Correcting processing method for elliptical edge contour of silicon wafer

Abstract

The invention relates to a silicon wafer elliptical edge contour correction processing method, which belongs to the technical field of silicon wafer processing, and comprises the following steps: firstly, carrying out multi-angle diameter measurement on an elliptical silicon wafer, calculating the position of a circle center according to multiple pieces of diameter data, and then resetting the coordinates of the circle center of a chamfering processing bearing table; the machining amount of the positioning notch position is increased by increasing the circle center coordinates, and the machining amount of the positioning notch position is reduced by reducing the circle center coordinates. The eccentric machining amount is calculated according to the depth of a positioning notch, the compensation feeding amount of each diameter is set, then the silicon wafer enters a chamfering grinding wheel groove to be machined according to the feeding amounts in different diameter directions, and finally the pure circular appearance is formed. The method has the advantages of convenient operation and good processing stability. And the problem of ellipse in the silicon wafer rolling process is solved. Shape measurement is added before silicon wafer chamfering processing, comparison calculation is performed according to positioning notch position diameter data and short edge diameter data, and then the long edge diameter removal amount is corrected according to a target value, so that the silicon wafer rounding process is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of silicon wafer processing, and in particular to a method for correcting the elliptical edge profile of a silicon wafer. Background Art

[0002] As the feature size of devices decreases, the quality requirements for the crystal part of silicon wafers are getting higher and higher. For polished silicon wafers, crystal native defects are a very important feature. After the crystal rod is pulled, it needs to go through processes such as roller grinding, grooving, slicing, chamfering, and polishing before checking for crystal native defects.

[0003] Wafer contour processing is also called chamfering. The purpose of silicon wafer chamfering is to eliminate the sharp edges and corners of the silicon wafer edge, reduce stress concentration and dislocation, and thus reduce the risk of mechanical damage and cracking of the silicon wafer. A grinding wheel with a specific shape is used to grind away the sharp edges and corners of the silicon wafer edge, and the edge collapse cracks, and after the chamfering process, it is necessary to ensure that the chamfered surface is free of scratches and has a good roughness. The chamfering wheel generally includes rough grinding grooves and fine grinding grooves, which are horizontally distributed at a certain interval.

[0004] In the current silicon wafer contour processing process, the carrier table transfers the silicon wafer horizontally to the groove of the grinding wheel, and grinds the edge of the silicon wafer in the order of rough grinding and fine grinding to form the contour shape required by the back-end customers. However, in the process of single crystal silicon rod to single crystal silicon wafer, there is a step of peripheral roller grinding. When the roller grinding process is not good, the single silicon wafer after cutting will become an elliptical shape. The chamfering process is a pure circular motion, which cannot effectively perform equivalent processing on the peripheral edge of the elliptical silicon wafer. Summary of the invention

[0005] The present invention mainly solves the deficiencies in the prior art and provides a method for correcting the elliptical edge contour of a silicon wafer, which has the advantages of convenient operation and good processing stability. The problem of elliptical appearance during the roller grinding process of silicon wafers is solved. By adding external shape measurement before the chamfering of the silicon wafer, and comparing and calculating the diameter data of the positioning notch position with the short side diameter data, and then correcting the long side diameter removal amount according to the target value, the silicon wafer rounding process is achieved, and the silicon wafer is processed into a pure circular appearance that meets the device processing.

[0006] The above technical problems of the present invention are mainly solved by the following technical solutions: A method for correcting the elliptical edge profile of a silicon wafer comprises the following steps: Step 1: Use a contour measuring instrument to measure the diameter data of the silicon wafer to be processed in all directions.

[0007] Step 2: Compare and calculate the diameter data of the positioning notch position with the short side diameter data to calculate the real center coordinates of the silicon wafer. According to the calculation formula (Dia-2×Vh) / 2=d, first measure the maximum diameter Dia of the notch of the entire silicon wafer, and calculate the inner circle radius d after removing the notch Vh; then calculate the horizontal inner circle radius d2 according to the formula (Dia2-2×Vh) / 2=d2, and then d-d2=d3, when d3>0, enter the adjusted center coordinates (0, d3); when d3<0, enter the coordinates (d3,0); when d3=0, do not adjust.

[0008] Step 3: Enter the true coordinates of the center of the circle into the processing software, and correct the long side diameter removal amount according to the target value. When the calculated result d3>0, the silicon wafer is placed on the processing stage, and the Y axis moves -d3 distance when the stage is at 0° and 180°; when d3<0, the silicon wafer is placed on the processing stage, and the Y axis moves -d3 distance when the stage is at 90° and 270°. When d3=0, no adjustment is made.

[0009] Step 4: Start the chamfering machine power supply, and the 1# vacuum adsorption robot starts the sheet picking and processing operation.

[0010] Step 5: Measure silicon wafer thickness and crystal orientation.

[0011] Step 6: The 1# vacuum manipulator adsorbs the silicon wafer and approaches the chamfering grinding wheel to roughly grind the groove after adjusting the center coordinates of the circle.

[0012] Step 7: 2# vacuum adsorption robot starts wafer picking and processing; silicon wafer thickness measurement and silicon wafer crystal orientation measurement.

[0013] Step 8: The 1# vacuum robot absorbs the silicon wafer and places it close to the chamfering wheel to finely grind the groove in a normal state.

[0014] Step 9: The 2# vacuum manipulator adsorbs the silicon wafer to adjust the center coordinates and then approaches the chamfering wheel to roughly grind the groove.

[0015] Step 10: The 1# vacuum robot carries the processed silicon wafer back to the wafer box.

[0016] Step 11: The 2# vacuum robot absorbs the silicon wafer and approaches the chamfering wheel to finely grind the groove in a normal state.

[0017] Step 12: Robot arm 1# cycles to process the next wafer, vacuum robot arm 2# carries the processed silicon wafer back to the wafer box, and robot arm 2# cycles to process the next wafer.

[0018] Preferably, the silicon wafer is in a normal state, that is, the circumference has been processed, and the edge of the silicon wafer is close to a pure circle.

[0019] Preferably, the actual position of the center of the circle is marked by calculating the diameter difference, which serves as a reference coordinate for feeding in all directions during processing.

[0020] Preferably, the positioning notch of the silicon wafer is aligned with the notch polishing cloth, and the positioning notch of the silicon wafer is polished.

[0021] Preferably, the silicon wafer that has completed the positioning notch polishing is subjected to centering treatment to align the center of the silicon wafer with the center of the machine, and the silicon wafer that has completed the centering treatment is subjected to round edge polishing treatment, and the polishing drum used includes a bevel polishing drum and a top polishing drum.

[0022] Preferably, the bevel polishing drum has a bevel with a processing angle of 35 degrees and a curved surface with a processing angle gradually transitioning from 35 degrees to 65 degrees, and the processing angle varies in the range of 35 degrees to 65 degrees during the entire processing stroke of the bevel edge polishing; the processing surface of the top polishing drum is an arched curved surface, and the processing angle varies in the range of 75 degrees to 85 degrees during the entire processing stroke of the top polishing.

[0023] The present invention can achieve the following effects: The present invention provides a method for correcting the elliptical edge contour of a silicon wafer, which has the advantages of convenient operation and good processing stability compared with the prior art. The problem of elliptical appearance during the roller grinding process of the silicon wafer is solved. By adding external shape measurement before the chamfering of the silicon wafer, and comparing and calculating the diameter data of the positioning notch position with the short side diameter data, and then correcting the long side diameter removal amount according to the target value, the silicon wafer rounding process is achieved, and the silicon wafer is processed into a pure circular appearance that meets the device processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the circle center calculation structure of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the invention is further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0026] Example: Figure 1 As shown, a method for correcting the elliptical edge profile of a silicon wafer includes the following steps: Step 1: Use a contour measuring instrument to measure the diameter data of the silicon wafer to be processed in all directions.

[0027] Step 2: Compare and calculate the diameter data of the positioning notch position with the short side diameter data to calculate the true center coordinates of the silicon wafer. By calculating the diameter difference, the actual position of the center is marked; it serves as the reference coordinate for feeding in all directions during processing.

[0028] According to the calculation formula (Dia-2×Vh) / 2=d, first measure the maximum diameter Dia of the notch of the entire silicon wafer, and calculate the inner circle radius d after removing the notch Vh; then calculate the horizontal inner circle radius d2 according to the formula (Dia2-2×Vh) / 2=d2, and then d-d2=d3. When d3>0, enter the adjusted center coordinates (0, d3); when d3<0, enter the coordinates (d3,0); when d3=0, do not adjust.

[0029] Step 3: Enter the true coordinates of the center of the circle into the processing software, and correct the long side diameter removal amount according to the target value. When the calculated result d3>0, the silicon wafer is placed on the processing stage, and the Y axis moves -d3 distance when the stage is at 0° and 180°; when d3<0, the silicon wafer is placed on the processing stage, and the Y axis moves -d3 distance when the stage is at 90° and 270°. When d3=0, no adjustment is made.

[0030] The positioning notch of the silicon wafer is aligned with the notch polishing cloth, and the positioning notch of the silicon wafer is polished. The silicon wafer that has completed the positioning notch polishing is centering, so that the center of the silicon wafer is aligned with the center of the machine, and the silicon wafer that has completed the centering process is polished at the edge. The polishing drums used include bevel polishing drums and top polishing drums.

[0031] The bevel polishing drum has a bevel with a processing angle of 35 degrees and a curved surface with a processing angle gradually transitioning from 35 degrees to 65 degrees. The processing angle varies in the range of 35 degrees to 65 degrees during the entire processing stroke of bevel edge polishing; the processing surface of the top polishing drum is an arched curved surface, and the processing angle varies in the range of 75 degrees to 85 degrees during the entire processing stroke of top polishing.

[0032] Step 4: Start the chamfering machine power supply, and the 1# vacuum adsorption robot starts the sheet picking and processing operation.

[0033] Step 5: Measure silicon wafer thickness and crystal orientation.

[0034] Step 6: The 1# vacuum manipulator adsorbs the silicon wafer and approaches the chamfering grinding wheel to roughly grind the groove after adjusting the center coordinates of the circle.

[0035] Step 7: 2# vacuum adsorption robot starts wafer picking and processing; silicon wafer thickness measurement and silicon wafer crystal orientation measurement.

[0036] Step 8: 1# vacuum manipulator adsorbs the silicon wafer and approaches the chamfering wheel to finely grind the groove in a normal state. The normal state of the silicon wafer is that the circumference has been processed and the edge of the silicon wafer is close to a pure circle.

[0037] Step 9: The 2# vacuum manipulator adsorbs the silicon wafer to adjust the center coordinates and then approaches the chamfering wheel to roughly grind the groove.

[0038] Step 10: The 1# vacuum robot carries the processed silicon wafer back to the wafer box.

[0039] Step 11: The 2# vacuum manipulator adsorbs the silicon wafer and approaches the chamfering wheel to finely grind the groove in a normal state. The normal state of the silicon wafer is that the circumference has been processed and the edge of the silicon wafer is close to a pure circle.

[0040] Step 12: Robot arm 1# cycles to process the next wafer, vacuum robot arm 2# carries the processed silicon wafer back to the wafer box, and robot arm 2# cycles to process the next wafer.

[0041] First, the multi-angle diameter measurement of the elliptical silicon wafer is carried out, and the position of the circle center is calculated based on multiple diameter data. Then, the coordinates of the circle center of the chamfering processing platform are reset. Increasing the coordinates of the circle center increases the processing volume of the positioning notch position, and decreasing the coordinates of the circle center reduces the processing volume of the positioning notch position. According to the depth of the positioning notch, the eccentric processing volume is calculated, and the various diameter compensation feed amounts are set. Then, the silicon wafer will enter the chamfering wheel groove processing according to the feed amount in different diameter directions, and finally form a pure circular appearance.

[0042] In summary, the silicon wafer elliptical edge contour correction processing method has the advantages of convenient operation and good processing stability. The problem of ellipse in the silicon wafer roller grinding process is solved. By adding appearance measurement before the silicon wafer chamfering process, and comparing and calculating the diameter data of the positioning notch position with the short side diameter data, and then correcting the long side diameter removal amount according to the target value, the silicon wafer rounding process is achieved, and the silicon wafer is processed into a pure circular appearance that meets the device processing.

[0043] 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 any technician in the field of the present invention are included in the patent scope of the present invention.

Claims

1. A method for correcting the elliptical edge profile of a silicon wafer, characterized in that The steps are as follows: Step 1: Use a contour measuring instrument to measure the diameter data of the silicon wafer to be processed in all directions; Step 2: Compare and calculate the diameter data of the positioning notch position with the short side diameter data to calculate the real center coordinates of the silicon wafer; according to the calculation formula (Dia-2×Vh) / 2=d, first measure the maximum diameter Dia of the notch of the entire silicon wafer, and calculate the inner circle radius d after removing the notch Vh; then calculate the horizontal inner circle radius d2 according to the formula (Dia2-2×Vh) / 2=d2, and then d-d2=d3, when d3>0, enter the adjusted center coordinates (0, d3); when d3<0, enter the coordinates (d3,0); when d3=0, do not adjust; Step 3: Enter the true coordinates of the center of the circle into the processing software, and correct the long side diameter removal amount according to the target value; when the calculated result d3>0, after the silicon wafer is placed on the processing stage, the Y axis moves a distance of -d3 when the stage is at 0° and 180°; When d3<0, after the silicon wafer is placed on the processing stage, the Y axis moves -d3 distance when the stage is at 90° and 270°. When d3=0, no adjustment is made. Step 4: Start the chamfering machine power supply, and the 1# vacuum adsorption manipulator starts the sheet picking and processing operation; Step 5: Silicon wafer thickness measurement and silicon wafer crystal orientation measurement; Step 6: The 1# vacuum manipulator adsorbs the silicon wafer and approaches the chamfering grinding wheel to roughly grind the groove after adjusting the center coordinates of the circle; Step 7: 2# vacuum adsorption manipulator starts to take out the wafer for processing; silicon wafer thickness measurement and silicon wafer crystal orientation measurement; Step 8: 1# vacuum manipulator adsorbs the silicon wafer and approaches the chamfering grinding wheel to finely grind the groove in a normal state; Step 9: The 2# vacuum manipulator absorbs the silicon wafer to adjust the center coordinates and then approaches the chamfering grinding wheel to roughly grind the groove; Step 10: The 1# vacuum manipulator carries the processed silicon wafer back to the wafer box; Step 11: The 2# vacuum manipulator adsorbs the silicon wafer and approaches the chamfering grinding wheel to finely grind the groove in a normal state; Step 12: Robot arm 1# cycles to process the next wafer, vacuum robot arm 2# carries the processed silicon wafer back to the wafer box, and robot arm 2# cycles to process the next wafer.

2. The method for correcting the elliptical edge profile of a silicon wafer according to claim 1, characterized in that: The normal state of a silicon wafer is that the circumference has been processed and the edge of the silicon wafer is close to a pure circle.

3. The method for correcting the elliptical edge profile of a silicon wafer according to claim 1, characterized in that: By calculating the diameter difference, the actual position of the circle center is marked, which serves as the reference coordinate for feeding in all directions during processing.

4. The method for correcting the elliptical edge profile of a silicon wafer according to claim 1, characterized in that: The positioning notch of the silicon wafer is aligned with the notch polishing cloth, and the positioning notch of the silicon wafer is polished.

5. The method for correcting the elliptical edge profile of a silicon wafer according to claim 4, characterized in that: The silicon wafer that has completed the positioning notch polishing is subjected to centering processing to align the center of the silicon wafer with the center of the machine, and the silicon wafer that has completed the centering processing is subjected to round edge polishing processing. The polishing drums used include bevel polishing drums and top polishing drums.

6. The method for correcting the elliptical edge profile of a silicon wafer according to claim 5, characterized in that: The bevel polishing drum has a bevel with a processing angle of 35 degrees and a curved surface with a processing angle gradually transitioning from 35 degrees to 65 degrees. The processing angle varies in the range of 35 degrees to 65 degrees during the entire processing stroke of bevel edge polishing; the processing surface of the top polishing drum is an arched curved surface, and the processing angle varies in the range of 75 degrees to 85 degrees during the entire processing stroke of top polishing.

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