore, the unscanned etch amount distribution can be used as a reference.

Next, the inventors of the present application separated the fluctuation amount of the etching amount distribution in the scan etching. Specifically, from the concept that there is an unscanned reference etching amount distribution, the ratio of the scanning etching etching amount distribution to the reference etching amount distribution is defined as the scanning ratio Ratio _scan in the following formula (7). This scanning ratio Ratio _scan can quantitatively separate the effect of scanning etching. FIG. 8 shows the scanning ratio Ratio _scan when the rotation speed S is S5, the scanning speed V is changed from V1 to V3, and the scanning width L is changed from L1 to L4. The horizontal axis of FIG. 8 represents the position in the radial direction from the center of the first wafer W (0 (zero) on the horizontal axis) to an outer end, and the vertical axis represents the scan ratio Ratio _scan . Referring to FIG. 8 , starting from the scanning width L, the scanning ratio Ratio _scan on the inner peripheral side changes, and the variation of the etching amount distribution of the above-mentioned scanning etching can be quantitatively separated and grasped. Then, the following equation (1) of the constant speed sweep model is derived from the following equation (7). Ratio _scan (R)=ER _scan (R)/ER _ref (R)・・・(7) ER _scan (R)=ER _ref (R)×Ratio _scan (R)・・・(1) Among them, Ratio _scan : scan ratio; ER _scan : etching amount when the etchant supply unit 102 is moved back and forth; ER _ref : etching amount when the etchant supply unit 102 is not moved back and forth.

Also, the non-discharge time T is defined in the following formula (6). The non-discharge time T is the time during which the etchant E is not supplied to the inner peripheral side through the etchant supply part 102 due to the movement of the etchant supply part 102 . Also, the amount of etching during the non-discharging time T decreases. FIG. 9 shows the non-discharging time T when the rotation speed S is S5, the scanning speed V is changed from V1 to V3, and the scanning width L is changed from L1 to L4. The horizontal axis of FIG. 9 represents the position in the radial direction from the center of the first wafer W (0 (zero) on the horizontal axis) to an outer end, and the vertical axis represents the non-discharge time T. Referring to FIG. 9 , it can be grasped that the non-discharge time T on the inner peripheral side varies with the scan width L as the starting point. T=(L-R)/V・・・(6) in, T: non-spraying time without supply of etching solution E; V: scanning speed when the etchant supply part 102 is moved back and forth; L: scanning width when the etchant supply unit 102 is moved back and forth.

Next, the inventors of the present case studied the relationship between the scan ratio Ratio _scan and the non-ejection time T. FIG. 10 shows the relationship between the scanning ratio Ratio _scan and the non-discharging time T when the rotation speed S is S5 and the scanning speed V is changed from V1 to V3. The horizontal axis in FIG. 10 represents the non-discharge time T, and the vertical axis represents the scanning ratio Ratio _scan . Referring to FIG. 10 , relative to the non-spraying time T, the scan ratio Ratio _scan decreases exponentially, and can be defined by the decay curve model of the following formula (2). This attenuation curve model is also applicable to explain the operation of the actual physical phenomenon that "the longer the time without supplying the etching solution E, the less the etching amount will be". Ratio _scan (R)=b ₀ ×exp(b ₁ ×T+b ₂ )+C・・・(2) Among them, b ₀ : scale (intercept); b ₁ : decay rate (slope); b ₂ : decay delay value; C: asymptote.

The above b ₀ is the scale (intercept) of the attenuation curve, and b ₁ is the attenuation rate (slope) of the attenuation curve. b ₂ is the decay delay value of the decay curve. For example, _b2 is a correction term used when the amount of etching solution E is large, and the residual liquid in the first wafer W is large and does not attenuate immediately. C is the asymptote of the decay curve. For example, when C does not exist, the scan ratio Ratio _scan approaches 0 (zero) mathematically. However, in reality, once the etchant E is supplied, the first wafer W must be etched, so the scan ratio Ratio _scan is not 0 (zero). C is the correction item used to correct this phenomenon. In addition, C can also be determined by, for example, analyzing the above formula (2), if C<0, then C=0, and if C>0, leave C alone.

Also, when b ₂ and C are judged to be unnecessary in practical use, b ₂ =0 and C=0 can be omitted.

Also, the scale b ₀ , the attenuation rate b ₁ and the attenuation delay value b ₂ depend on the rotation speed S and the scanning speed V, and can be defined by the following equations (3) to (5), respectively. b ₀ =f(S,V)・・・(3) b ₁ =f(S,V)・・・(4) b ₂ =f(S,V)・・・(5) Among them, S: make The rotation speed when the first wafer W is rotated; V: the scanning speed when the etchant supply unit 102 is moved back and forth.

Here, in FIG. 10 , the thick line is the measured value obtained through the experiment, and the thin line is the calculated value calculated by the above formula (2) of the constant speed scanning model. The measured value is roughly consistent with the calculated value, and it is confirmed that the attenuation curve model of the above formula (2) is appropriate.

As above, a constant-velocity scanning model (prediction model of etching amount distribution) composed of the following equations (1) to (6) was derived. ER _scan (R)=ER _ref (R)×Ratio _scan (R)・・・(1) Ratio _scan (R)=b ₀ ×exp(b ₁ ×T+b ₂ )+C・・・(2) b ₀ =f(S,V)・・・(3) b ₁ =f(S,V)・・・(4) b ₂ =f(S,V)・・・(5) T=(LR) /V・・・(6)

FIG. 11 is a graph comparing the measured value (thick line in FIG. 11 ) of the etching amount distribution obtained through experiments with the calculated value (thin line in FIG. 11 ) of the etching amount distribution calculated by the constant-velocity scanning model. The rotational speed S is changed from S1 to S4, the scanning speed V is changed from V1 to V3, and the scanning width L is changed from L1 to L4. The measured value is roughly consistent with the calculated value, and it is confirmed that the constant-velocity scanning model of the above-mentioned formulas (1) to (6) is appropriate.

Next, wafer processing performed by the wafer processing system 1 configured as above will be described. In addition, in this embodiment, the overlapping wafer T is formed in advance in a bonding device (not shown) outside the wafer processing system 1 . In addition, the peripheral portion of the first wafer W may be removed in advance, for example, a range of 0.5 mm to 3 mm in the radial direction from the outer end portion of the first wafer W.

First, the cassette C accommodating a plurality of overlapping wafers T is placed on the cassette mounting table 10 of the loading/unloading station 2 . Then, the overlapped wafer T in the cassette C is taken out through the wafer transfer device 20 and transferred to the transfer device 30 . The superimposed wafer T transferred to the transfer device 30 is transferred to the buffer device 62 through the wafer transfer device 50 . In addition, in the buffer device 62 , the center position of the overlapping wafer T with respect to the chuck 83 and/or the horizontal orientation of the overlapping wafer T may be adjusted.

Then, the overlapped wafer T is transported to the processing device 80 through the wafer transport device 70 , and transferred to the chuck 83 at the transfer position A0 . The back surface Sb of the second wafer S is sucked and 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 (overlapped wafer T) is reduced to the desired grinding target thickness (step S1 in FIG. 12 ).

Next, the superimposed wafer T is transferred to the thickness measurement device 61 by the wafer transfer device 70 . In the thickness measuring device 61, the thickness of the first wafer W (overlapping wafer T) after grinding is measured at multiple positions, and the thickness distribution of the first wafer W after grinding is obtained, and the thickness of the first wafer W is calculated. Flatness (step S2 of FIG. 12 ). The calculated thickness distribution and flatness of the first wafer W are output to the control device 90 , for example. In addition, when the processing device 80 is provided with a thickness measuring device, the thickness of the first wafer W after polishing can also be measured by the thickness measuring device of the processing device 80 .

In the control device 90, the optimum etching conditions for the subsequent etching process are determined from the thickness distribution and flatness of the outputted first wafer W (step S3 in FIG. 12 ). The detailed method for determining the optimal etching conditions of the control device 90 will be described later.

The overlapping wafer T whose thickness of the first wafer W has been measured is then transferred to the cleaning device 60 through the wafer transfer device 70 or the wafer transfer device 50 . In the cleaning device 60 , the polished surface of the first wafer W, that is, the back surface Wb is cleaned (step S4 in FIG. 12 ). In addition, in the cleaning device 60, the back surface Sb of the second wafer S may also be cleaned as described above. In addition, when the thickness after grinding is measured by the thickness measuring device 61 in this embodiment, the order of step S2, step S3, and step S4 can also be reversed. That is, after the back surface Wb of the first wafer W is cleaned by the cleaning device 60, the thickness of the first wafer W can be measured by the thickness measuring device 61 to determine optimum etching conditions for the etching process.

Next, the superimposed wafer T is transferred to the etching device 40 through the wafer transfer device 50 . In the etching device 40, the back surface Wb, which is the polished surface of the first wafer W, is etched through the etchant E under optimum etching conditions (step S5 in FIG. 12 ).

When etching the first wafer W, first, the wafer holding unit 100 (first wafer W) is rotated around the vertical rotation center line 100a, and at the same time, the supply (discharge) of the etchant E from the etchant supply unit 102 is started. , and start the etching of the backside Wb.

Moreover, when etching the first wafer W, the etchant E is continuously supplied from the etchant supply part 102, and at the same time, the etchant supply part 102 is passed above the center of rotation of the first wafer W as shown in FIG. centerline 100a, and move back and forth (scanning) with the rotation centerline 100a as an intermediate point. Further, detailed determination methods of etching conditions such as the rotation speed of the first wafer W, the scanning speed when the etchant supply unit 102 is moved back and forth, and the scan width of the etchant supply unit 102 will be described in detail later.

After the desired etching amount is obtained for the first wafer W, the supply of the etchant E from the etchant supply unit 102 is stopped, and the back surface Wb of the first wafer W is washed with pure water, followed by spin drying. 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.

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 polishing as described above. Specifically, the actual measured value of the thickness distribution and flatness of the first wafer W by the thickness measurement device 61 and the target surface shape of the first wafer W after etching (hereinafter referred to as "target shape") The difference in thickness distribution and flatness determines the optimum etching conditions. And, in step S5, by etching the first wafer W under optimal etching conditions, the difference between the 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 target shape. Thereby, according to this embodiment, regardless of the surface shape of the first wafer W after polishing, the surface shape of the first wafer W as the target can be appropriately obtained.

Next, the superimposed wafer T is transferred to the thickness measurement device 41 by the wafer transfer device 50 . In the thickness measuring device 41, the thickness of the etched first wafer W (overlapped wafer T) is measured at multiple positions to obtain the etched thickness distribution of the first wafer W, and the flatness of the first wafer W is calculated. Degree (step S6 of Fig. 12). The calculated thickness distribution and flatness of the first wafer W are output to the control device 90 , for example, and are used, for example, in the processing of other overlapped wafers T that are subsequently processed in the wafer processing system 1 . In addition, when the thickness of the polished first wafer W is measured by the thickness measuring device of the processing device 80 , the thickness of the etched first wafer W may be measured by the thickness measuring device 61 .

Then, the superimposed wafer T subjected to all the processes is transferred to the cassette C of the cassette mounting table 10 via the transfer device 30 . In this way, a series of wafer processing by the wafer processing system 1 ends.

Next, a detailed method for determining the optimum etching conditions described above (step S3 in FIG. 12 ) will be described.

First, when determining the optimum etching conditions, learning data are acquired before the overlapping wafer T is processed in the wafer processing system 1 (step S3-1 in FIG. 13 ). A prediction model of etching amount distribution is derived from the learning data (step S3-2 in FIG. 13 ).

In step S3-1, as described above, for example, the test wafer is etched in a constant-speed scanning sequence to obtain the learning data on the distribution of etching amount as shown in FIG. 6 .

In step S3-2, as described above, a predictive model of etching amount distribution constituted by the following equations (1) to (6), that is, a constant-velocity scanning model is derived. At this time, the functions in the following formulas (3) to (5) are respectively determined by analyzing the learning data obtained in step S3-1. ER _scan (R)=ER _ref (R)×Ratio _scan (R)・・・(1) Ratio _scan (R)=b ₀ ×exp(b ₁ ×T+b ₂ )+C・・・(2) b ₀ =f(S,V)・・・(3) b ₁ =f(S,V)・・・(4) b ₂ =f(S,V)・・・(5) T=(LR) /V・・・(6) Among them, ER _scan : the etching amount when the etching liquid supply part 102 is moved back and forth; ER _ref : the etching amount when the etching liquid supply part 102 is not moved back and forth; Ratio _scan : the scanning ratio; R : the position from the center of the first wafer W; T: the non-discharge time when the etching solution E is not supplied; C: a constant; S: the rotation speed when the first wafer W is rotated; V: the etching solution supply unit 102 Scanning speed when moving back and forth; L: scanning width when the etchant supply part 102 is moved back and forth.

Here, FIG. 14 is a graph showing the distribution of each etching amount when performing steps S3-3 to S3-8 described later to determine optimum etching conditions. 14 represents the position in the radial direction from the center of the first wafer W (0 (zero) on the horizontal axis) to an outer end, and the vertical axis represents the amount of etching (etching rate).

In parallel with steps S3-1 and S3-2, the first target etching amount distribution of the etching process in the above-mentioned step S5 is obtained (step S3-3 in FIG. 13 ). The first target etching amount distribution is based on the thickness distribution of the target shape of the first wafer W after etching (hereinafter referred to as "target thickness distribution") and the surface of the first wafer W after polishing obtained in the above step S2 The thickness distribution of the shape (hereinafter referred to as "measured thickness distribution") is obtained. The first target etching amount distribution can be obtained, for example, by calculating the difference between the target thickness distribution and the measured thickness distribution of the first wafer W. This first target etching amount distribution is shown by a solid line in FIG. 14 . Also, in this example, the first target etching amount distribution is flat within the wafer surface.

Next, in such a way that the first residual error distribution between the first etching amount distribution calculated by the constant-velocity scanning model in step S3-2 and the first target etching amount distribution obtained in step S3-3 is minimized, the least square The method optimizes the first etching condition of the first etching amount distribution (step S3-4 in FIG. 13 ). The optimized first etching conditions include the rotation speed S of the first wafer W, the scanning speed V of the etchant supply unit 102 , and the scan width L of the etchant supply unit 102 . In addition, the distribution of the first etching amount corresponding to the optimized first etching condition is shown by a dot chain line in FIG. 14 .

Next, the first residual distribution in step S3-4 is set as the second target etching amount distribution (step S3-5 in FIG. 13 ).

Next, in such a way that the second residual error distribution between the second etching amount distribution calculated by the constant-velocity scanning model in step S3-2 and the second target etching amount distribution set in step S3-5 is minimized, the least square The method optimizes the second etching condition of the second etching amount distribution (step S3-6 in FIG. 13 ). The optimized second etching conditions include the rotation speed S of the first wafer W, the scanning speed V and the scanning width L of the etchant supply unit 102 . Also, the distribution of the second etching amount corresponding to the optimized second etching condition is shown by a two-dot chain line in FIG. 14 .

Next, the first etching amount distribution and the second etching amount distribution corresponding time ratio (cycle number ratio) are linked (step S3-7 in FIG. 13 ). The time ratio (cycle number ratio) is the ratio of the time (cycle number) for performing the constant-speed scan sequence 1 under the first etching condition to the time (cycle number) for performing the constant-speed scan sequence 2 under the second etching condition. The etching amount distribution after connection (hereinafter referred to as "connection etching amount distribution") is shown by a dotted line in FIG. 14 .

In this example, the link etching amount distribution approximately coincides with the first target etching amount distribution. Therefore, the etching conditions corresponding to the connection etching amount distribution are determined as optimal etching conditions. Specifically, the combination of the first etching condition and the second etching condition corresponding to the time ratio is determined as an optimum etching condition (step S3-8 in FIG. 13 ).

Then, in step S4, after the back surface Wb of the first wafer W is cleaned, in step S5, the back surface Wb of the first wafer W is etched under optimum etching conditions. That is, in the etching apparatus 40, the superimposed wafer T (first wafer W) is rotated at a rotation speed determined by optimum etching conditions, and at the same time, the etchant supply unit 102 is moved at a determined scanning speed and scanning width, And the etchant E is supplied to the first wafer W.

As above, the determination of the optimum etching conditions according to this embodiment is performed, and the first wafer W is etched based on the optimum etching conditions.

Through the above embodiments, the etching amount distribution can be properly predicted by using the constant-velocity scanning model constituted by the above formulas (1)-(6). Therefore, when controlling the distribution of etching amount, it is different from relying on the ability of engineers in the past, and can suppress the operation time required for control and improve the degree of completion of control. In addition, it is possible to suppress variation in the workload when determining the optimum etching conditions in step S3, and improve the accuracy of the optimum etching conditions.

In addition, in step S3, the optimal etching conditions are determined by using the least squares method, so the first wafer W can be etched with the optimal etching conditions in subsequent step S5. Thereby, the etching amount distribution of the etching process can be brought close to the first target etching amount distribution, and as a result, the surface shape of the first wafer W after etching can be brought into the target shape. In other words, optimum etching conditions can be determined from uncertain etching conditions, and the surface shape of the first wafer W after etching can be appropriately controlled.

After actual simulation by the inventor of this case, no matter whether the first target etching amount distribution is V-shaped, A-shaped, M-shaped, or W-shaped, the thickness distribution of the first wafer W after etching can be made The deviation falls within the allowable range. In addition, the flatness (TTV) of the first wafer W after etching is also improved compared with the conventional one. Also, the V-shape means that the etching amount at the center of the first wafer W is smaller than the etching amount at both ends, and has a V-shape in a graph with the wafer position as the horizontal axis and the etching amount as the vertical axis. distributed. The A-shape means that the etching amount at the center of the first wafer W is larger than that at both ends, and has a substantially A-shape in the above-mentioned graph, and has a vertically opposite shape distribution to the V-shape. In the above graph, the M shape is a shape in which two A shapes are arranged sandwiching the center of the first wafer W, and generally has a substantially M shape distribution. In the above graph, the W shape is a shape in which two V shapes are arranged sandwiching the center of the first wafer W, and generally has a slightly W shape distribution.

In addition, steps S1 to S6 are performed on each overlapping wafer T, so even if the surface shape of each wafer before etching (after grinding in this embodiment) is different, the first wafer after etching can still be etched one by one. The surface shape of W is controlled to be the target shape.

In the above embodiment, in step S3-4 and step S3-6, the optimization of the etching conditions using the least squares method is performed twice, but the number of times of this optimization is not limited thereto.

For example, the optimization calculation by the least square method may be performed once. For example, after the first etching condition is optimized in step S3-4, if the first etching amount distribution corresponding to the first etching condition is roughly consistent with the first target etching amount distribution, the first etching condition can be determined as optimal etching conditions. In this case, steps S3-5 to S3-8 can be omitted.

For example, the optimization calculation using the least square method may be performed more than three times. For example, when the etching amount distribution linked in step S3-8 is not roughly consistent with the first target etching amount distribution, the third residual distribution linking the etching amount distribution and the first target etching amount distribution can be set as the third target etching amount distributed. Then, steps S3-6 to S3-8 are performed so that the connection etching amount distribution roughly coincides with the first target etching amount distribution. In this way, the residual distribution linking the etching amount distribution and the first target etching amount distribution is gradually reduced, and the optimization calculation using the least square method is repeated until the linking etching amount distribution roughly coincides with the first target etching amount distribution. Then, the etching conditions at the point in time at which the etching amount distribution approximately matches the first target etching amount distribution are combined and determined as the optimum etching conditions.

In the above embodiments, the case where various processes are performed on the back surface Wb of the first wafer W in the stacked wafer T obtained by bonding the first wafer W and the second wafer S is described as an example. Not limited to this. For example, it is also possible to perform thinning treatment and etching treatment on a single wafer. The processing object can also be a film formed on the surface of the wafer, such as an oxide film and titanium nitride. In this case, the etchant supply unit 102 of the etching device 40 can arbitrarily switch the supply of different types of etchant E according to the etching object. Also, for example, when a film formed on the surface of a wafer is used as an etching target, the result of etching the film can be stored as the above-mentioned learning data. The thickness of the film is measured in the thickness measuring device 61 . Also, when a protective tape is attached to the element surface of the wafer, thinning and etching may be performed on the surface opposite to the protective tape. Furthermore, the thinning process and etching process can also be performed on the wafer cut out from the wafer through a wire saw and polished. No matter what kind of object is to be processed, the etching process can be performed under the optimal etching conditions of the above-mentioned embodiments.

Also, for example, when a film is formed on the back surface Wb of the first wafer, the film can be used as an etching target. In this case, for example, the thickness measuring device 61 measures the thickness of the film, and instead of the thickness of the first wafer W, the film thickness is measured in step S2, and the film thickness distribution and film flatness are calculated. Then, in step S3, optimum etching conditions are determined based on the calculated thickness distribution and flatness of the film.

In addition, the wafer processing system 1 includes various devices other than the etching device 40, but the configuration of the devices to which the present invention is applied is not limited thereto. For example, the thinning device, that is, the processing device 80 may be omitted. In this case, the etching object is not limited to the thinned wafer. Also, for example, the technique of the present invention can also be applied when etching a wafer in a separate etching apparatus.

In the above embodiments, the processing device 80 is used to thin the first wafer W, but the thinning method is not limited thereto. For example, the thinning process of the first wafer W also includes the polishing of the back surface Wb of the first wafer W. Alternatively, for example, a modified layer (not shown) formed inside the first wafer W by laser processing may be used as a base point to perform separation and thinning. In this case, instead of the processing device 80 , a laser processing device (not shown) for forming a modified layer (not shown) is provided in the wafer processing system 1 .

It should be understood that the entire contents of the implementation aspects of the present invention are for illustration rather than limitation. The above-mentioned implementation forms can be omitted, replaced, or changed in various forms without departing from the scope of the appended patent application and its gist.

1: Wafer processing system 2: Moving in and out station 3: Processing station 10: Cassette loading table 20:Wafer handling device 21: Carrying Road 22: Carrying the arm 30: transfer device 40: Etching device 41: Thickness measuring device 50:Wafer handling device 51: Carrying arm 60: Cleaning device 61: Thickness measuring device 62: buffer device 70:Wafer handling device 71: Carrying arm 72: Arm member 80: Processing device 81:Rotary table 82: Centerline of rotation 83: suction cup 84: Grinding unit 85: Grinding department 86: Pillar 90: Control device 100: Wafer holding part 100a: Centerline of rotation 101: Rotary mechanism 102: Etching solution supply part 103: Mobile Mechanism A0: transfer location A1: Processing position B1: The first processing block B2: The second processing block B3: The third processing block C: Cassette E: etching solution T: Overlapped wafer W: 1st wafer Wa: surface Wb: back S: 2nd wafer Sa: surface Sb: back Dw: component layer Fw: film for bonding Ds: component layer Fs: film for bonding V: scan speed L: scan width S1~S6: steps S3-1~S3-8: Steps

FIG. 1 is a side view showing an example of superimposed wafers processed in a wafer processing system. FIG. 2 is a plan view schematically showing the outline of the configuration of the wafer processing system. Fig. 3 is a side view showing a schematic configuration of an etching device. Fig. 4 is a schematic diagram showing a state in which the etching liquid supply part moves in the radial direction. Fig. 5 is a schematic diagram showing a constant speed scanning sequence. Fig. 6 is a schematic diagram showing an example of learning materials. Fig. 7 is a schematic diagram showing an example of learning materials and a standard etching amount distribution. Fig. 8 is a schematic diagram showing the radial distribution of the scanning ratio. Fig. 9 is a schematic diagram showing the radial distribution of non-discharge time. Fig. 10 is a schematic diagram showing the relationship between the scanning ratio and the non-discharging time. 11 is a schematic diagram comparing the measured value of the etching amount distribution of the constant speed scanning sequence and the calculated value of the etching amount distribution of the constant speed scanning model. Fig. 12 is a flowchart showing the main steps of wafer processing. Fig. 13 is a flow chart showing the main steps of the method for determining optimum etching conditions. Fig. 14 is a schematic diagram showing the distribution of each etching amount in the step of determining the optimum etching conditions.

S2~S5, S3-1~S3-8: steps

Claims (14)

A substrate processing method, processing a substrate, comprising the steps of: determining optimum etching conditions; and, based on the optimum etching conditions, passing an etchant supply unit through the etching while rotating an object to be etched in the substrate above the center of rotation of the object and move back and forth in the radial direction, while supplying the etching liquid from the etching liquid supply part to the surface of the etching object to etch the surface; the step of determining the optimum etching conditions includes the following steps: Learning data of the etching amount distribution in the radial direction of the etching object after etching the surface of the etching object under a plurality of different etching conditions; The way to minimize the first residual distribution of the first etching amount distribution and the first target etching amount distribution is to optimize the first etching condition of the first etching amount distribution by using the least square method; ER _scan (R)= ER _ref (R)×Ratio _scan (R)・・・(1) Ratio _scan (R)=b ₀ ×exp(b ₁ ×T+b ₂ )+C・・・(2) b ₀ =f(S ,V)・・・(3) b ₁ =f(S,V)・・・(4) b ₂ =f(S,V)・・・(5) T=(LR)/V・・・( 6) Among them, ER _scan : the etching amount when the etching liquid supply part is moved back and forth; ER _ref : the etching amount when the etching liquid supply part is not moved back and forth; Ratio _scan : scanning ratio; R: distance from the etching object The position of the center; T: the non-spraying time when the etching solution is not supplied; C: constant; S: the rotation speed when the etching object is rotated; V: the scanning speed when the etching solution supply part is moved back and forth; The scan width when the etchant supply part moves back and forth. The substrate processing method according to claim 1, wherein, The optimal etching condition includes the rotation speed, the scanning speed and the scanning width. The substrate processing method described in claim 1 or 2 further includes the following steps: The first residual distribution is set as the second target etching amount distribution; In order to minimize the second residual error distribution between the second etching amount distribution predicted by the following equations (1) to (6) using the learning data and the second target etching amount distribution, the least square method is used to minimize the Optimizing the second etching condition of the second etching amount distribution; and, Corresponding to the time ratio, the optimized first etching condition and the optimized second etching condition are combined to determine the optimal etching condition. The substrate processing method according to claim 1 or 2, wherein, The functions in the above formulas (3) to (5) are determined based on the learning data by analyzing the learning data. The substrate processing method described in claim 1 or 2 further includes the following steps: Before etching the surface of the etching object, measure the thickness of the etching object, and obtain the thickness distribution of the radial direction of the etching object; and, Based on the obtained thickness distribution of the etching object, the first etching amount distribution is predicted. The substrate processing method described in claim 1 or 2 further includes the following steps: Before etching the surface of the etching object, measuring the thickness of the etching object, and obtaining the thickness distribution of the etching object in the radial direction; The first target etching amount distribution is obtained based on the acquired thickness distribution of the etching object and the target thickness distribution of the etching object. The substrate processing method as described in Claim 5 further includes the following steps: Before measuring the thickness of the object to be etched, the substrate is thinned. A substrate processing system for processing a substrate, comprising: an etching device that moves an etchant supply part radially back and forth over the center of rotation of the etching object while rotating an etching object in the substrate, Etching the surface while supplying the etching liquid from the etching liquid supply part to the surface of the etching object; and, the control device controls the etching of the surface of the etching object of the etching device based on the optimum etching conditions; the control device executes the following Steps: Obtain learning data including the etching amount distribution in the radial direction of the etching object after etching the surface of the etching object with a plurality of different etching conditions; 6) The method of minimizing the first residual distribution of the predicted first etching amount distribution and the first target etching amount distribution, using the least square method to optimize the first etching condition of the first etching amount distribution; ER _scan (R)=ER _ref (R)×Ratio _scan (R)・・・(1) Ratio _scan (R)=b ₀ ×exp(b ₁ ×T+b ₂ )+C・・・(2) b ₀ =f(S,V)・・・(3) b ₁ =f(S,V)・・・(4) b ₂ =f(S,V)・・・(5) T=(LR)/V・・・(6) Among them, ER _scan : the etching amount when the etching liquid supply part is moved back and forth; ER _ref : the etching amount when the etching liquid supply part is not moving back and forth; Ratio _scan : scanning ratio; R: auto The position of the center of the etching object; T: the non-spraying time when the etching liquid is not supplied; C: constant; S: the rotation speed when the etching object is rotated; V: the scanning speed when the etching liquid supply part is moved back and forth ; L: scanning width when the etching liquid supply part is moved back and forth. The substrate processing system according to claim 8, wherein, The optimal etching condition includes the rotation speed, the scanning speed and the scanning width. The substrate processing system according to claim 8 or 9, wherein, The control device further performs the following steps: The first residual distribution is set as the second target etching amount distribution; In order to minimize the second residual error distribution between the second etching amount distribution predicted by the following equations (1) to (6) using the learning data and the second target etching amount distribution, the least square method is used to minimize the Optimizing the second etching condition of the second etching amount distribution; and, Corresponding to the time ratio, the optimized first etching condition and the optimized second etching condition are combined to determine the optimal etching condition. The substrate processing system according to claim 8 or 9, wherein, The control device analyzes the learning data to determine the functions in the above formulas (3) to (5). The substrate processing system as described in Claim 8 or 9, further comprising: Thickness measuring device, measuring the thickness of the etching object before etching; The control device predicts the first etching amount distribution based on the thickness distribution of the etching object obtained from the thickness of the etching object measured by the thickness measuring device. The substrate processing system as described in Claim 8 or 9, further comprising: Thickness measuring device, measuring the thickness of the etching object before etching; The control device obtains the first target etching amount distribution based on the thickness distribution of the etching object obtained from the thickness of the etching object measured by the thickness measuring device and the target thickness distribution of the etching object. The substrate processing system as described in Claim 12, further comprising: a thinning device for thinning the substrate; The thickness measuring device measures the thickness of the etching object of the thinned substrate.

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