JPH07205019A - Pressure plate in polishing machine - Google Patents

Abstract

PURPOSE:To absorb roughness on a non-polished surface by a soft plate and to highly accurately polish a surface to be polished by sticking a soft plate to a base plate, sticking the non-polished surface of a workpiece thereto by liquid and circumferentially laying a control ring along the outer periphery of the workpiece. CONSTITUTION:A polishing machine is provided with a polishing plate 2 pivotally supported on one side rotary shaft 2a with polishing cloth 1 spread and a base plate 3 pivotally supported on the other side rotary shaft 3a by holding a workpiece W. The workpiece W is held between both plates 2 and 3 and polished. In such constitution, a soft plate 4 formed of a soft member is stuck to the base plate 3. The non-polished surface Wa of the workpiece W is stuck by liquid to the soft plate 4. A control ring 5 is circumferentially laid on the outer periphery of the workpiece W slightly lower than a surface Wa to be polished thereof. Thus, roughness on the non-polished surface Wa is absorbed by the soft plate 4 and the surface Wb to be polished is highly accurately polished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure plate of a polishing machine for polishing a work, which is a semiconductor wafer to be a substrate in a manufacturing process of VLSI, etc., and more specifically, it is held by a base plate of the polishing machine. The present invention relates to a pressure plate that finishes a polished surface of a workpiece made into a flat surface with ultra-high accuracy.

[0002]

BACKGROUND OF THE INVENTION A semiconductor wafer device of this type according to the present invention has been required to produce an ultra LSI (ULSI) of 64 megabytes or more in accordance with higher density and higher integration. In recent years, development of a super LSI of 256 megabytes or 1 gigabyte has been started.

A wiring layer (metal film), an insulating film (oxide film or the like) or a polysilicon film (semiconductor film) is formed as a multilayer film on the surface of these semiconductor devices.
That is, the LSI has a structure corresponding to a single-story structure, whereas a VLSI has a two-story structure and a three-story structure.

In the manufacturing process of ultra-LSI and the like, an ultra-high precision polishing technique for flat surfaces is indispensable for flattening each film layer of a multilayer film.

[0005]

2. Description of the Related Art Generally, a polished semiconductor wafer is mistaken for a completely flat semiconductor wafer, and from a microscopic point of view, a surface roughness of about 1 to 2 microns remains, and the remaining surface roughness is Is simple, for example,
If it is only a tapered surface that is inclined in a certain direction, it can be dealt with by inclining the polishing plate incorporating the universal joint, but the surface roughness of a complicated shape, such as medium-high, medium-low, or uneven surface The reality is that the roughness cannot be dealt with.

In addition, various kinds of ultra-high precision polishing techniques for flat surfaces have been developed, and some of them have actually been tried for practical use, but each has its own problems. This is a field that requires the most development efforts in the near future, and has already been developed and sold by some semiconductor manufacturers in the United States for several years.

[0007]

However, the initial cost of the polishing apparatus itself is expensive, and therefore the polishing cost per VLSI becomes high, which is not a generalized situation. In addition, there are many technical problems, and it is the reality that ultra-high precision flattening that eliminates the originally intended residual surface roughness of complicated shapes has not been achieved. It has been earnestly desired to solve the surface roughness of a complicated shape and to reduce the polishing cost for one VLSI to the limit.

[0008]

According to the present invention, a soft plate formed of a soft member is attached to a base plate of a polishing machine, a non-abrasive surface of a work is attached to the soft plate with a liquid, and the outer surface of the work is further removed. By arranging the control ring around the periphery, the surface roughness of the complicated shape remaining on the semiconductor wafer that is the work is absorbed by the soft plate attached to the base plate to provide a super-precision flat surface. .

[0009]

An object of the present invention is to deal with the surface roughness of a complicated shape remaining on a semiconductor wafer and to dramatically reduce the initial cost of a polishing machine in the process of manufacturing a VLSI. Therefore, the purpose is to significantly reduce the polishing cost per VLSI.

[0010]

The structure of the present invention is a polishing machine for sandwiching and polishing a work between a polishing plate and a base plate, in which a soft plate is attached to the base plate.
The non-polished surface of the work is adhered to the soft plate with a liquid, and the control ring is provided around the outer periphery of the work with the top surface slightly lower than the ground surface.

[0011]

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

FIG. 1 is a schematic side view of a polishing machine according to an embodiment of the present invention, and FIG. 2 is a schematic side view of an embodiment in which the surface roughness of a complex shape remaining on an actual semiconductor wafer is exaggerated. It is a figure.

The present invention relates to a pressure plate of a polishing machine for polishing a work W, which is a semiconductor wafer serving as a substrate in a manufacturing process of VLSI and the like, and more specifically, it is held by a base plate 3 of the polishing machine. The present invention relates to a pressure plate for finishing a polishing surface of a work W into an ultra-high-precision flat surface, which holds a work W and a polishing plate 2 to which a polishing cloth 1 is attached and which is axially attached to one rotating shaft 2a. In the polishing machine for sandwiching and polishing the work W between the base plate 3 axially attached to the other rotating shaft 3a and the polishing plate 2 and the base plate 3, the base plate 3 is formed of a soft member. The soft plate 4 is attached, and the work W is attached to the soft plate 4.
The non-polishing surface Wa is adhered by a liquid, and the control ring 5 is provided around the outer periphery of the work W with the top surface 5a slightly lower than the polishing surface Wb.

The polishing machine used in the present invention is a polishing machine or a lapping machine, and the work W is LS.
A semiconductor wafer which is a substrate for I, VLSI, or the like, and the semiconductor wafer which is the work W is polished on both sides in advance.

A photolithography method is applied to one side of the semiconductor wafer,
An insulating film, a wiring layer, a polysilicon film, etc. are formed by means of an epitaxial growth method, an aluminum vapor deposition method or the like. Further, in a VLSI, these steps are repeated and stacked. In forming
An ultra-high precision flat surface is required.

That is, the polishing machine shown in FIG. 1 has a polishing cloth 1 made of non-woven fabric, natural or artificial leather, and the like, and is attached to a rotary shaft 2a which is rotated by one drive source (not shown). The rotating polishing plate 2 and the workpiece W facing the polishing plate 2
And a base plate 3 made of alumina ceramic or the like that is attached to a rotary shaft 3a that is rotated by the other drive source (not shown). The polishing surface Wb such as an insulating film is polished by the polishing cloth 1 while holding the non-polished surface of the wafer.

According to the present invention, the soft plate 4 made of a soft material such as silicon resin is attached to the base plate 3 by utilizing the interfacial tension of an adhesive, a pressure sensitive adhesive, or a liquid such as pure water. Furthermore, by attaching the non-polished surface Wa of the work W to the soft plate 4 with a liquid such as pure water, the unevenness of a complicated shape or the like remaining on the non-polished surface of the semiconductor wafer which is the work W can be obtained. The surface roughness is absorbed by the soft plate 4 for polishing.

A control ring 5 is attached to the outer periphery so as to hold the work W inside.
That is, the top surface 5a of the control ring 5 is provided slightly lower than the polishing surface Wa of the work W, and when the polishing surface Wa of the work W and the polishing cloth 1 stretched on the polishing plate 2 are in a parallel state. It has a slight height such that it does not come into contact with each other but comes into contact with it in a non-parallel state so as to prevent edging of the polishing surface Wa of the workpiece W during polishing, particularly only at the edge of the polishing surface Wa.

The control ring 5 is made of a metal such as aluminum or a soft plastic which is slightly softer than the work W, and is attached to the soft plate 4 in the drawing. It is possible to obtain various effects.

[0020]

As described above, according to the present invention, the soft plate absorbs the surface roughness such as the unevenness of the complex shape of the non-polished surface of the semiconductor wafer, which is the work in the manufacturing process of the VLSI, so that the semiconductor wafer is processed. The polishing surface of the multi-layered film such as the wiring layer, the insulating film, or the polysilicon film formed on the above is polished with high precision. In the embodiment, the polishing can be performed with a flat precision of about 500 angstroms. Only by providing a ring, the initial cost of the polishing machine can be reduced at a stroke, the polishing cost per VLSI can be reduced, and its contribution is immeasurable, which is a very significant effect. Is played.

[Brief description of drawings]

FIG. 1 is a schematic side view of a polishing machine according to an embodiment of the present invention.

FIG. 2 is a schematic side view of an embodiment in which the surface roughness of a complicated shape remaining on an actual semiconductor wafer is exaggerated.

[Explanation of symbols]

 W Work Wa Non-polished surface Wb Polished surface 1 Polishing cloth 2 Polishing plate 2a Rotating shaft 3 Base plate 3a Rotating shaft 4 Soft plate 5 Control ring 5a Top surface

Claims (1)

[Claims] 1. A polishing plate having a polishing cloth attached thereto and axially attached to one rotary shaft, a base plate holding a work and axially attached to the other rotary shaft, and the polishing plate and the base plate. In a polishing machine for sandwiching and polishing a work in between, sticking a soft plate formed of a soft member to the base plate,
A non-polishing surface of a work is adhered to the soft plate with a liquid, and a control ring is provided around the outer periphery of the work with the top surface slightly lower than the polishing surface to surround the control plate. .