JPH10321566A - Method for polishing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the yield of a method for polishing semiconductor device by reducing the number of foreign matters in polishing the semiconductor device by polishing the semiconductor device with a second polishing cloth having lower hardness lower than a firs polishing cloth has after the device is polished with the first polishing cloth, and then, only with pure water by using the second polishing cloth in polishing the device. SOLUTION: In polishing a semiconductor device by using a chemical mechanical polishing device, the semiconductor device is polished with a second polishing cloth having lower hardness than a first polishing cloth has after the device is polishing with the first polishing cloth, and then, only with pure water by using the second polishing cloth. The suitable polishing amount X and polishing pressure P with the second polishing cloth are 100 Å<=X<=1,000 Å and 70 g/cm<2> <=P<=210 g/cm<2> , respectively, and the suitable polishing time T with the pure water is 10 sec<=T<=60 sec. The suitable hardness of the first and second polishing cloths are 60-95 (ASKER-C) and 20-70, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for polishing a semiconductor device using a CMP (Chemical Mechanical Polishing) apparatus, and more particularly to a method for polishing an interlayer insulating film of the semiconductor device.

[0002]

2. Description of the Related Art Conventionally, the CMP technique has been used for polishing a silicon wafer or the like, but recently, it has been used as a technique for flattening an interlayer insulating film in a semiconductor device manufacturing process. Was. It is no exaggeration to say that in a method of polishing a semiconductor device in which an interlayer insulating film is planarized, the final yield of the semiconductor device is determined by how to reduce foreign substances in the surface of a wafer to be polished.

[0003] The foreign matter means a residue of silica which is an abrasive grain at the time of polishing and a micro scratch which is a very superficial scratch generated at the time of polishing. In particular, micro-scratch greatly depends on the quality of the polishing agent and the hardness of the polishing cloth.Some polishing agents may cause tens of thousands of defects on the polishing surface, and the number of generated micro-scratch also depends on the polishing lot. There is a problem that varies greatly.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for polishing a semiconductor device, which reduces foreign matter during polishing and improves the yield.

[0005]

Means for Solving the Problems In order to solve the above problems, the present inventor has studied a polishing method, and as a result, has found a polishing method for reducing foreign matter during polishing. That is, the method for polishing a semiconductor device according to claim 1 is a method for polishing a semiconductor device using a CMP apparatus, the method comprising:
After polishing using a polishing cloth of above, after polishing using a second polishing cloth having a hardness equal to or lower than the first polishing cloth, only ultrapure water is used using the second polishing cloth. It is characterized by being polished by.

According to a second aspect of the present invention, in the method of polishing a semiconductor device according to the first aspect, the polishing amount X of the polishing using the second polishing cloth is 100.
{≦ X ≦ 1000}. Further, a polishing method of a semiconductor device according to claim 3 comprises:
2. The method for polishing a semiconductor device according to claim 1, wherein a polishing pressure P of polishing using said second polishing cloth is 70 g / cm.
² ≦ P ≦ 210 g / cm ² . According to a fourth aspect of the present invention, in the method for polishing a semiconductor device according to the first aspect, the polishing time T of polishing with the ultrapure water is 10 seconds ≦ T ≦ 60.
Seconds.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below.
Polishing using the first polishing cloth of the present invention means that the hardness is 60 to
Polishing using a polishing cloth in the range of 95 (ASKER-C). Specifically, the polishing is performed using a polishing cloth such as a foamed polyurethane pad (manufactured by Rodale) such as IC1400 and IC1000, and a fluorine resin pad (manufactured by Asahi Kasei). As the polishing agent at that time, fumed silica or colloidal silica which is dispersed in aqueous ammonia or aqueous potassium hydroxide solution is used.

The polishing using the second polishing cloth is a polishing using a polishing cloth having a hardness equal to or lower than the first polishing cloth and using the above-mentioned polishing agent. The hardness of the second polishing cloth at this time is preferably 20 to 70 (ASKER-C).
Specifically, polishing using a polishing cloth such as a polyurethane pad (made by Rodale) such as SUPREME or WHITEX or a non-woven fabric pad (made by Rodale) such as SUBA400 is used. The polishing conditions with the second polishing cloth are as follows: polishing pressure P is 70 g / cm ² ≦ P ≦ 210 g / cm ² , and polishing amount X
100 ° ≦ X ≦ 1000 °, polishing time T is 10 seconds ≦ T
≦ 60 seconds is preferred.

[0009] The hardness of the second polishing cloth is made lower than that of the first polishing cloth by polishing with a polishing cloth having a low hardness, thereby removing a very shallow portion of the surface with low damage and reducing micro scratches. That's why. The polishing using only ultrapure water is polishing using only ultrapure water using a second polishing cloth without using an abrasive. The polishing condition is such that the polishing pressure P is 70.
g / cm ² ≦ P ≦ 210 g / cm ² and polishing time T is 10
Seconds ≦ T ≦ 60 seconds are preferable, and almost no polishing is performed. That is, it is for effectively removing the silica adhered in the polishing by the first and second polishing cloths.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
FIG. 3 shows a polishing apparatus (WESTTECH 4) used in the present invention.
72). The feature of this polishing apparatus is that it has two surface plates. A first polishing cloth (with a hardness of 95
ASKER-C) and a second polishing pad (hardness: 50 ASKER-C) was attached to the surface plate B. Polishing agent is fumed silica (basic particle diameter 200 ~ 400)
Is dispersed in 13 wt% ammonia water (PH =
10.8) was used. That is, the polishing using the platen A is the polishing using the first polishing cloth, and the polishing cloth IC1000
(Rodel), polishing pressure 490 g / cm ² , platen rotation speed 28 rpm, polishing time 3 minutes, polishing agent 150 cc / m
In, polishing was performed under the conditions of a polishing amount of about 6000 °. Polishing using the platen B is polishing using the second polishing cloth, polishing cloth SUPREME (manufactured by Rodale), polishing pressure 210 g.
The polishing was performed under the following conditions: / cm ² , platen rotation speed 30 rpm, polishing time 1 minute, abrasive 200 cc / min, and polishing amount about 500 °.

In this embodiment, as a semiconductor device, a monitor wafer with an oxide film without a pattern (plasma TEO)
The S oxide film (with 1.2 μm) was polished, and foreign matter was checked (foreign matter inspection device using oblique incidence laser light).
In order to examine the effect of the polishing by the second polishing cloth, a foreign substance check was also performed as a comparative example when polishing was performed using only the first polishing cloth. Fig. 2 shows the comparison result of the foreign matter measurement.
Shown in From this comparison result, it can be seen that the number of foreign particles in the polishing using only the first polishing cloth is 3000 or more (0.15 μm or more), and the number of foreign substances is sharply reduced by performing polishing using the second polishing cloth. However, it was found that the number could be reduced to about 140 (0.15 microns or more). In other words, it can be seen that by performing polishing using the second polishing cloth, foreign matters in the polished surface mainly due to micro scratches can be significantly reduced.

Further, after the polishing of the second polishing cloth, polishing was carried out using only ultrapure water under the conditions of a polishing pressure of 210 g / cm ² , a platen rotation speed of 30 rpm, and a polishing time of 30 seconds. For the purpose of examining the polishing effect of ultrapure water only, for comparison, polishing was performed with a first polishing cloth and a second polishing cloth, and polishing with ultrapure water only was further performed using a second polishing cloth. Was checked for foreign substances. The result is shown in FIG.
Approximately 140 particles (0.15
It can be seen that the micron size is reduced to about 50 or less by ultrapure water polishing. That is, the silica adhered by polishing only with ultrapure water was effectively removed.

[0013]

According to the present invention, in the method of polishing a semiconductor device, the number of foreign substances at the time of polishing can be greatly reduced, and a decrease in the yield due to scratches such as micro scratches can be prevented. It has the effect of improvement.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an effect of polishing by a second polishing cloth of the present invention.

FIG. 2 is a diagram illustrating the effect of polishing using only ultrapure water according to the present invention.

FIG. 3 is a view showing a polishing apparatus used in the present invention.

Claims (4)

[Claims] 1. A semiconductor device polishing method for polishing a semiconductor device using a CMP (Chemical Mechanical Polishing) apparatus, wherein after the first polishing cloth is polished, the hardness is reduced to the first polishing value. A polishing method for a semiconductor device, comprising: polishing using a second polishing cloth that is not larger than a cloth, and then polishing using only the ultrapure water using the second polishing cloth. 2. The method for polishing a semiconductor device according to claim 1, wherein a polishing amount X of the polishing using said second polishing cloth is one.
A polishing method for a semiconductor device, wherein 00Å ≦ X ≦ 1000Å. 3. The polishing method for a semiconductor device according to claim 1, wherein a polishing pressure P for polishing using said second polishing cloth.
Satisfies 70 g / cm ² ≦ P ≦ 210 g / cm ² . 4. The method for polishing a semiconductor device according to claim 1, wherein a polishing time T for polishing with the ultrapure water is 10 seconds ≦ T ≦ 60 seconds.