JPH01199766A - Grinding stone and its dressing method and device - Google Patents

Abstract

PURPOSE:To uniformly obtain surface roughness of a workpiece in its work surface removing deflection of a crossing part for its rotating axial center by forming a side surface in an obtuse angle for a ground surface and preventing abrasive grains from falling off from the crossing part between these ground surface and side surface further dressing this crossing part. CONSTITUTION:A grinding stone 7 places its cut-in direction almost vertical for a ground surface 3, and in a condition that the grinding stone 7 is mounted to a main spindle 10, crossing parts 6a, 6b of side surfaces 4, 5 and the ground surface 3 perform dressing by dressing wheels 8a, 8b. In this way, the crossing parts 6a, 6b enable their deflection for the rotary axial center of the main spindle 10 to be removed. By the grinding stone 7 thus performing dressing, a silicon wafer 1 can be ground in uniform surface roughness. Here the stone 7 forms its side surfaces 4, 5 in obtuse angles alpha, beta for the ground surface 3. Consequently, abrasive grains can be prevented from falling off from the crossing parts 6a, 6b of these side surfaces 4, 5 and ground surface 3.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a grinding wheel and a dressing method and device for the grinding wheel, and in particular, a method and apparatus suitable for reducing scratches caused by grinding and obtaining a good ground surface. The present invention relates to a grinding wheel and a dressing method and device for the grinding wheel.

[Conventional technology]

As the density of integrated circuits increases, strict precision is required in the grinding process of silicon wafers, which are the substrate material for integrated circuits. As a method for realizing such high-precision grinding, for example, as disclosed in Japanese Patent Application Laid-open No. 187445/1987, a cup-shaped grinding wheel is used to cut a rotating silicon wafer in a direction perpendicular to the grinding surface. A method of grinding in parallel (hereinafter referred to as wafer rotation grinding method) has been put into practical use.

According to the wafer rotation grinding method, there is no change in the grinding width unlike the creep feed grinding method conventionally used for grinding silicon wafers, so the grinding resistance is constant and good flatness and parallelism can be obtained. .

In addition, in the wafer rotation grinding method, as shown in FIG. 4, grinding is performed by aligning the widthwise center of the grinding surface 3 of a cup-shaped grinding wheel 2 (hereinafter referred to as the grinding wheel) with the center O of the silicon wafer 1. do. Therefore, when the width of the grinding surface 3 is t, the silicon wafer 11 and the grindstone 2 are always in contact within the circumference M of a circle with a center of 0 and a diameter of t, and the contact time becomes shorter as the distance from the circumference M increases. In a relationship. In addition, methods for dressing the grinding surface 3 include a method of grinding 10 pieces of ordinary whetstone or mild steel before machining, and a method of dressing the grinding surface 3 in advance.
As disclosed in Japanese Patent No. 471, there is a method of dressing in parallel with the grinding process.

[Problem to be solved by the invention]

If the distance between the side surface of the grinding wheel 2 and the rotational axis of the grinding wheel 2 is not constant and there are irregularities, the protrusions may touch the silicon wafer 1 during grinding.
The silicon wafer 1, which is a brittle material, undergoes brittle fracture and becomes rougher. Therefore, the side surface is formed in advance to be parallel to the rotation axis, that is, to be perpendicular to the grinding surface 3. However, in the rotational grinding method, even immediately after dressing the grinding surface 3,
As shown in FIG. 5, the surface roughness of the silicon Ueno S1 sometimes became large in some areas. Note that the roughness curve shown in FIG. 5 was measured along the diameter of the silicon sea urchin /-,1.

As a result of investigating the relationship between the roughness curve shown in Fig. 5 and the grindstone 2 used for machining, the inventor found that the roughness becomes thicker when the center is 0 and the diameter is approximately t. I found out that it is a part. It was also found that the cause of the increase in roughness was abrasive grains falling off near the intersection 6 between the grinding surface 3 and the side surface 4.5.

That is, by dressing the grinding surface 3, for example, as shown in FIG. Only the binding material in the portion corresponding to 1/4 sphere is held, and the force with which the whetstone 2 holds the abrasive grains A is weak, and the abrasive grains A easily fall off from the whetstone 2. Therefore, it is an issue to prevent the abrasive grains A from falling off from the intersection 6.

[Means to solve the problem]

Means for solving the above problems will be explained with reference to FIG. 1, which is an embodiment of the present invention.

7 is a grindstone in which the angles α and β of the intersection 6 are obtuse angles. 8
is a dressing grindstone in which the dressing surface 9 is arranged to intersect the grinding surface 3 and the side surface 4.5.

[For production]

Since the intersection 6 of the grindstone 7 is formed at an obtuse angle, it has a strong holding power for the abrasive grains A, and can prevent the abrasive grains A from falling off.

Furthermore, the dressing grindstone 8 can also remove minute vibrations in the radial direction of the side surfaces 4 and 5, which will be described below. In other words, since the main shaft 10 of the grinding machine is made so as not to run out during rotation, if the grinding wheel 7 is mounted without support to the axis of the rotating shaft, theoretically no runout will occur on the side surface 4.5. Does not occur. However, when the grinding wheel 7 is attached to the main spindle 10 by fitting, for example, the axis of the main spindle 10 and the axis of the grinding wheel 7 are offset by 6 μm by 1 to 30 μm, and the side surfaces 4 and 5 are relative to the rotational axis of the main spindle 10. It will be 2 to 60 μmg.

According to the present invention, since the side surfaces 4 and 5 of the grinding wheel 7 are dressed when the main spindle 10 is attached, the side surface 45 is attached to the main spindle 10.
It does not swing about the axis of rotation.

Therefore, the surface roughness of the ground silicon wafer 1 becomes uniform.

〔Example〕

FIG. 1 is a front sectional view of a dressing device showing one embodiment of the present invention. Components that are the same as those in FIGS. 4 and 5 are designated by the same reference numerals.

7 is a grindstone in which the angles α and β between the grinding surface 3 and the side surface 4.5 are obtuse angles. 8 is a dressing grindstone fixed to the spindle 13. 9 is the dressing side. 10 is the main shaft of the grinding machine. A dresser body 14 rotatably supports the spindle 13 by a bearing 15. 16 is the brake shoe. 17
) chew one. 18 is a bolt. A base 19 holds two dresser bodies, each holding the dressing surface 9 at a predetermined angle with respect to the grindstone 7. The operation will be explained below.

The grindstone 7 is moved downward while rotating. When the whetstone 7 comes into contact with the dressing surface 9, the dressing whetstone 8 a
s 8 b begins to rotate driven by the rotational force of the grindstone 7. At this time, the brake shoe 16 16b is pressed against the spring 17a.
, 17b against the spindles 13a, 13b, this braking force creates a circumferential speed difference between the grinding wheel 7 and the dressing grinding wheels 8a, 8b, and the grinding wheel 7
Surfaces 11.12 are formed at the corners of.

In this embodiment, the grinding wheel 7 and the dressing grinding wheel 8 are made to have a relative speed by the braking force of the brake shoe 16, but the relative speed may also be given by forcing the spindle 13 to rotate by a motor or the like. good. Also,
As the dressing grindstone 8 for forming the surfaces 11.12 on the grindstone 7, if the cross-sectional shape with respect to the rotating shaft is circular, it is possible to use the dressing grindstone 8 which is a modified example shown in FIG. 1, FIGS. e
), the rotation axis P can be arbitrarily determined. Furthermore, the dressing grindstone 8 is reduced to one, and the surface 1
1.12 may be processed sequentially, or only the surface on the grinding side may be processed, or a dressing grindstone for dressing the grinding surface 3 may be provided separately, and processing may be performed simultaneously or sequentially. Good too.

FIG. 3 is a front sectional view showing another embodiment of the invention.

In this figure, the same parts or parts with the same functions as those in FIG. 1 are given the same numbers.

Reference numeral 20 denotes a plate on which a dressing grindstone 8 having an arcuate surface 21 is placed and is movable on the dresser body 14 in the direction of the arrow. Reference numeral 22 denotes a base that allows the dresser body 14 to be positioned at the position shown by the solid line as well as at the position shown by the two-dot chain line. The operation will be explained below.

The grindstone 7 is rotated and the dressing grindstone 8 is moved in the direction of the arrow so that they come into contact with each other to form a surface 11. Next, the dresser body 14 is moved to the position indicated by the two-dot chain line, and the surface 12 is formed in the same manner.

In addition, in this embodiment, the case where surfaces 11 and 12 are formed has been described, but if the surface roughness after grinding can be large, it may be used as is, but the intersection portion 6 may have an obtuse angle. This means that the abrasive grains A are less likely to fall off, and the surface roughness can be improved.

Furthermore, it goes without saying that the shape of the grindstone 7 is not limited to a cup-shaped grindstone, but can be applied to a general disc-shaped one.

〔Effect of the invention〕

As described in detail above, according to the present invention, since the intersection between the grinding surface and the side surface is formed at an obtuse angle, it is possible to prevent the abrasive grains from falling off. Furthermore, by dressing the intersection, it is possible to eliminate vibration of the intersection with respect to the rotation axis.

Therefore, there is an effect that the surface roughness of the processed workpiece becomes uniform.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of a dressing device showing an embodiment of the present invention. FIG. 2 is a schematic diagram of a modification of FIG. 1. FIG. 3 is a front view showing another embodiment. 4 to 6 are explanatory diagrams of the rotational grinding method. 2.7...Whetstone, 3...Grinding surface, 4,5...
...Side surface, 6...Intersection, 8...Dressing grindstone, 9...Dressing i[ffi, 1
1, 12... sides. Representative Patent Attorney Masaru Ogawa Figure 2 Figure $5 Figure $6

Claims (1)

[Scope of Claims] 1. A grinding wheel whose cutting direction is substantially perpendicular to the grinding surface, characterized in that the side surface is formed at an obtuse angle with respect to the grinding surface. 2. A method for dressing a grinding wheel in which the direction of cut is substantially perpendicular to the grinding surface, characterized by providing a chamfered portion at the intersection of the grinding surface and the side surface. 3. A dressing device for a grinding wheel whose cutting direction is substantially perpendicular to the grinding surface, characterized in that the dressing surface of the dressing wheel is arranged to intersect with the grinding surface of the grinding wheel.