JP2014004663A - Processing method for workpiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method capable of flattening a plurality of sheets of workpieces after grinding with high accuracy even if the sheets of workpieces are simultaneously ground or polished.SOLUTION: A processing method includes a holding step for holding a plurality of sheets of workpieces 1 having a smaller size than that of a holding surface 11 via a support member 4 covering a suction area of a holding table 10 in the holding table 10 sucking and holding the workpiece 1 and including the holding surface 11 having the whole surface on the same surface, and a processing step for arranging an outer peripheral edge 24b of a processing wheel 23 or an outer peripheral edge 35b of a polishing pad 35 to always pass a center portion 13 of the holding surface 11 of the holding table 10, making the outer peripheral edge 24b or the outer peripheral edge 35b abut on the plurality of sheets of workpieces 1 and executing processing for the workpieces 1. Accordingly, the lengths of processing points 5 in the workpieces 1 become substantially same. As a result, the workpieces 1 after the processing can be flattened with high accuracy.

Description

  The present invention relates to a processing method for grinding or polishing a workpiece.

  In the case of a sapphire wafer, SiC wafer, or the like having a small size (for example, φ3 inches), if processing such as grinding or polishing is performed individually, processing time is required, resulting in low production efficiency. Therefore, in order to improve the production efficiency of products, a plurality of workpieces such as sapphire wafers and Sic wafers are held on a holding table, and grinding and polishing are performed in one processing step (for example, the following) (See Patent Document 1).

  An example of a holding table provided in the processing apparatus is a rotatable holding table 40 shown in FIG. The holding surface 41 of the holding table 40 is a conical surface that descends radially outward with the central portion of the holding surface 41 through which the central axis 42 passes as a vertex. When grinding the workpiece held on the holding table 40, grinding is performed after aligning the processing surface of the grindstone 51 fixed to the lower part of the processing means 50 so as to be parallel to the holding surface 41. To do. Further, regarding a method of polishing by holding a workpiece on a conical holding table, there is one shown in Patent Document 2 below.

Japanese Patent Application Laid-Open No. 2010-247311 JP 2000-288888 A

  However, if the holding surface is a conical surface, a tool such as a grinding wheel is in contact with the workpiece only at the radius portion of the holding surface, and the machining is performed. The length of the trajectory of “working point”) varies greatly depending on the part of the workpiece. As described above, when there are a long portion and a short portion of the processing point, the degree of grinding is different, so that there is a problem that the workpiece after grinding is not finished flat.

  The present invention has been made in view of the above circumstances, and the present invention is directed to a processing method capable of flattening a workpiece after grinding with high accuracy even if a plurality of workpieces are ground or polished. There are issues to be solved.

  The present invention relates to a workpiece processing method for grinding or polishing a workpiece, wherein the workpiece is sucked and held, and a holding surface whose entire surface is on the same plane and a center of the holding surface are orthogonal to the holding surface Holding a workpiece having a size smaller than the size of the holding surface with a holding table having a rotating shaft, via a support member that covers a suction area of the holding table, and after performing the holding step, The processing surface of the processing wheel is set so that an outer peripheral edge of a processing wheel having a processing surface parallel to the holding surface and a rotation axis orthogonal to the processing surface passes through the center of the holding surface of the holding table. And a processing step of contacting a workpiece held by the holding table and rotating the holding table and the processing wheel to grind or polish a plurality of workpieces by the processing wheel. In step With 3 or more workpieces are disposed adjacent in the regular polygon, the center of the center and the holding surface of the regular polygon is held in the matched state.

  In the present invention, in the holding step, three or more workpieces are arranged adjacent to each other in the regular polygon on the holding surface whose entire surface is on the same plane, and the center of the regular polygon and the center of the holding surface are Since three or more workpieces are held in a matched state, in the machining step, a plurality of machining surfaces of the machining wheel are arranged so that the outer peripheral edge of the machining wheel always passes through the central portion of the holding surface of the holding table. When processing is performed by contacting the workpiece, the lengths of the processing points are substantially the same regardless of the contact portion of the processing surface. Therefore, it becomes possible to planarize the workpiece after processing with high accuracy.

It is sectional drawing which shows the structure of a holding table and a grinding means. It is sectional drawing which shows the holding | maintenance step which hold | maintains a some workpiece to a holding table. It is a top view which shows the state by which the several to-be-processed object was hold | maintained inside the equilateral triangle on a holding table. It is sectional drawing which shows the process step which implements grinding with respect to several workpieces hold | maintained at the holding table. It is a top view which shows the processing point of a processing wheel partially. It is a top view which shows the processing point of the processing wheel about a some workpiece. It is sectional drawing which shows the process step which implements grinding | polishing with respect to several workpieces hold | maintained at the holding table. It is a top view which shows the state by which the several to-be-processed object was rearranged and hold | maintained inside the equilateral triangle on the holding table. It is a top view which shows the state by which the some workpiece was hold | maintained inside the regular hexagon on the holding table. It is sectional drawing which shows the structure of the holding table and grinding | polishing means whose holding surface is a conical surface. It is a comparative example which shows the processing point of one sapphire wafer when the sapphire wafer held by the holding table of which the holding surface is a conical surface is ground. It is a comparative example which shows the processing point of three sapphire wafers when grinding the sapphire wafer hold | maintained on the holding table of a conical surface.

1 First Embodiment A holding table 10 shown in FIG. 1 is a holding table that rotatably holds a circular workpiece. The holding table 10 has a holding surface 11 that is a surface for sucking and holding a workpiece. The holding surface 11 is entirely flat on the same surface. A central portion of the holding surface 11 has a rotating shaft 12 orthogonal to the holding surface 11, and the holding table 10 can be rotated about the rotating shaft 12 as a rotation center.

  On the outer peripheral side of the holding table 10, clamping means 14 for fixing the workpiece on the holding surface 11 is disposed. The clamp means 14 includes a support portion 15 that can move up and down, a mounting table 16 connected to the support portion 15, and a clamp portion 17 that clamps a workpiece on the mounting table 16.

  A grinding means 20 shown in FIG. 1 includes a spindle 21 having a vertical axis, a processing wheel 23 mounted on a lower portion of the spindle 21 via a mounter 22, and a grinding fixed to the lower portion of the processing wheel 23 in an annular shape. And a grindstone 24. The grinding means 20 can move up and down while rotating the processing wheel 23.

  Below, the method to grind a workpiece by the grinding means 20 comprised as mentioned above is demonstrated.

(1) Holding Step The circular workpiece 1 shown in FIG. 2 is formed of, for example, sapphire or silicon carbide. As shown in FIGS. 2 and 3, the size of the workpiece 1 is smaller than the size of the holding surface 11, and even if a plurality of the workpieces 1 are arranged on the holding surface 11, the workpiece 1 fits the holding surface 11. The workpiece 1 in the example of FIG. 3 is formed in a circular shape of φ3 inches, for example.

  First, as shown in FIG. 2, the support member 3 that covers the holding surface 11 of the holding table 10 is attached to the lower part of the annular frame 4 whose center is opened. Next, the workpiece 1 is attached to the support member 3 exposed from the central portion of the frame 4. The support member 3 is formed of an extensible adhesive material, and the workpiece 1 is integrated with the frame 4 via the support member 3 by sticking the workpiece 1 to the support member 3. It becomes a state. The workpiece 1 is attached to the center portion of the support member 3 in close contact.

  Next, the support member 3 side to which the workpiece 1 is attached is placed and held on the holding surface 11 of the holding table 10, the frame 4 is placed on the placing table 16, and the clamp portion 17 is placed on the frame 4. Hold the top of to secure. Thus, the support member 3 covers the holding surface 11 and is held on the holding table 10 together with the workpiece 1.

  In the holding step, as shown in FIG. 3, three workpieces 1 are arranged adjacent to each other, and all the workpieces 1 are arranged inside an equilateral triangle 2 </ b> A inside the holding surface 11. The Further, the three workpieces 1 are held so that the center portion of the equilateral triangle 2 </ b> A and the center portion 13 of the holding surface 11 coincide with each other.

(2) Processing Step After performing the holding step, the workpiece 1 is ground by the grinding means 20 as shown in FIG. After the holding table 10 is moved below the grinding means 20, the holding table 10 rotates in the direction of arrow A, for example, and the spindle 21 rotates in the direction of arrow B, for example, while the processing surface 24 a of the processing wheel 23 is held on the holding surface 11. The workpiece 1 is lowered toward the workpiece 1 while being in a state parallel to the workpiece 1. Then, the processing surface 24 a of the processing wheel 23 is ground while pressing the plurality of workpieces 1. Here, the processing surface 24 a means the lower surface of the grinding wheel 24 that contacts the workpiece 1.

  During grinding of the workpiece 1, the grinding means 20 always rotates in an arc shape so that the outer peripheral edge 24b of the processing wheel 23 passes through the central portion 13 of the holding surface 11 of the holding table 10 shown in FIG. Thereby, the length of the processing point 5 with which the processing surface 24a abuts is substantially the same. Therefore, short processing points and long processing points are not mixed for a plurality of workpieces 1.

  In this manner, a plurality of workpieces 1 are ground by the processing wheel 23 until a predetermined thickness is reached with no variation in the length of the processing point 5. Then, as shown in FIG. 6, since the processing points 5 of the three workpieces 1 arranged adjacent to each other on the holding surface 11 have substantially the same length, the three workpieces after grinding are processed. All of the objects 1 can be finished to a highly accurate flat surface.

2 Second Embodiment The polishing means 30 shown in FIG. 7 includes a spindle 31 having a vertical axis, and a processing wheel 33 attached to the lower part of the spindle 31 via a mounter 32. The processing wheel 33 includes a base 34 and a polishing pad 35 attached to the lower part of the base 34. The polishing means 30 can raise and lower the processing wheel 33 in the vertical direction while rotating the processing wheel 33. Hereinafter, a method for polishing a workpiece by the polishing means 30 will be described.

(1) Holding Step In the polishing process shown in FIG. 7, the plurality of workpieces 1 are held on the holding table 10 by the same procedure as that shown in the holding step of the first embodiment. That is, the support member 3 side is placed and held on the holding surface 11 of the holding surface 10, and the frame 4 is placed on the mounting table 16. In this way, the support member 3 adhered to the lower part of the frame 4 is held on the holding table 10 together with the workpiece 1 so as to cover the holding surface 11.

(2) Processing Step After performing the holding step, the workpiece 1 is polished by the polishing means 30 as shown in FIG. After moving the holding table 10 below the polishing means 30, the holding table 10 rotates in the direction of arrow A, for example, and rotates the holding table 10. The polishing means 30 lowers the workpiece 31 toward the workpiece 1 while rotating the spindle 31 in the direction of the arrow B, for example, while keeping the processing surface 35a on the lower surface of the polishing pad 35 parallel to the holding surface 11.

  Then, the processing surface 35a of the polishing pad 35 and the workpiece 1 are slid while the polishing pad 35 and the holding table 10 are relatively rotated. During polishing of the workpiece 1, the outer peripheral edge 35 b of the rotating polishing pad 35 is rotated so as to always pass through the central portion 13 of the holding surface 11 of the holding table 10 shown in FIG. 5. Then, the processing points of the workpieces adjacent to each other have substantially the same length. Therefore, short processing points and long processing points are not mixed for a plurality of workpieces 1.

  The plurality of workpieces 1 are polished by the polishing pad 35 shown in FIG. 7 until a predetermined flatness is reached. Then, as shown in FIG. 6, since the processing points 5 of the three workpieces 1 arranged adjacent to each other on the holding surface 11 have substantially the same length, the three workpieces after polishing are processed. All of the objects 1 can be finished to a highly accurate flat surface.

  In any of the embodiments, the example in which the frame 5 integrated with the workpiece 1 is fixed by the clamping means 14 as an aspect of holding the workpiece 1 on the holding table 10, but as another example, For example, a holding table having a suction surface corresponding to the size of the workpiece may be used. When holding a work piece with this holding table, attach a protective tape or substrate to the work piece, and suck and hold the work piece by sucking the protective tape or substrate side on the suction surface of the holding table. To do.

  In addition to those shown in the first and second embodiments, as another arrangement example, as shown in FIG. 8, six workpieces 1a are adjacent to each other inside an equilateral triangle 2B inside a circular holding surface 11. You may make it arrange | position. In this case, the line connecting the centers of the six workpieces 1a may be an equilateral triangle. In addition, as shown in FIG. 9, inside the regular hexagon 2 </ b> C inside the circular holding surface 11, one workpiece 1 a is arranged at the center, and six workpieces 1 a around the workpiece 1 a. May be arranged.

  As described above, in the workpiece processing method according to the present invention, in the holding step, three or more workpieces 1 are adjacent to each other inside the regular polygon in the holding surface 11 of the holding table 10, and the regular polygon is formed. In order that the workpiece 1 is held on the holding surface 11 in a state where the center of the holding surface 11 coincides with the center of the holding surface 11, in the processing step after the holding step is performed, the outer peripheral edge 24b of the grinding wheel 24 or the polishing pad 35 When the outer peripheral edge 35b is brought into contact with a plurality of workpieces 1 so as to always pass through the central portion 13 of the holding surface 11 of the holding table 10, the lengths of the processing points 5 of the workpiece 1 are substantially the same. Become. Therefore, the processed workpiece 1 can be flattened with high accuracy.

  A holding table having a conical surface as a holding surface and a holding table having a flat holding surface are used. In each holding table, as shown in FIG. The workpiece 1 was held and grinding was performed. As a workpiece, a sapphire wafer having a diameter of 3 inches was used, and any holding table having a size of 8 inches was used.

  The holding surface 41 shown in FIG. 10 holds three sapphire wafers on a conical holding table 40 and is ground so that the outer peripheral edge 24 b of the grinding wheel 24 passes through the center of the holding surface 11. The TTV (Total Thickness Variation) on the wafer surface was 8 μm. On the other hand, when the holding surface 11 shown in FIG. 1-9 holds the sapphire wafer on the holding table 10 having a flat surface and is ground so that the outer peripheral edge 24b of the grinding wheel 24 passes through the center of the holding surface 11, The TTV on the surface of the sapphire wafer was 3 μm. Therefore, compared to grinding a sapphire wafer using a conical holding table, it is more accurate to grind the sapphire wafer using a flat holding table. It was confirmed that it can be flattened. This is because when the holding surface 41 shown in FIG. 10 holds the sapphire wafer 6 on the conical holding table 40, the grinding is performed at the processing point 7 shown in FIG. As described above, the sapphire wafers 6 are ground at the processing points 7a and 7b. However, since the processing point 7a is longer than the processing point 7b, there is a difference in the degree of grinding. It is believed that there is.

1, 1a: Workpiece 2A: Regular triangle 2B: Regular triangle 2C: Regular hexagon 3: Protection tape 4: Frame 5: Machining point 6: Workpiece 7, 7a, 7b: Machining point 10: Holding table 11: Holding Surface 12: Rotating shaft 13: Central portion 14: Clamping means 15: Supporting portion 16: Mounting table 17: Clamping portion 20: Grinding means 21: Rotating shaft 22: Mounter 23: Processing wheel 24: Grinding wheel 24a: Processing surface 24b: Outer peripheral edge 30: Polishing means 31: Rotating shaft 32: Mounter 33: Processing wheel 34: Base 35: Polishing pad 35a: Processing surface 35b: Outer peripheral edge 40: Holding table 41: Holding surface 42: Central shaft 50: Grinding means 51 : Grinding wheel

Claims (1)

A method of processing a workpiece for grinding or polishing the workpiece,
A workpiece having a size smaller than the size of the holding surface by a holding table having a holding surface that sucks and holds the workpiece and the entire surface is on the same plane and a rotation axis that is orthogonal to the holding surface at the center of the holding surface. Holding step through a support member that covers the suction area of the holding table;
After performing the holding step, an outer peripheral edge of a processing wheel having a processing surface parallel to the holding surface and a rotation axis orthogonal to the processing surface passes through the center of the holding surface of the holding table. Processing in which the processing surface of the processing wheel is brought into contact with the workpiece held by the holding table, and the holding table and the processing wheel are rotated to grind or polish a plurality of workpieces by the processing wheel. And comprising steps
In the holding step, three or more workpieces are arranged adjacent to each other in the regular polygon, and the workpiece is held in a state where the center of the regular polygon coincides with the center of the holding surface. Processing method of things.

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