A method for trimming grooves of polishing pads used in CMP equipment

Abstract

The present invention discloses a method for groove trimming of a polishing pad in a CMP device, comprising the following steps: obtaining an extension trajectory of a groove on the polishing pad and determining a groove trimming starting position; adjusting the position of a processing head so that it is directly above the groove trimming starting position and determining a processing depth zero point; lowering the processing head and moving it to a preset processing depth in the groove according to the processing zero point; and controlling the processing head to move along the groove extension trajectory of the rotating polishing pad to deepen the groove on the polishing pad. The polishing pad groove trimming device designed in the present invention can extend the service life of the polishing pad, reduce its operating costs, and fill a technical gap. A camera or a line laser is installed on the trimming device as a visual feedback sensor. Combined with an algorithm, it can identify different polishing pad groove patterns, making the device highly versatile. The camera or line laser provides real-time feedback on the positional relationship between the tool head and the groove, preventing the tool head from damaging the groove pattern.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor processing equipment, and in particular relates to a method for trimming grooves of a polishing pad of a CMP device. Background Art

[0002] Chemical mechanical planarization (CMP) is a key process step in the current semiconductor integrated circuit chip manufacturing process. The CMP process uses a polishing pad and slurry to grind the wafer. By combining chemical etching with mechanical grinding, it efficiently removes excess material from the wafer surface and achieves global nanoscale planarization. Chemical etching involves contact between the polishing slurry in the grooves of the polishing pad and the wafer, while mechanical grinding relies on the rough surface of the polishing pad.

[0003] As a large number of wafers undergo chemical mechanical planarization, the polishing pad gradually wears out, the groove depth becomes shallower, and the polishing liquid that can be accommodated is reduced, thereby reducing the efficiency of polishing. At the same time, the worn-out grooves make the polishing pad surface roughness insufficient, reducing the yield of the process and making it more likely to cause wafer slip. In the actual CMP process, a new polishing pad needs to be replaced every once in a while. Although the grooves of the discarded polishing pad are shallower, they still have a considerable thickness. The frequent replacement of polishing pads not only increases the cost of the enterprise, but also causes a certain amount of waste. Therefore, there is a need for a device that can trim the grooves of the polishing pad, so that the polishing pad that is about to be eliminated can be re-carved and cut into grooves of standard depth to meet the requirements for use, thereby extending the life of the polishing pad and reducing the cost of use of the enterprise.

[0004] Currently, there is still a lack of devices and methods for polishing pad groove dressing. The present invention can fill this gap in technology to a certain extent. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the present invention provides a method for trimming grooves in CMP equipment polishing pads. Combining visual recognition and control technologies, the method can trim the grooves of polishing pads. Shallowed grooves on the polishing pad are further cut and deepened, and the grooves are trimmed to a standard depth without damaging the groove pattern, allowing severely worn polishing pads to be reused.

[0006] The technical solution adopted by the present invention to solve the technical problem is: a method for trimming grooves of a polishing pad of a CMP device, comprising the following steps:

[0007] Obtaining the extension trajectory of the groove on the polishing pad and determining the starting position of the groove trimming;

[0008] Adjust the position of the machining head so that it is located directly above the starting position of the groove trimming and determine the machining depth zero point;

[0009] The machining head descends and moves to the preset machining depth in the groove according to the machining zero point;

[0010] The processing head is controlled to move along the groove extension trajectory of the rotating polishing pad to deepen the cutting of the groove on the polishing pad.

[0011] Furthermore, it also includes: a correction step, obtaining the distance between the processing head and the groove boundary, and judging whether the distance reaches a threshold value, and correcting the actual movement trajectory of the processing head if the threshold value is reached.

[0012] Furthermore, the extension trajectory of the groove on the polishing pad is obtained through image recognition or theoretical calculation.

[0013] Furthermore, in the step of obtaining the groove extension trajectory through image recognition, the calculation method is to calculate the trajectory in real time.

[0014] The polishing table rotates, calculating the position of the groove in the field of view in real time, marking the position of the n×n pixel point group on the groove that is about to reach the processing head, and calculating the average position of the pixel points in the X-axis direction; the X-direction position coordinates of the processing head are compared with the average position point of the pixel point group that is about to reach on the X-axis, and the difference is the position where the processing head needs to move next moment.

[0015] Furthermore, in the step of obtaining the extended trajectory of the groove by image recognition, the calculation method is a pre-recorded trajectory;

[0016] The polishing table rotates, and the high-speed camera captures the groove image and calculates the relationship between the groove trajectory and the polishing table rotation angle to generate an angle-trajectory curve;

[0017] or,

[0018] The polishing table rotates, and a low-speed camera is used to obtain the angle-trajectory key point information. The angle-trajectory curve is calculated using the difference algorithm, which is the motion trajectory of the machining head.

[0019] Furthermore, in the step of theoretically calculating the extension trajectory of the groove, the groove is a circular ring, the coordinate system is a rectangular coordinate system, the distance between the rotation center and the center of the groove is a, the distance between the rotation center and the landing point of the processing head is b, and the distance between the center of the groove and the landing point of the processing head is c.

[0020] Furthermore, the maximum and minimum values ​​of the groove in the extended trajectory in the X direction are obtained, and the difference between the maximum and minimum values ​​is 2a. The distance c between the center of the groove and the landing point of the processing head is the groove radius. The rotation angular velocity ω of the polishing table is obtained. After time t, the rotation angle of the groove center relative to the rotation center is ωt, then This is the groove extension trajectory.

[0021] Furthermore, in the step of theoretically calculating the extension trajectory of the groove, the groove is annular, the coordinate system is a polar coordinate system, the distance between the rotation center and the groove center is a, the distance between the rotation center and the landing point of the processing head is b, the distance between the groove center and the landing point of the processing head is c, the polar coordinate system coordinate of the rotation center at the initial moment is (ρ1,π-ωt), and the polar coordinate system coordinate of the processing head is (ρ2,0), then a=ρ1, b=ρ2, Calculate ρ2, the groove extension trajectory.

[0022] Furthermore, in the step of theoretically calculating the extension trajectory of the groove, the groove is square, the distance between the rotation center and the groove center is a, the distance between the rotation center and the landing point of the processing head is b, and the distance between the groove center and the landing point of the processing head is c. The above-mentioned a value and c value are obtained by image recognition, and the rotation angular velocity ω of the polishing table is obtained. After time t, the rotation angle of the groove center relative to the rotation center is ωt, then b = (ca) / coswt, which is the groove extension trajectory.

[0023] Furthermore, in the step of determining the processing depth zero point, the depth zero point is determined by using the change in the motor torque of the processing head, or by using a mechanical sensor / ranging sensor, or by using a camera.

[0024] Furthermore, in the step of cutting the groove by the machining head moving along the groove extension trajectory, the polishing pad window position is image recognized or theoretically calculated in advance and marked as a non-machining area. When the machining head reaches this area, the motor controls the machining head to avoid it.

[0025] Furthermore, the groove has a depth of 0.3-1.0 mm and a width of 0.2-0.6 mm.

[0026] Furthermore, the threshold is 8-12 um.

[0027] Furthermore, it also includes negative pressure adsorption or positive pressure blowing or high-pressure water flushing steps, which are used to clean up debris generated by cutting with the processing head.

[0028] Furthermore, before the processing head descends, or after the processing head descends to a preset processing depth in the groove, the polishing table rotates, driving the polishing pad to rotate.

[0029] Furthermore, in the step of controlling the processing head to move along the groove extension trajectory of the rotating polishing pad to deepen the cutting of the groove on the polishing pad, the chips generated by the processing head cutting or the continuity of the chips are detected in real time to determine whether the processing head is cutting according to the preset processing depth, or whether cutting has started, or whether cutting has ended.

[0030] Furthermore, the step of controlling the processing head to move along the groove extension trajectory of the rotating polishing pad to deepen the groove cutting on the polishing pad includes the following sub-steps:

[0031] Select the light intensity detection area A on the imaged surface of the processing head. When processing has not started and the tool tip of the processing head is in the groove, the average grayscale value of the pixels in the light intensity detection area A is

[0032] Before processing begins, the average grayscale value of the pixels in the reference area B in the groove is B;

[0033] according to and Determine reference values;

[0034] The processing head starts processing and detects the average grayscale value of each pixel in the light intensity detection area A in real time. when Less than the reference value, it means that the machining head does not cut according to the preset machining depth; when If it is greater than the reference value, it means that the machining head cuts according to the preset machining depth and records the first The time greater than the reference value is t1;

[0035] After time t1, get the next The time interval t greater than the reference value k , if t k >0, it means that the machining head does not cut continuously and the groove processing does not meet the requirements; if t k =0, indicating that the machining head performs continuous cutting and the groove machining meets the requirements.

[0036] The beneficial effects of the present invention are: 1) the designed polishing pad groove trimming device can extend the service life of the polishing pad, reduce the cost of use, and fill the technical gap; 2) a camera or a line laser is installed on the trimming device as a visual feedback sensor, which can be combined with an algorithm to identify different polishing pad groove patterns, making the device highly versatile; 3) the camera or line laser can provide real-time feedback on the positional relationship between the tool head and the groove to prevent the tool head from damaging the groove pattern; 4) the trimming device has three degrees of freedom in directions perpendicular to each other in space. The tool head performs complex movements during engraving and can complete the trimming of any groove pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the polishing pad groove dressing device in the present invention.

[0038] Figure 2 This is a flow chart of the groove trimming control in the first embodiment of the present invention.

[0039] Figure 3 Schematic diagram of machining head trajectory calculation in embodiment 1 of the present invention.

[0040] Figure 4 Schematic diagram of the rectangular coordinate system in the first embodiment of the present invention.

[0041] Figure 5 Schematic diagram of the polar coordinate system in Example 1 of the present invention.

[0042] Figure 6 This is a simplified diagram of determining whether the machining head has reached the preset machining depth of the groove in the first embodiment of the present invention.

[0043] Figure 7 Schematic diagram of machining head trajectory calculation in the second embodiment of the present invention.

[0044] Figure 8 This is a flow chart of groove trimming control in embodiment 3 of the present invention.

[0045] Figure 9 This is a simplified diagram of the coordination between the processing head and the rectangular area in the third embodiment of the present invention.

[0046] Among them, 1-polishing table, 2-polishing pad, 3-groove, 4-processing head, 5-camera / line laser, 6-slider, 7-Z-axis motor at the bottom of the processing head, 8-negative pressure pipette, 9-Y-axis motion slider, 10-Y-axis motion motor, 11-groove center, 12-groove rotation center, 13-processing head landing point, DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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 making creative efforts should fall within the scope of protection of the present invention.

[0048] Example 1

[0049] A method for trimming grooves of a polishing pad of a CMP device comprises the following steps:

[0050] S1. Obtaining the extension trajectory of the groove on the polishing pad and determining the starting position of the groove trimming;

[0051] S2. Adjust the position of the machining head so that it is located directly above the starting position of the groove trimming and determine the machining depth zero point;

[0052] S3. The machining head descends and moves to a preset machining depth in the groove according to the machining zero point. The machining zero point here can be the bottom of the groove to be trimmed, or of course, any depth within the groove to be trimmed.

[0053] S4. Controlling the processing head to move along the groove extension trajectory of the rotating polishing pad to deepen the groove on the polishing pad; wherein the groove extension trajectory on the polishing pad is obtained by image recognition or theoretical calculation; the polishing pad can rotate before the processing head is lowered, or after the processing head is lowered to a preset processing depth in the groove, the polishing table rotates, thereby driving the polishing pad to rotate; there is no specific restriction on when the rotation begins;

[0054] S5, a correction step, obtaining the distance between the machining head and the groove boundary, and determining whether the distance reaches a threshold value, and correcting the actual movement trajectory of the machining head if the threshold value is reached;

[0055] S6, negative pressure adsorption or positive pressure blowing or high pressure water washing step, which is used to clean the debris generated by the cutting of the processing head. Of course, this step S6 can be set at the same time as the step S4 of deepening the cutting of the processing head.

[0056] Specifically, such as Figure 1 As shown, during the CMP process, the polishing table 1 rotates, driving the polishing pad 2 mounted on the table 1 to rotate, grinding the wafer. Ring-shaped grooves 3 on the polishing pad 2 contain polishing liquid, which chemically etch the wafer surface. Grooves 3 have a depth of 0.3-1.0 mm and a width of 0.2-0.6 mm, with a typical width of 0.4 mm and a depth of 0.8 mm.

[0057] The groove trimming device's processing head 4 can move in the X, Y, and Z directions according to control commands to trim the grooves 3 on the polishing pad 2. The processing head 4 and camera / line laser 5 are mounted on a slider 6, which is driven by a motor (or cylinder) to move in the X direction, with the projected position of the end of the processing head 4 positioned at the center of the camera / line laser 5's field of view. A Z-axis motor (or cylinder) 7 at the base of the processing head 4 provides the processing head 4 with Z-axis freedom. A Y-axis motion slider 9 and motor (or cylinder) 10 provide the processing head 4 and camera / laser 5 with Y-axis freedom. The processing head 4's three-dimensional freedom enables it to perform complex trajectory motions to handle various groove trimming tasks. The camera / laser 5 is pre-calibrated after installation.

[0058] like Figure 2, is a flow chart of the control method for groove trimming. After the trimming device is started, the polishing table 1 and the polishing pad 2 rotate simultaneously, and the camera / line laser 5 starts to record the data of the polishing pad groove 3. Under the corresponding data analysis algorithm, the trajectory of the processing head 4 in the X direction when trimming the groove 3 is calculated. When the groove center 11, the rotation center 12 and the processing head 4 move to the same straight line, and the groove center 11 is located between the rotation center 12 and the processing head 4, the polishing table 1 stops rotating, as shown in FIG. Figure 3 shown.

[0059] Adjust the position of the machining head 4 in the X-axis direction so that it reaches directly above the groove 3 to be trimmed. Lower the machining head 4 in the Z-axis direction. Determine the depth zero point based on the torque change of the Z-axis motor 7 at the bottom of the machining head, thereby determining whether the machining head 4 has reached the bottom of the groove 3. Alternatively, a mechanical sensor / distance sensor can be used to determine the depth zero point, thereby determining whether the machining head 4 has reached the bottom of the groove 3. When using camera feedback, the camera can be combined with an additional distance sensor to determine the depth zero point, thereby determining depth information. When using a line laser sensor, the depth information obtained by the sensor is directly used to determine whether the machining head 4 has reached the bottom of the groove 3. After the machining head 4 reaches the bottom, it descends to a predetermined depth, which is the depth at which the groove 3 needs to be further machined. The polishing table 1 starts rotating, and the machining head 4 begins cutting the groove 3 in the depth direction. The camera / line laser 5 provides real-time feedback on the distance between the machining head 4 and both sides of the groove 3, and fine-tunes the distance to prevent the machining head 4 from contacting the edges of the groove 3. In this embodiment, the threshold for this distance is 8-12 μm, and can be set to 10 μm. The negative pressure adsorption tube 8 located near the processing head 4 adsorbs and cleans the debris generated by the processing head 4 during cutting, ensuring the cleanliness of the polishing pad 2. Of course, the negative pressure adsorption tube 8 can also be replaced with a positive pressure blower to blow away the debris generated by the processing head 4 during cutting, or it can be replaced with high-pressure water to flush the debris generated by the processing head 4 during cutting. After a single groove 3 is trimmed, the next groove 3 is trimmed until all grooves 3 are trimmed. Positions on the polishing pad 2 that do not require processing, such as windows, are fixed positions relative to the polishing table 1 and can be marked in advance as non-processing areas. When the processing head 4 moves to this position, it automatically avoids it.

[0060] In order to verify whether the processing head 4 has reached the required cutting depth, that is, to control the processing head 4 to move along the extension trajectory of the groove 3 of the rotating polishing pad 2 to deepen the cutting of the groove 3 on the polishing pad 2, it is judged whether the processing head 4 is cutting according to the preset processing depth. When using camera feedback, the image processing method can be used to detect the chips generated by the cutting of the processing head or the continuity of the chips in real time during the processing to determine whether the processing head is cutting according to the preset processing depth, or whether cutting has started, or whether cutting has ended.

[0061] Of course, the step of controlling the processing head 4 to move along the extension trajectory of the groove 3 of the rotating polishing pad 2 to deepen the cutting of the groove 3 on the polishing pad 2 may also include the following sub-steps:

[0062] Select the light intensity detection area A on the imaging surface of the processing head 4. When the processing has not started and the tool tip of the processing head 4 is in the groove 3, the average grayscale value of the pixels in the light intensity detection area A is

[0063] Before processing begins, the average grayscale value of the pixels in the reference area B in groove 3 is

[0064] according to and Determine reference values;

[0065] The processing head 4 starts processing and detects the average grayscale value of each pixel in the light intensity detection area A in real time. when is less than the reference value, indicating that the machining head 4 does not cut according to the preset machining depth; when If it is greater than the reference value, it means that the machining head 4 cuts according to the preset machining depth and records the first The time greater than the reference value is t1;

[0066] After time t1, get the next The time interval t greater than the reference value k , if t k >0, indicating that the machining head 4 does not cut continuously and the groove 3 machining does not meet the requirements; if t k =0, indicating that the machining head 4 continuously cuts and the groove 3 machining meets the requirements.

[0067] Specifically, since the material of the polishing pad 2 is different from that of the processing head 4, there is a certain difference in their reflectivity to light. By detecting the light intensity around the processing area of ​​the tool tip of the processing head 4, it is possible to determine in real time whether cutting occurs. Figure 6 As shown, the light intensity detection area A is selected on the imaging surface of the processing head 4. When the processing has not started but the tool tip of the processing head 4 is in the groove 3, the average grayscale value of each pixel in the light intensity detection area A is The average grayscale value of each pixel in the reference area B in the groove 3 before processing is according to and Set the reference value, here select the average value As a reference, when the processing head 4 reaches the set processing position and starts processing, the camera detects the average value of the grayscale value of each pixel in the light intensity detection area A in real time. The grayscale average value curve is recorded with time as the vertical axis.

[0068] 1. When Less than the reference value When , it means that cutting has not occurred (the machining head 4 has not reached the effective machining position); 2. Greater than the reference value When the cutting occurs (the machining head 4 reaches the effective machining position), the time at this moment is recorded as t1; 3. After t1, analyze Greater than the reference value The time interval t k When t k When t > 0, it means that the cutting is discontinuous and the groove processing does not meet the requirements; when t k =0, it means that the cutting is continuous and the groove processing meets the requirements.

[0069] In this embodiment, theoretical calculation is used to obtain the extension trajectory of the groove. Figure 3 , is a top view of the circular groove polishing pad. Due to errors in the production process, the center 11 of the polishing pad 2 and the rotation center 12 of the polishing pad 2 are not at the same point, and the distance between them is a; the distance between the rotation center 12 and the landing point 13 of the processing head 4 is b, and the distance between the center 11 of the polishing pad 2 and the landing point 13 of the processing head 4 is c. Figure 4 At the initial moment, the position of the rotation center 12 is the center of the polishing table 1, and its coordinate position is (0,0). The center 11 of the polishing pad 2 is calculated by contour recognition based on the data recorded by the camera / line laser 5. The center position of the polishing pad 2 is obtained (x1, y1), and the value of a can be calculated. The center of the polishing pad 2 rotates around the rotation center, so the value of a is constant. In addition, the position of the groove 3 in the X direction will have a maximum and a minimum when it moves. The difference between the two is 2a, twice the eccentric distance of the groove 3. The value of a can be directly calculated. And c is the radius of a circular groove 3 on the polishing pad 2. It is also a constant value and can be measured in advance. Assuming that the angular velocity of the polishing table 1 is w, after time t, the center 11 of the polishing pad 2 rotates by an angle wt relative to the rotation center 12. According to the cosine theorem, a 2 +b 2 -2abcos(π-ωt)=c 2 , we can solve Furthermore, based on the relationship between the lengths of the triangle sides and the uniqueness of the triangle, the motion trajectory of the machining head on the X-axis over time can be determined from the solution of the equation.

[0070] For polar coordinate systems, such as Figure 5, taking the rotation center 12 of the polishing pad 2 as the coordinate origin, the coordinate of the center of the polishing pad 2 is (ρ1,π-ωt), and the coordinate position of the processing head 4 is (ρ2,0), then a=ρ1, b=ρ2, According to the above cosine theorem, the trajectory of the machining head 4 can be calculated using the same calculation method, and ρ2, i.e., the groove extension trajectory, can be calculated. In the two coordinate systems, the two coordinate systems can be completely equivalent after conversion.

[0071] Example 2

[0072] The hardware equipment and control process in this embodiment are the same as those in the first embodiment, and will not be described in detail. The second embodiment illustrates that the present invention can be used to repair grooves of different types of polishing pads.

[0073] In this embodiment, theoretical calculation is used to obtain the extension trajectory of the groove. Figure 7 The figure shows a top view of a polishing pad 2 with square grooves. Due to manufacturing process errors, the center 11 of the polishing pad 2 and its rotation center 12 are not aligned, with a distance a between them. The distance between the rotation center 12 and the processing head landing point 13 is b, and the distance between the center 11 of the polishing pad 2 and the initial landing point 13 of the processing head 4 is c. At the initial moment, the position of the rotation center 12 is the center of the polishing table 1, while the center 11 of the polishing pad 2 is calculated from an image captured by a camera through edge detection and contour recognition. Therefore, the values ​​of a and c can be determined in advance, and the value of b is the required trajectory of the processing head 4 in the X direction. Assuming the angular velocity of the polishing table 1 is w, after time t, the center 11 of the polishing pad 2 has rotated by an angle wt relative to the center 12 of the polishing pad 2. From the trigonometric relationship, bcoswt = ca. Therefore, the trajectory of the processing head 4 in the X axis is b = (ca) / coswt.

[0074] Example 3

[0075] The third embodiment is used to illustrate that in this embodiment, the position of the processing head 4 can be fed back in real time by the camera / line laser 5 to trim the groove 3 of the polishing pad 2 .

[0076] In this embodiment, image recognition is used to obtain the extension trajectory of the groove. Figure 8The figure shows a flow chart of the control method for groove trimming. The trimming device is activated, the polishing table 1 does not rotate, and the camera 5 located on top begins capturing the topography of the groove 3 on the polishing pad 2. The groove 3 on the polishing pad 2 is narrow and deep. Under the same lighting conditions, the groove 3 is darker than the area without grooves, resulting in a significant contrast difference. The image contrast difference between the groove 3 and the area without grooves on the polishing pad 2 is used to calculate the position of the groove 3 to be machined in the field of view. This is then converted, based on the physical distance corresponding to each pixel, into the distance between the machining head 4 and the groove 3 in the X-axis direction. This represents the distance the machining head 4 needs to move in the X-axis direction before the cutting operation begins. Based on this distance, the X-axis motor controls the machining head 4 to move directly above the groove 3, where it then begins to descend in the Z-axis direction. The torque change of the Z-axis motor 7 at the bottom of the machining head determines whether the machining head 4 has bottomed out. When the machining head 4 has bottomed out, the motor's resistance in the Z-axis direction increases significantly. After bottoming out, the machining head 4 moves downward to the preset cutting depth. The polishing table 1 starts to rotate, and the controller selects a rectangular area centered on the processing head 4 in the field of view through the image captured by the camera 5 for calculation and analysis. The size of the rectangular area is defined according to the distance between the grooves 3 to ensure that there is only one groove 3 in the rectangular area, such as Figure 9 . The typical spacing between grooves 3 is 2.7mm, and the rectangular area can be a square with a side length of 5.4mm. The actual position of the groove 3 is calculated by contrast analysis within the rectangular area, and the position where the edge of the area intersects the groove 3 is the position that is about to reach the processing head 4. Mark the position of the n×n pixel point group on the groove center that is about to reach the processing head 4. In this embodiment, n can be 5, and the average position of these pixel points in the X-axis direction is calculated. Compare the X-direction position coordinates of the processing head 4 with the average position point of the pixel point group that is about to arrive on the X-axis. The difference is the position where the processing head 4 needs to move to the next moment. The PID algorithm controls the movement of the processing head 4 to reach the corresponding pixel position. After the processing head 4 adjusts its position, the above steps are repeated until the groove 3 is trimmed. During the processing process, when a non-groove area or an area that does not need to be processed is identified, the processing head 4 is controlled to lift up quickly to avoid it. That is, the above is real-time cutting deepening.

[0077] Or the dressing device and the polishing table 1 are started at the same time, and the camera 5 located on the top begins to capture and scan the pattern of the groove 3 on the polishing pad 2. The X-direction position coordinates of the groove 3 to be processed are calculated based on the difference in image contrast between the groove and the groove-free area on the polishing pad 2. At the same time, the rotation angle of the polishing table 1 is recorded and stored as angle-processing position information, which serves as the final movement position of the processing head 4.

[0078] Or, every 15-degree rotation of the polishing table 1, the camera 5 takes a picture and calculates the X-axis coordinates of the groove 3. Then, using an interpolation algorithm, the angle-processing position information is calculated as the final movement position of the processing head 4. Non-groove areas or areas that do not need to be processed are identified in advance. When the processing reaches such areas, the processing head 4 is controlled to quickly lift up and avoid them.

[0079] At the start of processing, the polishing table 1 and the processing head 4 move simultaneously. When the polishing table 1 rotates to a certain angle, the processing head 4 moves to the corresponding position until the groove is completed. In other words, this is not real-time cutting and deepening, but rather a pre-recorded trajectory, and the processing head 4 then moves according to the recorded trajectory.

[0080] Specifically, the polishing table 1 rotates, and a high-speed camera is used as the camera 5 to obtain the image of the groove 3 and calculate the relationship between the trajectory of the groove 3 and the rotation angle of the polishing table 1 to generate an angle-trajectory curve; or, the polishing table 1 rotates, and a low-speed camera is used as the camera 5 to obtain the angle-trajectory key point information, and the difference algorithm is used to calculate the angle-trajectory curve, which is the motion trajectory of the processing head 4.

[0081] More specifically, the angle-trajectory curve here means that every time the polishing table rotates a certain angle, there will be a corresponding groove offset, that is, the groove trajectory. For example, if the polishing plate rotates at an angle of X and the groove offset is Y, the relationship between X and Y is recorded. Subsequent groove processing and the movement of the processing head are determined according to the above relationship.

[0082] In the correction step of this embodiment, the distance between the processing head 4 and the boundary of the groove 3 is obtained in real time through the camera 5, and it is determined whether the distance reaches the threshold. When the distance between the processing head 4 and the boundary of one side of the groove 3 reaches the threshold, the motor uses the PID control algorithm in the subsequent motion trajectory to automatically reduce or increase the trajectory position, and moves in the opposite direction for trimming until the distance between the processing head 4 and the boundary of the groove 3 is lower than the threshold.

[0083] The above specific embodiments are used to illustrate the present invention rather than to limit the present invention. Any modifications and changes made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A method for trimming grooves of a polishing pad of a CMP device, characterized in that: The following steps are involved: Obtaining the extension trajectory of the groove on the polishing pad and determining the starting position of the groove trimming; Adjust the position of the machining head so that it is located directly above the starting position of the groove trimming and determine the machining depth zero point; The machining head descends and moves to the preset machining depth in the groove according to the machining zero point; Controlling the machining head to move along the groove extension trajectory of the rotating polishing pad to deepen the groove cutting on the polishing pad; The step of controlling the processing head to move along the groove extension trajectory of the rotating polishing pad to deepen the groove cutting on the polishing pad includes the following sub-steps: Select the light intensity detection area A on the imaged surface of the processing head. When processing has not started and the tool tip of the processing head is in the groove, the average grayscale value of the pixels in the light intensity detection area A is Before processing begins, the average grayscale value of the pixels in the reference area B in the groove is according to and Determine reference values; The processing head starts processing and detects the average grayscale value of each pixel in the light intensity detection area A in real time. when Less than the reference value, it means that the machining head does not cut according to the preset machining depth; when If it is greater than the reference value, it means that the machining head cuts according to the preset machining depth and records the first The time greater than the reference value is t1; After time t1, get the next The time interval t greater than the reference value k , if t k >0, it means that the machining head does not cut continuously and the groove processing does not meet the requirements; if t k =0, indicating that the machining head performs continuous cutting and the groove machining meets the requirements.

2. The method for groove dressing of a polishing pad of a CMP device according to claim 1, wherein: Also includes: In the correction step, the distance between the machining head and the groove boundary is obtained, and it is determined whether the distance reaches a threshold value. If the threshold value is reached, the actual movement trajectory of the machining head is corrected.

3. The method for groove dressing of a polishing pad of a CMP equipment according to claim 1, wherein: The extension trajectory of the groove on the polishing pad is obtained through image recognition or theoretical calculation.

4. The method for groove dressing of a polishing pad of a CMP equipment according to claim 3, wherein: In the step of obtaining the extension trajectory of the groove by image recognition, the calculation method is to calculate the trajectory in real time. The polishing table rotates, calculating the position of the groove in the field of view in real time, marking the position of the n×n pixel point group on the groove that is about to reach the processing head, and calculating the average position of the pixel points in the X-axis direction; the X-direction position coordinates of the processing head are compared with the average position point of the pixel point group that is about to reach on the X-axis, and the difference is the position where the processing head needs to move next moment.

5. The method for groove dressing of a polishing pad of a CMP equipment according to claim 3, wherein: In the step of obtaining the extended track of the groove by image recognition, the calculation method is a pre-recorded track; The polishing table rotates, and the high-speed camera captures the groove image and calculates the relationship between the groove trajectory and the polishing table rotation angle to generate an angle-trajectory curve; or, The polishing table rotates, and a low-speed camera is used to obtain the angle-trajectory key point information. The angle-trajectory curve is calculated using the difference algorithm, which is the motion trajectory of the machining head.

6. The method for groove dressing of a polishing pad of a CMP equipment according to claim 3, wherein: In the step of obtaining the extension trajectory of the groove by theoretical calculation, the groove is a circular ring, the coordinate system is a rectangular coordinate system, the distance between the rotation center and the center of the groove is a, the distance between the rotation center and the landing point of the processing head is b, and the distance between the center of the groove and the landing point of the processing head is c.

7. The method for groove dressing of a polishing pad of a CMP equipment according to claim 6, wherein: The maximum and minimum values ​​of the groove in the extended trajectory in the X direction are obtained, and the difference between the maximum and minimum values ​​is 2a. The distance c between the center of the groove and the landing point of the processing head is the groove radius. The rotation angular velocity ω of the polishing table is obtained. After time t, the rotation angle of the groove center relative to the rotation center is ωt, then This is the groove extension trajectory.

8. The method for groove dressing of a polishing pad of a CMP equipment according to claim 3, wherein: In the step of theoretically calculating the extension trajectory of the groove, the groove is annular, the coordinate system is a polar coordinate system, the distance between the rotation center and the groove center is a, the distance between the rotation center and the landing point of the processing head is b, the distance between the groove center and the landing point of the processing head is c, the polar coordinate system coordinate of the rotation center at the initial moment is (ρ1,π-ωt), and the polar coordinate system coordinate of the processing head is (ρ2,0), then a=ρ1, b=ρ2, Calculate ρ2, the groove extension trajectory.

9. The method for groove dressing of a polishing pad of a CMP equipment according to claim 3, wherein: In the step of theoretically calculating the extension trajectory of the groove, the groove is square, the distance between the rotation center and the groove center is a, the distance between the rotation center and the landing point of the processing head is b, and the distance between the groove center and the landing point of the processing head is c. The above-mentioned a value and c value are obtained by image recognition, and the rotation angular velocity ω of the polishing table is obtained. After time t, the rotation angle of the groove center relative to the rotation center is ωt, then b = (ca) / coswt, which is the groove extension trajectory.

10. The method for groove dressing of a polishing pad of a CMP equipment according to claim 1, wherein: In the step of determining the processing depth zero point, the depth zero point is determined by using the change in the motor torque of the processing head, or by using a mechanical sensor / distance sensor, or by using a camera.

11. The method for groove dressing of a polishing pad of a CMP equipment according to claim 1, wherein: In the step of cutting the groove by the machining head moving along the groove extension trajectory, the polishing pad window position is image recognized or theoretically calculated in advance and marked as a non-machining area. When the machining head reaches this area, the motor controls the machining head to avoid it.

12. The method for groove dressing of a polishing pad of a CMP equipment according to claim 1, wherein: The depth of the groove is 0.3-1.0 mm, and the width thereof is 0.2-0.6 mm.

13. The method for groove dressing of a polishing pad of a CMP equipment according to claim 2, wherein: The threshold value is 8-12 um.

14. The method for groove dressing of a polishing pad of a CMP equipment according to claim 1, wherein: It also includes negative pressure adsorption or positive pressure blowing or high-pressure water flushing steps, which are used to clean the debris generated by cutting with the processing head.

15. The method for groove dressing of a polishing pad of a CMP equipment according to claim 1, wherein: Before the processing head descends, or after the processing head descends to a preset processing depth in the groove, the polishing table rotates, driving the polishing pad to rotate.

16. The method for groove dressing of a polishing pad of a CMP equipment according to claim 1, wherein: In the step of controlling the processing head to move along the groove extension trajectory of the rotating polishing pad to deepen the cutting of the groove on the polishing pad, the chips generated by the processing head cutting or the continuity of the chips are detected in real time to determine whether the processing head is cutting according to the preset processing depth, or whether cutting has started, or whether cutting has ended.

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