Wafer grinding equipment and wafer grinding method

Abstract

The embodiment of the invention provides wafer grinding equipment and a wafer grinding method, and the wafer grinding equipment comprises a grinding pad which is arranged at a preset working position; the grinding pad trimmer is located on the top face of the preset working position, the grinding pad is parallel to a preset working plane where the preset working position is located, and the grinding pad trimmer is used for trimming the grinding pad in the process of grinding the wafer to be ground; the imaging sensor is arranged on the side, close to the preset working position, of the grinding pad trimmer, a probe of the imaging sensor points to the preset working plane, and the imaging sensor is used for obtaining a grinding pad surface graph in the process that the grinding pad trimmer trims the grinding pad; and the image analysis device is connected with the imaging sensor and is used for detecting the surface state of the grinding pad according to the surface image of the grinding pad. The surface graph of the grinding pad can be obtained in real time when the grinding pad is trimmed, and the situation that a wafer is scratched due to the fact that the surface of the grinding pad is low in cleanliness or uneven is avoided.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of semiconductor technology, and specifically to a wafer grinding device and a wafer grinding method. Background Art

[0002] The polishing pad dresser used in the semiconductor manufacturing process only has the function of using the polishing pad to dress the wafer and clean the residue on the surface of the polishing pad, but cannot prevent the polishing pad from scratching the wafer. Therefore, how to prevent the polishing pad from scratching the wafer has become an urgent problem to be solved by those skilled in the art. Summary of the invention

[0003] In view of this, the present application provides a wafer grinding device and a wafer grinding method, which can effectively prevent the grinding pad from scratching the wafer.

[0004] To achieve the above object, an embodiment of the present invention provides a wafer grinding device, comprising:

[0005] A grinding pad, arranged at a predetermined working position;

[0006] a grinding pad dresser, located on the top surface of the predetermined working position, the grinding pad being parallel to the predetermined working plane where the predetermined working position is located, and used for dressing the grinding pad during the process of grinding the wafer to be ground;

[0007] An imaging sensor is disposed on a side of the polishing pad dresser close to the predetermined working position, the probe of the imaging sensor points to the predetermined working plane, and is used to obtain a polishing pad surface image during the process of the polishing pad dresser dressing the polishing pad;

[0008] An image analysis device is connected to the imaging sensor and is used to detect the surface state of the polishing pad according to the polishing pad surface image.

[0009] Optionally, the imaging sensor is disposed at the center of the polishing pad dresser.

[0010] Optionally, the grinding pad dresser 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 grinding pad surface map with a preset surface map to obtain surface similarity, and determine whether to continue using the grinding pad dresser based on the surface similarity.

[0013] Optionally, also include:

[0014] An image generating device is connected to the imaging sensor and the image analyzing device, and is used for converting the parameters acquired by the imaging sensor into the surface image of the polishing pad.

[0015] Optionally, also include:

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

[0017] The dresser positioning device is arranged on the predetermined working plane, one end of which is arranged on the grinding pad dresser, and the other end of which is arranged with a rotating shaft, and the grinding pad positioning device rotates around the rotating shaft.

[0018] The present invention also provides a wafer grinding method, which is applied to the wafer grinding device as described above and includes:

[0019] Providing a wafer to be ground;

[0020] Clamping the wafer to be ground to a predetermined working position and grinding the wafer to be ground using a grinding pad;

[0021] obtaining a polishing pad surface image of the polishing pad conditioner;

[0022] Determine whether the surface state of the polishing pad meets the preset requirements according to the polishing pad surface map; if it does not meet the preset requirements, stop the step of using the polishing pad dresser to grind the wafer to be ground.

[0023] Optionally, the step of determining whether the surface state of the polishing pad meets preset requirements according to the polishing pad surface map includes:

[0024] A preset grinding pad surface map is obtained, and the grinding pad surface map is fitted with the preset surface map to obtain surface similarity, and whether the surface state of the grinding pad meets the preset requirements is determined according to whether the value of the surface similarity reaches an expected value.

[0025] Optionally, the method further includes: if the surface similarity is greater than an expected value, continuing the step of grinding the wafer to be ground using the grinding pad dresser.

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

[0027] The wafer grinding equipment provided in the embodiment of the present application includes: a wafer positioning device, used to clamp the wafer to be ground to a predetermined working position; a grinding pad dresser, located on the top surface of the predetermined working position, and the surface of the grinding pad dresser is parallel to a predetermined working plane of the predetermined working position; an imaging sensor, arranged on a side of the grinding pad dresser close to the predetermined working position, the probe of the imaging sensor points to the predetermined working plane, and is used to obtain a grinding pad surface image; an image analysis device, connected to the imaging sensor, and used to detect the surface state of the grinding pad dresser according to the grinding pad surface image.

[0028] In this way, by arranging an imaging sensor on the side of the grinding pad dresser close to the predetermined working position, the imaging sensor located on the inner side of the grinding pad dresser can move with the grinding pad dresser during the process of the grinding pad dresser dressing the grinding pad, so that no matter where the grinding pad dresser is, the grinding pad surface image can be obtained in real time, and then it can be judged whether the grinding pad is suitable for continuing to work according to the grinding pad surface image, thereby avoiding scratches on the wafer due to low cleanliness or unevenness of the grinding pad surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0030] Figure 1 is a schematic structural diagram of a wafer grinding device provided by an embodiment of the present invention;

[0031] Figure 2 is a schematic structural diagram of a polishing pad dresser provided by an embodiment of the present invention;

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

[0033] Figure 4 It is a flow chart of a wafer grinding method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0035] As semiconductor devices develop towards smaller feature sizes, the photolithography process has higher and higher requirements for wafer surface flatness. An uneven surface will lead to inaccurate photolithography focus, thus affecting the accuracy of the pattern. In order to improve the flatness of the wafer surface, the CMP (Chemical Mechanical Planarization) process can be used to trim the wafer surface flatness. However, during the CMP process, CMP scratches may occur.

[0036] The inventors believe that CMP scratches may occur during the CMP process, which can cause serious damage to the wafer surface and affect the performance and reliability of the final product. CMP scratches may be caused by uneven size or agglomeration of abrasive particles, problems with the grinding pad, and problems with CMP grinding operating conditions and equipment. After further consideration, the inventors believe that the problems with abrasive particles and CMP grinding operating conditions and equipment can be prevented in advance by taking measures before the CMP grinding equipment is started. The condition of the grinding pad will change during the CMP grinding process. Therefore, if there is a problem with the grinding pad and it cannot be solved during the CMP grinding process, the CMP grinding equipment must be stopped to solve it, which affects the grinding efficiency.

[0037] An existing polishing pad dresser includes the functions of dressing the polishing pad surface and cleaning the residue on the polishing pad surface to prevent the polishing pad surface from being contaminated. However, for the polishing pad surface after the polishing pad is dressed and cleaned, the polishing pad dresser cannot provide real-time feedback on the cleanliness and surface state of the polishing pad surface. Therefore, after the polishing pad is dressed and cleaned, there are still problems with the cleanliness and surface state of the polishing pad surface. At this time, if the polishing pad is continued to be used for polishing, there is a risk of scratching the wafer.

[0038] To solve the above problems, an embodiment of the present invention provides a wafer grinding device, which monitors the state of the grinding pad in real time by setting an imaging sensor on the grinding pad dresser. As an optional implementation, Figure 1 The structure of the wafer grinding equipment provided by the embodiment of the present application is shown. Figure 1 As shown, the wafer grinding equipment provided in the embodiment of the present application includes the following structure.

[0039] The polishing pad 100 is disposed at a predetermined working position.

[0040] The grinding pad dresser 200 is located on the top surface of the predetermined working position. The grinding pad is parallel to the predetermined working plane where the predetermined working position is located, and is used for dressing the grinding during the process of grinding the wafer to be ground.

[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 grind a portion of the polishing pad 100 during grinding. Therefore, the polishing pad dresser 200 needs to move relative to the polishing pad 100 in order to dress the entire polishing pad 100.

[0042] The surface area of ​​the grinding pad 100 is relatively large compared to the wafer or the grinding pad dresser 200. Therefore, during operation, the wafer or the grinding pad dresser 200 will simultaneously use the grinding pad 100. If the grinding pad dresser 200 fails to meet the requirements for dressing the grinding pad 100, that is, there are still residual abnormalities or residual scars in some areas of the grinding pad 100 after dressing, based on the scenario that the wafer or the grinding pad dresser 200 will simultaneously use the grinding pad 100, the area of ​​the grinding pad 100 that fails to meet the requirements may not be discovered in time and the operation of grinding the wafer may not be performed directly, thereby causing the residual abnormalities or residual scars on the grinding pad 100 to scratch the wafer, so the real-time monitoring of the state of the grinding pad 100 is very important.

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

[0044] It should be noted that if Figure 1 As shown, the imaging sensor 300 is disposed on the surface of the polishing pad conditioner 200 and the probe is directed to the polishing pad 100 of the predetermined working plane. At this time, the object monitored by the imaging sensor 300 is the part of the polishing pad 100 being polished by the polishing pad conditioner 200.

[0045] Since the imaging sensor 300 is disposed on the surface of the polishing pad conditioner 200, rather than being independent of the polishing pad conditioner 200, after the polishing pad conditioner 200 moves relative to the polishing pad 100, the imaging sensor 300 can move with the polishing pad conditioner 200. Thus, the state of the part of the polishing pad 100 currently being dressed by the polishing pad conditioner 200 can be fed back.

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

[0047] Further, such as Figure 2As shown, in an optional implementation, the grinding pad dresser 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 dresser 200 is a completely flat surface or a surface that bulges toward the predetermined working position, after the imaging sensor 300 is disposed on the surface of the polishing pad dresser 200, the imaging sensor 300 and the polishing pad 100 will rub against each other, thereby causing damage to the imaging sensor 300 and the polishing pad 100. When the polishing pad dresser 200 is recessed in a direction away from the predetermined working position, the imaging sensor 300 disposed at the center of the polishing pad dresser 200 can be 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 polishing pad 100 , in an optional implementation, the imaging sensor is an infrared sensor.

[0050] Furthermore, the wafer grinding equipment also includes an image analysis device (not shown), which is connected to the imaging sensor and is used to detect the surface state of the grinding pad according to the grinding pad surface image.

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

[0052] In this way, by arranging an imaging sensor on the side of the grinding pad dresser close to the predetermined working position, the imaging sensor located on the inner side of the grinding pad dresser can move with the grinding pad dresser during the process of the grinding pad dresser dressing the grinding pad, so that no matter where the grinding pad dresser is, the surface image of the grinding pad can be obtained in real time, and then it can be judged whether the grinding pad is suitable for continuing to work according to the surface image of the grinding pad, thereby avoiding low cleanliness or unevenness of the grinding pad surface, which may scratch the wafer.

[0053] Further, an example of the polishing pad surface diagram is Figure 3a and Figure 3b As shown, Figure 3a and Figure 3b The annual ring-shaped rings are lines representing the grooves on the surface of the polishing pad 100 . Figure 3a The scattered points are contaminants or damages on the surface of the polishing pad 100. Figure 3a is a surface diagram of the polishing pad 100 when the surface is not trimmed, and Figure 3b FIG. 4 is a diagram of the polishing pad surface of the polishing pad 100 that meets the requirements after being trimmed.

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

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

[0056] In an optional implementation, the image analysis device is used to compare the difference between the current surface state image of the polishing pad 100 and the polishing pad surface image of the polishing pad 100 that meets the requirements, and can also be used to obtain the number of points in the current surface state image of the polishing pad 100 that are used to represent the contaminants or damage on the surface of the polishing pad 100. If the number of points meets the requirements, the surface state of the polishing pad 100 meets the requirements.

[0057] Furthermore, in an optional implementation, the wafer grinding device provided in the embodiment of the present application also includes an image generating device (not shown), which connects the imaging sensor 300 and the image analyzing device (not shown) and is used to convert the parameters acquired by the imaging sensor 300 into the grinding pad surface image.

[0058] It should be noted that the imaging sensor 300 only acquires a status signal indicating the surface status of the polishing pad 100. The status signal needs to be converted into a polishing pad surface map, and then the polishing pad surface map is analyzed to determine the surface status of the polishing pad 100.

[0059] Further, in an optional implementation, please continue to refer to Figure 1 , the wafer grinding equipment provided in the embodiment of the present application also includes:

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

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

[0062] The embodiment of the present invention also provides a wafer grinding method, which uses an imaging sensor on a grinding pad dresser to monitor the state of the grinding pad in real time to avoid scratching the wafer. As an optional implementation, Figure 4 FIG. 1 is a flow chart of a wafer grinding method provided by an embodiment of the present application. Figure 4 As shown, the wafer grinding method provided in the embodiment of the present application includes the following steps.

[0063] Step S10: providing a wafer to be ground.

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

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

[0066] Step S30: obtaining a polishing pad surface image of the polishing pad conditioner.

[0067] Specifically, an example of the polishing pad surface diagram is Figure 3a and Figure 3b As shown, Figure 3a and Figure 3b The annual ring-shaped rings are lines representing the grooves on the surface of the polishing pad 100 . Figure 3a The scattered points are contaminants or damages on the surface of the polishing pad 100. Figure 3a is a surface diagram of the polishing pad 100 when the surface is not trimmed, and Figure 3b FIG. 4 is a diagram of the polishing pad surface of the polishing pad 100 that meets the requirements after being trimmed.

[0068] Step S40: determining whether the surface state of the polishing pad meets the preset requirements according to the polishing pad surface map. If it meets the preset requirements, continuing the step of using the polishing pad dresser to polish the wafer to be polished.

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

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

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

[0072] In this way, by arranging an imaging sensor on the side of the grinding pad dresser close to the predetermined working position, the imaging sensor located on the inner side of the grinding pad dresser can move with the grinding pad dresser during the process of the grinding pad dresser dressing the grinding pad, so that no matter where the grinding pad dresser is, the grinding pad surface image can be obtained in real time, and then it can be judged whether the grinding pad is suitable for continuing to work according to the grinding pad surface image, thereby avoiding scratches on the wafer due to low cleanliness or unevenness of the grinding pad surface.

[0073] The above describes multiple implementation schemes provided by the embodiments of the present invention. The various optional methods introduced in the implementation schemes can be combined and cross-referenced with each other without conflict, thereby extending a variety of possible implementation schemes, which can all be considered as implementation schemes disclosed and open in the embodiments of the present invention.

[0074] Although the embodiments of the present invention are disclosed above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A wafer grinding device, characterized in that: include: A grinding pad, arranged at a predetermined working position; a grinding pad dresser, located on the top surface of the predetermined working position, the grinding pad being parallel to the predetermined working plane where the predetermined working position is located, and used for dressing the grinding pad during the process of grinding the wafer to be ground; An imaging sensor is disposed on a side of the polishing pad dresser close to the predetermined working position, the probe of the imaging sensor points to the predetermined working plane, and is used to obtain a polishing pad surface image during the process of the polishing pad dresser dressing the polishing pad; An image analysis device is connected to the imaging sensor and is used to detect the surface state of the polishing pad according to the polishing pad surface image.

2. The wafer grinding equipment according to claim 1, characterized in that: The imaging sensor is disposed at the center of the polishing pad dresser.

3. The wafer grinding equipment according to claim 2, characterized in that: The grinding pad dresser is recessed in a direction away from the predetermined working position.

4. The wafer grinding equipment according to claim 1, characterized in that: The imaging sensor is an infrared sensor.

5. The wafer grinding equipment according to claim 1, characterized in that: The image analysis device is used to fit the grinding pad surface image with a preset surface image to obtain surface similarity, and to determine whether to continue to use the grinding pad dresser according to the surface similarity.

6. The wafer grinding equipment according to claim 1, characterized in that: Also includes: An image generating device is connected to the imaging sensor and the image analyzing device, and is used for converting the parameters acquired by the imaging sensor into the surface image of the polishing pad.

7. The wafer grinding equipment according to claim 1, characterized in that: Also includes: Wafer positioning device, used to clamp the wafer to be ground to a predetermined working position; A dresser positioning device is arranged on the predetermined working plane, one end of which is arranged on the grinding pad dresser, and the other end of which is arranged with a rotating shaft, and the grinding pad positioning device rotates around the rotating shaft.

8. A wafer grinding method, applied to the wafer grinding device as claimed in any one of claims 1 to 7, characterized in that: include: Providing wafers to be ground; Clamping the wafer to be ground to a predetermined working position and grinding the wafer to be ground using a grinding pad; obtaining a polishing pad surface image of the polishing pad conditioner; Determine whether the surface state of the polishing pad meets the preset requirements according to the polishing pad surface map; if it does not meet the preset requirements, stop the step of using the polishing pad dresser to grind the wafer to be ground.

9. The wafer grinding method according to claim 8, characterized in that: The step of determining whether the surface state of the polishing pad meets the preset requirements according to the polishing pad surface map comprises: A preset grinding pad surface map is obtained, and the grinding pad surface map is fitted with the preset surface map to obtain surface similarity, and whether the surface state of the grinding pad meets the preset requirements is determined according to whether the value of the surface similarity reaches an expected value.

10. The wafer grinding method according to claim 9, wherein: Also includes: If the surface similarity is greater than the expected value, the step of grinding the wafer to be ground using the grinding pad dresser is continued.

Images