Wafer polishing apparatus and wafer polishing method

Abstract

The embodiment of the present application provides a wafer grinding device and a wafer grinding method, which comprises: a grinding pad arranged at a predetermined working position; a grinding pad trimmer located on the top surface of the predetermined working position, the grinding pad being parallel to a predetermined working plane where the predetermined working position is located, and the grinding pad trimmer being used for trimming the grinding pad during the process of grinding a wafer to be ground; an imaging sensor arranged on the side of the grinding pad trimmer close to the predetermined working position, a probe of the imaging sensor being directed to the predetermined working plane, and the imaging sensor being used for acquiring a grinding pad surface image during the process of trimming the grinding pad by the grinding pad trimmer; and an image analysis device connected to the imaging sensor and used for detecting the surface state of the grinding pad according to the grinding pad surface image. The grinding pad surface image can be acquired in real time during the process of trimming the grinding pad, so that the wafer is prevented from being scratched due to the low surface cleanliness or unevenness of the grinding pad.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, specifically to a wafer grinding equipment and a wafer grinding method. Background Technology

[0002] Polishing pad dressers used in semiconductor manufacturing processes only have the function of dressing wafers with polishing pads and cleaning residues on the surface of the polishing pads; they cannot prevent the polishing pads from scratching the wafers. Therefore, how to avoid polishing pads scratching wafers has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0003] In view of this, this application provides a wafer grinding equipment and a wafer grinding method, which can effectively avoid scratching the wafer by the grinding pad.

[0004] To achieve the above objectives, embodiments of the present invention provide a wafer grinding apparatus, comprising:

[0005] Abrasive pad, positioned at a predetermined working location;

[0006] A polishing pad dresser is located on the top surface of the predetermined working position, and the polishing pad is parallel to the predetermined working plane where the predetermined working position is located. It is used to dress the polishing pad during the polishing of the wafer to be polished.

[0007] An imaging sensor is disposed on the side of the polishing pad dresser near the predetermined working position, and the probe of the imaging sensor points to the predetermined working plane, for acquiring a surface image of the polishing pad during the polishing pad dresser's process of dressing the polishing pad.

[0008] An image analysis device, connected to the imaging sensor, is used to detect the surface state of the abrasive pad based on the surface map of the abrasive pad.

[0009] Optionally, the imaging sensor is located at the center of the abrasive pad conditioner.

[0010] Optionally, the abrasive pad trimmer is recessed in a direction away from the predetermined working position.

[0011] Optionally, the imaging sensor is an infrared sensor.

[0012] Optionally, the image analysis device is used to fit the surface image of the abrasive pad with a preset surface image to obtain surface similarity, and to determine whether to continue using the abrasive pad trimmer based on the surface similarity.

[0013] Optional, also includes:

[0014] An image generation device, connecting the imaging sensor and the image analysis device, is used to convert the parameters acquired by the imaging sensor into a surface image of the abrasive pad.

[0015] Optional, also includes:

[0016] A wafer positioning device is used to clamp the wafer to be ground to a predetermined working position;

[0017] A dressing device is positioned on the predetermined working plane, with one end on the grinding pad dressing device and the other end on a rotating shaft, and the grinding pad positioning device rotates around the rotating shaft.

[0018] The present invention also provides a wafer grinding method, applied to the wafer grinding equipment described above, comprising:

[0019] Provide wafers to be ground;

[0020] The wafer to be polished is clamped to a predetermined working position and polished using a polishing pad;

[0021] Obtain a surface view of the abrasive pad of the abrasive pad dresser;

[0022] Determine whether the surface condition of the polishing pad meets the preset requirements based on the polishing pad surface diagram; if it does not meet the preset requirements, stop the step of polishing the wafer to be polished using the polishing pad dresser.

[0023] Optionally, the step of determining whether the surface condition of the abrasive pad meets the preset requirements based on the surface map of the abrasive pad includes:

[0024] A preset surface image of the abrasive pad is obtained, and the surface image of the abrasive pad is fitted with the preset surface image to obtain surface similarity. Based on whether the surface similarity value reaches the expected value, it is determined whether the surface state of the abrasive pad meets the preset requirements.

[0025] Optionally, it also includes: if the surface similarity is greater than the expected value, then continue the step of polishing the wafer to be polished using the polishing pad dresser.

[0026] Compared with the prior art, the technical solution of the embodiments of the present invention has the following advantages:

[0027] The wafer polishing apparatus provided in this application includes: a wafer positioning device for gripping a wafer to be polished to a predetermined working position; a polishing pad conditioner located on the top surface of the predetermined working position, the surface of the polishing pad conditioner being parallel to a predetermined working plane of the predetermined working position; an imaging sensor disposed on the side of the polishing pad conditioner near the predetermined working position, the probe of the imaging sensor pointing towards the predetermined working plane, for acquiring a surface image of the polishing pad; and an image analysis device connected to the imaging sensor for detecting the surface state of the polishing pad conditioner based on the surface image of the polishing pad.

[0028] In this way, by setting an imaging sensor on the side of the polishing pad dresser close to the predetermined working position, the imaging sensor located inside the polishing pad dresser can move together with the polishing pad dresser during the polishing pad dressing process. Thus, regardless of the position of the polishing pad dresser, the surface image of the polishing pad can be obtained in real time. Then, based on the surface image of the polishing pad, it can be determined whether the polishing pad is suitable for continued operation, thereby avoiding scratching the wafer due to low surface cleanliness or unevenness of the polishing pad. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structure of the wafer grinding equipment provided in an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of the abrasive pad dressing device provided in an embodiment of the present invention;

[0032] Figures 3a-3b This is a schematic diagram of the surface of the polishing pad provided in an embodiment of the present invention;

[0033] Figure 4 This is a flowchart of the wafer grinding method provided in the embodiments of the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] As semiconductor devices evolve towards smaller feature sizes, the requirements for wafer surface flatness in photolithography processes are becoming increasingly stringent. Uneven surfaces can lead to inaccurate photolithography focus, thus affecting pattern precision. To improve wafer surface flatness, CMP (Chemical Mechanical Planarization) processes can be used to refine the wafer surface. However, CMP scratches can occur during the CMP process.

[0036] The inventors believe that CMP scratches can occur during the CMP process, causing severe damage to the wafer surface and affecting the performance and reliability of the final product. CMP scratches may be caused by uneven abrasive particle size or agglomeration, problems with the polishing pad, and issues with CMP operating conditions and equipment. The inventors further believe that problems with the abrasive particles and CMP operating conditions and equipment can be prevented by taking measures before starting the CMP equipment. However, the condition of the polishing pad changes during the CMP process; therefore, if problems with the polishing pad cannot be resolved during CMP, the CMP equipment must be stopped for rectification, thus affecting polishing efficiency.

[0037] An existing polishing pad dresser includes functions for dressing the polishing pad surface and cleaning residues from the polishing pad surface to prevent contamination. However, after dressing and cleaning the polishing pad surface, the dresser cannot provide real-time feedback on the cleanliness and surface condition of the polishing pad. Therefore, if the cleanliness and surface condition of the polishing pad are still problematic after dressing and cleaning, continuing to use the polishing pad for polishing poses a risk of scratching the wafer.

[0038] To address the aforementioned problems, embodiments of the present invention provide a wafer polishing apparatus that uses an imaging sensor mounted on a polishing pad conditioner to monitor the state of the polishing pad in real time. As an optional implementation, Figure 1 The diagram illustrates the structural intent of the wafer grinding apparatus provided in an embodiment of this application. For example... Figure 1 As shown in the embodiments of this application, the wafer grinding equipment includes the following structure.

[0039] Abrasive pad 100 is set in the predetermined working position.

[0040] The polishing pad dresser 200 is located on the top surface of the predetermined working position. The polishing pad is parallel to the predetermined working plane where the predetermined working position is located, and is used to dress the polishing pad during the polishing of the wafer to be polished.

[0041] like Figure 1As shown, the surface area of ​​the polishing pad dresser 200 is smaller than that of the polishing pad 100, and the polishing pad dresser 200 can only polish a portion of the polishing pad 100 during polishing. Therefore, the polishing pad dresser 200 needs to move relative to the polishing pad 100 in order to polish all of the polishing pad 100.

[0042] Since the surface area of ​​the polishing pad 100 is relatively large compared to the wafer or the polishing pad dresser 200, during operation, the wafer or the polishing pad dresser 200 will simultaneously use the polishing pad 100. If the polishing pad dresser 200 fails to meet the requirements for polishing the polishing pad 100, that is, if some areas of the polishing pad 100 still have residual abnormalities or scratches after polishing, given that the wafer or the polishing pad dresser 200 will simultaneously use the polishing pad 100, the areas of the polishing pad 100 that fail to meet the requirements may not be detected in time and the wafer polishing operation may be directly performed. This could lead to the residual abnormalities or scratches on the polishing pad 100 scratching the wafer. Therefore, the real-time monitoring of the polishing pad 100's status is very important.

[0043] An imaging sensor 300 is disposed on the side of the polishing pad dresser near the predetermined working position. The probe of the imaging sensor 300 points to the predetermined working plane and is used to acquire a surface image of the polishing pad during the polishing pad dressing process.

[0044] It should be noted that, as Figure 1 As shown, the imaging sensor 300 is disposed on the surface of the abrasive pad dresser 200 and the probe is pointed towards the abrasive pad 100 on the predetermined working plane. At this time, the object monitored by the imaging sensor 300 is the part of the abrasive pad 100 that is being abraded by the abrasive pad dresser 200.

[0045] Because the imaging sensor 300 is disposed on the surface of the abrasive pad trimmer 200, rather than independently of the abrasive pad trimmer 200, the imaging sensor 300 can move along with the abrasive pad trimmer 200 when the abrasive pad trimmer 200 moves relative to the abrasive pad 100. This allows for feedback on the state of the portion of the abrasive pad 100 currently being trimmed by the abrasive pad trimmer 200.

[0046] Furthermore, in an optional implementation, the imaging sensor 300 is disposed at the center of the abrasive pad trimmer 200. In this way, the imaging sensor 300 can more completely monitor the portion of the abrasive pad 100 currently being trimmed by the abrasive pad trimmer 200.

[0047] Furthermore, such as Figure 2As shown, in one alternative implementation, the abrasive pad conditioner 200 is recessed in a direction away from the predetermined working position.

[0048] It should be noted that if the surface of the polishing pad trimmer 200 is a completely flat surface or a surface that bulges towards the predetermined working position, after the imaging sensor 300 is placed on the surface of the polishing pad trimmer 200, the imaging sensor 300 and the polishing pad 100 will rub against each other, resulting in damage to both the imaging sensor 300 and the polishing pad 100. However, when the polishing pad trimmer 200 is recessed away from the predetermined working position, the imaging sensor 300, which is located at the center of the polishing pad trimmer 200, can move away from the polishing pad 100, thereby avoiding friction between the imaging sensor 300 and the polishing pad 100.

[0049] Furthermore, in order to obtain a more accurate state of the surface of the abrasive pad 100, in one optional implementation, the imaging sensor is an infrared sensor.

[0050] Furthermore, the wafer polishing equipment also includes an image analysis device (not shown), connected to the imaging sensor, for detecting the surface condition of the polishing pad based on the surface map of the polishing pad.

[0051] It should be noted that after the imaging sensor 300 acquires the surface image of the polishing pad, the surface image of the polishing pad needs to be analyzed in order to specifically determine the surface state of the polishing pad 100.

[0052] In this way, by setting an imaging sensor on the side of the polishing pad dresser close to the predetermined working position, the imaging sensor located inside the polishing pad dresser can move together with the polishing pad dresser during the polishing pad dressing process. Thus, regardless of the position of the polishing pad dresser, the surface image of the polishing pad can be obtained in real time. Then, based on the surface image of the polishing pad, it can be determined whether the polishing pad is suitable for continued operation, thereby avoiding low surface cleanliness or unevenness of the polishing pad, which could scratch the wafer.

[0053] Furthermore, one example of the surface pattern of the abrasive pad is... Figure 3a and Figure 3b As shown, Figure 3a and Figure 3b The ring-shaped rings are lines representing the grooves on the surface of the abrasive pad 100. Figure 3a The scattered points represent contaminants or damage on the surface of the abrasive pad 100. Therefore... Figure 3a This is a surface view of the polishing pad 100 before it has been trimmed. Figure 3b A surface view of the polishing pad 100 after it has been repaired and meets the requirements.

[0054] To determine the surface condition of the polishing pad 100, it can be determined by comparing the current surface condition diagram of the polishing pad 100 with the surface condition diagram of a polishing pad 100 that meets the requirements. If the difference between the current surface condition diagram of the polishing pad 100 and the surface condition diagram of a polishing pad 100 that meets the requirements is too large, then the current surface condition of the polishing pad 100 does not meet the requirements; otherwise, it does meet the requirements.

[0055] Specifically, the image analysis device is used to compare the differences between the current surface state map of the polishing pad 100 and the polishing pad surface map of the polishing pad 100 that meets the requirements. In one optional implementation, the polishing pad surface map is fitted with a preset surface map to obtain a surface similarity, and the polishing pad 100 is determined based on the surface similarity to continue to be used.

[0056] In one alternative implementation, the image analysis device may further be used to compare the differences between a current surface state image of the abrasive pad 100 and a surface image of the abrasive pad 100 that meets the requirements. This may involve obtaining the number of points representing contaminants or damage on the surface of the abrasive pad 100 in the current surface state image. If the number of points meets the requirements, then the surface state of the abrasive pad 100 meets the requirements.

[0057] Furthermore, in an optional implementation, the wafer polishing apparatus provided in this application embodiment further includes an image generation device (not shown), which connects the imaging sensor 300 and the image analysis device (not shown), and is used to convert the parameters acquired by the imaging sensor 300 into a surface map of the polishing pad.

[0058] It should be noted that the imaging sensor 300 only acquires a state signal representing the surface state of the polishing pad 100. The surface state of the polishing pad 100 can only be determined by converting the state signal into a surface image of the polishing pad and then analyzing the surface image.

[0059] Furthermore, in one alternative implementation, please refer to [link / reference needed]. Figure 1 The wafer grinding equipment provided in this application embodiment also includes:

[0060] The wafer positioning device 400 is used to clamp the wafer to be ground to the predetermined working position.

[0061] A dressing device 210 is disposed on the predetermined working plane, with one end disposed on the abrasive pad dressing device 200 and the other end disposed on a rotating shaft. The dressing device 210 can rotate around the rotating shaft. In this way, the abrasive pad dressing device 200 can be moved by the dressing device 210, so that only one abrasive pad dressing device 200 with a relatively small working surface area can be used to dress the abrasive pad 100 with a relatively large working surface area.

[0062] This invention also provides a wafer polishing method that uses an imaging sensor on a polishing pad conditioner to monitor the condition of the polishing pad in real time, thereby preventing wafer scratches. As an optional implementation, Figure 4 A flowchart of a wafer polishing method provided in an embodiment of this application is shown. Figure 4 As shown in the embodiments of this application, the wafer grinding method includes the following steps.

[0063] Step S10: Provide the wafer to be ground.

[0064] Step S20: Clamp the wafer to be ground to the predetermined working position and grind the wafer using the grinding pad.

[0065] It should be noted that the wafer to be ground is clamped to the preset working position and fixed by the wafer positioning device to await the subsequent grinding process.

[0066] Step S30: Obtain a surface view of the abrasive pad of the abrasive pad dresser.

[0067] Specifically, one example of the surface pattern of the abrasive pad is... Figure 3a and Figure 3b As shown, Figure 3a and Figure 3b The ring-shaped rings are lines representing the grooves on the surface of the abrasive pad 100. Figure 3a The scattered points represent contaminants or damage on the surface of the abrasive pad 100. Therefore... Figure 3a This is a surface view of the polishing pad 100 before it has been trimmed. Figure 3b A surface view of the polishing pad 100 after it has been repaired and meets the requirements.

[0068] Step S40: Determine whether the surface condition of the polishing pad meets the preset requirements based on the polishing pad surface diagram. If it meets the preset requirements, continue with the step of polishing the wafer to be polished using the polishing pad dresser.

[0069] In one alternative implementation, if the surface similarity is less than the expected value, the step of grinding the wafer to be ground using the polishing pad dresser is stopped.

[0070] It should be noted that, to determine the surface condition of the polishing pad 100, the difference can be determined by comparing the current surface condition diagram of the polishing pad 100 with the surface condition diagram of a polishing pad 100 that meets the requirements. If the difference between the current surface condition diagram of the polishing pad 100 and the surface condition diagram of a polishing pad 100 that meets the requirements is too large, then the current surface condition of the polishing pad 100 does not meet the requirements; otherwise, it does meet the requirements.

[0071] Furthermore, in an optional implementation, step S40 includes step S41: obtaining a preset surface map of the polishing pad, fitting the surface map of the polishing pad with the preset surface map to obtain surface similarity, and determining whether the surface state of the polishing pad meets the preset requirements based on whether the value of the surface similarity reaches the expected value.

[0072] In this way, by setting an imaging sensor on the side of the polishing pad dresser close to the predetermined working position, the imaging sensor located inside the polishing pad dresser can move together with the polishing pad dresser during the polishing pad dressing process. Thus, regardless of the position of the polishing pad dresser, the surface image of the polishing pad can be obtained in real time. Then, based on the surface image of the polishing pad, it can be determined whether the polishing pad is suitable for continued operation, thereby avoiding scratching the wafer due to low surface cleanliness or unevenness of the polishing pad.

[0073] The foregoing describes multiple embodiments of the present invention. The optional methods described in each embodiment can be combined and cross-referenced without conflict, thereby extending to a variety of possible embodiments. These can all be considered as embodiments disclosed or made public by the present invention.

[0074] While the embodiments of the present invention have been disclosed above, the present invention is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A wafer grinding device, characterized in that, include: Abrasive pad, positioned at a predetermined working location; A polishing pad dresser is located on the top surface of the predetermined working position, and the polishing pad is parallel to the predetermined working plane where the predetermined working position is located. It is used to dress the polishing pad during the polishing of the wafer to be polished. An imaging sensor is disposed on the surface of the polishing pad dresser and on the side close to the predetermined working position. The probe of the imaging sensor points to the predetermined working plane and is used to acquire a real-time image of the polishing pad surface during the polishing pad dresser's process of dressing the polishing pad. The polishing pad dresser is recessed in a direction away from the predetermined working position, and the imaging sensor is disposed in the recess. An image analysis device, connected to the imaging sensor, is used to detect the surface condition of the polishing pad after it has been trimmed, based on the surface map of the polishing pad.

2. The wafer grinding equipment as described in claim 1, characterized in that, The imaging sensor is positioned at the center of the abrasive pad conditioner.

3. The wafer grinding equipment as described in claim 1, characterized in that, The imaging sensor is an infrared sensor.

4. The wafer grinding equipment as described in claim 1, characterized in that, The image analysis device is used to fit the surface image of the abrasive pad with a preset surface image to obtain surface similarity, and to determine whether to continue using the abrasive pad trimmer based on the surface similarity.

5. The wafer grinding equipment as described in claim 1, characterized in that, Also includes: An image generation device, connecting the imaging sensor and the image analysis device, is used to convert the parameters acquired by the imaging sensor into a surface image of the abrasive pad.

6. The wafer grinding equipment as described in claim 1, characterized in that, Also includes: A wafer positioning device is used to clamp the wafer to be ground to a predetermined working position; A dressing device is positioned on the predetermined working plane, with one end on the grinding pad dressing device and the other end on a rotating shaft, and the dressing device rotates around the rotating shaft.

7. A wafer grinding method, applied to the wafer grinding equipment as described in any one of claims 1-6, characterized in that, include: Provide wafers to be ground; The wafer to be polished is clamped to a predetermined working position and polished using a polishing pad; Obtain a surface view of the abrasive pad of the abrasive pad dresser; Determine whether the surface condition of the polishing pad meets the preset requirements based on the polishing pad surface diagram; if it does not meet the preset requirements, stop the step of polishing the wafer to be polished using the polishing pad dresser.

8. The wafer grinding method as described in claim 7, characterized in that, The step of determining whether the surface condition of the abrasive pad meets the preset requirements based on the surface diagram of the abrasive pad includes: A preset surface image of the abrasive pad is obtained, and the surface image of the abrasive pad is fitted with the preset surface image to obtain surface similarity. Based on whether the surface similarity value reaches the expected value, it is determined whether the surface state of the abrasive pad meets the preset requirements.

9. The wafer grinding method as described in claim 8, characterized in that, Also includes: If the surface similarity is greater than the expected value, then continue with the step of polishing the wafer to be polished using the polishing pad dresser.

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