JPH07263385A - Surface plate for polishing semiconductor wafer - Google Patents

Abstract

PURPOSE:To improve the flateness on surface level of a semiconductor wafer by forming a polishing face with a groove, on one main surface of a rigid surface plate where the surface grading is in roughly specified numerical range, and forming a resin film on the surface of the polishing face. CONSTITUTION:A surface plate 1 for polishing is constituted of material being little in mechanical and thermal transformation and besides flat, for example, ceramic material such as high-purity quartz, etc. Grooves 2 crossing each other are made on one main surface (polishing face) 1a of this surface plate for polishing so that polishing liquid may cover all the semiconductor wafer. Moreover, to secure the sticking tendency with a resin film 3, the grading (roughness) of, at least, the polishing face 1a is in the range of about 10-100mum, and a resin film 3 consisting of polyurethane resin or fluoric resin is made on the surface of the polishing face 1a, which enables the chemical mechanical polishing of a semiconductor wafer W to improve the flatness on surface level. Hereby, the stoppage of the polishing by the hard stopper made of resin film is expected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing platen for polishing a semiconductor wafer capable of polishing the surface of the semiconductor wafer with high precision.

[0002]

2. Description of the Prior Art Conventionally, a polishing cloth made of unsaturated polyester fiber having a thickness of about 2 mm has been used for non-strained mirror polishing of a silicon (semiconductor) wafer. Since the wafer is submerged in a soft polishing cloth and is subjected to chemical mechanical polishing (: CMP = Chemical Mechanical Polishing) with an alkaline liquid in which colloidal silica particles are suspended, so-called sag occurs at the periphery of the semiconductor wafer. There was a problem. On the SOI substrate, the oxide film insulating cell pattern serves as a stopper to form an active layer having a certain thickness, but the active layer surrounded by the insulating wall is polished in a concave shape (the central portion is concave). To be done. Therefore, in the method disclosed in JP-A-2-36069, it is proposed to directly polish a semiconductor wafer using a rigid surface plate made of a ceramic material such as high-purity quartz.

[0003]

However, polishing with a rigid surface plate has a problem that scratches are likely to occur on the polishing surface of a semiconductor wafer. Although the flatness is improved as compared with polishing with a polishing cloth, the problem of scratches is I couldn't solve it.

The present invention has been made in view of the above problems of the prior art, and an object thereof is polishing for improving the flatness of a semiconductor wafer on the basis of the surface.

[0005]

In order to achieve the above object, the polishing plate of the semiconductor wafer according to the present invention is a rigid platen having a surface grain size (surface roughness) of about 10 to 100 μm. It is characterized in that a polishing surface having grooves on the main surface is formed and a resin film is formed on the surface of the polishing surface.

[0006]

In the method of directly polishing a semiconductor wafer using a rigid surface plate, if the accuracy of the rigid surface plate having a flatness of 5 μm and a surface roughness of 0.01 μm is ensured, a semiconductor wafer to be chemically mechanically polished can be obtained. The flatness of is also asymptotic to the flatness of the surface plate. Compared with polishing using a soft polishing cloth, the flatness on the surface basis is improved, and if there is a stopper such as an oxide film, the polishing rate is drastically reduced on this surface and a flat surface is obtained. However, when forming a groove on a rigid surface plate, the edge of the groove becomes a sharp corner, and if the corner is missing, the semiconductor wafer will be scratched,
In addition, even if careful polishing is performed, there is a high probability that scratches will occur during insertion and removal of the semiconductor wafer.

In the semiconductor polishing platen of the present invention, by forming a resin film on the surface of the polishing surface, scratches on the semiconductor wafer can be prevented and handling can be facilitated. In addition, the surface grain size (roughness) of the surface plate is approximately 10 to 1
By using a porous platen of about 00 μm, flattening and grooving of the platen can be facilitated, and the resin formed on the surface of the platen permeates into and adheres to the platen, while polishing the resin film. It is possible to prevent chipping of the edge of the groove and peeling of the resin film even if it comes into contact with the hard oxide film stopper. In addition to this, when a rigid polishing machine with high flatness is used, the polishing heat cannot be sufficiently removed and the temperature of the polishing surface rises and the polishing conditions change, so when the grooves are formed, the polishing liquid can be spread over the entire wafer, It also functions to dissipate the frictional heat generated by polishing.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 (A) is a half sectional view showing a surface plate for polishing a semiconductor wafer according to an embodiment of the present invention, and FIG. 1 (B) is an enlarged sectional view showing an enlarged main part of the surface of the surface plate. FIG. 6C is an enlarged cross-sectional view of a main part showing the surface of the platen in an enlarged manner, showing an example in which a resin film is formed by another method. 2 is a plan view of a main part of a polishing surface plate of a semiconductor wafer according to the present invention, and FIG. 3 is a plan view of a main part of a polishing surface plate of a semiconductor wafer according to another embodiment of the present invention. FIG. 6 is a plan view of a principal part showing a polishing platen for polishing a semiconductor wafer according to still another embodiment of the present invention.

First, as shown in FIG. 1 (A), the polishing surface plate 1 of this embodiment is made of a flat material, for example, a ceramic material such as high-purity quartz, which has little mechanical and thermal deformation. ing. On one main surface (polishing surface) 1a of this polishing platen, grooves 2 that cross vertically and horizontally are formed as shown in plan views in FIGS. 2 to 4, and, for example, when mechano-chemical polishing is performed. Functioning so as to spread the polishing liquid over the entire semiconductor wafer W. Further, it also has a function of dissipating frictional heat generated between the semiconductor wafer W and the polishing platen. Therefore, the shape of the groove 2 is not limited to the lattice shape shown in FIG. 2, and can be various shapes other than the surface shape of the soccer ball shown in FIG. 3 or the triangular shape shown in FIG. This groove has, for example, a width of 1.5 mm,
The depth can be about 1 mm.

The polishing surface plate 1 of this embodiment is not limited to ceramics as long as it is a rigid body, but at least the grain size of the polishing surface 1a ( The roughness is preferably in the range of about 10 to 100 μm. When the polishing platen 1 is made of a porous ceramic material as described above, the particle size thereof corresponds to # 20 to # 350.

On the surface of the polishing surface 1a of this polishing platen,
As shown in FIG. 1B, a resin film 3 made of, for example, polyurethane resin or fluorine resin is formed. The type of resin forming the resin film 3 is not particularly limited,
The above-mentioned polyurethane-based resin is excellent in polishability for a silicon (semiconductor) wafer W, and also excellent in moldability of a film on the polishing platen 1 and removal performance by a chemical solution.

The resin film 3 has, for example, 20 μm to 10 μm.
It is desirable to set the film thickness to about 0 μm. The polishing platen 1 shown in FIG. 1 (B) is a specific example in which a thin resin film 3 is formed by a so-called wet process, which can be formed as follows. First, a polyurethane DMF forming the resin film 3 with a fence (prevention of overflow of polyurethane solution) attached to the periphery of the polishing surface plate 1.
A (dimethylformamide) solution is cast on the entire polishing surface 1a and left standing. Then, after sufficiently impregnating and leaving the surface of the polishing surface 1a until the liquid pool is completely removed, the polishing surface 1a is faced downward and immersed in water to solidify the polyurethane DMF solution. Finally, by drying the resin film 3 with a hot air of about 40 ° C., a thin resin film 3 of about 20 μm can be obtained.

On the other hand, the polishing platen 1 shown in FIG. 1 (C) is a specific example in which the thick resin film 3 is formed by a so-called dry process, and can be formed as follows. it can. First, with a fence attached to the periphery of the polishing surface plate 1, first, MEK (methyl ethyl ketone)
The polishing surface 1a is impregnated with the solvent. Next, the polyurethane MEK solution forming the resin film 3 is cast on the entire polishing surface 1a and left standing. Then, the above casting and standing are repeated until the liquid is accumulated on the surface of the polishing surface 1a, the fence is removed to remove the excess polyurethane solution accumulated in the groove, and then it is dried and cured at about 140 ° C. . As a result, the resin film 3 having a thick film of about 100 μm can be obtained.

It is preferable that the film thickness of the resin film 3 is properly used depending on the polishing process. For example, since it is important to secure a polishing rate in the initial step of mirror polishing, it is desirable to use a thick resin film (FIG. 1C) suitable for increasing the flatness of the entire semiconductor wafer. On the other hand, since it is extremely important to secure microroughness in the finishing step of mirror polishing, it is desirable to use a thin resin film (FIG. 1B) suitable for this.

Next, the operation will be described. In the method of directly polishing the semiconductor wafer W using the rigid surface plate 1 made of a ceramic material or the like, the accuracy of the surface roughness of the rigid surface plate 1 is set to 0.
If the thickness is secured to 01 μm, the semiconductor wafer W is flattened and polished by chemical mechanical polishing. Further, the flatness of the rigid body surface plate 1 can be easily achieved as compared with ensuring the flatness in the wafer polishing. Therefore, according to this rigid polishing, the flatness of the wafer is significantly improved as compared with the conventional polishing using a soft polishing cloth.

On the other hand, if the rigid body surface plate 1 has a coarse grain size, the semiconductor wafer W is not subjected to chemical mechanical polishing, and is mechanically polished, so that mirror surface strain-free polishing is not performed. Therefore, in the semiconductor polishing plate of the present invention, the semiconductor wafer W is formed by forming the resin film 3 on the surface of the polishing surface 1a.
It enables chemical mechanical polishing. In addition to this, since the resin film 3 can be easily removed with a predetermined chemical solution, the resin film 3 can be regenerated, and once the platen having excellent flatness is manufactured, the resin film 3 can be formed. Can be used any number of times just by repainting.

The surface roughness of the polishing surface 1a is approximately 10 to 10.
By using porous ceramics having a thickness of about 100 μm, the resin film 3 formed on the surface of the surface plate is impregnated on the surface of the surface plate and solidified. As a result, the adhesiveness of the resin film is improved and peeling of the resin film during polishing can be prevented. In addition to this, when the groove 2 is formed on the polishing surface, the polishing liquid is spread over the entire semiconductor wafer,
The polishing liquid can be retained, or the polishing product generated by polishing can be discharged. It also functions to dissipate frictional heat generated by polishing.

It should be noted that the embodiments described above are described for facilitating the understanding of the present invention, and not for limiting the present invention. Therefore, each element disclosed in the above-described embodiments is intended to include all design changes and equivalents within the technical scope of the present invention.

[0019]

As described above, according to the present invention, a polishing surface having grooves is formed on one main surface of a rigid surface plate having a surface grain size (roughness) of about 10 to 100 μm. Since a resin film is formed on the surface of the, it is expected that the surface standard flatness of the rigid surface plate will be improved and at the same time polishing by the hard stopper of the resin film will be stopped. In addition, it is easy to regenerate the resin film. In addition, by forming a groove on the polishing surface, the polishing liquid can be spread over the entire semiconductor wafer, and the friction heat generated by polishing can be dissipated.

[Brief description of drawings]

FIG. 1A is a half sectional view showing a polishing platen for polishing a semiconductor wafer of the present invention, FIG. 1B is an enlarged sectional view of an essential part showing the surface of the platen in an enlarged manner, and FIG. It is a principal part expanded sectional view which expands and shows the surface of a board | substrate, and is a figure which shows the Example which formed the resin film by another method.

FIG. 2 is a plan view of relevant parts showing a polishing platen for polishing a semiconductor wafer according to the present invention.

FIG. 3 is a main part plan view showing a polishing platen for polishing a semiconductor wafer according to another embodiment of the present invention.

FIG. 4 is a plan view of essential parts showing a polishing platen for polishing a semiconductor wafer according to still another embodiment of the present invention.

[Explanation of symbols]

 1 ... Polishing surface plate 1a ... Polishing surface 2 ... Groove 3 ... Resin film

Claims (1)

[Claims] 1. Surface grain size (roughness) is approximately 10 to 100 μm.
A polishing surface plate for a semiconductor wafer, characterized in that a polishing surface having grooves is formed on one main surface of a rigid surface plate, and a resin film is formed on the surface of the polishing surface.