JPH08174404A - Wafer polishing method and device - Google Patents

Abstract

PURPOSE: To produce semiconductor chips, with a good yield, to heighten the degree of integration of the semiconductor chips, and to miniaturize the chips by uniformly polishing the surface of wafers. CONSTITUTION: In a wafer polishing device 10, a wafer surface 25A is pressed against an abrasive cloth 27, while a wafer 25 is moved relative to the abrasive cloth 27 in order to polish the wafer surface 25A. In the device 10, a pressing means 12 presses an abrasive pad 24 by means of a fluid-pressure cylinder 18 to give the wafer 25 the pressing force, thereby uniformly pressing the wafer surface 25A against the abrasive cloth 27. Since the rigidity of the pad 24 is increased by pressing the wafer 25 by means of the pressure of liquid, whose volume is invariable, the pressing force of the abrasive pad 24 can be kept constant even when vibration occurs during polishing work. Accordingly, the wafer surface 25A is polished uniformly, thereby enhancing the processing accuracy in every work-stage (such as film-forming, etching stages) in which the semiconductor chips are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing method and apparatus, and more particularly to a wafer polishing method and apparatus for polishing a work surface such as a wafer by pressing it against a polishing cloth with a suction pad.

[0002]

2. Description of the Related Art In recent years, as wafers have been highly integrated and miniaturized, it has been required to sharpen an exposure focus with the high integration and miniaturization of wafers. For this reason, it is necessary to highly accurately flatten the wafer surface to be the exposure surface, and a chemical mechanical polishing method is known as a method for achieving highly precise flattening. The chemical mechanical polishing method polishes the wafer surface by pressing the surface of the wafer against a polishing cloth while supplying a chemical polishing agent to the polishing surface.

In this chemical mechanical polishing method, the following method is known as a method for pressing the wafer surface against a polishing cloth. In the first method, a polishing pad is fixed to a rotary shaft, a pressing force is applied to the polishing pad, and the wafer held by the polishing pad is pressed against a polishing cloth to polish the wafer surface. In the second method, the polishing pad is freely supported so as to correspond to the inclined surface of the wafer, air pressure is applied to the polishing pad, and the wafer held on the polishing pad is pressed against the polishing cloth to polish the wafer surface. . In the third method, similarly to the second method, the polishing pad is supported so as to correspond to the inclined surface of the wafer, and an urging force of an elastic body such as rubber is applied to the polishing pad to polish the polishing pad. The wafer held on the pad is pressed against a polishing cloth to polish the wafer surface.

[0004]

However, in the first method, since the polishing pad is fixed to the rotary shaft, when the parallelism between the back surface and the front surface of the wafer is low, the wafer held by the polishing pad is Since the surface is inclined with respect to the polishing cloth, there is a problem that uneven polishing occurs on the wafer surface.

In the second method, the polishing pad is freely supported so as to correspond to the inclined surface of the wafer. However, since the volume of air changes, the rigidity is low, and when vibration or the like occurs during polishing, the polishing pad is polished. There is a problem that the pressing force of the pad changes and polishing unevenness occurs on the wafer surface. Further, in the third method, similarly to the second method, the polishing pad is supported so as to correspond to the inclined surface of the wafer, but since the rigidity of the elastic body is low, uneven polishing occurs on the wafer surface. There is a problem.

As described above, when the parallelism between the front surface and the back surface of the wafer is poor, the wafer surface cannot be uniformly polished. Therefore, the insulating film on the wafer surface and the film thickness of the wiring should be uniformly polished. I can't. Therefore, in the semiconductor chip manufacturing process, it is not possible to perform film formation and etching in the post process of the polishing process with high accuracy. As a result, semiconductor chips cannot be produced with a high yield, and there is a problem that it becomes difficult to achieve high integration and miniaturization of the semiconductor chips.

The present invention has been made in view of such circumstances, and by uniformly polishing the surface of a wafer, semiconductor chips can be produced with high yield, and further high integration and miniaturization of semiconductor chips can be achieved. An object of the present invention is to provide a wafer polishing method and apparatus.

[0008]

In order to achieve the above object, the present invention applies a pressing force to a work supported by a pad to press the polishing surface of the work against a polishing cloth and to polish the work. In a wafer polishing method of polishing a polishing surface of a work by moving it relative to a cloth, the pad is pressed by a hydraulic cylinder to apply the pressing force to the work, and the polishing surface of the work is polished by the polishing cloth. It is characterized by being pressed evenly against.

[0009]

According to the present invention, in the wafer polishing apparatus for pressing the polishing surface of the work against the polishing cloth and moving the work relative to the polishing cloth to polish the polishing surface of the work, the pressing means is a pad for the hydraulic cylinder. The work was pressed with a pressing force to apply the pressing force to the work, and the polishing surface of the work was evenly pressed against the polishing cloth. As described above, since the rigidity is increased by pressing the work with the pressure of the liquid that does not change in volume, the pressing force of the pad is maintained constant even when vibration or the like occurs during polishing.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wafer polishing method and apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a side view showing a wafer polishing apparatus according to the present invention. Wafer polishing device 1
0 is provided with a pressing means 12, and the pressing means 12 is a rotating plate 1
6, a hydraulic cylinder 18, a pressurizing cylinder 20, and a counter balance 22. The rotary plate 16 is formed in a disc shape, and a flow path (not shown) is formed in the rotary plate 16. On the lower surface of the rotary plate 16, three hydraulic cylinders 18 are arranged at equal intervals on the same circumference (see FIG. 2).

A space (not shown) in the cylinder portion 18A of the hydraulic cylinder 18 is communicated with a flow path in the rotary plate 16. Further, a piston 18C is supported in the cylinder portion 18A so as to be able to move up and down, and the piston 18C has a rod portion 18B.
Is attached. The rod portion 18B is rotatably attached to the polishing pad 24 via the spherical body 19.
A recess 24A is formed on the back surface of the polishing pad 24, and the wafer 25 is adsorbed inside the recess 24A. Wafer 25
Has a surface 25A facing downward, and the wafer surface 25A is in contact with the polishing cloth 27. The polishing cloth 27 is attached on the surface plate 39.

The lower end of the hollow shaft 26 is fixed to the center of the upper surface of the rotary plate 16 described above, and the hollow shaft 2
6 communicates with the flow path in the rotary plate 16. A joint 28 is rotatably supported on the upper end of the hollow shaft 26. A seal 29 is provided on the inner circumference of the joint 28.
(See FIG. 3) and the seal 29 is a hollow shaft 2
6 and the joint 28 are sealed. One end of a supply pipe 30 is fixed to the joint 28, and the other end of the supply pipe 30 is connected to the cylinder portion 20A of the pressurizing cylinder 20.

As a result, the cylinder space 20C communicates with the respective spaces of the hydraulic cylinders 18, 18, 18. A piston 36 is liftably supported in the pressurizing cylinder 20, and a counter balance 22 is fixed to an upper end portion of a rod 32 fixed to the piston 36. As a result, the piston 36 descends due to the weight of the counter balance 22, and the pressure P acts on the liquid such as oil filled in the cylinder space 20C, and the pressure P is the hydraulic cylinders 18 and 1.
8 and 18 are transmitted.

The operation of the wafer polishing apparatus according to the present invention constructed as above will be described with reference to FIGS. 1 and 4. First, the wafer 25 is placed face down on the polishing cloth 27.
As a result, the surface 25A of the wafer 25 contacts the polishing cloth 27 uniformly. When the parallelism between the back surface and the front surface of the wafer 25 is low, the back surface of the wafer 25 is inclined. Next, the wafer 25 is sucked into the recess 24A of the polishing pad 24. As a result, the recess 24A of the polishing pad 24 comes into contact with the back surface of the wafer 25, and the polishing pad 24 is inclined like the back surface of the wafer 25.

In this state, when the piston 36 is lowered by its own weight of the counter balance 22, the pressure P acts on the liquid filled in the cylinder space 20C, and the pressure P is transmitted to the hydraulic cylinders 18, 18, 18. It Therefore, the pressing force acts on the hydraulic cylinders 18, 18, 18 to uniformly press the wafer surface 25A against the polishing cloth 27. As a result, the wafer surface 25A is flatly polished with high accuracy.

In the above embodiment, the case where the pressing force is applied to the wafer 25 by using the counter balance 22 has been described, but the present invention is not limited to this, and the pressing force may be applied to the wafer 25 by using a pump or the like. Good. Further, in the above-described embodiment, the case where three hydraulic cylinders are used has been described, but the present invention is not limited to this, and the same effect can be obtained by using a plurality of hydraulic cylinders other than three.

Furthermore, in the above-mentioned embodiment, the case where the three hydraulic cylinders 18, 18, 18 are used to uniformly press the wafer surface 25A against the polishing cloth 27 has been described. Even with the configuration shown in FIG. 5, it is possible to obtain the same effect as that of the above embodiment. Another embodiment of the wafer polishing apparatus according to the present invention will be described below with reference to FIG. In FIG. 5, the same members as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 5, the lower end of the hollow shaft 26 is connected to the center of the pressing cylinder 30, and the polishing pad 24 is supported in the pressing cylinder 30 so as to be movable up and down. A seal member 32 is attached to the upper surface of the polishing pad 24, and the seal member 32 seals the space 30A in the pressing cylinder 30. According to another embodiment of the wafer polishing apparatus according to the present invention configured as above, the wafer 25 is sucked into the recess 24A of the polishing pad 24 while the surface 25A of the wafer 25 is in uniform contact with the polishing cloth 27. To do. And
When the parallelism between the back surface and the front surface of the wafer 25 is low, the wafer 2
Although the back surface of No. 5 is inclined, the recess 24A of the polishing pad 24 is also inclined along the inclined surface of the wafer 25.

In this state, when the piston 36 is lowered by its own weight of the counter balance 22 in this state, the pressure P acts on the liquid filled in the cylinder space 20C, and the pressure P is transmitted to the pressing cylinder 30. To be done. Therefore, the pressing force acts on the polishing pad 24, and the wafer surface 2
5A is evenly pressed against the polishing cloth 27. This allows
The wafer surface 25A is highly precisely flat-polished.

[0020]

As described above, according to the wafer polishing method and apparatus of the present invention, the pressing means presses the pad with the hydraulic cylinder to apply the pressing force to the work, and the polishing surface of the work is polished. Evenly pressed against. In this way, by pressing the work with the pressure of the liquid that does not change in volume, the rigidity is increased and the pressing force of the pad is maintained constant even when vibration etc. occurs during polishing, so the wafer surface is uniformly polished. can do.

As a result, even if the parallelism between the back surface and the front surface of the wafer is poor, the processing accuracy is improved in each step (film formation, etching, etc.) of uniformly polishing the wafer surface to form semiconductor chips. Therefore, the semiconductor chips can be produced with a high yield, and the semiconductor chips can be highly integrated and miniaturized.

[Brief description of drawings]

FIG. 1 is a schematic view showing an entire wafer polishing apparatus according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG. 1;

FIG. 3 is a cross-sectional view showing an attached state of a joint used in the wafer polishing apparatus according to the present invention.

FIG. 4 is an explanatory view explaining the operation of the wafer polishing apparatus according to the present invention.

FIG. 5 is a sectional view showing another embodiment of the wafer polishing apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Wafer polishing apparatus 12 ... Pressing means 18 ... Hydraulic cylinder 24 ... Polishing pad 25 ... Wafer 25A ... Wafer surface (wafer polishing surface) 27 ... Polishing cloth

Claims (2)

[Claims] 1. A pressing force is applied to a work supported by a pad to press the polishing surface of the work against a polishing cloth, and the work is moved relative to the polishing cloth to polish the polishing surface of the work. In the wafer polishing method, the pad is pressed by a hydraulic cylinder to apply the pressing force to the work, and the polishing surface of the work is evenly pressed to the polishing cloth. 2. A pressing force is applied to a work supported by a pad to press the polishing surface of the work against a polishing cloth, and the work is moved relative to the polishing cloth to polish the polishing surface of the work. The wafer polishing apparatus is provided with a hydraulic cylinder that presses the pad with hydraulic pressure to apply the pressing force to the work.