Grinding method and device and control system

Abstract

The invention provides a grinding method and device and a control system. The method comprises the steps that the actual grinding amount and the actual grinding time of a plurality of wafers ground by a target grinding head are obtained; fitting the actual grinding amount and the actual grinding time of the plurality of wafers; the preset grinding amount and the preset grinding rate R1 of the to-be-ground wafer to be ground through the target grinding head are obtained; inputting a preset grinding amount into the fitting formula to obtain predicted grinding time; dividing the preset grinding amount by the predicted grinding time to obtain a predicted grinding rate R2; calculating an actual grinding rate R3 corresponding to the wafer to be ground; calculating the actual grinding time T corresponding to the wafer to be ground; and the target grinding head is used for grinding the to-be-ground wafer at the preset grinding speed R1 and the actual grinding time T. According to the scheme, the grinding effect of the target grinding head on the to-be-ground wafer can be improved in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of grinding, and particularly relates to a grinding method, device and control system. Background Art

[0002] As Figure 1 shown, chemical mechanical planarization is a commonly used grinding technology in wafer manufacturing. This technology flattens the surface of the wafer 4 by sucking the wafer 4 with the grinding head 1 (Head) and making the wafer 4 and the rotating polishing pad 2 (Polish Pad) move relatively. When the grinding head 1 carries the wafer 4 to rotate, pressure can be applied to the wafer 4. A grinding fluid 3 (Slurry) is also added between the wafer 4 and the polishing pad 2 to improve the grinding effect. During the grinding process, some main process parameters such as the grinding rate and grinding time can be set through the APC (Advanced Process Control) system.

[0003] As Figure 1 and Figure 2 shown, in some grinding machines, one polishing pad 2 is configured with multiple grinding heads 1, such as 4 grinding heads 1. The multiple grinding heads 1 can successively carry the wafers 4 to make different wafers 4 grind with the same polishing pad 2 in turn. Currently, wafers 4 of the same batch usually use the same grinding rate, and the grinding rate usually refers to the grinding rate of the grinding head 1. Due to reasons such as the wear amount of each grinding head 1, the residue amount generated by grinding, and the temperature change of the grinding fluid, this will cause the ground wafers 4 to be too thick or too thin. To solve this problem, the APC system can adjust the grinding time, and the adjustment steps are as follows: for different grinding heads 1 respectively, measure the actual grinding amount of a wafer 4 ground by each grinding head 1 through a measuring device; calculate the difference between the actual grinding amount and the target grinding amount; divide the difference by the grinding rate to obtain the compensated grinding time; adjust the grinding time of each grinding head 1 to grind the subsequent wafers to be ground; after the wafers to be ground are ground, repeat the previous steps to adjust the grinding time of the wafers to be ground.

[0004] However, the above method of adjusting the grinding time only adjusts the grinding time of the wafers to be ground according to the difference between the actual grinding amount and the target grinding amount of a previous wafer 4 of the wafers to be ground. It does not consider the changing trend of the actual grinding amount of the wafers caused by reasons such as the wear amount of each grinding head 1, the residue amount generated by grinding, and the temperature change of the grinding fluid. This results in the ground wafers 4 still being too thick or too thin. Summary of the Invention

[0005] The present invention provides a grinding method, device and control system to solve the technical problem that the ground wafers are too thick or too thin.

[0006] To solve the above technical problems, the present invention provides a grinding method, including the following steps: S1. Obtain the actual grinding amount and actual grinding time of multiple wafers ground by the target grinding head; S2. Fit the actual grinding amount and actual grinding time of the multiple wafers in the time sequence of grinding the wafers to obtain a fitting formula; S3. Obtain the preset grinding amount and preset grinding rate R1 of the wafer to be ground that is to be ground using the target grinding head; S4. Input the preset grinding amount into the fitting formula to obtain a predicted grinding time; S5. Divide the preset grinding amount by the predicted grinding time to obtain a predicted grinding rate R2; S6. Calculate the actual grinding rate R3 corresponding to the wafer to be ground, where R3 = R1 + W*(R1 - R2), and W represents a preset weight; S7. Calculate the actual grinding time T corresponding to the wafer to be ground, where T = THK target / R3, and THKtarget represents the preset grinding amount; S8. Grind the wafer to be ground using the target grinding head at the preset grinding rate R1 and the actual grinding time T.

[0007] Preferably, step S1 includes the following steps: Determine the starting moment when the target grinding head is to be used to grind the wafer to be ground; Obtain the actual grinding amount and actual grinding time of multiple wafers that have been ground qualified by the target grinding head before the starting moment.

[0008] Preferably, step S2 includes the following steps: Fit the actual grinding amount and actual grinding time of the multiple wafers using an exponential function.

[0009] Preferably, the expression of the fitting formula is y = ae -bx , where y represents the actual grinding time of the ground wafer, x represents the actual grinding amount of the ground wafer, e represents the natural constant, and a and b represent parameters to be fitted.

[0010] Preferably, between steps S7 and S8, the following steps are further included: Grind a sample using the target grinding head at the preset grinding rate R1 and the actual grinding time T, and the preset grinding amount and preset grinding rate of the sample and the wafer to be ground are equal; Determine whether the actual grinding amount of the sample is equal to the preset grinding amount. If so, execute step S8; If not, adjust the parameters of the fitting formula and return to step S4.

[0011] The present invention also provides a grinding device, including the following modules: A first acquisition module, configured to acquire the actual grinding amount and actual grinding time of a plurality of wafers ground by a target grinding head; A fitting module, configured to fit the actual grinding amount and actual grinding time of the plurality of wafers in the order of the time when the plurality of wafers are ground, to obtain a fitting formula; A second acquisition module, configured to acquire a preset grinding amount and a preset grinding rate R1 of a wafer to be ground that is to be ground using the target grinding head; A first calculation module, configured to input the preset grinding amount into the fitting formula to obtain a predicted grinding time; A second calculation module, configured to divide the preset grinding amount by the predicted grinding time to obtain a predicted grinding rate R2; A third calculation module, configured to calculate an actual grinding rate R3 corresponding to the wafer to be ground, where R3 = R1 + W * (R1 - R2), and W represents a preset weight; A fourth calculation module, configured to calculate an actual grinding time T corresponding to the wafer to be ground, where T = THKtarget / R3, and THK target represents the preset grinding amount; An output module, configured to grind the wafer to be ground using the target grinding head at the preset grinding rate R1 and the actual grinding time T.

[0012] Preferably, the first acquisition module is configured to perform the following steps: determine a starting moment when a target grinding head is to be used to grind a wafer to be ground; acquire the actual grinding amount and actual grinding time of a plurality of wafers that have been ground qualified by the target grinding head before the starting moment.

[0013] Preferably, the fitting module is configured to perform the following steps: fit the actual grinding amount and actual grinding time of the plurality of wafers using an exponential function.

[0014] Preferably, the expression of the fitting formula is y = ae -bx , where y represents the actual grinding time of the ground wafer, x represents the actual grinding amount of the ground wafer, e represents the natural constant, and a and b represent parameters to be fitted.

[0015] The present invention also provides a grinding control system, and the grinding control system includes a grinding device as described in any one of the above.

[0016] A grinding method, device and control system provided by the present invention can be applied to a grinding machine tool including more than 1 grinding head, especially a grinding machine tool including more than 2 grinding heads. In this solution, the actual grinding amount and actual grinding time of multiple wafers are fitted to obtain a fitting formula; then, according to the fitting formula and a preset grinding amount, a predicted grinding rate R2 is obtained; then, according to a preset grinding rate R1 and the predicted grinding rate R2, the actual grinding rate R3 corresponding to the wafer to be ground is determined; then, according to R3 and the preset grinding amount, the actual grinding time T corresponding to the wafer to be ground is determined; finally, the target grinding head grinds the wafer to be ground at the preset grinding rate R1 and the actual grinding time T. The unexpected effect of this solution is that it takes into account the change trend of the actual grinding amount of the wafer caused by reasons such as the wear amount of the target grinding head, the residue amount generated by grinding, and the temperature change of the grinding fluid. During the wafer grinding process, the actual grinding time T of the wafer to be ground can be adjusted in real time according to the actual grinding amount and actual grinding time of multiple wafers, so as to improve the grinding effect of the target grinding head on the wafer to be ground in real time and prevent the wafer to be ground from being too thick or too thin after grinding. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 FIG. is a schematic structural diagram of a grinding machine tool for grinding a wafer in the prior art.

[0018] Figure 2 FIG. is a schematic structural diagram of another grinding machine tool in the prior art.

[0019] Figure 3 FIG. is a flowchart of a grinding method provided by an embodiment of the present invention.

[0020] Figure 4 FIG. is a fitting curve of the actual grinding amount and actual grinding time of multiple wafers provided by an embodiment of the present invention.

[0021] The reference numerals are as follows: Grinding head - 1, polishing pad - 2, grinding fluid - 3, wafer - 4. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] To make the objectives, advantages and features of the present invention clearer, a grinding method, device and control system provided by the present invention will be further described in detail below with reference to the accompanying drawings. It should be noted that the drawings are all in very simplified forms and use non-precise scales, only for the purpose of facilitating and clearly assisting in explaining the objectives of the embodiments of the present invention.

[0023] In the description of the present invention, the qualifiers such as "first", "second", etc. are added for convenient description and reference, and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with qualifiers such as "first", "second", etc. may explicitly or implicitly include one or more of such features.

[0024] As Figure 3 shown, this embodiment provides a grinding method, including the following steps: S1. Obtain the actual grinding amount and actual grinding time of multiple wafers ground by the target grinding head. This method can be applied to a grinding machine with more than 1 grinding head, especially a grinding machine with more than 2 grinding heads. If the grinding machine has only 1 grinding head, then this grinding head is the target grinding head; if the grinding machine has more than 2 grinding heads, each grinding head is taken as the target grinding head respectively, and then each step of this method is executed for each target grinding head respectively. There are multiple layers of slots for placing wafers in the wafer cassette, and the number of the slot can be used as the number of the wafer in this slot. The number of the wafer picked up by each grinding head is fixed. For example, the 1st grinding head only picks up the wafers in the first layer slot and the eleventh layer slot, and the 2nd grinding head only picks up the wafers in the second layer slot and the twelfth layer slot. The wafers ground by each grinding head can be distinguished by the number of the wafers. This method can be executed by the APC system. After the wafer is ground, it is necessary to detect whether it is ground qualified by a measuring device. The APC system can obtain the actual grinding amount and actual grinding time of multiple qualified and unqualified wafers ground by the target grinding head through the measuring device.

[0025] S2. Fit the actual grinding amount and actual grinding time of the multiple wafers according to the time sequence in which the multiple wafers are ground to obtain a fitting formula; when fitting, a fitting formula can be set first, and the fitting formula can be a non-linear exponential function or a polynomial function, etc.

[0026] S3. Obtain the preset grinding amount and preset grinding rate R1 of the wafer to be ground that is going to be ground using the target grinding head; the preset grinding amount and preset grinding rate R1 are parameters set in advance and can be input into the APC system in advance.

[0027] S4. Input the preset grinding amount into the fitting formula to obtain a predicted grinding time; the predicted grinding time is the result output by the fitting formula and can reflect the influence degree of the actual grinding time of the multiple ground wafers on the actual grinding time of the wafer to be ground.

[0028] S5. Divide the preset grinding amount by the predicted grinding time to obtain a predicted grinding rate R2.

[0029] S6. Calculate the actual grinding rate R3 corresponding to the wafer to be ground, where R3 = R1 + W * (R1 - R2), and W represents a preset weight. The actual grinding rate R3 corresponding to the wafer to be ground is obtained by weighting R1 and R2, which can make the final grinding effect better. W can be set according to the experience of the operator or determined by experiments.

[0030] S7. Calculate the actual grinding time T corresponding to the wafer to be ground, where T = THK target / R3, and THKtarget represents the preset grinding amount.

[0031] S8. Use the target grinding head to grind the wafer to be ground at the preset grinding rate R1 and the actual grinding time T. Through experimental verification, wafers ground by this method rarely show the phenomenon of being too thick or too thin.

[0032] A grinding method provided in this embodiment can be applied to a grinding machine tool including more than 1 grinding head, especially a grinding machine tool including more than 2 grinding heads. This solution fits the actual grinding amounts and actual grinding times of multiple wafers to obtain a fitting formula; then determines the predicted grinding rate R2 according to the fitting formula and the preset grinding amount; then determines the actual grinding rate R3 corresponding to the wafer to be ground according to the preset grinding rate R1 and the predicted grinding rate R2; then determines the actual grinding time T corresponding to the wafer to be ground according to R3 and the preset grinding amount; finally, the target grinding head grinds the wafer to be ground at the preset grinding rate R1 and the actual grinding time T. The unexpected effect of this solution is that it considers the changing trend of the actual grinding amount of the wafer caused by reasons such as the wear amount of the target grinding head, the residue amount generated by grinding, and the temperature change of the grinding fluid. During the wafer grinding process, the actual grinding time T of the wafer to be ground can be adjusted in real time according to the actual grinding amounts and actual grinding times of multiple wafers, so as to improve the grinding effect of the target grinding head on the wafer to be ground in real time and prevent the wafer to be ground from being too thick or too thin after grinding.

[0033] Preferably, step S1 includes the following steps: determine the starting moment when it is ready to use the target grinding head to grind the wafer to be ground; obtain the actual grinding amounts and actual grinding times of multiple wafers that have been ground qualified by the target grinding head before the starting moment. During a period of time before the starting moment of grinding the wafer to be ground, the target grinding head has ground multiple wafers qualified. The changing trends of the actual grinding amounts and actual grinding times of the multiple ground qualified wafers will directly affect the actual grinding time of the wafer to be ground. Analyzing and using these data can make the grinding effect of the wafer to be ground better.

[0034] Preferably, step S2 includes the following steps: using an exponential function to fit the actual grinding amount and actual grinding time of the multiple wafers. Using a non-linear exponential function can well fit the actual grinding amount and actual grinding time of the multiple wafers, preventing some data from being too far away from the fitting curve. Specifically, the expression of the fitting formula can be y = ae -bx , where y represents the actual grinding time of the ground wafer, x represents the actual grinding amount of the ground wafer, e represents the natural constant, and a and b represent the parameters to be fitted. For example, as Figure 4 shown, Figure 4 the large dots in represent the discrete data before fitting, and the curve shown by the dotted line represents the fitted curve. The fitting formula corresponding to the curve is y = 21.348e -0.025x . In other embodiments, the fitting formula can be a linear function, a quadratic function, or a polynomial function, etc. When fitting, the best fitting formula can be selected according to the goodness of fit R 2 , and the closer the goodness of fit R 2 is to 1, the better the fitting effect.

[0035] Preferably, between step S7 and step S8, the following steps are further included: using the target grinding head to grind the sample at the preset grinding rate R1 and the actual grinding time T, where the preset grinding amount and preset grinding rate of the sample and the wafer to be ground are equal; determining whether the actual grinding amount of the sample is equal to the preset grinding amount. If so, step S8 is executed; if not, the parameters of the fitting formula are adjusted, and step S4 is returned. First, use the sample for grinding verification, and then grind the wafer to be ground after successful verification, which can prevent the wafer from being worn and wasted. If the sample is ground unqualified, the parameters of the fitting formula can be adjusted manually or through the APC system, and then step S4 is returned. After executing steps S4 - S7, the sample is ground using the updated actual grinding time T to verify whether the adjusted fitting formula is appropriate. If it is appropriate, step S8 is executed; if it is not appropriate, the parameters of the fitting formula are adjusted, and step S4 is returned and the above steps are repeated until the sample is ground qualified.

[0036] Based on the same technical concept as the above-mentioned grinding method, this embodiment provides a grinding device, including the following modules: A first acquisition module, configured to acquire the actual grinding amount and actual grinding time of multiple wafers ground by the target grinding head; A fitting module, configured to fit the actual grinding amount and actual grinding time of the multiple wafers in the order of the time when the multiple wafers are ground, to obtain a fitting formula; A second acquisition module, configured to acquire a preset grinding amount and a preset grinding rate R1 of a wafer to be ground that is to be ground using the target grinding head; A first calculation module, configured to input the preset grinding amount into the fitting formula to obtain a predicted grinding time; A second calculation module, configured to divide the preset grinding amount by the predicted grinding time to obtain a predicted grinding rate R2; A third calculation module, configured to calculate an actual grinding rate R3 corresponding to the wafer to be ground, where R3 = R1 + W*(R1 - R2), and W represents a preset weight; A fourth calculation module, configured to calculate an actual grinding time T corresponding to the wafer to be ground, where T = THKtarget / R3, and THK target represents the preset grinding amount; An output module, configured to grind the wafer to be ground using the target grinding head at the preset grinding rate R1 and the actual grinding time T.

[0037] A grinding device provided in this embodiment can be applied to a grinding machine including more than 1 grinding head, especially a grinding machine including more than 2 grinding heads. In this solution, the actual grinding amounts and actual grinding times of multiple wafers are fitted to obtain a fitting formula; then, according to the fitting formula and the preset grinding amount, a predicted grinding rate R2 is obtained; then, according to the preset grinding rate R1 and the predicted grinding rate R2, an actual grinding rate R3 corresponding to the wafer to be ground is determined; then, according to R3 and the preset grinding amount, an actual grinding time T corresponding to the wafer to be ground is determined; finally, the target grinding head grinds the wafer to be ground at the preset grinding rate R1 and the actual grinding time T. An unexpected effect of this solution is that it takes into account the change trend of the actual grinding amount of the wafer caused by reasons such as the wear amount of the target grinding head, the residue amount generated during grinding, and the temperature change of the grinding fluid. During the wafer grinding process, the actual grinding time T of the wafer to be ground can be adjusted in real time according to the actual grinding amounts and actual grinding times of multiple wafers, so as to improve the grinding effect of the target grinding head on the wafer to be ground in real time and prevent the wafer to be ground from being too thick or too thin after grinding.

[0038] Preferably, the first acquisition module is configured to perform the following steps: determine the starting moment when the target grinding head is to start grinding the wafer to be ground; acquire the actual grinding amounts and actual grinding times of multiple wafers that have been ground qualified by the target grinding head before the starting moment. During a period of time before the starting moment when the wafer to be ground is ground, the target grinding head has ground multiple wafers qualified. The change trends of the actual grinding amounts and actual grinding times of the multiple ground qualified wafers will directly affect the actual grinding time of the wafer to be ground. Analyzing and using these data can make the grinding effect of the wafer to be ground better.

[0039] Preferably, the fitting module is configured to perform the following steps: fitting the actual grinding amount and the actual grinding time of the plurality of wafers using an exponential function. Using a non-linear exponential function can well fit the actual grinding amount and the actual grinding time of the plurality of wafers, preventing some data from being too far away from the fitting curve. Specifically, the expression of the fitting formula can be y = ae -bx , where y represents the actual grinding time of the ground wafer, x represents the actual grinding amount of the ground wafer, e represents the natural constant, and a and b represent the parameters to be fitted.

[0040] Based on the same technical concept as the above-mentioned grinding device, this embodiment provides a grinding control system, which includes the above-mentioned grinding device of any one of the above.

[0041] In summary, a grinding method, device, and control system provided by the present invention can be applied to a grinding machine including more than 1 grinding head, especially a grinding machine including more than 2 grinding heads. This solution fits the actual grinding amount and the actual grinding time of a plurality of wafers to obtain a fitting formula; then, according to the fitting formula and the preset grinding amount, the predicted grinding rate R2 is obtained; then, according to the preset grinding rate R1 and the predicted grinding rate R2, the actual grinding rate R3 corresponding to the wafer to be ground is determined; then, according to R3 and the preset grinding amount, the actual grinding time T corresponding to the wafer to be ground is determined; finally, the target grinding head grinds the wafer to be ground at the preset grinding rate R1 and the actual grinding time T. The unexpected effect of this solution is that it takes into account the change trend of the actual grinding amount of the wafer caused by factors such as the wear amount of the target grinding head, the residue amount generated by grinding, and the temperature change of the grinding fluid. During the wafer grinding process, the actual grinding time T of the wafer to be ground can be adjusted in real time according to the actual grinding amount and the actual grinding time of a plurality of wafers, so as to improve the grinding effect of the target grinding head on the wafer to be ground in real time, and prevent the wafer to be ground from being too thick or too thin after grinding.

[0042] The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art according to the above disclosure belong to the protection scope of the present invention.

Claims

1. A grinding method, characterized in that, It includes the following steps: S1. Determine the starting moment when preparing to use the target grinding head to grind the wafer to be ground; obtain the actual grinding amount and actual grinding time of multiple wafers that have been ground qualified by the target grinding head before the starting moment; S2. Fit the actual grinding amount and actual grinding time of the multiple wafers in the time sequence of grinding of the multiple wafers to obtain a fitting formula; S3. Obtain the preset grinding amount and preset grinding rate R1 of the wafer to be ground when preparing to use the target grinding head for grinding; S4. Input the preset grinding amount into the fitting formula to obtain a predicted grinding time; S5. Divide the preset grinding amount by the predicted grinding time to obtain a predicted grinding rate R2; S6. Calculate the actual grinding rate R3 corresponding to the wafer to be ground, where R3 = R1 + W*(R1 - R2), and W represents a preset weight; S7. Calculate the actual grinding time T corresponding to the wafer to be ground, where T = THK target / R3, and THK target represents the preset grinding amount; S8. Use the target grinding head to grind the wafer to be ground at the preset grinding rate R1 and the actual grinding time T.

2. The grinding method according to claim 1, wherein, Step S2 includes the following steps: Fit the actual grinding amount and actual grinding time of the multiple wafers using an exponential function.

3. The grinding method according to claim 2, wherein, The expression of the fitting formula is y = ae -bx , where y represents the actual grinding time of the ground wafer, x represents the actual grinding amount of the ground wafer, e represents the natural constant, and a and b represent the parameters to be fitted.

4. A grinding method according to claim 1, characterized in that Between steps S7 and S8, there are also the following steps: Use the target grinding head to grind a sample at the preset grinding rate R1 and the actual grinding time T, where the preset grinding amount and preset grinding rate of the sample and the wafer to be ground are equal; determine whether the actual grinding amount of the sample is equal to the preset grinding amount, if so, execute step S8; if not, adjust the parameters of the fitting formula and return to step S4.

5. A grinding device, characterized in that, It includes the following modules: The first acquisition module is used to determine the starting moment when preparing to use the target grinding head to grind the wafer to be ground; obtain the actual grinding amount and actual grinding time of multiple wafers that have been ground qualified by the target grinding head before the starting moment; The fitting module is used to fit the actual grinding amount and actual grinding time of the multiple wafers in the time sequence of grinding of the multiple wafers to obtain a fitting formula; The second acquisition module is used to obtain the preset grinding amount and preset grinding rate R1 of the wafer to be ground when preparing to use the target grinding head for grinding; The first calculation module is used to input the preset grinding amount into the fitting formula to obtain a predicted grinding time; The second calculation module is used to divide the preset grinding amount by the predicted grinding time to obtain a predicted grinding rate R2; The third calculation module is used to calculate the actual grinding rate R3 corresponding to the wafer to be ground, where R3 = R1 + W*(R1 - R2), and W represents a preset weight; The fourth calculation module is used to calculate the actual grinding time T corresponding to the wafer to be ground, where T = THK target / R3, and THK target represents the preset grinding amount; An output module for grinding the wafer to be ground using the target grinding head at the preset grinding rate R1 and the actual grinding time T.

6. A grinding device according to claim 5, characterized in that, The fitting module is configured to perform the following steps: fitting the actual grinding amount and the actual grinding time of the plurality of wafers using an exponential function.

7. The grinding device according to claim 6, characterized in that, The expression of the fitting formula is y = ae -bx , where y represents the actual grinding time of the ground wafer, x represents the actual grinding amount of the ground wafer, e represents the natural constant, and a and b represent the parameters to be fitted.

8. A grinding control system, characterized in that, The grinding control system includes a grinding device according to any one of claims 5-7.

Images