Polishing pad structure for silicon wafer grinding and method of controlling the same

Abstract

This invention relates to a polishing pad structure and its control method for silicon wafer grinding, belonging to the technical field of silicon wafer processing equipment. It includes a polishing frame with a polishing disk below it. A polishing pad, nested and flat, is mounted on the upper end of the polishing disk. Several annularly distributed magnetic chucks for silicon wafers are mounted on the lower end of the polishing frame and are movably pressed against the polishing pad. A grinding telescopic cylinder is provided between the magnetic chucks and the polishing frame. The polishing pad has several annularly distributed grinding grooves. It has the advantages of simple structure, convenient operation, and good results. By simultaneously applying different pressures to different areas of the polishing head, the polishing rate of each area can be adjusted, thereby optimizing the overall flatness of the wafer surface. This is beneficial for handling complex silicon wafer surface conditions and effectively improving the flatness of the polished silicon wafer.

Description

Technical Field

[0001] This invention relates to the field of silicon wafer processing equipment technology, and specifically to a polishing pad structure and control method for silicon wafer grinding. Background Technology

[0002] CMP (Chemical Motion Processing) has become an indispensable step in the modern IC industry. CMP uses chemical etching and mechanical force to planarize silicon wafers or other substrate materials during processing. CMP can achieve nanoscale material removal, resulting in wafer surface planarization.

[0003] CMP (Chemical Motion Polishing) utilizes a combination of chemical etching and mechanical polishing. It achieves wafer surface planarization through the relative movement between a polishing head and a polishing pad that holds the wafer. A specific flow rate of polishing slurry is dripped between the polishing pad and the wafer. The chemical components in the slurry, along with the mechanical friction generated by the slurry particles, remove excess material from the wafer surface, achieving global wafer planarization. During the polishing process, different pressures are applied simultaneously to different areas of the polishing head to adjust the polishing rate in those areas, thereby optimizing the overall planarization of the wafer surface.

[0004] Currently, in the chemical etching and mechanical polishing processes, the interaction force between the polishing head and the polishing pad during polishing is generally larger at the center and smaller at the edges. This results in the final polished silicon wafer having a flatness where the thickness of the outer edge area is larger than that of the center area. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a polishing pad structure and its control method for silicon wafer grinding. It boasts advantages such as simple structure, convenient operation, and excellent performance. By simultaneously applying different pressures to different areas of the polishing head, the polishing rate of each area is adjusted, thereby optimizing the overall flatness of the wafer surface. This is beneficial for handling complex silicon wafer surface conditions and effectively improving the flatness of the polished silicon wafer.

[0006] The above-mentioned technical problems of the present invention are mainly solved by the following technical solutions: A polishing pad structure for silicon wafer grinding includes a polishing frame, a polishing disk below the polishing frame, a polishing pad that is nested and laid flat on the upper end of the polishing disk, and several silicon wafer magnetic chucks arranged in a ring at the lower end of the polishing frame and movably pressed against the polishing pad. A grinding telescopic cylinder is provided between each silicon wafer magnetic chuck and the polishing frame. The polishing pad has several grinding grooves arranged in a ring.

[0007] Preferably, the polishing pad has a central guide wheel at the upper center, a central shaft is provided between the central guide wheel and the polishing frame, and a central shaft telescopic cylinder is provided between the central shaft and the polishing frame.

[0008] Preferably, the upper surface of the outer circle of the polishing disc is provided with a plurality of side guide wheels that limit and press the polishing pad.

[0009] Preferably, the number of side guide wheels is four, named P1, P2, P3 and P4 respectively.

[0010] Preferably, the grinding grooves are progressively deeper from the inside to the outside, or the outer grinding grooves are deeper than the inner grinding grooves.

[0011] A method for controlling the structure of a polishing pad includes the following steps: Step 1: Switch the knob on the CMP grinding equipment control panel to manual mode.

[0012] Step 2: Loosen the locking screws on the central shaft, lift the central shaft to the top, rotate it to the desired angle, and then hang the central shaft up.

[0013] Step 3: Use a wrench to turn the center guide wheel and remove it.

[0014] Step 4: Unscrew the fixing screws on the side guide wheels, flip the three side guide wheels P1, P3 and P4, and click on the P2 side guide wheel in the manual interface to raise it; then lift the polishing pad up a little, insert it into the gap of the roller, and then roll up the polishing pad with the roller.

[0015] Step 5: Thoroughly clean the center guide wheel, side guide wheels, and polishing pad.

[0016] Step 6: Apply the polishing pad smoothly and naturally to the surface of the polishing pad.

[0017] Step 7: Adjust the speed of the polishing disc to 30-50 rpm, and use the pressure bar to press the polishing pad from the center of the polishing disc outwards.

[0018] Step 8: Use a utility knife to cut off the excess polishing pad in the middle and at the edges, leaving a small corner at the edge to make it easier to peel off the fabric the next time you change the fabric.

[0019] Step 9: Reassemble the center guide wheel, center shaft, and side guide wheel back to their original assembly state.

[0020] Step 10: Clean the polishing pad.

[0021] As a preferred method, for thorough cleaning, rinse with water for 3 minutes and then wipe clean with a lint-free cloth; in the manual interface, adjust the polishing disc speed to 50, wipe the surface of the polishing disc clean with isopropyl alcohol, and wait for the polishing disc to dry completely.

[0022] As a preferred method, when pressing the polishing pad, a suitable amount of pure water should be sprayed with a water gun to ensure that the polishing pad adheres well to the surface of the polishing pad. If small air bubbles remain on the surface of the polishing pad and the polishing pad, puncture the air bubbles with an awl before pressing the polishing pad.

[0023] As a preferred method, for the polishing pad used in coarse polishing, first wash it with high-pressure water 3 times, then use a ceramic polishing cloth to polish with water for 5 minutes at a speed of 30 rpm, then use a disc brush to polish with water for 15 minutes, and then wash it with high-pressure water 2 times.

[0024] For the polishing pad used in intermediate polishing, first wash it with high-pressure water 3 times, then manually brush it with TSC-1 / EC-1 solution for 5 minutes to make the polishing pad hydrophilic; then wash it with water with a disc brush for 15 minutes, and then wash it with high-pressure water 2 times.

[0025] For the polishing pad used in fine polishing, first wash it with high-pressure water 3 times, then manually brush the cloth with TSC-1 / EC-1 solution for 5 minutes, then turn the knob to automatic, change the fluid selection for the disc brush to fine polishing solution in the interface settings, change the washing time to 15 minutes, click brushing, and after completion, wash it with high-pressure water 2 times in online state.

[0026] The present invention can achieve the following effects: This invention provides a polishing pad structure and its control method for silicon wafer grinding. Compared with existing technologies, it has the advantages of simple structure, convenient operation, and good results. By applying different pressures to different areas of the polishing head simultaneously, the polishing rate of each area is adjusted, thereby optimizing the overall flatness of the wafer surface. This is beneficial for handling complex silicon wafer surface conditions and effectively improving the flatness of the polished silicon wafer. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the present invention.

[0028] Figure 2 This is a cross-sectional view of the polishing pad of the present invention.

[0029] In the diagram: 1. Polishing frame; 2. Central shaft telescopic cylinder; 3. Central shaft; 4. Grinding telescopic cylinder; 5. Silicon wafer magnetic chuck; 6. Central guide wheel; 7. Side guide wheel; 8. Polishing disc; 9. Polishing pad; 10. Grinding groove. Detailed Implementation

[0030] The technical solution of the invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0031] Example: Figure 1 and Figure 2As shown, a polishing pad structure for silicon wafer grinding includes a polishing frame 1, a polishing disk 8 below the polishing frame 1, a polishing pad 9 nested on the upper end of the polishing disk 8, and four silicon wafer magnetic chucks 5 arranged in a ring at the lower end of the polishing frame 1, which are movably pressed against the polishing pad 9. A grinding telescopic cylinder 4 is provided between each silicon wafer magnetic chuck 5 and the polishing frame 1. A central guide wheel 6 is provided at the middle of the upper end of the polishing pad 9, a central shaft 3 is provided between the central guide wheel 6 and the polishing frame 1, and a central shaft telescopic cylinder 2 is provided between the central shaft 3 and the polishing frame 1. Several side guide wheels 7 are provided on the upper surface of the outer circle of the polishing disk 8 to limit and press the polishing pad 9. There are four side guide wheels 7, named P1, P2, P3, and P4 respectively. The polishing pad 9 has 12 rings of grinding grooves 10 arranged in a ring. The depth of the grinding grooves 10 increases from the inside to the outside, or the outer grinding grooves 10 are deeper than the inner grinding grooves 10.

[0032] A method for controlling the structure of a polishing pad includes the following steps: Step 1: Switch the knob on the CMP grinding equipment control panel to manual mode.

[0033] Step 2: Loosen the locking screws on the central shaft 3, lift the central shaft 3 to the top, rotate the angle, and then hang the central shaft up.

[0034] Step 3: Use a wrench to turn the center guide wheel 6 and remove it.

[0035] Step 4: Unscrew the fixing screws on the side guide wheels, flip the three side guide wheels P1, P3 and P4, and click on the P2 side guide wheel in the manual interface to raise it; then lift the polishing pad 9 slightly and insert it into the gap of the roller, and then roll up the polishing pad 9 with the roller.

[0036] Step 5: Thoroughly clean the center guide wheel 6, side guide wheel 7, and polishing disc 8. Rinse with water for 3 minutes and then wipe clean with a lint-free cloth; adjust the speed of the polishing disc (8) to 50 in the manual interface, wipe the surface of the polishing disc 8 clean with isopropyl alcohol, and wait for the polishing disc 8 to dry completely.

[0037] Step 6: Apply the polishing pad 9 smoothly and naturally to the surface of the polishing disc 8.

[0038] Step 7: Adjust the speed of the fixed plate to 30-50 rpm, and use the pressure bar to press the polishing pad 9 from the center of the polishing plate (8) outward.

[0039] When pressing the polishing pad 9, spray an appropriate amount of pure water with a water gun to make the polishing pad 9 adhere well to the surface of the polishing disc 8. If there are small air bubbles on the surface of the polishing pad 9 and the polishing disc 8 that cannot be removed, use an awl to puncture the air bubbles before pressing the polishing pad.

[0040] Step 8: Use a utility knife to cut off the excess polishing pad 9 in the middle and at the edges, leaving a small corner at the edge to make it easier to remove the fabric the next time you change the fabric.

[0041] Step 9: Reassemble the center guide wheel 6, center shaft 3, and side guide wheel 7 back to their original assembly state.

[0042] Step 10: Clean the polishing pad 9.

[0043] For the polishing pad 9 used in rough polishing, first wash it with high pressure water 3 times, then use the ceramic cloth polishing disc to polish with water for 5 minutes at a speed of 30 rpm, then use the disc brush to polish with water for 15 minutes, and then wash it with high pressure water 2 times. For the polishing pad 9 used in intermediate polishing, first wash it with high-pressure water 3 times, then manually brush it with TSC-1 / EC-1 solution for 5 minutes to make the polishing pad 9 hydrophilic; then wash it with water with a disc brush for 15 minutes, and then wash it with high-pressure water 2 times. For the polishing pad 9 used in fine polishing, first wash it with high-pressure water 3 times, then manually brush the cloth with TSC-1 / EC-1 solution for 5 minutes, then turn the knob to automatic, change the fluid selection for the disc brush to fine polishing liquid in the interface settings, change the washing time to 15 minutes, click brushing, and after completion, wash it with high-pressure water 2 times in online state.

[0044] In summary, the polishing pad structure and its control method for silicon wafer grinding have the advantages of simple structure, convenient operation, and good results. By applying different pressures to different areas of the polishing head simultaneously, the polishing rate of each area can be adjusted, thereby optimizing the overall flatness of the wafer surface. This is beneficial for handling complex silicon wafer surface conditions and effectively improving the flatness of the polished silicon wafer.

[0045] The above description is only a specific embodiment of the present invention, but the structural features of the present invention are not limited thereto. Any changes or modifications made by those skilled in the art within the scope of the present invention are covered by the patent scope of the present invention.

Claims

1. A method for controlling a polishing structure used in silicon wafer grinding, characterized in that: The polishing structure for silicon wafer grinding includes a polishing frame (1), a polishing disc (8) is provided below the polishing frame (1), a polishing pad (9) is provided at the upper end of the polishing disc (8) and is nested with the polishing pad (8), and a number of silicon wafer magnetic chucks (5) are provided at the lower end of the polishing frame (1) in a ring and are movably pressed with the polishing pad (9). A grinding telescopic cylinder (4) is provided between the silicon wafer magnetic chuck (5) and the polishing frame (1); and a number of grinding grooves (10) are provided on the polishing pad (9). The polishing pad (9) is provided with a central guide wheel (6) at the middle of its upper end. A central shaft (3) is provided between the central guide wheel (6) and the polishing frame (1). A central shaft telescopic cylinder (2) is provided between the central shaft (3) and the polishing frame (1). The upper surface of the outer circle of the polishing disc (8) is provided with several side guide wheels (7) that limit and press the polishing pad (9). There are 4 side guide wheels (7), which are named P1, P2, P3 and P4 in sequence. A method for controlling a polished structure includes the following steps: Step 1: Switch the knob on the CMP grinding equipment control panel to manual mode; Step 2: Loosen the locking screw on the central shaft (3), lift the central shaft (3) to the top, rotate the angle and hang the central shaft up; Step 3: Use a wrench to turn the center guide wheel (6) and remove the center guide wheel (6); Step 4: Unscrew the fixing screws on the side guide wheels, flip the three side guide wheels P1, P3 and P4, and click on the P2 side guide wheel in the manual interface to raise it; then lift the polishing pad (9) a little, insert it into the gap of the roller, and then roll up the polishing pad (9) with the roller. Step 5: Thoroughly clean the center guide wheel (6), side guide wheels (7), and polishing disc (8); Step 6: Apply the polishing pad (9) smoothly and naturally to the surface of the polishing disc (8); Step 7: Adjust the speed of the fixed plate to 30-50 rpm, and use the pressure bar to press the polishing pad (9) from the center of the polishing plate (8) outwards. Step 8: Use a utility knife to cut off the excess polishing pad in the middle and at the edges (9), leaving a small corner at the edge to make it easier to peel off the fabric the next time you change the fabric; Step 9: Reassemble the center guide wheel (6), center shaft (3), and side guide wheel (7) back to their original assembly state; Step 10: Clean the polishing pad (9); For the polishing pad (9) used in rough polishing, first wash it with high pressure water 3 times, then use the repair cloth ceramic disc to repair the cloth and wash it with water for 5 minutes. The rotation speed of the repair cloth ceramic disc is 30 rpm. Then use the disc brush to wash it with water for 15 minutes, and then wash it with high pressure water 2 times. For the polishing pad (9) used in the intermediate polishing, first use high pressure water to brush it 3 times, then use TSC-1 solution to manually brush it for 5 minutes to make the polishing pad (9) hydrophilic; then use a disc brush to brush it with water for 15 minutes, and then use high pressure water to brush it 2 times. For the polishing pad (9) used in fine polishing, first use high pressure water to brush it 3 times, then use TSC-1 solution to manually brush it for 5 minutes, then turn the knob to automatic, change the fluid selection of the disc brush to fine polishing liquid in the interface settings, change the washing time to 15 minutes, start brushing, and after completion, use high pressure water to brush it 2 times in the online state.

2. The control method for the polishing structure used in silicon wafer grinding according to claim 1, characterized in that: The grinding grooves (10) are progressively deeper from the inside to the outside, or the outer grinding grooves (10) are deeper than the inner grinding grooves (10).

3. The control method for the polishing structure used in silicon wafer grinding according to claim 1, characterized in that: For thorough cleaning, rinse with water for 3 minutes and then wipe clean with a lint-free cloth; adjust the speed of the polishing disc (8) to 50 rpm in the manual interface, wipe the surface of the polishing disc (8) clean with isopropyl alcohol, and wait for the polishing disc (8) to dry completely.

4. The control method for the polishing structure used in silicon wafer grinding according to claim 1, characterized in that: When pressing the polishing pad (9), a suitable amount of pure water needs to be sprayed with a water gun so that the polishing pad (9) can adhere well to the surface of the polishing disc (8). If there are small air bubbles on the surface of the polishing pad (9) and the polishing disc (8) that cannot be eliminated, use an awl to puncture the air bubbles and then press the polishing pad.

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