JPH0419065A - Silicon wafer polishing device and high flatness polishing method of silicon wafer - Google Patents

Abstract

PURPOSE:To enable the high flatness polishing of an Si wafer by providing a chuck to be sucked to the lower face of an integral type holder, having plural through suction holes of a specified diameter at the lower part thereof. CONSTITUTION:A chuck provided with plural suction holes 23 of 0.5 mmphi or less at the lower part thereof is vacuum-sucked to an integral type holder 10 provided with plural suction holes. An Si wafer 3 is then vacuum-sucked to the chuck 11 to perform polishing with abrasive cloth.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a polishing apparatus for Si wafers and removal of polishing force.

[Conventional technique] In conventional polishing (mirror finishing) of Si wafers, as shown in Fig. 2, the Si wafer 3 was fixed to a plate 1 of ceramic fuchs (for example, alumina) with wax 2 and polished. . For this, the plate is warmed, the wax is melted, the Si wafer is pressed, and the wax is
It is necessary to harden the wax, and after polishing, it is necessary to peel off the Si wafer from the plate and remove the wax from the navigation plate, which reduces efficiency and makes it difficult to ensure that the wax thickness is uniform. The problem was that wafers with good flatness could not be obtained.

[Problems to be solved by the invention] In view of the above-mentioned problems, the present invention provides Si material with high efficiency and high flatness.
The purpose of this paper is to share an apparatus and method for bossing wafers.

[Means for Solving the Problems] The present invention provides an apparatus for vacuum suctioning and bossing a Si wafer to a holder, which includes: an integrated holter having a suction hole supported in a hollow shaft via a spherical bearing; A chuck that is suctioned to the lower surface of the holder and has a plurality of suction holes with a diameter of 0.5 mm or less penetrated through the upper part of the holder, and a vacuum pump connected to the hollow part of the shaft via a rotary joint. A vacuum hose is screwed from the bottom to a conduction hole above the suction hole on the upper surface of the integrated holder, and the suction hole has a vertical hole from the conduction hole and communicates with a groove provided on the lower surface of the integrated holder, The chuck is a Si wafer polishing apparatus characterized in that the chuck is arranged with the drill hole aligned with the groove.

In addition, in the method of polishing the Si wafer by suctioning it to a holder, the Si wafer is placed in an integrated holder having a plurality of suction holes, and a chuck having a plurality of suction holes of 0.5 mmφ or less in the lower part is vacuum-suctioned. , S on the chuck
This is a high flatness polishing method for Sj wafers, which is characterized by vacuum suctioning and bossing the Sj wafers.

[Operations] The present invention will now be described in detail. What is Bossink?
A disk-shaped single crystal plate (S
i wafer) is placed on a polishing cloth 4 fixed on a surface plate S as shown in FIG.
n2 and average particle diameter of 0.02 μm) with the polishing cloth and the S
A load 9 (for example, 250 g/cm2 in terms of wafer surface thickness) is applied to the Si wafer, and a relative velocity of 8 (for example 3
m/m1n) and by contacting the Si wafer with the abrasive grains, the Si wafer is flattened into a mirror-like surface.

The present invention provides a method for polishing a Si wafer 3 extremely flat and quickly.

For this reason, the present invention has invented a vacuum chuck that can be easily attached and detached with or without vacuum suction and that can polish the Si wafer with high flatness.

The mechanism is shown in Figure 1. Spherical bearing 13 on shaft 12
The integrated holder 10 is supported by the support. The chuck 11 is vacuum-suctioned into the integrated holder, and the Si
Wafer 3 is vacuum-suctioned.

To explain the vacuum suction route, the vacuum pump 14 is about 5
00 mmaq is brought to a negative pressure with respect to the atmosphere and reaches a rotary joint 15 fixed to the shaft. The shaft is hollow and extends to the vacuum hose 16.

Screw the vacuum hose to the top of the integrated holder. A conductive hole 7 is provided inside the integrated holder 10. The conduction hole 17 communicates with the mantle 21 via the vertical hole 20. A drill hole 22 is provided in the chuck 11 at a position corresponding to the forward bending groove 21. The drilled hole 22 is passed through the small diameter opening 23, and the S
j Suction the wafer 3.

By providing the conduction hole 17, it becomes possible to integrate the spherical bearing portion and the groove portion of the chuck contact surface (2).

If the conduction hole 17 is not present, the integrated holter '-1O
18 in Figure 1, it has to be moved separately, and it may be necessary to fasten it with bolts or the like. However, when it is fixed by a bolt, the contact surface 19 is deformed due to the fastening force, the chuck is also deformed, the Si wafer is also deformed, and the flatness of the Si wafer after bossing is not good.

The feature of the present invention is that the Si wafer is not drawn directly to the integrated holder, but is drawn by using the chuck.

The suction hole (small diameter opening 23) in the contact surface 24 with the Si wafer
) must have a hole of 0.5mmφ or less.

If the diameter exceeds 0.5 mm, local concentration of pressure during bossing will cause damage such as dislocations to the Si wafer, causing it to lose its properties as a semiconductor. Moreover, the contact surface 24 must be 8 inches in length, for example, and have a flatness of 3 μm or more. For this reason, the material is ceramic, and the laser
．． Drill a hole with a diameter of 5 mm or less, but the maximum depth is 2 mm. Therefore, if the thickness of the chuck is 201DII+, it is necessary to drill a drill hole 22 with a depth of 18n+m from the back side. For this reason, the suction hole cannot be provided in the integrated holder.

The width of the groove 21 of the body holder must be 5 mm or less. If it exceeds 5 mm, the integrated holder itself will be deformed, the chuck will be deformed, and the Si wafer will also be deformed.

It is desirable that the height of the 21st peak is 1mm to 10InI11.

11[1[If 11 or less, the integrated holder itself will deform,
l At 0 mm or more -F, the suction force is insufficient. Further, in order to synchronize the rotation of the integrated holder with the shaft 12, a drive arm 25 is provided.

[Example] Hereinafter, the present invention will be described in detail.
11, and the through hole 22 was 0.5n+mφ and 61n, and a Sl wafer was polished for 30 minutes.
The flatness 26 of the Si wafer shown in Figure 4 is 0.45 μm.
or obtained. The total working time was 45 minutes, which was significantly shorter than the 70 minutes of the conventional method. It can also be seen that the flatness of the conventional method was at the limit of 2 AJm, which could not be improved by the present invention.

In another embodiment, the width of said groove 21 of the integrated holder is 1 m.
m, the height of the groove 21 is 2 mm, and the drill hole 22 is 0.
When an 8-inch Sj wafer with a diameter of 3 mm was polished for 30 minutes, the flatness 26 of the Si wafer shown in FIG. 4 was 1.2 μm. The total working time was 50 minutes, which was significantly shorter than the 80 minutes of the conventional method. Further, the flatness of the conventional method was limited to 4 urfI, but this was improved by the present invention.

In another embodiment, the width of the groove 21 of the integrated holder is 3 mm, the height of the groove 21 is 3 mm, and the through hole 22 is 3 mm wide.
When 51 6 inch wafers were polished for 30 minutes with a diameter of 0.5+n+nφ, a flatness of 25 08 νm was obtained for the Si wafer shown in FIG. The total working time was 45 minutes, which was significantly shorter than the 70 minutes of the conventional method. Furthermore, the flatness of the conventional method was limited to 2 μm, but this was improved by the present invention.

In yet another example, the width of the groove 21 of the integrated holder is 1 mm, the ridge of the groove 21 is 3 mm, and the drilled hole 22 is O, Immφ, and an S1 wafer of 6]n is polished for 30 minutes. As a result, the flatness 26 of the S1 wafer shown in FIG. 4 was found to be 0.3 μm. The total working time was 45 minutes, which was significantly shorter than the 70 minutes of the conventional method. Further, the flatness of the conventional method was limited to 2LIIl, but it has been improved by the present invention.

[Effects of the Invention] According to the present invention, it is possible to polish an S1 wafer with a higher degree of flatness than in the conventional method, and a flatness that can correspond to an IC density of 64 megabytes was obtained. In addition, machining efficiency has been improved by 30%.
% of fixed costs were reduced.

[Brief explanation of drawings]

FIG. 1 shows the structure of an integrated holder and chuck, and shows a state in which a Si wafer is sucked. FIG. 2 shows a conventional method of fixing a Si wafer using wax. FIG. 3 shows the polishing state of the Sj wafer, and FIG. 4 shows the flatness of the Si wafer. 3... Si wafer, 4... Polishing cloth, 10... Integrated holder, 11... Chuck, 12... Shaft, 13... Spherical bearing, 14... Vacuum pump, 15
...Rotary joint 516...Vacuum hose,
17... Conductive hole, 19.24... Contact surface, 20...
・Vertical hole, 21... groove, 22... drill hole, 23...
Small diameter opening, 26...flatness

Claims (1)

[Claims] 1. An apparatus for polishing a Si wafer by vacuum suction on a holder, comprising: an integrated holder having a suction hole supported via a spherical bearing in a hollow shaft; and a lower surface of the integrated holder. A chuck has a plurality of suction holes with a diameter of 0.5 mm or less penetrated through the upper part of the chuck while being sucked, and a vacuum pump is connected to the hollow part of the shaft via a rotary joint, and a vacuum hose is connected to the lower part of the shaft. The suction hole is screwed into a conduction hole above the suction hole on the upper surface of the integrated holder, and the suction hole has a structure in which a vertical hole is provided from the conduction hole and communicates with a groove provided on the lower surface of the integrated holder, and the chuck is connected to the groove. A polishing apparatus for Si wafers, characterized in that the drill holes are arranged to align with each other. 2. In the method of polishing the Si wafer by suctioning it to a holder, the Si wafer is placed in an integrated holder having a plurality of suction holes, and a chuck having a plurality of suction holes of 0.5 mmφ or less in the lower part is vacuum-suctioned. , Si on the chuck
A method for polishing a Si wafer to a high degree of flatness, characterized by polishing the wafer by vacuum suction.