JP2003145398A - Disc workpiece grinding method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give highly precise grinding machining to chamfered surfaces of a disc workpiece such as a semiconductor wafer. SOLUTION: This grinding device comprises a workpiece driving shaft 1 for rotationally driving the disc workpiece W and tool driving shafts 11, 21 for rotationally driving grinding tools 12, 22. The grinding tools 12, 22 have grinding surfaces 14, 24 formed in a recessed shape on the inside of outer periphery edges 13, 23, respectively, so that the workpiece W intersects the outer periphery edges 13, 23 to make chamfered surfaces Ca, Cb in contact with the grinding surfaces 14, 24 between intersections. The grinding tools 12, 22 are rotationally driven in the state that the workpiece W is pushed out of the grinding tools 12, 22 with portions of the chamfered surfaces Ca, Cb in contact with the grinding surfaces between intersections.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for polishing a disk-shaped work, such as a silicon semiconductor wafer, for polishing a chamfer surface formed on an outer peripheral portion of the disk-shaped work.

[0002]

2. Description of the Related Art A semiconductor integrated circuit is formed on a surface of a silicon semiconductor wafer or a compound semiconductor wafer such as gallium arsenide through a series of manufacturing processes, and a semiconductor integrated circuit, that is, a semiconductor device is obtained by cutting a chip piece from the semiconductor wafer. Manufactured. Silicon semiconductor wafer
It is formed by cutting a cylindrical silicon single crystal ingot with a cutter into a disc shape.

The chamfer surface and the outer peripheral surface are ground by the chamfering process using a grindstone on the outer peripheral portion of the cut semiconductor wafer. Further, the chamfer surface and the outer peripheral surface are lapped or polished by using a polishing tool. To be done. Orientation flats and notches are to be formed on the semiconductor wafer in order to determine the crystal orientation and position, and these portions are also subjected to lapping and polishing using a polishing pad. As such a polishing technique for the outer peripheral portion of the semiconductor wafer, for example, as disclosed in JP-A-7-60624, the outer peripheral surface of the semiconductor wafer is rotated by rotating a spindle provided with a polishing cloth on a flat surface. And a chamfer surface are polished, and a notch is polished by rotating a rotating disk having a polishing cloth on the outer peripheral surface.

The polishing process includes a lapping process for adjusting the dimensional error of the work and improving the surface finish condition, and a polishing process for forming a high-level mirror surface on the work surface. A polishing cloth or polishing liquid is selected.

[0005]

As described above, when polishing the chamfer surface by pressing it against the flat polishing surface of the polishing tool, the polishing surface has a small area near the line contact of the semiconductor wafer. Since it comes into contact with the chamfer surface, it takes a long time to polish, and the polishing efficiency cannot be improved.

On the other hand, in the chamfering processing technique disclosed in Japanese Patent Laid-Open No. 10-29142, the polishing surface and the semiconductor wafer are pressed against the concave polishing surface while the entire outer peripheral chamfered portion is pressed. And are rotated relative to each other so that the chamfered portion, that is, the chamfered surface is polished. However, if the entire chamfer surface is pressed against the concave polishing surface, the portion of the surface of the semiconductor wafer adjacent to the chamfer surface will be polished by the polishing surface, and the surface of the wafer will be dented. There is a problem that a step is generated. The generation of the step becomes particularly remarkable when a track-shaped groove is formed on the polishing surface by repeatedly processing a large number of semiconductor wafers using the same polishing member.

Since semiconductor wafers having such dents or steps cannot be commercialized, the processing yield is lowered, and the polishing member must be frequently replaced with a new polishing member in order to increase the processing yield. Therefore, it becomes impossible to improve the processing efficiency.

An object of the present invention is to enable the chamfer surface of a disk-shaped work such as a semiconductor wafer to be polished with high accuracy.

Another object of the present invention is to improve the processing efficiency of the chamfer surface processing of a disk-shaped work.

[0010]

A method for polishing a disk-shaped work according to the present invention is a method for polishing a chamfer surface of an outer peripheral portion of a disk-shaped work, and is for polishing an outer peripheral edge of a polishing tool. Of the polishing surface formed in a concave shape on the inside, the chamfer surface is brought into contact between intersections where the work intersects the outer peripheral edge portion, and the work is driven to rotate by a work drive shaft, and the polishing tool is used as a tool. The chamfer surface is polished by being driven to rotate by a drive shaft so that a part of the chamfer surface is brought into contact with the polishing surface between the intersecting portions and the work is pushed out of the polishing tool.

In the method for processing a disk-shaped work according to the present invention, the chamfer surface on one side of the work and the chamfer surface on the other side of the work are simultaneously polished by the two polishing tools. And

The disk-shaped workpiece polishing apparatus of the present invention is a workpiece polishing apparatus for polishing a chamfer surface on the outer peripheral portion of a disk-shaped workpiece, the workpiece-drive shaft rotating and driving the disk-shaped workpiece. A polishing tool having a polishing surface formed in a concave shape on the inner side of the outer peripheral edge portion, wherein the workpiece intersects the outer peripheral edge portion and the chamfer surface contacts the polishing surface between the intersecting portions; A tool drive shaft for rotating and driving the polishing tool in a state in which a part of the chamfer surface is brought into contact with the polishing surface between and the work is pushed out of the polishing tool.

In the disk-shaped work polishing apparatus of the present invention, there is provided a first polishing tool for polishing the chamfer surface on one side of the work, and a first polishing tool for polishing the chamfer surface on the other side of the work. The present invention is characterized in that the chamfer surface on both sides of the work is polished at the same time.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a perspective view showing a disk-shaped workpiece polishing apparatus according to an embodiment of the present invention, and FIG. 2 shows a disk-shaped workpiece polishing apparatus according to another embodiment of the present invention. It is a perspective view shown. At the outer peripheral portion of the work W, as shown in FIG. 1, a chamfer surface Ca between the front surface, that is, the one surface Sa and the outer peripheral surface P, and a chamfer surface Cb between the rear surface, that is, the other surface Sb and the outer peripheral surface P are provided. Are formed. 1 and 2
With the polishing apparatus shown in FIG. 1, the silicon semiconductor wafer is used as a disk-shaped work W, and the chamfer surfaces Ca and Cb formed on the outer peripheral portion of the front and back surfaces are polished. Orientation flats and notches are formed on the semiconductor wafer for the purpose of determining the crystal orientation and alignment, but these are omitted in the figure.

The work W is, as shown in FIGS. 1 and 2,
The work is held by a work holding table 2 provided on a work driving shaft 1 that rotates about a vertical rotation center axis Ow and is driven to rotate. A vacuum suction mechanism (not shown) is incorporated in the work holding table 2, and the work W is sucked and held by negative pressure air. Of the work W, the chamfer surface Ca on the front surface Sa side is polished by the polishing apparatus shown in FIG. 1, and the chamfer surface Cb on the back surface Sb side is polished by the polishing apparatus shown in FIG.

As shown in FIG. 1, the polishing apparatus for polishing the chamfer surface Ca on the one side has a tool drive shaft 11 which rotates about a rotation center axis Oga inclined with respect to the rotation center axis Ow. A polishing tool 12 is provided on the tool drive shaft 11. The polishing tool 12 has a cylindrical outer peripheral surface, and a polishing surface 14 formed in a concave shape is formed inside the circular outer peripheral edge portion 13. The tool drive shaft 11 is movable back and forth in the axial direction, and the forward movement of the tool drive shaft 11 causes the polishing tool 1 to move.
The second polishing surface 14 comes into contact with the chamfer surface Ca of the work W. The workpiece W contacts the polishing surface 14 so as to cross the polishing surface 14 of the polishing tool 12 and intersect the outer peripheral edge portion 13 at each intersection 15, and the workpiece W has its entire chamfered surface Ca polished surface 14. However, only the portion between the intersecting portions 15 comes into contact with the polishing surface 14 at the same time. Therefore, as shown in FIG. 1, the portion of the work W that does not come into contact with the polishing surface 14 is polished in a state of protruding from the polishing tool 12, that is, in an overhang state.

As shown in FIG. 2, the polishing apparatus for polishing the chamfer surface Cb on the other side has a tool drive shaft 21 which rotates about a rotation center axis Ogb inclined with respect to the rotation center axis Ow, The tool drive shaft 21 is provided with a polishing tool 22, and the tool drive shaft 21 is movable in the axial direction and movable in the radial direction. Similar to the polishing tool 12, the polishing tool 22 has a concave polishing surface 24 formed inside the outer peripheral edge portion 23, and the chamfered surface Cb of the work W has only the polishing surface 24 between the intersecting portions 25.
Will be contacted at the same time. Therefore, as shown in FIG. 2, the work W has a polishing surface 24 of the chamfer surface Cb.
The portion that does not come into contact with is polished such that it protrudes from the polishing tool 22, that is, it overhangs.

The polishing surfaces 14 and 24 are made of a polishing material such as cloth, and a polishing liquid such as a polishing liquid or a lapping liquid is applied to the polishing surfaces 14 and 24 during polishing.

To polish the chamfer surface Ca on the front side of the work W using the polishing apparatus shown in FIG.
The work W is held on the work W, and the polishing tool 12 shown in FIG. Thereby, the polishing tool 12
Thus, a part of the chamfer surface Ca is in contact with the polishing surface 14 between the two intersecting portions 15 so as to cross the two intersecting portions 15. Under this condition, when the work drive shaft 1 and the tool drive shaft 11 are rotated in the directions indicated by arrows, the entire chamfer surface Ca is ground.

Next, in order to polish the chamfered surface Cb on the back surface side, the work W is conveyed to another work support base 2 provided with the polishing tool 22 shown in FIG. 2 and the work W is held thereon. Then, the polishing tool 22 is moved toward the work W, and a part of the chamfer surface Cb is brought into contact with the polishing surface 24 between the intersections 25 so as to cross the intersections 25. Under this state, the tool drive shaft 21 and the work drive shaft 1 are respectively rotated in the directions indicated by the arrows, so that the entire chamfer surface Cb is polished. However, by providing two polishing tools 12 and 22 for one work support base 2 without installing the work support base 2 corresponding to the respective polishing tools 12 and 22, The chamfer surfaces Ca and Cb on both sides may be sequentially polished by the respective polishing tools 12 and 22 with the work W being installed.

In the case described above, the polishing tool 12 shown in FIG.
One chamfer surface Ca is polished by using the polishing tool, and the other chamfer surface Cb is polished by using the polishing tool 22 shown in FIG. 2. However, one chamfer surface is polished by using the polishing tool 12 shown in FIG. After polishing Ca, the work W may be turned upside down on the work support base 2 and the other polishing surface Cb may be polished using the polishing tool 12. Similarly, if the work W is inverted on the work holding table 2,
With the polishing tool 22 shown in FIG. 2, both chamfer surfaces Ca,
Cb may be sequentially polished.

As described above, as a polishing method using the above-mentioned polishing apparatus, the work W is inverted on the work holding table 2 and one of the polishing apparatus shown in FIG. 1 and the polishing apparatus shown in FIG. Depending on the chamfer surfaces Ca and Cb on both sides
2 is sequentially polished, and after the chamfer surface Ca is polished by the polishing apparatus shown in FIG.
There is a method of polishing the chamfer surface Cb by the polishing apparatus shown in FIG.

FIG. 3A shows a concave polishing surface 14 when polishing the work W by the polishing apparatus shown in FIG.
3 is an enlarged cross-sectional view showing a portion of the work W that is in contact with the bottommost side of the work, that is, a portion A in FIG. 1. FIG. 3B shows a portion of the work W near the outer peripheral edge portion 13, that is, a portion B in FIG. It is an expanded sectional view shown. Work W has a polished surface 14
Across the same, and simultaneously contact between one crossing portion 15 and the other crossing portion 15 of both outer peripheral edge portions 13.

This contact portion gradually wears as a large number of workpieces W are polished, as shown by the chain double-dashed line Q in FIG. 3A, and the innermost portion in the radial direction contacts the workpiece W. A step T is generated between the portion and the portion not to be formed, as shown in FIG. However, since the work W is protruding from the outer peripheral edge portion 13 to the outside thereof, FIG.
As shown in, no step is formed on the outer peripheral edge portion 13. Thereby, by polishing a large number of workpieces W,
Even if the polishing surface 14 is worn as indicated by the symbol Q, the polishing surface 1
Since 4 is prevented from getting around the surface Sa of the work W, it is possible to prevent dents and steps from being generated on the surface Sa even when polishing a large number of works, and to replace the polishing tool 12 frequently. Therefore, it is possible to polish a large number of works with high accuracy. Similarly, in the polishing apparatus shown in FIG. 2, it is possible to prevent the other surface Sb of the work W from being dented or stepped.

FIG. 4 is a perspective view showing a polishing apparatus according to another embodiment of the present invention, FIG. 5 is a partially cutaway front view of FIG. 4, and FIG. 6 is a plan view of FIG. , FIG. 7 is a sectional view taken along the line CC in FIG.

This polishing apparatus has chamfered surfaces C on both front and back sides.
This is a device for simultaneously polishing a and Cb, and a polishing tool 12 shown in FIG. 1 and a polishing tool 22 shown in FIG. 2 are provided adjacent to the work support base 2. Therefore, both chamfer surfaces of the work W can be simultaneously polished, but both polishing tools 12 and 22 may be polished with a time difference. When both chamfer surfaces can be polished by one device like the polishing device shown in FIGS. 4 to 7, the polishing process of notches and orientation flats, the polishing process of the surface Sa, and the cleaning process are included. Further, the size of the entire work polishing apparatus can be reduced.

In the polishing apparatus shown in FIGS. 4 to 7, both of the polishing tools 12 and 22 are in contact with the outer peripheral portions of the work W, which are shifted by 180 degrees from each other, but 90 degrees relative to each other. It is also possible to make contact with a shifted portion or a portion with another angle shift. In addition, each polishing surface 14, 2
As shown in FIG. 5, the curvature of the concave surface of No. 4 is set by the angles α, β formed by the respective rotation center axes Oga, Ogb and the surface of the work W and the outer diameter of the work W, and between the intersections. The chamfered surface portions corresponding to the polishing surfaces 14 and 24 come into contact with the polishing surfaces 14 and 24.

The present invention is not limited to the above-mentioned embodiment, but various modifications can be made without departing from the scope of the invention. For example, the illustrated polishing apparatus is used for lapping and polishing a semiconductor wafer as a work, but the work is not limited to the semiconductor wafer and can be used for polishing other disk-shaped members such as a hard disk. It can be applied and can also be used to machine chamfer surfaces with a grindstone. Also,
Although the rotation center axis Ow of the illustrated polishing apparatus is oriented in the vertical direction, it may be oriented in the horizontal direction or may be oriented in a direction inclined with respect to the vertical line.

[0030]

According to the present invention, the polishing surface of the polishing tool is prevented from entering the flat surface of the disk-shaped work, and the chamfer surface can be polished with high precision. Even if a dent or a step is generated on the polishing surface by polishing a large amount of the work with the same polishing tool, the polishing surface is prevented from getting around the surface of the work due to the step.
It is possible to improve the efficiency of polishing by reducing the frequency of exchanging the polishing tool.

[Brief description of drawings]

FIG. 1 is a perspective view showing a disk-shaped workpiece polishing apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a disk-shaped workpiece polishing apparatus according to another embodiment of the present invention.

3 (A) is an enlarged sectional view showing a portion A in FIG. 1, and FIG. 3 (B) is an enlarged sectional view showing a portion B in FIG.

FIG. 4 is a perspective view showing a disk-shaped workpiece polishing apparatus according to another embodiment of the present invention.

5 is a partially cutaway front view of FIG. 4. FIG.

FIG. 6 is a plan view of FIG.

7 is a cross-sectional view taken along the line CC in FIG.

[Explanation of symbols] 1 Work drive shaft 2 Work holder 11 Tool drive shaft 12 Polishing tools 13 outer peripheral edge 14 Polished surface 15 intersection 21 Tool Drive Shaft 22 Polishing tool 23 Outer edge 24 Polished surface 25 intersection W Disk-shaped work (semiconductor wafer) Ca, Cb chamfer surface Sa surface (one side) Sb back surface (other surface) P outer peripheral surface

Claims (4)

[Claims] 1. A method of polishing a chamfer surface on the outer peripheral portion of a disk-shaped workpiece, wherein the outer peripheral edge is a concave surface formed inside the outer peripheral edge portion of the polishing tool. The chamfer surface is brought into contact between intersections where a work intersects a portion, the work is driven to rotate by a work drive shaft, and the polishing tool is driven to rotate by a tool drive shaft. A method of processing a disk-shaped work, comprising polishing the chamfer surface in a state where a part of the chamfer surface is brought into contact with the chamfer surface and the work is pushed out of the polishing tool. 2. The polishing method according to claim 1, wherein the chamfer surface on one side of the work and the chamfer surface on the other side of the work are simultaneously polished by the two polishing tools. Polishing method for disk-shaped work. 3. A work polishing apparatus for polishing a chamfer surface of an outer peripheral portion of a disk-shaped work, the work drive shaft rotating and driving the disk-shaped work, and a concave surface inside the outer peripheral edge portion. A polishing tool having a formed polishing surface, wherein the chamfer surface contacts the polishing surface between the intersections by intersecting the work with the outer peripheral edge; and one of the chamfer surfaces on the polishing surface between the intersections. And a tool driving shaft for rotating and driving the polishing tool in a state where the work pieces are brought out of contact with each other and the work is pushed out of the polishing tool. 4. The disk-shaped workpiece polishing apparatus according to claim 3, wherein a first polishing tool that polishes the chamfer surface on one side of the workpiece and a chamfer surface on the other side of the workpiece are polished. A disk-shaped workpiece polishing apparatus comprising a second polishing tool and polishing both chamfer surfaces of the workpiece at the same time.