Grinding method, device and control system

Abstract

The present invention provides a lapping method, apparatus, and control system. The method includes: obtaining the actual lapping amount and actual lapping time of multiple wafers already lapping by a target lapping head; fitting the actual lapping amount and actual lapping time of the multiple wafers; obtaining a preset lapping amount and a preset lapping rate R1 for a wafer to be lapped using the target lapping head; inputting the preset lapping amount into a fitting formula to obtain a predicted lapping time; dividing the preset lapping amount by the predicted lapping time to obtain a predicted lapping rate R2; calculating the actual lapping rate R3 corresponding to the wafer to be lapped; calculating the actual lapping time T corresponding to the wafer to be lapped; and lapping the wafer to be lapped using the target lapping head at the preset lapping rate R1 and the actual lapping time T. This solution can improve the lapping effect of the wafer to be lapped by the target lapping head in real time.

Description

Technical Field

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

[0002] like Figure 1 As shown, chemical mechanical planarization (CMP) is a commonly used lapping technology in wafer manufacturing. This technology flattens the surface of wafer 4 by gripping wafer 4 with a lapping head 1 (Lapping Head) and causing relative motion between wafer 4 and a rotating polishing pad 2 (Lapping Pad). The lapping head 1 applies pressure to wafer 4 as it rotates, and a lapping slurry 3 (Lapping Slurry) is introduced between wafer 4 and polishing pad 2 to enhance the lapping effect. During the lapping process, key process parameters, such as lapping rate and time, can be set using the Advanced Process Control (APC) system.

[0003] like Figure 1 and Figure 2 As shown, some grinding machines utilize a single polishing pad 2 equipped with multiple grinding heads 1, for example, four grinding heads 1. These multiple grinding heads 1 can sequentially carry wafers 4, allowing different wafers 4 to be polished sequentially on the same polishing pad 2. Currently, wafers 4 in the same batch typically use the same polishing rate, which typically refers to the polishing rate of the grinding head 1. Due to factors such as wear on each grinding head 1, the amount of polishing residue generated, and temperature fluctuations in the polishing fluid, this can result in wafers 4 being too thick or too thin after polishing. To address this issue, the APC system can adjust the polishing time using the following steps: For each grinding head 1, a measuring device measures the actual polishing depth of a wafer 4 polished by each grinding head 1; the difference between the actual polishing depth and the target polishing depth is calculated; the difference is divided by the polishing rate to obtain a compensated polishing time; the polishing time of each grinding head 1 is adjusted to polish subsequent wafers to be polished; and after the wafers to be polished are polished, the aforementioned steps are repeated to adjust the polishing time for each wafer to be polished.

[0004] However, the above-mentioned method of adjusting the grinding time only adjusts the grinding time of the wafer to be ground according to the difference between the actual grinding amount of a wafer 4 before the wafer to be ground and the target grinding amount. It does not take into account the changing trend of the actual grinding amount of the wafer caused by reasons such as the wear of each grinding head 1, the amount of residue generated by grinding, and the temperature change of the grinding liquid. This causes the wafer 4 after grinding to still be too thick or too thin. Summary of the Invention

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

[0006] In order to solve the above technical problems, the present invention provides a grinding method, comprising the following steps:

[0007] S1, obtaining the actual grinding amount and actual grinding time of multiple wafers ground by the target grinding head;

[0008] S2. fitting actual grinding amounts and actual grinding times of the plurality of wafers according to the time sequence in which the plurality of wafers are ground to obtain a fitting formula;

[0009] S3, obtaining a preset grinding amount and a preset grinding rate R1 of a wafer to be ground using the target grinding head;

[0010] S4, inputting the preset grinding amount into the fitting formula to obtain a predicted grinding time;

[0011] S5, dividing the preset grinding amount by the predicted grinding time to obtain a predicted grinding rate R2;

[0012] S6. Calculate the actual polishing rate R3 corresponding to the wafer to be polished, where R3=R1+W*(R1-R2), where W represents a preset weight;

[0013] S7, calculating the actual grinding time T corresponding to the wafer to be ground, where T=THK target / R3, THK target represents the preset grinding amount;

[0014] S8. Use the target polishing head to polish the wafer to be polished at the preset polishing rate R1 and the actual polishing time T.

[0015] Preferably, step S1 includes the following steps: determining the starting time for preparing to use the target grinding head to grind the wafer to be ground; obtaining the actual grinding amount and actual grinding time of multiple wafers that have been ground qualified by the target grinding head before the starting time.

[0016] Preferably, step S2 includes the following steps: fitting the actual grinding amounts and actual grinding times of the plurality of wafers using an exponential function.

[0017] 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 the parameters that need to be fitted.

[0018] Preferably, the following steps are also included between steps S7 and S8: using the target grinding head, grinding the sample 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; judging whether the actual grinding amount of the sample is equal to the preset grinding amount, if yes, executing step S8; if not, adjusting the parameters of the fitting formula and returning to step S4.

[0019] The present invention also provides a grinding device, comprising the following modules:

[0020] A first acquisition module is used to obtain actual grinding amount and actual grinding time of multiple wafers ground by the target grinding head;

[0021] A fitting module, configured to fit actual grinding amounts and actual grinding times of the plurality of wafers according to a time sequence in which the plurality of wafers are ground, to obtain a fitting formula;

[0022] A second acquisition module is configured to acquire a preset grinding amount and a preset grinding rate R1 of a wafer to be ground using the target grinding head;

[0023] A first calculation module is used to input the preset grinding amount into the fitting formula to obtain a predicted grinding time;

[0024] a second calculation module, configured to divide the preset grinding amount by the predicted grinding time to obtain a predicted grinding rate R2;

[0025] A third calculation module is used to calculate an actual polishing rate R3 corresponding to the wafer to be polished, wherein R3=R1+W*(R1-R2), where W represents a preset weight;

[0026] a fourth calculation module, configured to calculate an actual grinding time T corresponding to the wafer to be ground, wherein T=THKtarget / R3, where THKtarget represents the preset grinding amount;

[0027] The output module is 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.

[0028] Preferably, the first acquisition module is used to perform the following steps: determining the starting time for preparing to use the target grinding head to grind the wafer to be ground; obtaining the actual grinding amount and actual grinding time of multiple wafers that have been ground qualified by the target grinding head before the starting time.

[0029] Preferably, the fitting module is used to perform the following steps: fitting the actual grinding amounts and actual grinding times of the plurality of wafers using an exponential function.

[0030] 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 the parameters that need to be fitted.

[0031] The present invention also provides a grinding control system, which includes a grinding device as described in any one of the above items.

[0032] The present invention provides a grinding method, device, and control system that can be applied to a grinding machine comprising more than one grinding head, particularly a grinding machine comprising more than two grinding heads. This solution fits the actual grinding amount and actual grinding time of multiple wafers to obtain a fitting formula; then, based on the fitting formula and the preset grinding amount, a predicted grinding rate R2 is obtained; then, based on 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, based on 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 changing trend of the actual grinding amount of the wafer caused by factors such as the wear of the target grinding head, the amount of residue generated by grinding, and the temperature change of the grinding liquid. During the wafer grinding process, the actual grinding time T of the wafer to be ground can be adjusted in real time based on the actual grinding amount and actual grinding time of multiple wafers, thereby improving the grinding effect of the target grinding head on the wafer to be ground in real time and preventing the wafer to be ground from being too thick or too thin after grinding. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a structural diagram of a grinding machine in the prior art grinding a wafer.

[0034] Figure 2 It is a structural diagram of another grinding machine in the prior art.

[0035] Figure 3 This is a flow chart of a grinding method provided by one embodiment of the present invention.

[0036] Figure 4 This is a fitting curve of actual grinding amount and actual grinding time of multiple wafers provided by one embodiment of the present invention.

[0037] The reference numerals are as follows:

[0038] Grinding head-1, polishing pad-2, polishing fluid-3, wafer-4. DETAILED DESCRIPTION

[0039] To further clarify the objectives, advantages, and features of the present invention, the following describes in further detail a grinding method, apparatus, and control system according to the present invention, with reference to the accompanying drawings. It should be noted that the drawings are highly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the objectives of the present invention.

[0040] In the description of the present invention, qualifiers such as "first" and "second" are added for convenience of description and reference and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features qualified with qualifiers such as "first" and "second" may explicitly or implicitly include one or more of such features.

[0041] like Figure 3 As shown, this embodiment provides a grinding method, comprising the following steps:

[0042] S1. Obtain the actual grinding amount and actual grinding time of multiple wafers that have been ground by the target grinding head. This method can be applied to a grinding machine comprising more than one grinding head, especially a grinding machine comprising more than two grinding heads. If the grinding machine comprises only one grinding head, the grinding head is the target grinding head; if the grinding machine comprises more than two grinding heads, each grinding head is used as the target grinding head, and then the steps of this method are performed on each target grinding head. There are multiple layers of slots for placing wafers in the wafer box. The slot numbers can be used as the numbers of the wafers in the slots, and the numbers of the wafers picked up by each grinding head are fixed. For example, grinding head No. 1 only picks up wafers in the first and eleventh layer slots, and grinding head No. 2 only picks up wafers in the second and twelfth layer slots. The wafer numbers can be used to distinguish the wafers that have been ground by each grinding head. This method can be executed by an APC system. After the wafer is ground, it needs to be checked by a measuring device to see if it has passed the grinding test. The APC system can use the measuring device to obtain the actual grinding amount and actual grinding time of multiple wafers that have passed and failed grinding by the target grinding head.

[0043] S2. According to the time sequence in which the multiple wafers are ground, the actual grinding amount and the actual grinding time of the multiple wafers are fitted to obtain a fitting formula; when fitting, the fitting formula can be set first, and the fitting formula can be a nonlinear exponential function or a multi-time function.

[0044] S3. Obtaining a preset grinding amount and a preset grinding rate R1 of the wafer to be ground using the target grinding head; the preset grinding amount and the preset grinding rate R1 are pre-set parameters and can be input into the APC system in advance.

[0045] 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, which can reflect the degree of influence of the actual grinding time of multiple wafers that have been ground on the actual grinding time of the wafer to be ground.

[0046] S5. Divide the preset grinding amount by the predicted grinding time to obtain a predicted grinding rate R2.

[0047] S6. Calculate the actual polishing rate R3 for the wafer to be polished, where R3 = R1 + W*(R1 - R2), where W represents a preset weight. The actual polishing rate R3 for the wafer to be polished is obtained by weighting R1 and R2, which can achieve a better final polishing effect. W can be set based on the operator's experience or determined through experiments.

[0048] 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.

[0049] S8, using the target grinding head to grind the wafer at the preset grinding rate R1 and the actual grinding time T. Experimental verification shows that wafers ground by this method rarely become too thick or too thin.

[0050] The present embodiment provides a grinding method that can be applied to a grinding machine comprising more than one grinding head, particularly a grinding machine comprising more than two grinding heads. This solution fits the actual grinding amount and actual grinding time of multiple wafers to obtain a fitting formula; then, based on the fitting formula and the preset grinding amount, a predicted grinding rate R2 is obtained; then, based on 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, based on 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 changing trend of the actual grinding amount of the wafer caused by factors such as the wear of the target grinding head, the amount of residue generated by grinding, and the temperature change of the grinding liquid. During the wafer grinding process, the actual grinding time T of the wafer to be ground can be adjusted in real time based on the actual grinding amount and actual grinding time of multiple wafers, thereby improving the grinding effect of the target grinding head on the wafer to be ground in real time and preventing the wafer to be ground from being too thick or too thin after grinding.

[0051] Preferably, step S1 includes the following steps: determining a starting time for preparing to use the target grinding head to grind the wafer to be ground; and obtaining the actual grinding amount and actual grinding time of multiple wafers that have been ground and qualified by the target grinding head before the starting time. In a period of time before the starting time of grinding the wafer to be ground, the target grinding head has ground and qualified multiple wafers. The changing trends of the actual grinding amount and actual grinding time of the multiple wafers that have been ground and qualified will directly affect the actual grinding time of the wafer to be ground. Analyzing and utilizing this data can improve the grinding effect of the wafer to be ground.

[0052] Preferably, step S2 includes the following steps: fitting the actual grinding amount and actual grinding time of the plurality of wafers using an exponential function. Using a nonlinear exponential function can well fit the actual grinding amount and 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. For example, Figure 4 As shown, Figure 4 The large dots in the figure represent the discrete data before fitting, and the dotted curve represents the fitted curve. The fitting formula corresponding to the curve is y=21.348e -0.025x In other embodiments, the fitting formula may be a linear function, a quadratic function, or a multi-time function. 2 Select the best fitting formula and the goodness of fit R 2 The closer it is to 1, the better the fitting effect.

[0053] Preferably, the following steps are further included between step S7 and step S8: using the target grinding head, grinding the sample at the preset grinding rate R1 and the actual grinding time T, the preset grinding amount and preset grinding rate of the sample and the wafer to be ground are equal; judging whether the actual grinding amount of the sample is equal to the preset grinding amount, if so, executing step S8; if not, adjusting the parameters of the fitting formula, and returning to step S4. First, use the sample for grinding verification, and after successful verification, grind the wafer to be ground, so as to prevent the wafer from being worn and wasted. If the sample is not ground to standard, the parameters of the fitting formula can be adjusted manually or through the APC system, and then return to step S4. 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 appropriate, execute step S8; if not, adjust the parameters of the fitting formula, return to step S4 and repeat the above steps until the sample is ground to standard.

[0054] Based on the same technical concept as the above-mentioned grinding method, this embodiment provides a grinding device, including the following modules:

[0055] A first acquisition module is used to obtain actual grinding amount and actual grinding time of multiple wafers ground by the target grinding head;

[0056] A fitting module, configured to fit actual grinding amounts and actual grinding times of the plurality of wafers according to a time sequence in which the plurality of wafers are ground, to obtain a fitting formula;

[0057] A second acquisition module is configured to acquire a preset grinding amount and a preset grinding rate R1 of a wafer to be ground using the target grinding head;

[0058] A first calculation module is used to input the preset grinding amount into the fitting formula to obtain a predicted grinding time;

[0059] a second calculation module, configured to divide the preset grinding amount by the predicted grinding time to obtain a predicted grinding rate R2;

[0060] A third calculation module is used to calculate an actual polishing rate R3 corresponding to the wafer to be polished, wherein R3=R1+W*(R1-R2), where W represents a preset weight;

[0061] a fourth calculation module, configured to calculate an actual grinding time T corresponding to the wafer to be ground, wherein T=THKtarget / R3, where THKtarget represents the preset grinding amount;

[0062] The output module is 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.

[0063] The present embodiment provides a grinding device that can be applied to a grinding machine table including more than one grinding head, particularly a grinding machine table including more than two grinding heads. This solution fits the actual grinding amount and actual grinding time of multiple wafers to obtain a fitting formula; then, based on the fitting formula and the preset grinding amount, a predicted grinding rate R2 is obtained; then, based on 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, based on 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 changing trend of the actual grinding amount of the wafer caused by factors such as the wear of the target grinding head, the amount of residue generated by grinding, and the temperature change of the grinding liquid. During the wafer grinding process, the actual grinding time T of the wafer to be ground can be adjusted in real time based on the actual grinding amount and actual grinding time of multiple wafers, thereby improving the grinding effect of the target grinding head on the wafer to be ground in real time and preventing the wafer to be ground from being too thick or too thin after grinding.

[0064] Preferably, the first acquisition module is configured to perform the following steps: determining the start time for preparing to use the target grinding head to grind the wafer to be ground; and acquiring the actual grinding amount and actual grinding time of multiple wafers that have been ground to a satisfactory level by the target grinding head before the start time. Within a period of time before the start time of grinding the wafer to be ground, the target grinding head has already ground multiple wafers to a satisfactory level. The changing trends of the actual grinding amount and actual grinding time of the multiple wafers that have been ground to a satisfactory level will directly affect the actual grinding time of the wafer to be ground. Analyzing and utilizing this data can improve the grinding effect of the wafer to be ground.

[0065] Preferably, the fitting module is used to perform the following steps: using an exponential function to fit the actual grinding amount and actual grinding time of the plurality of wafers. Using a nonlinear exponential function can well fit the actual grinding amount and actual grinding time of the plurality of wafers, and prevent 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 that need to be fitted.

[0066] Based on the same technical concept as the above-mentioned grinding device, this embodiment provides a grinding control system, which includes any one of the above-mentioned grinding devices.

[0067] In summary, the present invention provides a grinding method, device and control system that can be applied to a grinding machine comprising more than one grinding head, in particular, a grinding machine comprising more than two grinding heads. This solution fits the actual grinding amount and actual grinding time of multiple wafers to obtain a fitting formula; then, based on the fitting formula and the preset grinding amount, a predicted grinding rate R2 is obtained; then, based on 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, based on 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 changing trend of the actual grinding amount of the wafer caused by factors such as the wear of the target grinding head, the amount of residue generated by grinding, and the temperature change of the grinding liquid. 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, thereby improving the grinding effect of the target grinding head on the wafer to be ground in real time, and preventing the wafer to be ground from being too thick or too thin after grinding.

[0068] 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. Any changes and modifications made by ordinary technicians in this field based on the above disclosure are within the scope of protection of the present invention.

Claims

1. A grinding method, characterized in that: The method is applied to a grinding machine comprising two or more grinding heads, with each grinding head being used as a target grinding head, and then the steps of the method are performed on each target grinding head respectively; the method comprises the following steps: S1, determining a starting time for preparing to use a target polishing head to polish a wafer to be polished; obtaining actual polishing amount and actual polishing time of multiple wafers that have been polished to a qualified level by the target polishing head before the starting time; S2. fitting actual grinding amounts and actual grinding times of the plurality of wafers according to the time sequence in which the plurality of wafers are ground to obtain a fitting formula; S3, obtaining a preset grinding amount and a preset grinding rate R1 of a wafer to be ground using the target grinding head; S4, inputting the preset grinding amount into the fitting formula to obtain a predicted grinding time; S5, dividing the preset grinding amount by the predicted grinding time to obtain a predicted grinding rate R2; S6. Calculate the actual polishing rate R3 corresponding to the wafer to be polished, where R3=R1+W*(R1-R2), where W represents a preset weight; S7, calculating the actual grinding time T corresponding to the wafer to be ground, wherein T=THK target / R3, THK target represents the preset grinding amount; S8. Use the target polishing head to polish the wafer to be polished at the preset polishing rate R1 and the actual polishing time T.

2. A grinding method according to claim 1, characterized in that, Step S2 includes the following steps: fitting the actual grinding amounts and actual grinding times of the plurality of wafers using an exponential function.

3. A grinding method according to claim 2, 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 that need to be fitted.

4. A grinding method according to claim 1, characterized in that, The following steps are also included between steps S7 and S8: using the target grinding head, grinding the sample 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; judging whether the actual grinding amount of the sample is equal to the preset grinding amount, if so, executing step S8; if not, adjusting the parameters of the fitting formula and returning to step S4.

5. A grinding device, characterized in that: The device is applied to a grinding machine with two or more grinding heads, with each grinding head being used as a target grinding head, and each target grinding head corresponding to one of the devices; the device includes the following modules: The first acquisition module is used to determine the starting time of preparing to use the target grinding head to grind the wafer to be ground; and obtain the actual grinding amount and actual grinding time of multiple wafers that have been ground and qualified by the target grinding head before the starting time; A fitting module, configured to fit actual grinding amounts and actual grinding times of the plurality of wafers according to a time sequence in which the plurality of wafers are ground, to obtain a fitting formula; A second acquisition module is configured to acquire a preset grinding amount and a preset grinding rate R1 of a wafer to be ground using the target grinding head; A first calculation module is used 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 is used to calculate an actual polishing rate R3 corresponding to the wafer to be polished, wherein R3=R1+W*(R1-R2), where W represents a preset weight; a fourth calculation module, configured to calculate an actual grinding time T corresponding to the wafer to be ground, wherein T=THK target / R3, where THK target represents the preset grinding amount; The output module is 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.

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

7. A 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 that need to be fitted.

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

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