Method for stabilizing grinding rate and grinding method

Abstract

The invention provides a method for stabilizing the grinding rate and a grinding method. The method for stabilizing the grinding rate comprises the steps that a passivation step is executed on a diamond disc to be replaced; carrying out a grinding process in the first manufacturing process by using the diamond disc subjected to the passivation step; wherein the passivation step comprises the steps that the diamond disc to be replaced is used for conducting the grinding procedure in the second manufacturing procedure, and the grinding procedure lasts for preset time, so that the grinding efficiency of the diamond disc enters a stable interval. According to the configuration, the passivating step is carried out on the diamond disc to be replaced, the diamond disc to be replaced is used for carrying out the grinding procedure of the second manufacturing procedure for preset time, the originally sharp diamond disc is passivated, the grinding efficiency of the passivated diamond disc enters a stable interval, it is guaranteed that the diamond disc can effectively grind a grinding pad, and the grinding efficiency of the diamond disc is improved. The holes in the grinding pad are opened, the hardness of the grinding pad is stabilized, then the grinding rate is stabilized, the running time of a machine table is prolonged, the product yield is guaranteed, and the loss of raw materials and the consumption of energy are reduced.

Description

Technical Field

[0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for stabilizing a grinding rate and a grinding method. Background Art

[0002] In the current STI (Shallow Trench Isolation) process, a complete isolation structure is obtained after thin film deposition, dry etching, photoresist removal, thermal oxidation, trench filling, chemical mechanical polishing (CMP), and removal of the silicon nitride mask.

[0003] Among them, the main abrasive particles of the polishing liquid used in the CMP process of the STI process are cerium oxide particles, which are positively charged and are usually surrounded by negatively charged additives. During the polishing process, the polishing head needs to absorb the wafer and apply downward pressure to break the particle clusters and expose the cerium oxide particles to grind and polish the wafer surface.

[0004] The existing grinding process uses a diamond disc to grind the grinding pad to open the pores of the grinding pad and stabilize the hardness of the grinding pad. However, the diamond disc needs to be replaced after a certain period of use. The surface of the replaced diamond disc is too sharp, which will cause the grinding pad to wear seriously and become too soft. This stage usually lasts for several hours, seriously affecting the running efficiency.

[0005] At the same time, a polishing pad that is too soft may not be able to break up the particle clusters under pressure, affecting the polishing efficiency. Even if the particle clusters are broken, the cerium oxide particles are easily trapped in the pores due to their large pores, further affecting the polishing efficiency.

[0006] Based on this, how to stabilize the grinding efficiency of the diamond disk on the grinding pad and then stabilize the grinding rate has become a technical problem that technicians in this field need to solve. Summary of the invention

[0007] The purpose of the present invention is to provide a method for stabilizing the grinding rate and a grinding method to solve the problem in the prior art that the diamond disk is too sharp, causing the grinding pad to be too soft, thus affecting the grinding efficiency.

[0008] In order to achieve the above object, the present invention provides a method for stabilizing the grinding rate, comprising:

[0009] Perform a passivation step on the diamond disc to be replaced;

[0010] Using the diamond disk that has completed the passivation step to perform a grinding step in the first process;

[0011] Wherein, the passivation step comprises:

[0012] The diamond disk to be replaced is used to perform the grinding process in the second process for a predetermined time so that the grinding efficiency of the diamond disk enters a stable range.

[0013] Optionally, the type of polishing liquid used in the first process and the second process is the same.

[0014] Optionally, the first process includes an STI process.

[0015] Optionally, the second process includes an ILD process.

[0016] Optionally, the predetermined time includes: using the diamond disk to be replaced to perform the grinding step in the second process for 7.5 hours to 8.5 hours.

[0017] Optionally, the stable interval includes: within a range of 8 hours to 30 hours of using the diamond disk for the grinding process, the grinding efficiency of the diamond disk remains stable.

[0018] In order to achieve the above object, the present invention also provides a grinding method, comprising:

[0019] Perform replacement steps for the diamond disc used for a preset time period;

[0020] Using the diamond disc that has completed the replacement step to perform grinding, and after the diamond disc that has completed the replacement step reaches the preset time length, repeating the replacement step;

[0021] Wherein, the replacement step comprises:

[0022] The passivation step is performed on the diamond disk to be replaced using the method of stabilizing the grinding rate as described above.

[0023] Optionally, the preset duration includes: the total usage duration of the diamond disk in the first process and the second process.

[0024] Optionally, the preset time length includes: using the diamond disk for a grinding process of 29.5 hours to 30.5 hours.

[0025] Optionally, the replacing step further includes:

[0026] Performing a polishing efficiency test on the diamond disk that has completed the passivation step to obtain a real-time polishing efficiency;

[0027] If the real-time grinding efficiency is within the stable interval or within the controllable range, the diamond disk is used to perform the grinding process; wherein the controllable range includes the stable interval;

[0028] If the real-time polishing efficiency is outside the controllable range, it is determined that the diamond disk has failed in passivation and the diamond disk is scrapped.

[0029] Compared with the existing grinding methods, the method for stabilizing the grinding rate and the grinding method provided in the present application have the following advantages:

[0030] In the method for stabilizing the grinding rate of the present application, a passivation step is performed on the diamond disk to be replaced, and the diamond disk to be replaced is used to perform the grinding process of the second process for a predetermined time, so that the originally sharp diamond disk is passivated, so that the grinding efficiency of the passivated diamond disk enters a stable range, ensuring that the diamond disk can effectively grind the grinding pad, opening the pores on the grinding pad, stabilizing the hardness of the grinding pad, and then stabilizing the grinding rate, increasing the running time of the machine and ensuring the yield of the product, and reducing the loss of raw materials and energy consumption.

[0031] In the grinding method of the present application, the diamond disk to be replaced is passivated by using the above-mentioned method for stabilizing the grinding rate, thereby stabilizing the grinding efficiency of the diamond disk and thus stabilizing the grinding rate; at the same time, after the diamond disk has been used for a preset period of time, it is repeatedly replaced, thereby ensuring that the grinding efficiency of the replaced diamond disk is always within a stable range, thereby being able to maintain the product yield on the basis of increasing the productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of a grinding process in a conventional STI process;

[0033] Figure 2 Schematic diagram of grinding the abrasive pad for an existing diamond disk;

[0034] Figure 3 A flow chart of a method for stabilizing a polishing rate provided by an embodiment of the present invention;

[0035] Figure 4 A flow chart of a grinding method provided in an embodiment of the present invention.

[0036] The description of each reference numeral is as follows:

[0037] 1-diamond disk; 2-polishing pad; 3-polishing fluid; 4-wafer. DETAILED DESCRIPTION

[0038] In order to make the purpose, advantages and features of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In addition, the structure shown in the drawings is often a part of the actual structure. In particular, the emphasis of each drawing is different, and sometimes different scales are used.

[0039] As used in this specification, the singular forms "a", "an" and "the" include plural objects, the term "or" is generally used to include the meaning of "and / or", the term "several" is generally used to include the meaning of "at least one", and the term "at least two" is generally used to include the meaning of "two or more". In addition, the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second" and "third" may explicitly or implicitly include one or at least two of the features, "one end" and "the other end" and "the proximal end" and "the distal end" generally refer to two corresponding parts, which include not only the endpoints, and the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. In addition, as used in this specification, an element disposed on another element generally only indicates that there is a connection, coupling, cooperation or transmission relationship between the two elements, and the connection, coupling, cooperation or transmission between the two elements may be direct or indirect through an intermediate element, and it cannot be understood as indicating or implying the spatial position relationship between the two elements, that is, one element may be in any orientation such as inside, outside, above, below or on one side of another element, unless the content clearly indicates otherwise. The terms "upper", "lower", "top" and "bottom" are generally relative position relationships arranged in the direction of gravity; the terms "vertical, vertical direction" generally refer to the direction of gravity, which is generally perpendicular to the ground, and "horizontal, horizontal plane direction" generally refers to the direction parallel to the ground; for ordinary technicians in this field, the specific meanings of the above terms in this specification can be understood according to specific circumstances.

[0040] The purpose of the present invention is to provide a method for stabilizing the grinding rate and a grinding method to solve the problem in the prior art that the diamond disk is too sharp, causing the grinding pad to be too soft, thus affecting the grinding efficiency.

[0041] Please refer to Figure 1 to Figure 2 In the grinding process of the STI (Shallow Trench Isolation) process, the grinding liquid 3 uses cerium oxide particles, which have a positive charge and are usually surrounded by negatively charged additives during transportation and storage, forming particle clusters (such as Figure 1As shown). Therefore, in the grinding process, it is necessary to drive the wafer 4 to apply downward pressure through the grinding head to break the particle clusters, so that the cerium oxide particles are exposed and grinded and polished with the surface of the wafer 4. It can be understood by those skilled in the art that the grinding process also requires the cooperation of the grinding pad 2 and the diamond disk 1, such as Figure 2 As shown, the grinding pad 2 has certain pores, which helps to retain and transport the grinding liquid 3 on the surface of the grinding pad 2, and the role of the diamond disk 1 is to keep the pores of the grinding pad 2 open and maintain the hardness of the grinding pad 2. In the normal production process, the diamond disk 1 will become too passivated after a certain period of use, and the pores of the grinding pad 2 cannot be opened, which will cause the grinding rate to be too fast and uncontrollable, and it is easy to cause wear on the surface of the wafer 4, thereby generating waste sheets, resulting in a decrease in yield and an increase in production costs. Therefore, it is necessary to replace the diamond disk 1 in time after the diamond disk 1 reaches a certain time limit, and the diamond disk 1 to be replaced is often too sharp, which will make the grinding pad 2 too soft. When the grinding head applies downward pressure, it is easy to be unable to press open the particle cluster, resulting in a decrease in grinding efficiency; and even if the particle cluster is opened, the cerium oxide particles are easy to fall into the overly soft pores, further affecting the grinding efficiency. In summary, in the grinding process in the STI process, it is necessary to stabilize the grinding efficiency of the diamond disk 1 first, and then stabilize the grinding efficiency.

[0042] As can be understood by those skilled in the art, the diamond disk 1 is also called a diamond dressing disk or a diamond grinding disk. The pores of the grinding pad 2 are trimmed with diamond to maintain the hardness of the grinding pad 2, thereby maintaining the grinding efficiency. Diamonds will also wear out during the trimming process, thereby affecting the grinding efficiency and the hardness of the grinding pad 2. As can be seen from the foregoing, the diamond disk 1 is too sharp or too passivated, which is not conducive to the control of the grinding efficiency. Tests have shown that if the diamond disk 1 is too sharp in the early stage, the grinding efficiency will be low; and if the diamond disk 1 is too worn in the later stage, the grinding efficiency will be too high and uncontrolled, and waste sheets will be easily generated; and when the wear of the diamond disk 1 is at a moderate level, the grinding efficiency of the diamond disk 1 enters a stable range. At this time, the diamond disk 1 trims the grinding pad 2 so that the hardness of the grinding pad 2 is appropriate, thereby stabilizing the grinding efficiency. Therefore, those skilled in the art need to reasonably use the diamond disk 1 in the stable range, and take appropriate measures to make the diamond disk 1 to be replaced in the stable range.

[0043] Please refer to Figures 1 to 3 The present invention provides a method for stabilizing a grinding rate, comprising:

[0044] Step S1: performing a passivation step on the diamond disk 1 to be replaced;

[0045] Step S2: using the diamond disk 1 that has completed the passivation step to perform the grinding process in the first process;

[0046] Wherein, the passivation step comprises:

[0047] Step S1 - 1 : using the diamond disk 1 to be replaced to perform the grinding process in the second process for a predetermined time so that the grinding efficiency of the diamond disk 1 enters a stable range.

[0048] It should be noted that in this embodiment, the diamond disk 1 to be replaced is a new diamond disk 1 that has not been used, the first process is the STI process, and the second process is the ILD (Inter Level Dielectric) process. Those skilled in the art can understand that the ILD process refers to the formation of a dielectric material layer between the transistor and the first metal layer to form electrical isolation. The ILD dielectric layer can effectively reduce the parasitic capacitance between the metal and the substrate, and improve the parasitic field effect transistor formed by the metal crossing different regions. The grinding process in the ILD process usually requires two steps of grinding. In the first step of grinding, large pieces of oxide are polished and removed, and its main goal is to remove the initial oxide morphology generated by the lower gate module to make the surface of the wafer 4 flat; in the second step of grinding, mild process conditions (such as low pressure and soft pads) are used to wipe off the remaining oxide, and its main goal is to remove defects such as scratches generated by the first step. In addition, the second step of grinding needs to ensure the target thickness of the final oxide.

[0049] Since the type and properties of the grinding liquid 3 used in the grinding process of the STI process are similar to those of the grinding liquid 3 used in the grinding process of the ILD process, the diamond disk 1 that completes the passivation step in the ILD process can directly replace the diamond disk 1 used in the STI process without considering the impact of different grinding liquids 3. In other embodiments, the first process and the second process can also be other processes in the semiconductor manufacturing process, but it should be noted that the type and properties of the grinding liquid 3 used in the first process and the second process should be the same or similar to avoid the impact of the diamond disk 1 dipped in different grinding liquids 3 on the grinding efficiency. The stable interval in this embodiment refers to a certain degree of passivation of the diamond on the diamond disk 1. In this interval, the hardness of the grinding pad 2 after being trimmed by the diamond disk 1 is moderate, and it will not be too hard or too soft. At this time, the operator can adjust the grinding parameters (such as the downward pressure of the grinding head, the rotation speed of the carrier, etc.) to make the grinding rate tend to be stable, thereby effectively increasing the running time of the machine and ensuring the yield of the product.

[0050] With such configuration, by performing a passivation step on the diamond disk 1 to be replaced, the diamond disk 1 to be replaced is first used to perform the grinding process of the second process for a predetermined time, and the originally sharp diamond disk 1 is passivated, so that the grinding efficiency of the passivated diamond disk 1 enters a stable range, ensuring that the diamond disk 1 can effectively grind the grinding pad 2, open the pores on the grinding pad 2, stabilize the hardness of the grinding pad 2, and then stabilize the grinding rate, increase the running time of the machine, ensure the yield of the product, and reduce the loss of raw materials and energy consumption.

[0051] Optionally, the predetermined time includes: using the diamond disk 1 to be replaced to perform the grinding process in the second process for 7.5h to 8.5h. It should be noted that experiments have shown that after the diamond disk 1 to be replaced is used for about 8h, its grinding efficiency will enter a stable range, that is, the diamond surface on the diamond disk 1 is partially passivated, and the hardness of the grinding pad 2 can be effectively maintained. Therefore, in this embodiment, it is necessary to use the diamond disk 1 to be replaced in the ILD process for about 8h before replacing it for use in the STI process. And because the grinding process in the ILD process is a two-step grinding, and the first step of grinding is mainly to remove the original morphology, and does not involve the control of the thickness of the oxide layer, therefore, using a sharp diamond disk 1 in the ILD process will not cause irreversible effects on product yield and production efficiency. Of course, in other embodiments, the predetermined time can also be set to other reasonable values ​​based on the different diamond disks 1, and this embodiment does not limit this.

[0052] As an optional embodiment, the stable interval includes: the grinding efficiency of the diamond disk 1 remains stable within the range of 8h to 30h when the diamond disk 1 is used for the grinding process. Experiments have shown that the stable interval of the diamond disk 1 is usually within the range of 8h to 30h. When the diamond disk 1 is used for less than 8h, it is still in a relatively sharp stage, causing the grinding pad 2 to be too soft; and when the diamond disk 1 is used for more than 30h, it may be over-passivated, causing the grinding pad 2 to be too hard. Of course, in some other embodiments, the stable interval may vary due to the different quality and type of the diamond disk 1 itself, as well as the different grinding parameters. Those skilled in the art can configure the stable interval according to the actual situation, and then reasonably determine the use time of the passivation step.

[0053] In another embodiment, please refer to Figure 1 , Figure 2 and Figure 4 The present invention also provides a grinding method, comprising:

[0054] Step S10: performing a replacement step on the diamond disk 1 used for a preset time;

[0055] Step S20: grinding with the diamond disk 1 that has completed the replacement step, and repeating the replacement step after the diamond disk 1 that has completed the replacement step reaches a preset time length;

[0056] The replacement steps include:

[0057] Step S10 - 1 : using the method for stabilizing the grinding rate as described above, a passivation step is performed on the diamond disk 1 to be replaced.

[0058] Generally speaking, after the diamond disk 1 is used for a preset time, the passivation of the diamond is usually too large. At this time, if the diamond disk 1 is not replaced in time, the pores on the grinding pad 2 will not be opened, causing the grinding pad 2 to be too hard. Although the grinding rate will be greatly increased, the thickness of the film on the wafer 4 will become uncontrollable for the operator, and it is easy to cause wear on the surface of the wafer 4, thereby generating waste sheets. Therefore, in this embodiment, once the diamond disk 1 is used for a preset time, the replacement step is immediately performed, and the real-time grinding efficiency of the diamond disk 1 is no longer tested to avoid the risk of generating waste sheets. It should be noted that in this embodiment, the replacement step and the passivation step can be performed simultaneously, and there is no need to wait until the diamond disk 1 needs to perform the replacement step before the passivation step is performed on the diamond disk 1 to be replaced.

[0059] With such configuration, by using the above-mentioned method for stabilizing the grinding rate, the diamond disk 1 to be replaced is passivated, the grinding efficiency of the diamond disk 1 is stabilized, and thus the grinding rate is stabilized; at the same time, after the diamond disk 1 has been used for a preset period of time, it is repeatedly replaced, thereby ensuring that the grinding efficiency of the replaced diamond disk 1 is always within a stable range, thereby being able to maintain the product yield on the basis of increasing the productivity.

[0060] As an optional embodiment, the preset duration includes: the sum of the usage time of the diamond disk 1 in the first process and the second process. Further, the preset duration includes: using the diamond disk 1 for the grinding process for 29.5h to 30.5h. It should be noted that the preset duration refers to the usage time of the diamond disk 1 to be replaced, that is, the sum of the usage time of the diamond disk 1 to be replaced in the first process and the second process. In this embodiment, the preset duration is about 30h. After the diamond disk 1 has been ground for 30h, it is possible that excessive passivation may cause damage to the surface of the wafer 4, thereby affecting the yield. In other embodiments, the preset duration may also change based on the diamond disk 1 and the grinding parameters. Those skilled in the art can configure this according to the actual situation, and this embodiment does not limit this.

[0061] In an alternative embodiment, please continue to refer to Figure 4 , the replacement steps also include:

[0062] Step S10-2: performing a polishing efficiency test on the diamond disk 1 that has completed the passivation step to obtain a real-time polishing efficiency;

[0063] Step S10-3: If the real-time grinding efficiency is within the stable interval or within the controllable range, the diamond disk 1 is used to perform the grinding process; wherein the controllable range includes the stable interval;

[0064] Step S10 - 4 : If the real-time polishing efficiency is outside the controllable range, it is determined that the diamond disk 1 has failed in passivation, and the diamond disk 1 is scrapped.

[0065] It should be noted that in an alternative embodiment, after the diamond disk 1 that has completed the passivation step is installed in the grinding equipment of the STI process, a grinding efficiency test will be performed and a real-time grinding efficiency will be obtained. In this embodiment, the controllable range includes a stable interval and is greater than the range of the stable interval. For example, the stable interval has an upper limit and a lower limit, and the controllable range can be within the range from 90% of the lower limit to the upper limit; when the real-time grinding efficiency is within the stable interval or the controllable range, the diamond disk 1 is allowed to perform the grinding process of the STI process; and when the real-time grinding efficiency of the diamond disk 1 is outside the stable interval but within the controllable range, passivation is directly performed again on the grinding equipment of the STI process so that the grinding efficiency of the diamond disk 1 is within the stable interval. Once it is found that the real-time grinding efficiency of the diamond disk 1 that has completed the passivation step is outside the controllable range, it is considered that the passivation of the diamond disk 1 has failed and it is directly scrapped.

[0066] In summary, in the method for stabilizing the grinding rate and the grinding method provided in the embodiments of the present invention, the method for stabilizing the grinding rate includes: performing a passivation step on the diamond disk to be replaced; using the diamond disk that has completed the passivation step to perform the grinding process in the first process; wherein the passivation step includes: using the diamond disk to be replaced to perform the grinding process in the second process, and continuing for a predetermined time, so that the grinding efficiency of the diamond disk enters a stable range.

[0067] With such configuration, by executing the passivation step on the diamond disk to be replaced, the diamond disk to be replaced is first used to perform the second process grinding process for a predetermined time, and the originally sharp diamond disk is passivated, so that the grinding efficiency of the passivated diamond disk enters a stable range, ensuring that the diamond disk can effectively grind the grinding pad, open the pores on the grinding pad, stabilize the hardness of the grinding pad, and then stabilize the grinding rate, thereby increasing the running time of the machine, ensuring the yield of the product, and reducing the loss of raw materials and energy consumption.

[0068] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A method for stabilizing a grinding rate, characterized in that: include: Perform a passivation step on the diamond disc to be replaced; Using the diamond disk that has completed the passivation step to perform a grinding step in the first process; Wherein, the passivation step comprises: The diamond disk to be replaced is used to perform the grinding process in the second process for a predetermined time so that the grinding efficiency of the diamond disk enters a stable range.

2. The method for stabilizing the polishing rate according to claim 1, wherein: The type of polishing liquid used in the first process and the second process is the same.

3. The method for stabilizing the polishing rate as claimed in claim 2, characterized in that: The first process includes an STI process.

4. The method for stabilizing the polishing rate as claimed in claim 2, wherein: The second process includes an ILD process.

5. The method for stabilizing the polishing rate according to any one of claims 1 to 4, characterized in that: The predetermined time includes: using the diamond disk to be replaced to perform the grinding process in the second process for 7.5 hours to 8.5 hours.

6. The method for stabilizing the polishing rate according to any one of claims 1 to 4, characterized in that: The stable interval includes: within the range of 8 hours to 30 hours of using the diamond disk for the grinding process, the grinding efficiency of the diamond disk remains stable.

7. A grinding method, characterized in that: include: Perform replacement steps for the diamond disc used for a preset time period; Grinding with the diamond disc that has completed the replacement step, and repeating the replacement step after the diamond disc that has completed the replacement step reaches the preset time length; Wherein, the replacement step comprises: The passivation step is performed on the diamond disk to be replaced using the method for stabilizing the grinding rate according to any one of claims 1 to 6.

8. The grinding method according to claim 7, characterized in that: The preset duration includes: the total usage duration of the diamond disk in the first process and the second process.

9. The grinding method according to claim 8, characterized in that: The preset time includes: using the diamond disc to perform the grinding process for 29.5 hours to 30.5 hours.

10. The grinding method according to claim 7, characterized in that: The replacement step further comprises: Performing a polishing efficiency test on the diamond disk that has completed the passivation step to obtain a real-time polishing efficiency; If the real-time grinding efficiency is within the stable interval or within the controllable range, the diamond disk is used to perform the grinding process; wherein the controllable range includes the stable interval; If the real-time polishing efficiency is outside the controllable range, it is determined that the diamond disk has failed in passivation and the diamond disk is scrapped.

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