JPH075983Y2 - Deformed cup type grinding wheel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a modified cup-type grinding wheel for flatly grinding a workpiece such as a semiconductor substrate.

[Conventional technology]

A cup-type grinding wheel is widely used as a tool for flatly grinding an object to be processed (hereinafter referred to as a wafer) such as a semiconductor substrate. As shown in FIG. 4, this type of cup-shaped grinding wheel has diamond or diamond on the end face of a perfect circular cup-shaped base 1.
Multiple cutting edges made by sintering abrasive grains such as CBN with a bond material 2
Are arranged in an annular shape by an adhesive such as brazing or bonding.

When the wafer is ground using this cup-shaped grinding wheel, the cup-shaped grinding wheel is mounted on the spindle of the grinding device and driven to rotate, and is attached to the chuck table 3 by suction and fixed to the rotating wafer 4. It is performed by pressing the cutting edge 2.

When the wafer 4 is ground, as shown in FIG. 5, when the cutting edge 2 is ground before the rotation center O of the wafer 4 is ground, the center portion of the wafer 4 becomes a non-ground region S. It remains and is not appropriate. Therefore, generally, as shown in FIG. 4, the cutting edge 2 is advanced to the rotation center O of the wafer 4 to prevent the non-grinding region S from being generated.

However, as the use of the grindstone progresses, the peripheral speed of the outer peripheral side of the annular cutting edge 2 is higher than that of the inner peripheral side thereof, and therefore the outer peripheral side of the cutting edge 2 is more easily worn than the inner peripheral side. In this way, if the flatness of the cutting edge 2 deviates even a little, as shown in FIG. 4, a protruding portion 4a is formed at the center of the wafer 4 and the wafer 4 cannot be ground flat.

Therefore, in recent years, an oscillating device is provided on the chuck table 3 side or the cup-shaped grinding wheel 1 side, and grinding is performed while oscillating the cutting edge 2 relative to the wafer 4, and the central portion of the wafer 4 is It prevents the projection from being generated.

[Problems to be solved by the device]

However, the provision of the oscillating device has a problem that the device configuration becomes complicated and the device cost becomes high.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object thereof is to provide a modified cup-type grinding wheel capable of flatly grinding the surface of a wafer without providing a rocking device.

[Means for Solving the Problems]

The present invention is configured as follows to achieve the above object. That is, the present invention relates to a cup-shaped grinding wheel in which a cutting edge is annularly attached to an end surface portion of a peripheral wall of a cup-shaped base, and the peripheral walls of the cup-shaped base are opposed to each other with a center of the cup-shaped base interposed therebetween. A pair of parts are formed in an annular shape that is asymmetric with respect to the center of the cup-shaped base, and a cutting edge is also formed in the center of the cup-shaped base along the centerline of the end surface of the annular peripheral wall that is asymmetric with respect to this point. On the other hand, it is configured so as to be non-point symmetrical.

[Action]

In the present invention configured as described above, for example,
As shown in FIG. 2, sandwiching the center C of the cup-shaped base,
Focusing on the pair of cutting edge portions 2a, 2b provided in a non-point symmetrical position with respect to the center C, distances R ₁ , R ₂ from the center C to the respective cutting edge portions 2a, 2b are set as radii. When a circle is drawn with C as the center, the shaded portion surrounded by both circles Q ₁ and Q ₂ is the portion that is subjected to the swinging action by the cutting edge.

Therefore, if the central portion of the wafer is located at the shaded portion, the central portion of the wafer will be ground flat without any protruding portion due to the swinging action of the cutting edge.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of a modified cup type grinding wheel according to the present invention. In the figure, a cup-shaped base 1
Is formed by projecting the peripheral wall 6 at a right angle from the edge portion of the top wall 5, and a plurality of cutting edges 2 are formed on the end surface of the peripheral wall 6.
Are attached in an annular shape via a minute gap 7. This cutting edge 2 is made of diamond or CBN as in the conventional example.
It is formed by sintering abrasive grains such as, for example, using a bond material such as a resin bond or a metal bond.

When attaching the cutting edge 2 to the cup-shaped base 1, the cutting edge 2 may be directly fixed to the flat end surface of the peripheral wall 6 by brazing or bond bonding, but in the present embodiment, it is annular on the flat end surface of the peripheral wall 6. The groove 2 is provided, and the cutting edge 2 is fixed to the end surface of the peripheral wall 6 by brazing or bonding with the root of the cutting edge 2 embedded in the groove.

A feature of the first embodiment is that the center C of the cup-shaped base 1 (in this specification, the center C of the cup-shaped base is the front surface of the cup-shaped base as shown in FIG. 1). When drawing in the figure, it refers to the center of drawing of the peripheral wall of the base, in other words, the grindstones arranged in an annular shape, and this center C is also the center of rotation of the cup-shaped base. And 2b are arranged at a point-symmetrical position, and similarly, the cutting edges 2c and 2d are also arranged at a point-symmetrical position with respect to the center C. In Fig. 1, the distance from the center C to the center of the cutting edges 2a, 2c, that is, the short radius R
₁ is 98.75 mm, and the distance from the center C to the centers of the cutting edges 2b and 2d, that is, the major axis distance R ₂ is 101.25 mm. Then, the centers of these cutting edges 2a, 2d, 2b, 2c are gently connected by an involute, cycloid, or other appropriate curve, and the other cutting edges 2 have minute gaps along the gently-sloping center line L. 7 are arranged, and a generally annular cutting edge is formed. The center line L connecting the centers of the cutting edges is also the center line of the end surface of the annular peripheral wall 6 of the cup-shaped base 1, in other words, the cutting edges 2a, 2d, 2b, 2c are the asymmetrical annular peripheral wall end surfaces. It is provided along the center line L.

As described above, according to the first embodiment, the cutting edges 2a, 2c
And the same 2b and 2d corresponding to this are arranged in a point-symmetrical position with respect to the center C, the distance R ₁ from the center C to the cutting edges 2a and 2c is set as shown in FIG. Circle Q with radius
_The cutting edge 2 swings and grinds in a shaded area surrounded by 1 and a circle Q ₂ having a radius R ₂ from the center C to the cutting edges 2b and 2d. Moreover, since there are two pairs of cutting edges (2a and 2b, and 2c and 2d) that are arranged in non-point-symmetrical positions, the cutting edges 2 are in the shaded area every time the cup-shaped base 1 makes one rotation. Will be rocked twice, further improving the grinding efficiency. Further, by locating the central portion of the wafer 4 in the shaded area, the central portion of the wafer 4 is ground by the swinging motion of the cutting edge 2, so that the wafer 4 does not have a protruding portion at the central portion. The surface of can be ground uniformly (flat).

Further, since each cutting edge 2 is arranged through the minute gap 7, grinding dust flows out through the minute gap 7 together with the grinding liquid applied to the wafer 4 during the grinding process of the wafer 4. It is possible to further improve the accuracy of grinding processing.

Furthermore, the positions of the cutting edges 2a, 2c of the short diameter distance and the positions of the cutting edges 2b, 2d of the long diameter distance are connected by a smooth curve of the involute or cycloid, and other cutting edges are positioned on the curve. Therefore, when the grindstone (cup-shaped base 1) rotates, the distance from the center C to each cutting edge 2 gradually increases or decreases without sudden change. Therefore, the cutting edge 2 swings smoothly, and the grinding resistance does not suddenly change to vibrate the grindstone, so that highly accurate precision grinding can be performed in a stable state. By the way, when the swinging range of the cutting edge 2 is increased in order to improve the grinding accuracy, as is apparent from FIG. 2, the distance R ₁ of the cutting edge 2a at the shortest position from the center of the cup-shaped base 1 is It is necessary to make a large difference in the distance R ₂ between the cutting edge 2b located at the longest position, and if the peripheral wall of the cup-shaped base is a perfect circular wall, it is inevitable to increase the difference between the distances R ₁ and R _2. In addition, the thickness of the peripheral wall becomes too thick, the weight of the cup-shaped base increases, and the material cost increases, which leads to an increase in cost.However, in this embodiment, the peripheral wall of the cup-shaped base itself is formed as an asymmetrical annular peripheral wall. Therefore, even if the swinging range of the cutting edge 2 is increased, it is not necessary to thicken the peripheral wall of the cup-shaped base 1,
It is possible to effectively eliminate the above-mentioned problem that occurs when the peripheral wall of the cup-shaped base is a perfect circular peripheral wall.

FIG. 3 shows a second embodiment of the modified cup type grinding wheel according to the present invention, in which the same parts as those in the first embodiment are designated by the same reference numerals.

The difference of the second embodiment from the first embodiment is that the annular shape of the peripheral wall 6 is provided in a cam shape. That is, as shown in FIG. 3, the radius a ₁
= 98.75 mm of the circumferential wall, and the distance R ₂ between the center d of the ring on the other half side and the center C of the cup-shaped base 1 is 101.25.
mm, each point of c, d, and a is connected by an appropriate smooth curve such as involute or cycloid, and a plurality of cutting edges 2 are arranged along the curve with a minute gap 7.

In the second embodiment, the cutting edges 2b and 2d are asymmetric with respect to the center C. Therefore, the cutting edge 2 swings and grinds in the hatched area shown in FIG.
The surface can be uniformly ground, and the same effect as in the case of the first embodiment can be obtained.

The present invention is not limited to the above embodiments,
Various embodiments may be adopted. For example, although the cutting edges 2 are arranged with the minute gaps 7 in each of the above-described embodiments, the cutting edges 2 may be arranged side by side without any gaps without providing the minute gaps 7.

In addition, in each of the above-mentioned embodiments, the cutting edge 2 is attached to the cup-shaped base 1 by brazing or an adhesive, but unlike this, abrasive grains are formed by electroforming or the like over the entire circumference of the end face of the peripheral wall 6. You may form by a plating method. In this case, if necessary, slits or holes may be provided in the peripheral wall 6 to form an outflow passage for the grinding liquid (corresponding to the minute gap 7 in each of the above-mentioned embodiments), so that the grinding debris can be discharged more effectively.

[Effect of device]

Since the present invention is configured as described above,
The wafer surface can be ground by rocking the cutting edge without separately providing a rocking device, and the entire surface of the wafer can be ground flat without forming a protruding portion in the center of the wafer. It becomes possible.

Further, as described above, since it is not necessary to separately provide the rocking device, the device structure is simplified, and the cost of the grinding device can be reduced accordingly. Further, in the present invention, the annular peripheral wall of the cup-shaped base is formed non-point-symmetrically, and the cutting edge portion is formed along the center line of the end surface of the non-point-symmetrical annular peripheral wall,
Since the cutting edges are formed asymmetrically, the cutting edge when the cup-shaped base rotates by increasing the distance between the cutting edge with the shortest distance from the center of the cup-shaped base and the cutting edge with the longest distance. Even if the blade is formed so as to have a large swing range, the thickness of the annular peripheral wall of the cup-shaped base can be maintained at an optimum constant thickness regardless of the swing range. It is possible to effectively solve various problems such as excessive thickening of the peripheral wall, which is a problem when the cutting edge is formed point-symmetrically on the end face of the peripheral wall, an increase in weight due to this, and a high cost due to an increase in material cost.

[Brief description of drawings]

FIG. 1 is a front view showing a first embodiment of a modified cup type grinding wheel according to the present invention, FIG. 2 is an explanatory view of a swinging action of the modified cup type grinding wheel, and FIG. 3 is related to the present invention. A front view showing a second embodiment of a modified cup-type grinding wheel, FIG. 4 is a sectional view showing an example of grinding a wafer using a conventional cup-type grinding wheel, and FIG. 5 is a non-grinding region in the center of the wafer. It is explanatory drawing of the grinding example which causes. 1 ... Cup-shaped base, 2 ... Cutting edge 2, 3 ... Chuck table, 4 ... Wafer, 4a ... Projection part, 5 ... Top wall, 6 ... Peripheral wall, 7 ... Minute gap.

Claims (1)

[Scope of utility model registration request] 1. A cup-shaped grinding wheel in which a cutting edge is annularly attached to an end face portion of a peripheral wall of a cup-shaped base, and at least a pair of peripheral walls of the cup-shaped base face each other with a center of the cup-shaped base interposed therebetween. Is formed in an annular shape that is asymmetric with respect to the center of the cup-shaped base, and the cutting edge is likewise with respect to the center of the cup-shaped base along the center line of the end surface of the annular peripheral wall that is non-point-symmetrical. The irregular shaped cup grinding wheel characterized in that it is provided non-point symmetrically.