JPH01268032A - Method and apparatus for wafer polishing - Google Patents

Abstract

PURPOSE:To enable accurately polish a wafer into plane form, by polishing the wafer held in a polishing chuck with a part thereof sticking out from a polishing surface plate or a polishing cloth. CONSTITUTION:Each polishing chuck 4 holds one semiconductor wafer 5, which is polished with a part thereof sticking out from a polishing surface plate 1 or a polishing cloth 3. For example, the semiconductor wafer 5 to be polished is held by the polishing chuck 4 by vacuum absorption or any other means, rotating the polishing chuck 4 with a motor 9 forces the semiconductor wafer 5 to rotate together with the polishing chuck 4 at a rotating speed n and presses the wafer 5 on the polishing cloth 3 on the polishing surface plate 1 forcibly rotated by a motor 2 at a rotating speed N. The semiconductor wafer 5 in this state rotates together with the polishing chuck 4 at a rotating speed n while reciprocating in the direction of the diameter of the polishing surface plate 1 and is polished by the friction between said wafer and the polishing cloth 3, with a part thereof sticking out from the polishing cloth 3 in the inside and outside of the polishing surface plate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polishing technique, and particularly to a technique that is effective when applied to polishing thin plate materials such as semiconductor wafers.

[Conventional technology]

Conventionally, polishing technology for semiconductor wafers (hereinafter simply referred to as wafers) has been described in "Electronic Materials J 1983 Special Issue, P49 to P56, published by Kogyo Research Association Co., Ltd., November 15, 1983. ing.

By the way, the present inventor has studied polishing techniques for semiconductor wafers. That is, in polishing a semiconductor wafer, the entire surface of the wafer is strongly pressed against a polishing cloth, and the polishing cloth and wafer are rotated while a polishing agent is flowed onto the polishing cloth, and the polishing is performed using the friction generated by the polishing.

[Problem to be solved by the invention]

However, the above conventional technology has the problem that when the wafer is pressed against the polishing cloth, the polishing pressure is high at the outer periphery of the wafer and low at the center, resulting in non-uniformity as a whole.
There is a problem in that the polishing cloth wears unevenly because the wafer does not work uniformly on the entire surface of the polishing cloth. Furthermore, there is a problem in that foreign matter tends to accumulate on or in the polishing cloth.

An object of the present invention is to provide a technique for polishing a wafer to a flat surface with high precision.

Another object of the present invention is to provide a technique for polishing a wafer without damaging it.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means for Solving the Problems] A brief overview of typical inventions disclosed in this application is as follows.

That is, polishing is performed with a part of the semiconductor wafer held by the polishing chuck protruding outward from the polishing surface plate or polishing cloth.

[Effect]

According to the above-mentioned means, a portion of the wafer protrudes outside the polishing cloth, and the protruding portion of the wafer is not polished, thereby making it possible to cancel out the wobbling of the outer periphery of the wafer.

Further, since the wafer comes out from the polishing cloth, the entire surface of the polishing cloth is worn uniformly. Furthermore, foreign matter on or in the polishing cloth may be removed from the polishing cloth (;
It can be swept out.

〔Example〕

FIG. 1 is a cross-sectional view schematically showing a polishing apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the relationship between wafer flatness accuracy and protrusion.

The polishing apparatus of this embodiment is a single-wafer type @calendar apparatus in which one semiconductor wafer (thin plate material) is held in one polishing chuck by, for example, vacuum suction force.

This polishing apparatus has a polishing surface plate 1, which is forcibly rotated by a motor 2 at a rotational speed N in the direction of the arrow.

A polishing cloth 3 is placed on the upper surface of this polishing surface plate 1, that is, the surface to be polished.
is provided in a portion excluding the inner diameter d.

A polishing chuck 4 is provided above the polishing surface plate 1, and a semiconductor wafer 5, which is an example of a thin plate, is held on the polishing chuck 4 in a single-wafer manner so as to face the polishing surface plate 1. Further, the polishing chuck 4 has a pad 6 and a guard ring 7 for vacuum suction of the semiconductor wafer 5 on the polishing surface plate 1 side.

The Kenmaro chichotsuk 4 is operated by a motor 9 via a printing mechanism 8.
It is forcibly rotated in the same direction as the polishing surface plate 1 at a rotational speed n. Further, the polishing chuck 4 of this embodiment is adapted to reciprocate in the horizontal direction with respect to the polishing surface plate 1.

Further, a nozzle 10 for supplying an abrasive is suspended above the polishing surface plate 1, and the abrasive is drained from the center and outside of the polishing surface plate 1.

Next, the operation of this embodiment will be explained.

The semiconductor wafer 5 to be polished is moved by the polishing chuck 4.
Each chuck 4 holds one sheet at a time by vacuum suction or the like. This semiconductor wafer 5 is forcibly rotated together with the polishing chuck 4 at a rotational speed n by rotating the polishing chuck 4 with a motor 9, and the polishing cloth on the polishing surface plate l which is forcibly rotated at a rotational speed N with the motor 2. Pressed on top of 3.

In this state, the semiconductor wafer 5 reciprocates in the radial direction of the polishing surface plate 1 while rotating together with the polishing chuck 4 at rotational speeds N and n. As a result, the semiconductor wafer 5 is polished by friction with the polishing cloth 3, with parts of the semiconductor wafer 5 protruding from the polishing cloth 3 inside and outside the polishing surface plate 1.

As a result, in this embodiment, since the portion of the semiconductor wafer 5 that protrudes from the polishing cloth 3 is not polished, it can be polished into a convex or concave shape by changing the protrusion ilW as shown in FIG. By selecting the right type, you can polish with good flatness and precision.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the polishing chuck 4 may have a structure in which the polishing chuck 4 is rotated eccentrically so that a portion of the semiconductor wafer 5 protrudes outside the polishing surface plate 1 or the polishing cloth 3.

In the above explanation, the invention made by the present inventor is mainly applied to semiconductor wafers, which is its field of application, but it is not limited to this, and the invention can also be applied to wafers such as other thin plate materials. be able to.

〔Effect of the invention〕

A brief overview of typical inventions disclosed in this application is as follows.

That is, a method for polishing semiconductor wafers, in which one semiconductor wafer is held in each polishing chuck, and a part of the semiconductor wafer is polished with a part of the semiconductor wafer protruding from the polishing surface plate or polishing cloth. It is possible to eliminate wobbling on the outer periphery of the wafer and to polish the entire surface to be polished uniformly and with high flatness accuracy.

Further, according to the present invention, by changing the amount of protrusion, it is possible to polish from a convex shape to a concave shape, and by selecting an appropriate amount of protrusion, it is possible to perform polishing with high desired flatness accuracy.

Further, according to the present invention, the wafer is moved out of the polishing cloth by the horizontal reciprocating movement or eccentric rotational movement of the polishing chuck, so that the abrasion of the polishing cloth becomes uniform. Since the wafer is swept out of the polishing cloth, polishing can be performed without damaging the wafer.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view schematically showing a polishing apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the relationship between wafer flatness accuracy and protrusion amount.

Claims (1)

[Claims] 1. A method for polishing semiconductor wafers, in which one semiconductor wafer is held in each polishing chuck, with a portion of the semiconductor wafer protruding outward from the polishing surface plate or polishing cloth. A wafer polishing method characterized by polishing. 2. The wafer polishing method according to claim 1, wherein the polishing surface plate is reciprocated or eccentrically rotated in the radial direction while rotating the semiconductor wafer. 3. A polishing device for semiconductor wafers, which includes a polishing surface plate that rotates in a horizontal plane in a predetermined direction at a predetermined rotation speed, a polishing cloth provided on the polishing surface plate, and a surface to be polished of a semiconductor wafer. Each semiconductor wafer is held in contact with the polishing cloth, rotated in the same direction as the polishing surface plate at a predetermined rotation speed, and capable of reciprocating movement or eccentric rotation in the radial direction of the polishing surface plate. A wafer polishing device comprising a polishing chuck.