JP2006043787A - Segment grinding wheel for plane grinding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a segment grinding wheel for plane grinding, improving in-plane uniformity of roughness of a wafer. <P>SOLUTION: This segment grinding wheel for plane grinding includes: a rotary disk 2; a first grinding wheel row 3 formed by disposing a plurality of grinding wheel segments 3s at fixed spaces p<SB>1</SB>like a ring on the surface of the rotary disk 2; a second grinding wheel row 4 formed by disposing a plurality of grinding wheel segments 4s at fixed spaces p<SB>2</SB>with a gap g<SB>1</SB>from the inside of the first grinding wheel row 3; and a third grinding wheel row 5 formed by disposing a plurality of grinding wheel segments 5s at fixed spaces p<SB>3</SB>with a gap g<SB>2</SB>from the inside of the second grinding wheel row 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface grind segment grindstone, and more particularly to a surface grind segment grindstone provided with three or more grindstone rows in which a plurality of grindstone segments are arranged in a ring shape at regular intervals in the circumferential direction.

  In the manufacturing process of a silicon wafer (hereinafter simply referred to as a wafer) that is suitably used as a substrate for forming a semiconductor element such as an LSI or MOSFET, one or both sides are ground for the purpose of high planarization of the wafer. Is going. Conventionally, a grinding wheel (hereinafter referred to as a segment grindstone) used in such grinding is generally known in which a row of grinding stones are arranged on the outer periphery of a rotating disk.

  Conventionally, when grinding using such a segment grindstone, as shown in FIG. 5, the wafer and the segment grindstone are brought into contact with a position shifted by about a radius, the wafer and the grindstone are rotated in reverse, Grinding. In this case, since the segment grindstone is always in contact with the center of the wafer, the roughness of the grinding surface is very good, but due to the processing temperature during grinding and the processing time of the grindstone, etc. As a result, the center of the wafer after grinding is likely to be recessed. Moreover, since the grinding width is narrow, it is easy to perform partial grinding. Further, since the grinding is performed while rotating the wafer, the ratio of the grinding stone existing at the time of grinding decreases from the center of the wafer toward the outer periphery, and the roughness deteriorates from the center toward the outer periphery. Such a deterioration in roughness increases the amount of machining allowance in a subsequent process (such as a polishing process), resulting in a decrease in productivity.

  In order to solve such problems of the conventional grindstone, the segment grindstone described in Patent Document 1 is provided with two rows of grindstones on the inside and outside, and the inner grindstone row has a higher hardness than the outer circumference to ensure a wide grinding width. It is intended for uniform grinding. In addition, the segment described in Patent Document 2 is designed to reduce the dent in the center of the wafer by grinding the center of the wafer by making the grindstone interval of the inner grindstone row wider than the outer grindstone among the two rows of grindstones. ing.

However, in the inventions described in Patent Document 1 and Patent Document 2, there remains a problem that the roughness of the outer peripheral portion of the wafer is not improved.
JP 2000-301465 A JP 2003-251567 A

  Therefore, an object of the present invention is to provide a segment grindstone for surface grinding that can solve the above-described problems and can achieve in-plane uniformity of the roughness of the wafer.

  In order to achieve the above object, a segment grindstone for surface grinding according to the present invention includes a rotating disk, and a first structure in which a plurality of grindstone segments are arranged in a ring shape at regular intervals on the surface of the rotating disk. A grindstone row, a second grindstone row that is arranged with an interval inside the first grindstone row, and in which a plurality of grindstone segments are arranged with a constant interval, and the second grindstone row And a third grindstone row in which a plurality of grindstone segments are arranged at regular intervals.

Moreover, the segment grindstone for surface grinding according to the present invention includes a rotating disk, and a plurality of fan-shaped grindstone segments formed on the surface of the rotating disk at intervals in the circumferential direction. A first grindstone row arranged in a ring shape with a gap, a second grindstone row arranged inside the first grindstone row, and a gap inside the second grindstone row. A grinding wheel groove portion is formed between the grinding wheel rows, and the spacing between the grinding wheel segments in the circumferential direction is linear from the outer circumference toward the inner circumferential direction. It is characterized by a narrow fan shape that gradually decreases.

  According to the segment grindstone for surface grinding according to the present invention, it is possible to provide a segment grindstone for surface grinding that can suppress the deterioration of the roughness at the outer peripheral portion of the wafer and achieve in-plane uniformity of the roughness of the wafer. .

  Hereinafter, a segment grindstone for surface grinding according to an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a conceptual diagram of a segment grindstone for surface grinding according to an embodiment of the present invention.

As shown in FIG. 1, a segment grindstone 1 for surface grinding according to this embodiment includes a rotating disc 2 and an outer grindstone row 3 as a first grindstone row arranged in a ring shape on the surface of the rotating disc 2. And an intermediate grindstone row 4 as a second grindstone row arranged with a gap g ₁ inside the outer grindstone row 3, and a gap g ₂ arranged inside the intermediate grindstone row 4. Further, an inner grindstone row 5 as a third grindstone row is provided.

The outer grinding wheel train 3, a plurality of arc-shaped grindstone segments 3s is disposed in a ring shape provided with a predetermined interval p ₁ in the circumferential direction, intermediate grinding wheel column 4, a plurality of arc-shaped grindstone segments 4s outer The inner grindstone row 5 is arranged with an interval p ₂ on the inner periphery of the grindstone row 3, and the inner grindstone row 5 has a plurality of arc-shaped grindstone segments 5 s with an interval p ₃ on the inner circumference of the intermediate grindstone row 4. Are arranged.

Difference radius r ₂ of a radius r ₁ and the inner grinding wheel column 5 of the outer grinding wheel column 3, the radius r ₁ radius of 7 / 20-9 / a preferably is 10 (the outer grinding wheel column 3 of object to be ground And the ratio of the difference between the radius r ₂ of the inner grindstone row 5 and the radius of the workpiece to be ground is hereinafter referred to as a radius ratio with the workpiece). If the ratio is smaller than 1/4, the ratio of the grinding stone existing in the outer peripheral portion of the wafer decreases, so that the grinding load increases and the effect of improving the roughness of the outer peripheral portion of the workpiece cannot be exhibited sufficiently. If it exceeds 9/10, although the roughness of the outer peripheral portion is improved, the gap g _1, the width of the gap g ₂ increases, that grindstone at a specific position of the wafer radial direction is always present Therefore, since the amount of grinding at that portion increases and a dent is generated, the flatness deteriorates. The radius ratio with respect to the workpiece is more preferably 7/20 to 13/20. By setting it as this range, while having the effect of improving the roughness of the outer peripheral part of a to-be-ground object, the effect of improving the flatness at the time of grinding can also be acquired.

Also, wider than the spacing p ₁ interval p _2, wider than the interval p ₂ interval p _3, i.e. the distance between the plurality of grinding segments, preferably gradually decreases to that of the inner column from the outer row ones . By ensuring a wide interval p ₁ between the first grindstone rows 3 for grinding the wafer center, the state where the grindstone is always in contact with the central portion of the wafer is reduced, and the central recess is improved. By gradually decreasing the distance between the grindstone segments from the outer row toward the inner row, that is, when contacting the wafer and the grindstone, by reducing the grindstone segment distance from the wafer center to the outer periphery. Contrary to the central portion, the roughness in grinding can be improved by increasing the number of contacted grinding wheels.

  With such a configuration, the cooling water at the time of grinding can be supplied evenly to each grindstone segment located on the inside, center, and outside.

  Next, a wafer grinding method using the surface grind segment grindstone according to this embodiment will be described.

  For example, the segment grindstone 1 according to the present invention is attached to a grinding apparatus 21 as shown in FIG. 2, and the wafer W is held by holding means (not shown). Thereafter, the segment grindstone 1 and the wafer W are rotated in the opposite directions, and the segment grindstone 1 is pressed against the semiconductor wafer W while supplying cooling water to the wafer W to perform grinding. The segment grinding stone for surface grinding according to the present invention is suitable for single-side grinding as shown in FIG. 2, but can also be applied to a general double-side grinding apparatus.

  In this grinding process, as shown in FIG. 3, the grinding wheel row of three rows increases the abundance ratio of the grinding wheel on the outer periphery of the wafer during grinding to secure the contact area of the grinding wheel, and the work applied to one point of the grinding stone is reduced. Since the wafer outer peripheral portion and the inner peripheral portion are made uniform, the roughness of the wafer outer peripheral portion is improved, and the wafer surface roughness after grinding can be made uniform.

  In addition, the segment grindstone for surface grinding of the said embodiment is not restricted to the structure shown in FIG. 1, but as shown in FIG. 4, as shown in FIG. The grindstone segment 13 is formed with a space in the circumferential direction, and the grindstone segment 13 is disposed inside the first grindstone row 14 with a first grindstone row 14 arranged in a ring shape with a constant space. A second grindstone row 15 and a third grindstone row 16 disposed inside the second grindstone row 15 with a gap therebetween, and a grindstone groove portion 17 is formed between the grindstone rows. Has been. Moreover, the space | interval P between the said grindstone segments with respect to the circumferential direction becomes a narrow fan shape which reduces gradually linearly toward the inner peripheral direction from the outer periphery. By adopting this configuration, the same operation and effect as the configuration shown in FIG. 1 can be obtained.

  By using the segment grindstone for surface grinding according to the present invention as shown in FIG. 1, by changing the diameters of the intermediate grindstone row and the inner grindstone row, the interval between the grindstone rows is changed to grind a silicon wafer having a diameter of 200 mm. The roughness of the wafer outer periphery, wafer R / 2 and wafer center, and the flatness were measured and compared.

The results are shown in Table 1.

  As can be seen from Table 1, in Examples 1 to 4, that is, when the radius ratio to the workpiece is in the range of 7/20 to 9/10, the maximum tolerance of roughness is much higher than that of the comparative example and the reference example. Excellent results were obtained. In particular, it was confirmed that when the radius ratio to the object to be ground is in the range of 7/20 to 13/20, there is an effect of improving the flatness as well as the maximum tolerance of roughness.

The conceptual diagram of the segment grindstone for surface grinding which concerns on one Embodiment of this invention. The conceptual diagram of the single-sided grinding apparatus which attached the segment grindstone for surface grinding which concerns on one Embodiment of this invention. The conceptual diagram which shows the grinding state of the to-be-ground object using the segment grindstone for surface grinding which concerns on this invention. The conceptual diagram of the segment grindstone for surface grinding which concerns on other embodiment of this invention. The conceptual diagram which shows the grinding state of the to-be-ground object using the conventional segment grindstone for surface grinding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Segment grindstone for surface grinding 2 Rotary disk 3 Outer grindstone row (1st grindstone row)
3s Wheel segment 4 Intermediate wheel row (second wheel row)
4s grinding wheel segment 5 inner grinding wheel row (third grinding wheel row)
5s grinding wheel segment

Claims (4)

A rotating disk, at least a first grindstone row in which a plurality of grindstone segments are arranged in a ring shape on the surface of the rotating disc with a certain interval, and an interval is provided inside the first grindstone row. And a second grindstone row in which a plurality of grindstone segments are arranged at a constant interval, and a plurality of grindstone segments are arranged at intervals inside the second grindstone row. A segment grindstone for surface grinding, comprising a third grindstone row arranged at intervals. A rotating disk and a plurality of fan-shaped grindstone segments are formed on the surface of the rotating disk at intervals in the circumferential direction, and the grindstone segments are arranged in a ring shape at regular intervals. A second grindstone row arranged inside the first grindstone row, and a third grindstone row arranged with a space inside the second grindstone row. In addition, a grindstone groove is formed between the grindstone rows, and the interval between the grindstone segments in the circumferential direction forms a narrow fan shape that gradually decreases linearly from the outer circumference toward the inner circumference. Segment grindstone for surface grinding. 3. The plane according to claim 1, wherein a difference between a radius of the first grindstone row and a radius of the third grindstone row is 7/20 to 9/10 of a radius of the workpiece. Segment grindstone for grinding. 3. The plane according to claim 1, wherein a difference between a radius of the first grindstone row and a radius of the third grindstone row is 7/20 to 13/20 of a radius of the workpiece. Segment grindstone for grinding.

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