Bubble positioning device and bubble positioning method for chemical mechanical polishing equipment

Abstract

The invention provides a bubble positioning device and method for chemical mechanical polishing equipment, the chemical mechanical polishing equipment comprises a polishing disc and a polishing pad bonded to the polishing disc, the bubble positioning device is used for positioning the position of bubbles between the polishing pad and the polishing disc, and the bubble positioning device comprises a light emitting device used for emitting detection light, the detection light extends along the surface of the grinding pad; the visual identification equipment is used for acquiring a polishing pad image of the detection light passing through the surface of the polishing pad, performing image processing on the polishing pad image, and calculating and acquiring position information of bubbles in the polishing pad image; and the positioner is connected with the visual identification equipment and used for forming a macroscopic bubble identifier on the grinding pad according to the position information fed back by the visual identification equipment, and the bubble identifier indicates that bubbles exist between the grinding pad and the grinding disc. According to the invention, positioning indication of bubbles between the grinding pad and the grinding disc can be automatically realized.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor equipment, and in particular to a bubble positioning device and a bubble positioning method for chemical mechanical polishing equipment. Background Art

[0002] In chemical mechanical polishing equipment, the polishing pad is a pad installed on the grinding disc for supporting and grinding workpieces (such as semiconductor wafers). It mainly provides a uniform hardness and smoothness. During the chemical mechanical polishing process, the polishing pad uses friction and wafer contact to complete the mechanical polishing. At the same time, the hardness of the polishing pad affects the flow of the polishing liquid and the discharge of the waste liquid. The polishing pad is pasted on the grinding disc by adhesive backing, but the polishing pad is prone to bubbles when pasting. The presence of bubbles is likely to cause additional wear on the wafer and components such as the grinding head, reducing the product yield. The current way to deal with bubbles is to manually touch the polishing pad to sense whether there are bubbles under the polishing pad, and if there are bubbles, remove them. Based on this, there are high requirements for the operator's bubble detection experience. In addition, manual detection takes a long time, and there is a risk of missing bubbles.

[0003] Therefore, it is necessary to develop a bubble positioning device that can accurately detect and indicate the position of the bubble. Summary of the invention

[0004] The object of the present invention is to provide a bubble positioning device and a bubble positioning method for chemical mechanical polishing equipment, which can detect the bubble position between the polishing pad and the polishing disk and give a position indication to facilitate bubble removal.

[0005] The present invention provides a bubble positioning device for a chemical mechanical polishing device, wherein the chemical mechanical polishing device comprises a polishing disc and a polishing pad bonded to the polishing disc, wherein the bubble positioning device is used to position bubbles between the polishing pad and the polishing disc, and the bubble positioning device comprises: A light emitting device, used for emitting a detection light, wherein the propagation direction of the detection light is along the surface of the polishing pad; A visual recognition device, used for acquiring a polishing pad image of the detection light passing through the polishing pad surface, performing image processing on the polishing pad image, and calculating and acquiring position information of bubbles in the polishing pad image; A locator is connected to the visual recognition device, and is used to form a bubble mark visible to the naked eye on the polishing pad according to the position information fed back by the visual recognition device, wherein the bubble mark indicates that there are bubbles between the polishing pad and the polishing disc.

[0006] Preferably, the positioner comprises a rotatable light emitting module, and the light emitting module is used to emit a colored positioning light, and the bubble mark is formed at the intersection of the positioning light and the polishing pad.

[0007] Preferably, the locator comprises a rotary motor driving the light emission module to rotate, and the rotary motor is communicatively connected to the visual recognition device.

[0008] Preferably, the light emitting module is a laser pen or an infrared pointer.

[0009] Preferably, the visual recognition device includes: an imaging module, used to collect the polishing pad image of the detection light passing through the polishing pad surface; a target detection module, used to perform image processing on the polishing pad image to obtain the grayscale change characteristics of the image, and calculate and obtain the position information of the bubbles in the polishing pad image based on the grayscale change characteristics, wherein the grayscale change characteristics include: grayscale values ​​and geometric characteristics at the grayscale change location.

[0010] Preferably, the geometric features of the grayscale change include: the area of ​​the grayscale change, the target detection module first compares the area of ​​the grayscale change with a preset area threshold to determine whether the grayscale change is a bubble, and when the area of ​​the grayscale change is within the preset area threshold, it is determined that the grayscale change is a bubble, and then the position information of the grayscale change in the polishing pad image is calculated as the position information of the bubble in the polishing pad image.

[0011] Preferably, the bubble positioning device comprises a mounting frame, and the light emitting device, the visual recognition device and the positioner are all mounted on the mounting frame.

[0012] Preferably, the mounting frame is provided with a water baffle for stopping splashing of grinding liquid on the grinding disc.

[0013] Preferably, the light emitting device comprises a light source and a focusing cup, and the detection light is emitted by the light source and passes through the focusing cup to form a focusing area.

[0014] The present invention also provides a bubble positioning method for a chemical mechanical polishing device, wherein the chemical mechanical polishing device comprises a polishing disc and a polishing pad bonded to the polishing disc, and the bubble positioning method comprises a bubble detection step and a bubble positioning step, wherein: The bubble detection step includes: emitting a detection light to the surface of the polishing pad, and extending the detection light along the surface of the polishing pad; acquiring a polishing pad image of the polishing pad surface after the detection light passes through the polishing pad surface, performing image processing on the polishing pad image, and calculating and acquiring position information of bubbles in the polishing pad image; The bubble positioning step includes: obtaining position information of bubbles in the polishing pad image, and forming a bubble mark visible to the naked eye on the polishing pad according to the position information, wherein the bubble mark indicates that bubbles exist between the polishing pad and the polishing disk.

[0015] The bubble positioning device and bubble positioning method for chemical mechanical polishing equipment of the present invention have the following beneficial effects: it obtains an image of the detection light on the surface of the polishing pad, processes the image, and uses the principle that the existence of bubbles will block the detection light and thus cause grayscale changes in the image, thereby detecting and judging grayscale changes in the image to obtain the bubble position, and then forms a bubble mark on the polishing pad through a locator, so that the operator can efficiently identify the bubble position and eliminate the bubble. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A diagram showing a specific embodiment of a bubble positioning device. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0018] The chemical mechanical polishing equipment includes a grinding disc 1 and a grinding pad 2 bonded to the grinding disc 1. The grinding pad 2 of this embodiment is bonded to the grinding disc 1 by a backing adhesive. The grinding pad 2 realizes the grinding process of the surface of the workpiece through the relative movement between the grinding pad 2 and the workpiece (the workpiece is a wafer in this embodiment) and the participation of abrasive particles in the grinding liquid. In the connection between the grinding pad 2 and the grinding disc 1, the backing adhesive plays a vital role. It can not only provide sufficient adhesive force to ensure that the grinding pad 2 will not fall off or shift during the grinding process, but also enable the grinding pad 2 to be evenly distributed on the grinding disc 1, thereby ensuring the uniformity of grinding. The bonding process of the grinding pad 2 in this embodiment may include: sticking the backing adhesive to the back of the grinding pad 2. This step needs to ensure that the backing adhesive and the grinding pad 2 are tightly fitted without bubbles or gaps; aligning the grinding pad 2 with the backing adhesive to the grinding disc 1, ensuring that the flow hole of the grinding pad 2 is aligned with the corresponding position of the grinding disc 1. Then, slowly peel off the adhesive backing paper from one side of the polishing pad 2, and use a roller or similar tool to press the polishing pad 2 onto the polishing disc 1. This step needs to ensure that the polishing pad 2 fits tightly onto the polishing disc 1 without bubbles or gaps. After the pasting is completed, it is necessary to check whether the polishing pad 2 is firmly pasted onto the polishing disc 1 and whether there are bubbles or uneven areas.

[0019] The embodiment of the present invention provides a bubble positioning device for chemical mechanical polishing equipment, which can be used to detect whether there are bubbles between the bonding polishing pad 2 and the polishing disc 1, and locate the position of the bubbles. Figure 1 As shown, the bubble positioning device includes: The light emitting device 32 is used to emit a detection light, the detection light (see Figure 1 The dotted arrow in the middle is the extension direction of the detection light) and the propagation direction is along the surface of the polishing pad; A visual recognition device 31 is used to obtain a polishing pad image of the polishing pad surface after the detection light passes through the polishing pad surface, perform image processing on the polishing pad image, and calculate and obtain position information of bubbles in the polishing pad image; The locator 33 is connected to the visual recognition device 31 , and is used to form a bubble mark visible to the naked eye on the polishing pad 2 according to the position information fed back by the visual recognition device 31 , and the bubble mark indicates that there are bubbles 101 between the polishing pad 2 and the polishing disc 1 .

[0020] In this embodiment, the detection light extending along the surface of the polishing pad is emitted by the light emitting device 32. The propagation direction of the detection light extends along the surface of the polishing pad, and the image of the detection light passing through the polishing pad 2 is obtained by the visual recognition device 31. In this embodiment, the detection light is a light beam parallel to the horizontal plane where the chemical mechanical polishing device is located, that is, the detection light is parallel to the surface of the polishing disk 1, and there is basically no gap or a small gap between the detection light and the surface of the polishing disk 1 in the vertical direction. In order to facilitate the control of the path of the detection light, the light emitting device 32 in this embodiment is located above the surface of the polishing pad, and the maximum gap between it and the polishing pad 2 in the vertical direction is 3mm. In this way, the principle that the grayscale change in the image will be caused when the detection light is blocked by the bubble 101 can be used. Figure 1 The propagation path of the detection light changes when encountering the bubble 101, causing a darkened area to appear behind the bubble 101. Based on this, the grayscale change in the image can be identified, so as to detect and obtain the position information of the bubble in the image. The locator 33 forms a bubble mark visible to the naked eye on the polishing pad 2 according to the position information, thereby realizing the positioning indication of the bubble position on the polishing pad 2, and the operator can perform bubble removal operations at the bubble mark. The bubble positioning device of this embodiment is easy to implement, and improves the efficiency of bubble identification, detection and positioning, thereby avoiding missed bubble detection.

[0021] The above-mentioned light emitting device 32 may include a light source and a focusing cup. The detection light is emitted from the light source and passes through the focusing cup to form a focusing area. In this embodiment, the focusing cup is a cup-shaped part. The light source is placed at the focus of the focusing cup, so that the light emitted by the light source is reflected by the surface of the focusing cup and condensed into a parallel light beam. In this embodiment, the light emitted by the light source is irradiated on the polishing pad 2 after being focused. The light source is located above the surface of the polishing pad, and the maximum vertical distance between it and the polishing pad 2 is 3mm. By focusing the detection light to form a parallel light beam, it can increase the brightness of the main irradiation area on the polishing pad 2, reduce the problem of unclear bubble positioning caused by excessive reflection of diffuse light, and thus better present grayscale changes in the polishing pad image, which is convenient for the visual recognition device 31 to obtain and detect.

[0022] In one embodiment, the visual recognition device 3 includes: an imaging module, such as a camera, for collecting the image of the polishing pad where the detection light passes through the surface of the polishing pad; a target detection module, for performing image processing on the polishing pad image to obtain the grayscale change characteristics of the image, and calculating and obtaining the location information of the bubbles in the polishing pad image according to the grayscale change characteristics, wherein the grayscale change characteristics include: grayscale value and geometric characteristics at the grayscale change. This embodiment can improve the accuracy of bubble recognition by extracting grayscale change characteristics, such as extracting geometric characteristics at the grayscale change. On the one hand, it can be convenient to identify and exclude the windows of the sensors corresponding to the grinding disc and the polishing pad, because the shape of the sensor window is rectangular, and its length, width and area are known. It can be known that the geometric characteristics of the grayscale change of the sensor window in the image can be set in the target detection module. The relevant software algorithm can be set in the target detection module to judge and exclude; on the other hand, it can be convenient to identify and exclude the grayscale changes caused by the grooves in the polishing pad in the image.

[0023] The geometric features of the grayscale change include: the area of ​​the grayscale change. The target detection module first compares the area of ​​the grayscale change with the preset area threshold to determine whether the grayscale change is a bubble. When the area of ​​the grayscale change is within the preset area threshold, the grayscale change is determined to be a bubble. Then the position information of the grayscale change in the polishing pad image is calculated as the position information of the bubble in the polishing pad image. The shape of the bubble between the polishing pad and the polishing disc is not uniform. Generally, it can appear circular, elliptical, cashew-shaped or long strips. Its area is roughly 1 square centimeter to 10 square centimeters. Therefore, by setting a software algorithm in the target detection module, using the preset area threshold as the judgment basis, and comparing the area of ​​the grayscale change with the preset area threshold, it is judged whether the grayscale change is a bubble.

[0024] In this embodiment, the visual recognition technology of the visual recognition device 3 is used to detect whether there are bubbles between the polishing pad and the polishing disc, and to calculate the bubble position. The specific principle includes the steps of image acquisition, image preprocessing, grayscale change feature extraction in the image, bubble recognition and position calculation. The software algorithm used in the visual recognition technology in this embodiment is an existing algorithm and will not be described in detail here.

[0025] In order to better automatically locate and indicate the position of the bubbles on the polishing pad 2, in one embodiment, the above-mentioned positioner 33 includes a rotatable light emitting module, which is used to emit a colored positioning light ( Figure 1The solid arrow in the middle represents the positioning light, and a bubble mark is formed at the intersection of the positioning light and the polishing pad; the rotation of the light emission module can change the position where the positioning light and the polishing pad intersect. In this embodiment, on the one hand, the light emission module can be rotated to facilitate the adjustment of the emission angle of the positioning light, and accurate positioning can be achieved through angle control; on the other hand, the colored positioning light is easier for the operator to view.

[0026] In a specific embodiment, the above-mentioned locator 33 includes a rotary motor that drives the light emission module to rotate, and the rotary motor is connected to the visual recognition device 31 for communication. The rotation of the light emission module is not limited to the drive of the rotary motor, and it can be driven by other power parts, such as a telescopic cylinder, and the linear motion of the telescopic cylinder can be converted into the rotation of the light emission module through a transmission component. It is only necessary to realize that the light emission module can swing to change the emission angle of the positioning light. Preferably, the light emission module is a laser pen or an infrared indicator.

[0027] The above-mentioned positioner is not limited to this, and it can form a mark visible to the naked eye on the polishing pad, such as a text mark or a graphic mark.

[0028] As a specific embodiment, the bubble positioning device includes a mounting frame 34, and the light emitting device 32, the visual recognition device 31 and the locator 33 are all mounted on the mounting frame 34. In this embodiment, the light emitting device 32, the visual recognition device 31 and the locator 33 are integrated together through the mounting frame 34, which can facilitate the portability and use of the bubble positioning device.

[0029] For better application in chemical mechanical polishing equipment, the mounting frame 34 is provided with a water baffle 35 for stopping the splashing of the grinding liquid on the grinding disc 1. The water baffle 35 of this embodiment can prevent the grinding liquid from splashing to the outside and polluting the environment during bubble detection and positioning.

[0030] The present invention also provides a bubble positioning method for chemical mechanical polishing equipment, which can be implemented by using the above-mentioned bubble positioning device, and specifically includes a bubble detection step and a bubble positioning step, wherein the bubble detection step is: emitting a detection light to the surface of the polishing pad, and extending the detection light along the surface of the polishing pad; obtaining a polishing pad image of the detection light passing through the polishing pad surface, performing image processing on the polishing pad image and calculating and obtaining the position information of the bubble in the polishing pad image; in this embodiment, the bubble detection step can be completed by the above-mentioned light emitting device and visual recognition device; The bubble positioning step includes: obtaining the position information of the bubbles in the polishing pad image, and forming a visible bubble mark on the polishing pad according to the position information, wherein the bubble mark indicates that there are bubbles between the polishing pad and the polishing disc. In this embodiment, the bubble detection step can be completed by the above-mentioned locator.

[0031] In this embodiment, the entire surface of the grinding pad is detected by the rotation of the grinding disc itself.

[0032] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A bubble positioning device for a chemical mechanical polishing device, the chemical mechanical polishing device comprising a grinding disc and a grinding pad bonded to the grinding disc, the bubble positioning device being used to locate the position of bubbles between the grinding pad and the grinding disc, characterized in that: The bubble positioning device comprises: A light emitting device, used for emitting a detection light, wherein the propagation direction of the detection light is along the surface of the polishing pad; A visual recognition device, used for acquiring a polishing pad image of the detection light passing through the polishing pad surface, performing image processing on the polishing pad image, and calculating and acquiring position information of bubbles in the polishing pad image; A locator is connected to the visual recognition device, and is used to form a bubble mark visible to the naked eye on the polishing pad according to the position information fed back by the visual recognition device, wherein the bubble mark indicates that there are bubbles between the polishing pad and the polishing disc.

2. The bubble positioning device according to claim 1, characterized in that: The positioner comprises a rotatable light emitting module, which is used to emit colored positioning light, and the bubble mark is formed at the intersection of the positioning light and the polishing pad; the rotation of the light emitting module can change the position where the positioning light intersects with the polishing pad.

3. The bubble positioning device according to claim 2, characterized in that: The locator includes a rotary motor driving the light emission module to rotate, and the rotary motor is communicatively connected to the visual recognition device.

4. The bubble positioning device according to claim 2, characterized in that: The light emitting module is a laser pen or an infrared indicator.

5. The bubble positioning device according to claim 1, characterized in that: The visual recognition device comprises: an imaging module for collecting a polishing pad image of the detection light passing through the polishing pad surface; The target detection module is used to perform image processing on the polishing pad image to obtain the grayscale change characteristics of the image, and calculate and obtain the position information of the bubbles in the polishing pad image based on the grayscale change characteristics, wherein the grayscale change characteristics include: grayscale value and geometric characteristics at the grayscale change location.

6. The bubble positioning device according to claim 5, characterized in that: The geometric features of the grayscale change include: the area of ​​the grayscale change. The target detection module first compares the area of ​​the grayscale change with a preset area threshold to determine whether the grayscale change is a bubble. When the area of ​​the grayscale change is within the preset area threshold, the grayscale change is determined to be a bubble, and then the position information of the grayscale change in the polishing pad image is calculated as the position information of the bubble in the polishing pad image.

7. The bubble positioning device according to claim 1, characterized in that: The bubble positioning device comprises a mounting frame, and the light emitting device, the visual recognition device and the positioner are all mounted on the mounting frame.

8. The bubble positioning device according to claim 7, characterized in that: The mounting frame is provided with a water baffle plate for stopping the splashing of grinding liquid on the grinding disc.

9. The bubble positioning device according to claim 1, characterized in that: The light emitting device comprises a light source and a focusing cup. The detection light is emitted by the light source and passes through the focusing cup to form a focusing area.

10. A bubble positioning method for a chemical mechanical polishing device, the chemical mechanical polishing device comprising a polishing disc and a polishing pad bonded to the polishing disc, characterized in that: The bubble positioning method comprises a bubble detection step and a bubble positioning step: The bubble detection step includes: emitting a detection light to the surface of the polishing pad, and extending the detection light along the surface of the polishing pad; acquiring a polishing pad image of the polishing pad surface after the detection light passes through the polishing pad surface, performing image processing on the polishing pad image, and calculating and acquiring position information of the bubbles in the polishing pad image; The bubble positioning step includes: obtaining position information of bubbles in the polishing pad image, and forming a bubble mark visible to the naked eye on the polishing pad according to the position information, wherein the bubble mark indicates that bubbles exist between the polishing pad and the polishing disk.

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