A bubble positioning device and a bubble positioning method for a chemical mechanical polishing apparatus

Abstract

The application provides a bubble positioning device and a positioning method for a chemical mechanical polishing device, the chemical mechanical polishing device comprising a polishing disc and a polishing pad adhered to the polishing disc, the bubble positioning device being used for positioning a bubble position between the polishing pad and the polishing disc, the bubble positioning device comprising: a light emitting device used for emitting detection light, the detection light extending along a surface of the polishing pad; a visual recognition device 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 position information of a bubble in the polishing pad image; and a positioner connected with the visual recognition device, the positioner being used for forming a bubble mark visible to the naked eye on the polishing pad according to the position information fed back by the visual recognition device, the bubble mark indicating that there is a bubble between the polishing pad and the polishing disc. The application can automatically realize positioning indication of the bubble between the polishing pad and the polishing disc.

Description

Technical Field

[0001] This invention relates to the field of semiconductor equipment technology, and more particularly to a bubble positioning device and bubble positioning method for chemical mechanical polishing equipment. Background Technology

[0002] In chemical mechanical polishing (CMP) equipment, the polishing pad is a mat mounted on the polishing disc to support and polish the workpiece (such as a semiconductor wafer), primarily providing a uniform hardness and smoothness. During CMP, the polishing pad utilizes friction to contact the wafer and achieve mechanical polishing. The hardness of the polishing pad affects the flow of the polishing slurry and the discharge of waste liquid. The polishing pad is attached to the polishing disc using adhesive, but air bubbles are easily generated during attachment. These bubbles can cause additional wear on the wafer and polishing head, reducing product yield. Currently, air bubbles are handled by manually touching the polishing pad to detect bubbles underneath. If bubbles are found, they are removed. This method requires a high level of experience in bubble detection, is time-consuming, and carries the risk of missing bubbles.

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

[0004] The purpose of this invention is to provide a bubble positioning device and bubble positioning method for chemical mechanical grinding equipment, which can detect the position of bubbles between the grinding pad and the grinding disc and provide a position indication, so as to facilitate the removal of bubbles.

[0005] This invention provides a bubble positioning device for a chemical mechanical grinding (CMP) apparatus, the CMP apparatus including a grinding disc and a grinding pad adhered to the grinding disc, the bubble positioning device being used to position the bubbles between the grinding pad and the grinding disc, the bubble positioning device comprising: A light-emitting device for emitting detection light, wherein the propagation direction of the detection light extends along the surface of the polishing pad; A visual recognition device is used to acquire an image of the abrasive pad through which the detection light passes, to perform image processing on the abrasive pad image, and to calculate and obtain the location information of the bubbles in the abrasive pad image. A locator, connected to the visual recognition device, is used to form a visible bubble mark on the grinding pad based on the position information fed back by the visual recognition device. The bubble mark indicates that there is an air bubble between the grinding pad and the grinding disc.

[0006] Preferably, the locator includes a rotatable light-emitting module for emitting colored positioning light rays, the intersection of which forms the bubble mark with the abrasive pad.

[0007] Preferably, the locator includes a rotary motor that drives 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 pointer or an infrared indicator.

[0009] Preferably, the visual recognition device includes: an imaging module for acquiring an image of the polishing pad as the detection light passes through the surface of the polishing pad; and a target detection module for performing image processing on the polishing pad image to obtain grayscale change features of the image, and calculating and obtaining the location information of the bubble in the polishing pad image based on the grayscale change features, wherein the grayscale change features include: grayscale value and geometric features at the grayscale change point.

[0010] Preferably, the geometric features at the grayscale change point include: the area of ​​the grayscale change point. The target detection module first compares the area of ​​the grayscale change point with a preset area threshold to determine whether the grayscale change point is a bubble. When the area of ​​the grayscale change point is within the range of the preset area threshold, the grayscale change point is determined to be a bubble. Then, the position information of the grayscale change point 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 includes a mounting frame, and the light-emitting device, the visual recognition device, and the locator are all mounted on the mounting frame.

[0012] Preferably, the mounting bracket is provided with a baffle plate for preventing the grinding fluid from splashing onto the grinding disc.

[0013] Preferably, the light-emitting device includes a light source and a focusing cup, and the detection light is emitted from the light source and forms a focusing area after passing through the focusing cup.

[0014] This invention also provides a bubble positioning method for a chemical mechanical polishing (CMP) apparatus, the CMP apparatus including a polishing disc and a polishing pad adhered to the polishing disc, the bubble positioning method including a bubble detection step and a bubble positioning step, wherein... The bubble detection step includes: emitting detection light onto the surface of the polishing pad and extending the detection light along the surface of the polishing pad; acquiring an image of the polishing pad through which the detection light passes; performing image processing on the polishing pad image; and calculating and acquiring the location information of the bubbles in the polishing pad image. The bubble positioning step includes: obtaining the location information of the bubbles in the image of the grinding pad, and forming a visible bubble mark on the grinding pad according to the location information, wherein the bubble mark indicates that there are bubbles between the grinding pad and the grinding disc.

[0015] The bubble positioning device and bubble positioning method for chemical mechanical grinding equipment of the present invention have the following beneficial effects: by acquiring an image of the detection light on the surface of the grinding pad, processing the image, and utilizing the principle that the presence of bubbles will block the detection light and thus cause grayscale changes in the image, the bubble position is obtained by detecting and judging the grayscale changes in the image, and then forming a bubble mark on the grinding pad by the locator, so that the operator can efficiently identify the bubble position and remove the bubble. Attached Figure Description

[0016] Figure 1 This is a diagram of a specific embodiment of a bubble positioning device. Detailed Implementation

[0017] To make the objectives, 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 only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.

[0018] The chemical mechanical polishing (CMP) equipment includes a polishing disc 1 and a polishing pad 2 bonded to the polishing disc 1. In this embodiment, the polishing pad 2 is bonded to the polishing disc 1 with adhesive. The polishing pad 2 achieves polishing processing on the surface of the workpiece through relative movement between itself and the workpiece (a wafer in this embodiment), and the participation of abrasive particles in the polishing fluid. The adhesive plays a crucial role in the connection between the polishing pad 2 and the polishing disc 1. It not only provides sufficient adhesive force to ensure that the polishing pad 2 does not fall off or shift during polishing, but also allows the polishing pad 2 to be evenly distributed on the polishing disc 1, thereby ensuring the uniformity of polishing. The bonding process of the polishing pad 2 in this embodiment may include: applying adhesive to the back of the polishing pad 2, ensuring a tight fit between the adhesive and the polishing pad 2 without air bubbles or gaps; aligning the polishing pad 2 with adhesive to the polishing disc 1, ensuring that the fluid outlet of the polishing pad 2 is aligned with the corresponding position on the polishing disc 1. Next, starting from one side of the polishing pad 2, slowly peel off the protective paper from the backing. Simultaneously, use a roller or similar tool to press the polishing pad 2 firmly onto the polishing disc 1. This step requires ensuring a tight fit between the polishing pad 2 and the polishing disc 1, without any air bubbles or gaps. After pasting, check whether the polishing pad 2 is firmly attached to the polishing disc 1 and whether there are any air bubbles or uneven areas.

[0019] This invention provides a bubble positioning device for a chemical mechanical polishing (CMP) apparatus. The bubble positioning device can be used to detect whether there are air bubbles between the bonded polishing pad 2 and the polishing disc 1, and to locate the position of the air bubbles. (See attached image.) Figure 1 As shown, the bubble positioning device includes: Light-emitting device 32 is used to emit detection light, the detection light (see...) Figure 1 The direction of propagation (the dashed arrow in the middle indicates the direction of the detection light extension) is along the surface of the abrasive pad; The visual recognition device 31 is used to acquire an image of the abrasive pad through which the detection light passes, perform image processing on the abrasive pad image, and calculate and obtain the location information of the bubbles in the abrasive pad image. The locator 33 is connected to the visual recognition device 31. The locator 33 is used to form a visible bubble mark on the grinding pad 2 based on the position information fed back by the visual recognition device 31. The bubble mark indicates that there is a bubble 101 between the grinding pad 2 and the grinding disk 1.

[0020] In this embodiment, a 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 acquired by the visual recognition device 31. In this embodiment, the detection light is a beam parallel to the horizontal plane of the chemical mechanical polishing equipment, that is, the detection light is parallel to the surface of the polishing disk 1, and the detection light and the surface of the polishing disk 1 are basically without gap or have a small gap in the vertical direction. To facilitate the control of the detection light path, in this embodiment, the light-emitting device 32 is located above the surface of the polishing pad, and the maximum vertical gap between it and the polishing pad 2 is 3mm. This utilizes the principle that the detection light will cause a grayscale change in the image when it is blocked by the bubble 101. Figure 1 When the propagation path of the detection light encounters bubble 101, it changes, causing a darkened area to appear behind bubble 101. Based on this, the grayscale change in the image can be identified, thereby detecting and obtaining the location information of the bubble in the image. The locator 33 forms a visible bubble mark on the grinding pad 2 according to the location information, thereby realizing the positioning indication of the bubble position on the grinding pad 2. The operator can perform bubble removal operation at the bubble mark. The bubble positioning device of this embodiment is easy to implement and improves the efficiency of bubble recognition, detection and positioning, avoiding missed bubble detection.

[0021] The aforementioned light-emitting device 32 may include a light source and a focusing cup. The detection light emitted from the light source forms a focusing area after passing through the focusing cup. In this embodiment, the focusing cup is a cup-shaped component. The light source is placed at the focal point of the focusing cup, so that the light emitted from the light source is reflected by the surface of the focusing cup and condensed into a parallel beam. In this embodiment, the light emitted from the light source is focused and then illuminates the polishing pad 2. The light source is located above the surface of the polishing pad, and the maximum vertical distance between the light source and the polishing pad 2 is 3mm. By focusing the detection light to form a parallel beam, the brightness of the main irradiated area on the polishing pad 2 can be increased, and the problem of unclear bubble positioning caused by excessive reflection of diffuse light can be reduced. This allows for better presentation of grayscale changes in the polishing pad image, facilitating acquisition and detection by the visual recognition device 31.

[0022] In one embodiment, the aforementioned visual recognition device 3 includes: an imaging module, such as a camera, for acquiring images of the grinding pad through which detection light passes; and a target detection module for processing the grinding pad image to obtain grayscale change features, and calculating and obtaining the location information of bubbles in the grinding pad image based on the grayscale change features. The grayscale change features include grayscale values ​​and geometric features at the grayscale change points. This embodiment improves the accuracy of bubble recognition by extracting grayscale change features. For example, extracting geometric features at grayscale change points facilitates the identification and exclusion of windows on the grinding disc and grinding pad corresponding to sensors. Since the sensor window is rectangular and its length, width, and area are known, the geometric features of the grayscale change points presented by the sensor window in the image can be determined, and relevant software algorithms can be set within the target detection module for judgment and exclusion. Furthermore, it facilitates the identification and exclusion of grayscale changes caused by the grooves within the grinding pad in the image.

[0023] The geometric features of the aforementioned grayscale changes 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 range, it is determined that the grayscale change is a bubble. Then, the position information of the grayscale change in the polishing pad image is calculated as the location 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; it can generally be round, elliptical, cashew-shaped, or elongated, with an area of ​​approximately 1 square centimeter to 10 square centimeters. Therefore, by setting a software algorithm in the target detection module, using a preset area threshold as a judgment criterion, the area of ​​the grayscale change is compared with the preset area threshold to determine 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 air bubbles between the grinding pad and the grinding disc, and to calculate the position of the air bubbles. The specific principle includes steps such as image acquisition, image preprocessing, extraction of grayscale variation features from the image, air bubble recognition, and position calculation. The software algorithm used in this embodiment is an existing algorithm and will not be described in detail here.

[0025] To better automatically locate the position of air bubbles on the grinding pad 2, in one embodiment, the positioner 33 includes a rotatable light-emitting module for emitting colored positioning light. Figure 1The solid arrow represents the positioning ray (a bubble mark is formed where the positioning ray intersects with the grinding pad); the rotation of the light emission module changes the position where the positioning ray intersects with the grinding pad. In this embodiment, on the one hand, the light emission module can be rotated to easily adjust the emission angle of the positioning ray, and precise positioning can be achieved through angle control; on the other hand, the colored positioning ray is easier for the operator to see.

[0026] In one specific embodiment, the locator 33 includes a rotary motor that drives the light-emitting module to rotate, and the rotary motor is communicatively connected to the visual recognition device 31. The rotation of the light-emitting module is not limited to being driven by a rotary motor; it can be driven by other power components, such as a telescopic cylinder. The linear motion of the telescopic cylinder can be converted into the rotation of the light-emitting module through a transmission assembly, as long as the light-emitting module can swing to change the emission angle of the positioning light. Preferably, the light-emitting module is a laser pointer or an infrared indicator.

[0027] The locator mentioned above is not limited to this; it can form a visible mark on the grinding pad, such as a text mark or a graphic mark.

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

[0029] To better facilitate its application in chemical mechanical grinding equipment, the mounting bracket 34 is equipped with a baffle plate 35 to prevent the grinding fluid from splashing onto the grinding disc 1. In this embodiment, the baffle plate 35 prevents the grinding fluid from splashing to the outside and polluting the environment during bubble detection and positioning.

[0030] This invention also provides a bubble positioning method for a chemical mechanical grinding (CMP) apparatus, which can be implemented using the aforementioned bubble positioning device. Specifically, it includes a bubble detection step and a bubble positioning step. The bubble detection step involves: emitting detection light onto the surface of the grinding pad and extending the detection light along the surface of the grinding pad; acquiring an image of the grinding pad through which the detection light passes; performing image processing on the grinding pad image; and calculating and obtaining the location information of the bubbles in the grinding pad image. In this embodiment, the bubble detection step can be completed by the aforementioned light-emitting device and visual recognition device. The bubble location step is as follows: The location information of the bubbles in the polishing pad image is obtained; based on the location information, a visible bubble marker is formed on the polishing pad, indicating the presence of a bubble between the polishing pad and the polishing disc. In this embodiment, the bubble detection step can be completed by the aforementioned locator.

[0031] In this embodiment, the entire surface of the grinding pad is inspected by the self-rotation of the aforementioned grinding disc.

[0032] While embodiments of the present invention have been described in detail above, it will be apparent 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 fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A bubble positioning device for a chemical mechanical grinding (CMP) apparatus, the CMP apparatus comprising a grinding disc and a grinding pad adhered to the grinding disc, the bubble positioning device being used to position the bubble between the grinding pad and the grinding disc, characterized in that: The bubble positioning device includes: A light-emitting device for emitting detection light, wherein the propagation direction of the detection light extends along the surface of the polishing pad; A visual recognition device is used to acquire an image of the abrasive pad through which the detection light passes, to perform image processing on the abrasive pad image, and to calculate and obtain the location information of the bubbles in the abrasive pad image. A locator, connected to the visual recognition device, is used to form a visible bubble mark on the grinding pad based on the position information fed back by the visual recognition device. The bubble mark indicates that there is an air bubble between the grinding pad and the grinding disc. The visual recognition device includes an imaging module for acquiring an image of the polishing pad as the detection light passes through the surface of the polishing pad. The target detection module is used to perform image processing on the polishing pad image to obtain the grayscale change features of the image, and to calculate and obtain the location information of the bubble in the polishing pad image based on the grayscale change features. The grayscale change features include grayscale values ​​and geometric features at the grayscale change points. The geometric features at the grayscale change points include the area of ​​the grayscale change points. The target detection module first compares the area of ​​the grayscale change points with a preset area threshold to determine whether the grayscale change points are bubble points. When the area of ​​the grayscale change points is within the preset area threshold range, the grayscale change points are determined to be bubble points. Then, the location information of the grayscale change points in the polishing pad image is calculated as the location information of the bubble in the polishing pad image.

2. The bubble positioning device according to claim 1, characterized in that: The locator includes a rotatable light-emitting module, which emits colored positioning light rays. The bubble mark is formed where the positioning light rays intersect with the abrasive pad. Rotation of the light-emitting module changes the position where the positioning light rays intersect with the abrasive pad.

3. The bubble positioning device according to claim 2, characterized in that: The locator includes a rotary motor that drives 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 emission module is a laser pointer or an infrared indicator.

5. The bubble positioning device according to claim 1, characterized in that: The bubble positioning device includes a mounting frame, on which the light-emitting device, the visual recognition device, and the locator are all mounted.

6. The bubble positioning device according to claim 5, characterized in that: The mounting bracket is equipped with a baffle plate to prevent the grinding fluid from splashing onto the grinding disc.

7. The bubble positioning device according to claim 1, characterized in that: The light-emitting device includes a light source and a focusing cup, and the detection light is emitted from the light source and forms a focusing area after passing through the focusing cup.

8. A method for bubble positioning in a chemical mechanical grinding apparatus, the chemical mechanical grinding apparatus comprising a grinding disc and a grinding pad adhered to the grinding disc, characterized in that: The bubble positioning method includes a bubble detection step and a bubble positioning step: The bubble detection step includes: emitting detection light onto the surface of the polishing pad, and extending the detection light along the surface of the polishing pad; acquiring an image of the polishing pad through which the detection light passes; performing image processing on the polishing pad image to obtain grayscale change features of the image; and calculating the location information of the bubble in the polishing pad image based on the grayscale change features; wherein, the grayscale change features include: grayscale value and geometric features at the grayscale change point; the geometric features at the grayscale change point include: the area of ​​the grayscale change point; firstly, the area of ​​the grayscale change point is compared with a preset area threshold to determine whether the grayscale change point is a bubble; when the area of ​​the grayscale change point is within the range of the preset area threshold, the grayscale change point is determined to be a bubble; then, the location information of the grayscale change point in the polishing pad image is calculated as the location information of the bubble in the polishing pad image; The bubble positioning step includes: obtaining the location information of the bubbles in the image of the grinding pad, and forming a visible bubble mark on the grinding pad according to the location information, wherein the bubble mark indicates that there are bubbles between the grinding pad and the grinding disc.

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