Grinding method

Abstract

The application provides a polishing method, comprising the following steps: firstly, setting an actual polishing amount according to a previous value influencing factor value, a later value influencing factor value and a lifetime of a polishing pad; then, obtaining a corresponding actual polishing time according to the actual polishing amount, and executing N times of rough polishing processes on a wafer by using an IAPC system according to the actual polishing time, wherein N is an integer greater than or equal to 1; finally, executing a fine polishing process on the wafer by using the IAPC system. According to the previous value influencing factor value, the later value influencing factor value and the lifetime of the polishing pad, the polishing amount of the IAPC system is optimized, the dynamic adjustment of the polishing amount is realized in different lifetime periods, the existing feedback logic is optimized, the optimization of the polishing time is realized, the success rate of the batch overstock is greatly improved, and the abnormal situation of the polishing thickness of the chips in the first several batches when the platform works again is avoided due to long-term overstock.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wafer grinding, and particularly relates to a grinding method. BACKGROUND

[0002] In semiconductor manufacturing, chemical mechanical grinding (CMP) technology can realize the planarization of the whole wafer, and becomes one of the important steps in the chip manufacturing process.

[0003] At present, most of the Fab7 platforms have the situation of non-concentrated incoming goods, and the initial grinding rate cannot meet the demand when the actual goods are run, so that the inline continuously suffers from the problem of poor control of grinding amount when the batch goods are run (especially the first few batches), resulting in the thickness of the ground wafer (chip) being abnormal, thereby causing the IAPC system to fail to run the goods. Specifically, the grinding time set by the IAPC system satisfies the following formula: grinding time = grinding amount / grinding rate (constant value), wherein the grinding rate is a constant value set in advance after the machine PM (preventive maintenance) is measured; as can be seen from the above formula, the grinding time is determined by the grinding amount and the grinding rate, and is set by the IAPC system and given to the wafer to be ground. However, since the grinding amount is not well controlled at present, the set grinding time is uncontrollable, thereby causing the thickness of the ground wafer to be abnormal during the grinding process of the wafer, resulting in the problem of IAPC system failure to run the goods (run the chip). In addition, the grinding rate of CMP will change with the increase of the service life (Lifetime) of the consumables, and the grinding rate of CMP is prone to decrease in the grinding process of oxide materials, which will also affect the grinding time of the IAPC system and cause the IAPC system to fail to run the goods. SUMMARY

[0004] The present application provides a grinding method, which can solve the problem that the grinding time and / or the grinding amount of the IAPC system are abnormal during the grinding process of the wafer, resulting in the thickness of the ground wafer (chip) being abnormal, thereby causing the IAPC system to fail to run the goods.

[0005] In one aspect, the present application provides a grinding method, comprising:

[0006] According to the previous value influence factor value, the subsequent value influence factor value and the service life of the grinding pad, the actual grinding amount is set;

[0007] According to the actual grinding amount, the corresponding actual grinding time is obtained, and the IAPC system is used to perform N times of coarse grinding process on the mth wafer according to the actual grinding time, wherein m and N are integers greater than or equal to 1;

[0008] The IAPC system is used to perform fine grinding process on the mth wafer.

[0009] Optionally, in the grinding method, when N is an integer greater than 1, the step of obtaining a corresponding actual grinding time according to the actual grinding amount, and performing N times of coarse grinding processes on the mth wafer according to the actual grinding time by using the IAPC system, comprises:

[0010] dividing the actual grinding amount into N parts to obtain an actual average grinding amount;

[0011] obtaining an actual average grinding time corresponding to each coarse grinding process according to the actual average grinding amount;

[0012] performing N times of coarse grinding processes on the wafer according to the actual average grinding time by using the IAPC system.

[0013] Optionally, in the grinding method, the actual grinding amount satisfies the following formula: W m =(X m -E m +d×F), wherein W m is the actual grinding amount of the mth wafer, X m is a preset grinding amount of the mth wafer with a previous value influence factor value, E m is a feedback thickness with a previous value influence factor value and a subsequent value influence factor value, d is a coefficient, and F is the service life of the grinding pad, wherein the range of the coefficient is 0.1-1.

[0014] Optionally, in the grinding method, the preset grinding amount of the mth wafer with the previous value influence factor value satisfies the following formula: X m =A+B m , wherein A is an ideal grinding amount, and B m is the previous value influence factor value of the mth wafer.

[0015] Optionally, in the grinding method, the previous value influence factor value of the mth wafer satisfies the following formula: B m =b1 m -b2 m , wherein b1 m is an actual measurement of the thickness of the mth wafer before coarse grinding, and b2 m is a target measurement of the thickness of the mth wafer before coarse grinding; wherein the subsequent value influence factor value of the 1st wafer is 0.

[0016] Optionally, in the grinding method, the feedback thickness with the previous value influence factor value and the subsequent value influence factor value satisfies the following formula: E m =(Y m -X m )÷X m , wherein Y mThe preset polishing amount of the mth wafer with the post-value influencing factor value brought in;

[0017] The preset polishing amount of the mth wafer with the post-value influencing factor value brought in satisfies the following formula: Y m =A+B m -C m , wherein C m is the post-value influencing factor value of the mth wafer;

[0018] The post-value influencing factor value of the mth wafer satisfies the following formula: C m =c1 m-1 -c2 m-1 , wherein c1 m-1 is the actual measurement of the thickness of the m-1th wafer after rough polishing, and c2 m-1 is the target amount of the thickness of the m-1th wafer after rough polishing.

[0019] Optionally, in the polishing method, the thickness of the mth wafer removed by rough polishing is proportional to the value of the selected coefficient.

[0020] Optionally, in the polishing method, the actual average polishing amount of the mth wafer satisfies the following formula: W1 m =W m ÷N, wherein W1 m is the actual average polishing amount of the mth wafer;

[0021] The actual average polishing time satisfies the following formula: t m =W1 m ÷v, wherein t m is the actual average polishing time of the mth wafer, and v is a polishing rate, wherein the polishing rate is set in advance by the IAPC system.

[0022] Optionally, in the polishing method, the step of performing fine polishing process on the wafer by the IAPC system comprises:

[0023] Polishing and removing particles on the surface of the wafer by the IAPC system to planarize the surface of the wafer.

[0024] Optionally, in the polishing method, the rough polishing process and the fine polishing process are both chemical mechanical polishing processes.

[0025] The technical scheme of the present application at least has the following advantages:

[0026] The application first sets an actual polishing amount according to a previous value influencing factor value, a later value influencing factor value and a lifetime of the polishing pad; then acquires a corresponding actual polishing time according to the actual polishing amount, and executes N times of coarse polishing processes on the wafer by the IAPC system according to the actual polishing time; finally, executes fine polishing processes on the wafer by the IAPC system. The application optimizes the polishing amount of the IAPC system through the previous value influencing factor value, the later value influencing factor value and the lifetime of the polishing pad, realizes dynamic adjustment of the polishing amount in different lifetime periods, optimizes the existing feedback logic to realize optimization of the polishing time, greatly improves the success rate of the batch overstock, avoids the situation that the polishing thickness of the chips in the first few batches is abnormal when the platform works again due to long-term overstock, and makes the IAPC system run more stably. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the specific embodiments or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0028] Figure 1 is a flowchart of the polishing method of the embodiment of the application. DETAILED DESCRIPTION

[0029] The technical solutions in the application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0030] In the description of the application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0031] In the description of the present application, it is necessary to point out that unless explicitly defined and limited, the terms "mount", "connect", "connection" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the internal communication of two elements, it can be wireless connection, or wired connection. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict between them.

[0033] The embodiment of the present application provides a grinding method, please refer to Figure 1 , Figure 1 is a flow chart of the grinding method of the embodiment of the present application, the grinding method comprises:

[0034] S10: according to the previous value influence factor value, the later value influence factor value and the service life of the grinding pad, the actual grinding amount is set. Specifically, the previous value influence factor value and the later value influence factor value are two feedbacks in a PM cycle.

[0035] S20: according to the actual grinding amount, the corresponding actual grinding time is obtained, and the IAPC system executes N times of coarse grinding process on the wafer according to the actual grinding time, wherein m and N are integers greater than or equal to 1.

[0036] In the embodiment, the actual grinding amount satisfies the following formula: W m =(X m -E m +d×F), wherein W m is the actual grinding amount of the mth wafer, X m is the preset grinding amount of the mth wafer with the previous value influence factor value, E m is the feedback thickness with the previous value influence factor value and the later value influence factor value, d is a coefficient, and F is the service life of the grinding pad, wherein the range of the coefficient is 0.1-1. Preferably, the thickness of the wafer removed by coarse grinding is proportional to the value of the selected coefficient d, that is, the thicker the thickness of the wafer removed by coarse grinding, the closer the value of the coefficient to 1; on the contrary, the thinner the thickness of the wafer removed by coarse grinding, the closer the value of the coefficient to 0.1.

[0037] Wherein, the preset grinding amount of the mth wafer with the previous value influence factor value satisfies the following formula: X m =A+B m , wherein A is the ideal grinding amount, and B mThe previous value of the influencing factor of the mth wafer. In this embodiment, the ideal polishing amount A can be a constant (preset value).

[0038] Further, the previous value of the influencing factor of the mth wafer satisfies the following formula: B m = b1 m - b2 m , wherein b1 m is the actual measurement of the thickness of the mth wafer before rough polishing, and b2 m is the target amount of the thickness of the mth wafer before rough polishing.

[0039] Preferably, the feedback thickness with the previous value of the influencing factor and the subsequent value of the influencing factor satisfies the following formula: E m = (Y m - X m ) ÷ X m , wherein Y m is the preset polishing amount with the subsequent value of the influencing factor.

[0040] Further, the preset polishing amount of the mth wafer with the subsequent value of the influencing factor satisfies the following formula: Y m = A + B m - C m , wherein C m is the subsequent value of the influencing factor of the mth wafer.

[0041] Preferably, the subsequent value of the influencing factor of the mth wafer satisfies the following formula: C m = c1 m-1 - c2 m-1 , wherein c1 m-1 is the actual measurement of the thickness of the (m-1)th wafer after rough polishing, and c2 m-1 is the target amount of the thickness of the (m-1)th wafer after rough polishing. It is worth noting that if m = 1, the first wafer in this embodiment has no subsequent value of the influencing factor, and the subsequent value of the influencing factor of the first wafer is 0; in another embodiment, the subsequent value of the influencing factor of the first wafer can be the difference between the actual measurement and the target amount (target estimated value) of the thickness of the last wafer in the wafer of the previous batch; when m is an integer greater than 1, the subsequent value of the influencing factor of the mth wafer comes from the feedback of the previous wafer.

[0042] In this embodiment, the actual polishing time satisfies the following formula: T m = W m ÷ v, wherein T mis the actual polishing time of the mth wafer, and v is a polishing rate, wherein the polishing rate is set in advance by the IAPC system, and the polishing rate can be set in advance after the machine PM.

[0043] The application optimizes the polishing amount of the IAPC system through the front value influence factor value, the rear value influence factor value and the lifetime of the polishing pad, realizes dynamic adjustment of the polishing amount in different lifetime periods, optimizes the existing feedback logic, and thus realizes optimization of the polishing time.

[0044] When N is an integer of 1, a corresponding actual polishing time is obtained according to the actual polishing amount, and one-time coarse polishing process is performed on the wafer by the IAPC system according to the actual polishing time. Embodiments of the application can realize dynamic adjustment of the polishing amount in different lifetime periods, optimize the existing feedback logic, and thus realize optimization of the polishing time, greatly improve the success rate of random batch arrival, avoid the abnormal polishing thickness of the chips in the first few batches when the platform is worked again due to long-term non-arrival, and also avoid the abnormal polishing thickness of the wafers in other batches that are not in the front, so that the IAPC system runs more stably.

[0045] Further, when N is an integer greater than 1, the step of obtaining a corresponding actual polishing time according to the actual polishing amount and performing N-time coarse polishing process on the mth wafer by the IAPC system according to the actual polishing time comprises:

[0046] The actual polishing amount is evenly divided into N parts to obtain an actual average polishing amount;

[0047] An actual average polishing time corresponding to each coarse polishing process is obtained according to the actual average polishing amount;

[0048] N-time coarse polishing process is performed on the wafer by the IAPC system according to the actual average polishing time.

[0049] When N is an integer greater than 1, the actual average polishing amount of the mth wafer satisfies the following formula: W1 m = W m ÷ N, wherein W1 m is the actual average polishing amount of the mth wafer.

[0050] The actual average polishing time satisfies the following formula: t m = W1 m ÷ v, wherein t m is the actual average polishing time of the mth wafer.

[0051] Optionally, the actual average polishing time t mThe actual polishing time can also be calculated by the following formula: t m = T m ÷ N, T m is the actual polishing time of the mth wafer.

[0052] The present application can avoid the damage of the wafer surface caused by directly polishing too much material at one time, and can improve the uniformity of the polishing thickness of the wafer.

[0053] S30: performing a fine polishing process on the mth wafer by using the IAPC system. Specifically, the IAPC system is used to polish and remove the particles on the wafer surface to planarize the wafer surface. In this process, a wafer with a certain thickness (very thin wafer) can also be polished and removed.

[0054] In the embodiment, the coarse polishing process and the fine polishing process can both be chemical mechanical polishing processes.

[0055] In summary, the embodiment of the present application provides a polishing method, which comprises: first, setting an actual polishing amount according to a previous value influencing factor value, a subsequent value influencing factor value and the lifetime of a polishing pad; then, obtaining a corresponding actual polishing time according to the actual polishing amount, and performing N times of coarse polishing processes on a wafer by using an IAPC system according to the actual polishing time; finally, performing a fine polishing process on the mth wafer by using the IAPC system. The present application optimizes the polishing amount of the IAPC system by using the previous value influencing factor value, the subsequent value influencing factor value and the lifetime of the polishing pad, realizes the dynamic adjustment of the polishing amount of each wafer in different lifetime periods, optimizes the existing feedback logic to realize the optimization of the polishing time, greatly improves the success rate of the batch overstock of random stations, avoids the abnormal polishing thickness of the chips in the first few batches when the platform is worked again due to long-term overstock, and makes the IAPC system run more stably.

[0056] Obviously, the above embodiment is only an example for clear illustration, and does not limit the implementation. For those skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the implementations do not need to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A polishing method characterized by, The method comprises the following steps: According to the previous value influence factor value, the post-value influence factor value and the life of the polishing pad, the actual polishing amount is set; According to the actual polishing amount, the corresponding actual polishing time is obtained, and the IAPC system is used to perform N times of coarse polishing process on the mth wafer according to the actual polishing time, wherein m and N are integers greater than or equal to 1; The IAPC system is used to perform fine polishing process on the mth wafer; Wherein, the actual polishing amount satisfies the following formula: W m =(X m -E m +d×F), wherein, W m is the actual polishing amount of the mth wafer, X m is the preset polishing amount of the mth wafer with the previous value influence factor value, E m is the feedback thickness with the previous value influence factor value and the subsequent value influence factor value, d is a coefficient, and F is the service life of the polishing pad, wherein the range of the coefficient is 0.1-1. The preset polishing amount of the mth wafer affected by the previous value of the influencing factor satisfies the following formula: X m = A + B m , wherein A is an ideal polishing amount, and B m is the previous value of the influencing factor of the mth wafer. The previous value of the influencing factor of the mth wafer satisfies the following formula: B m = b1 m - b2 m , wherein b1 m is the actual measurement of the thickness of the mth wafer before rough grinding, and b2 m is the target value of the thickness of the mth wafer before rough grinding. The feedback thickness of the pre-value influence factor value and the post-value influence factor value satisfies the following formula: E m = (Y m - X m ) ÷ X m , wherein Y m is a preset grinding amount of the mth wafer with the post-value influence factor value. The preset polishing amount of the mth wafer affected by the post-value influencing factor value satisfies the following formula: Y m = A + B m - C m , wherein C m is the post-value influencing factor value of the mth wafer. The post-value influencing factor value of the mth wafer satisfies the following formula: C m = c1 m-1 - c2 m-1 , wherein c1 m-1 is the actual measurement of the thickness of the m-1th wafer after rough grinding, c2 m-1 is the target value of the thickness of the m-1th wafer after rough grinding; wherein the post-value influencing factor value of the 1st wafer is 0.

2. The polishing method according to claim 1, wherein When N is an integer greater than 1, the step of obtaining the corresponding actual polishing time according to the actual polishing amount and performing N times of coarse polishing process on the mth wafer according to the actual polishing time by using the IAPC system comprises: The actual polishing amount is evenly divided into N parts to obtain an actual average polishing amount; According to the actual average polishing amount, the actual average polishing time corresponding to each coarse polishing process is obtained; The IAPC system is used to perform N times of coarse polishing process on the wafer according to the actual average polishing time.

3. The polishing method according to claim 1, wherein The thickness of the mth wafer removed by coarse polishing is proportional to the value of the selected coefficient.

4. The polishing method according to claim 1, wherein the actual average polishing amount of the mth wafer satisfies the following formula: W1 m = W m ÷ N, wherein W1 m is the actual average polishing amount of the mth wafer; The actual average polishing time satisfies the following formula: t m = W1 m ÷ v, wherein t m is the actual average polishing time of the mth wafer, and v is a polishing rate, wherein the polishing rate is set in advance by the IAPC system.

5. The polishing method according to claim 1, wherein The step of performing fine polishing process on the wafer by using the IAPC system comprises: The IAPC system is used to polish and remove the particles on the surface of the wafer to planarize the surface of the wafer.

6. The polishing method according to claim 1, wherein The coarse polishing process and the fine polishing process are both chemical mechanical polishing processes.

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