JPH0386468A - Polishing method for semiconductor substrate - Google Patents

Abstract

PURPOSE:To enable a specular polishing that the surface roughness is less than 10Angstrom by specifying the conditions of the pH of the alkali liquid of an abrasive and contained abrasive grain size, the feeding quantity, polishing pressure, etc., of the abrasive. CONSTITUTION:An abrasive 8 containing the abrasive grain in 10 - 300Angstrom grain size in the alkali liquid of less than 11.0 pH is used and a finishing polishing is executed under the conditions of 0.01 - 0.2cc/cm<2> feed quantity of the abrasive 8 and 100 - 200g/cm<2> polishing pressure. Thus, the mechanical action as well as the etching action are slightly strengthened and the semiconductor board 5 surface can be polished in less than 10Angstrom surface roughness without causing a flaw and damage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for polishing a semiconductor substrate, and particularly to a method for final polishing the average surface roughness Ra of a semiconductor substrate to be less than IOA.

[Summary of the invention]

The present invention provides a semiconductor substrate polishing method in which a semiconductor substrate is brought into contact with a polishing plate and a polishing agent is supplied to polish the surface of the semiconductor substrate.
Using an abrasive containing abrasive grains of 0.00 to 300, the supply amount of the abrasive was set to 0. Ol~0.2cc/c++l・
By polishing at a polishing pressure of 100 to 200 g/cat, the average surface roughness Ra was 10 Å.
This enables the following final polishing.

[Conventional technology]

Conventional final polishing of semiconductor substrates is carried out using a polishing plate with a soft polyurethane foam cloth attached to the surface plate, and a polishing agent containing SiO□ particles, which are abrasive grains, in an alkaline solution. There is. The semiconductor substrate is adhered to the glass plate with adhesive or is held using a holder called a template. Then, an appropriate amount of polishing agent is supplied to a rotating polishing disk, and the semiconductor substrate is brought into contact with the polishing disk to perform polishing. This final polishing is characterized by polishing mainly using a so-called etching effect, which is performed by using a soft cloth and reducing the pressure applied to the polishing disk. The polishing conditions at this time are as follows.

Polishing pressure crab 100 g/crl Low pressure polishing agent supply amount 20.4~2. Occ/ci/water Alkaline solution of polishing agent: Strong alkaline with pH exceeding 0 Abrasive grain of polishing agent (Sto=) Particle size: Particle size of more than 300 people This polishing method may cause scratches on the surface of the semiconductor substrate. , it is possible to obtain a mirror surface without damage.

[Problem to be solved by the invention]

However, since the above-mentioned conventional finish polishing method is mainly based on etching, the average surface roughness Ra is 20.
Å or more. In the case of surface roughness of 20 Å or more, there is no particular problem with the current device pattern rules, but if the pattern becomes even finer in the future, surface roughness may become a problem. Currently, bonded wafers made by directly bonding two silicon wafers, or bonded S○■ (s
Research is progressing on so-called bonded wafers such as ilicon on 1 nsulator) substrates, but when used in such bonded wafers, surface roughness of 20 Å or more may cause air bubbles to occur between the wafers. Confirmed by experiment.

In view of the above-mentioned points, the present invention provides a method for polishing a semiconductor substrate, which enables final polishing so that the average surface roughness is 10 Å or less.

[Means to solve the problem]

The present invention provides a method for polishing a semiconductor substrate in which the surface of the semiconductor substrate (5) is polished by bringing the semiconductor substrate (5) into contact with a polishing plate (2) and supplying an abrasive agent (8). Using an abrasive (8) containing abrasive grains with a particle size of 100 to 300 in an alkaline solution, the supply amount of the abrasive (8) was set to 0.
01~0.2cc/crl・min, polishing pressure 1
Characterized by polishing as 00-200 g/cn.

[Effect]

According to the present invention described above, an abrasive containing abrasive grains with a particle size of 100 to 300 particles is used in an alkaline solution having a pH of 11.0 or less, and the supply amount of the abrasive is 0.01 to 0.2 cc/al.
By final polishing at a polishing pressure of 100 to 200 g/Cd for 1 minute, the mechanical action is slightly strengthened in addition to the etching action, and the semiconductor substrate can be polished to a surface roughness of IOÅ or less without causing scratches or damage. The surface can be polished.

Example E] Hereinafter, an example of a method for polishing a semiconductor substrate according to the present invention will be explained using the drawings.

Figure 1 shows the polishing device (1), and (2) the surface plate (
A polishing plate (3) is made of a soft polyurethane foam cloth (4) attached to the polishing plate, (5) is a semiconductor substrate to be polished, such as a silicon wafer, and the wafer (5) is attached to a holder (6) via an adhesive. ) is fixed. During polishing, wafer (5)
This is carried out by contacting the surface of the foam cloth (4) of the rotating polishing disk (2) and supplying the abrasive (8) from the abrasive supply child (7).

The final polishing method according to the present invention is performed under polishing conditions with a slightly stronger mechanical action than the conventional polishing mainly using an etching action. In this example, polishing conditions are set as follows.

As the abrasive (8), an abrasive (suspension) containing SiQ2 particles (abrasive grains) with a particle size of 100 to 300 is used in an alkaline solution of 9H11.0 or less.
The content of O□ particles is about 5 wt%. As the alkaline solution, for example, an aqueous solution of sodium hydroxide or ammonia can be used.

The supply amount of abrasive (8) is 0.01~0.2cc/c
Let it be lfI・min. The polishing pressure, that is, the pressing force of the wafer (5) to the polishing plate (2) is 100 to 200 g/cm. Further, the peripheral speed of the polishing plate (2) is 34 m/min.

If the wafer (5) is polished under such polishing conditions, scratches,
A polished surface with an average surface roughness of 10 Å or less can be obtained without causing damage.

The results are shown in the graphs of FIGS. 2 to 4.

Curve (I) in FIG. 2 shows SiQ contained in the abrasive,
It is a graph showing the relationship between particle size and surface roughness of particles. Sin
If the grain size is 300A or less, the surface roughness will be IOA or less.

Figure 3 shows the relationship between polishing pressure, surface roughness, and damage, where the curve (ff) is a damage graph and the curve (II
[> indicates a graph of surface roughness. Polishing pressure is 100g
If /cI11 or more, the surface roughness will be 10 Å or less, but if the polishing pressure exceeds 200 g/cut, damage will occur. Therefore, increase the polishing pressure to 100-200 g.
/ crj, no damage can be caused and a surface roughness of 10 Å or less can be obtained.

FIG. 4 shows the relationship between the supply amount of abrasive and damage and surface roughness, where the curve (rV) shows the damage graph and the curve (V) shows the surface roughness graph. Abrasive supply amount is 0.0
If it is less than 1 CC/Cl11·min, damage may occur, and if it exceeds 0.2 CC/cM·min, the surface roughness becomes rougher than 10. Therefore, the abrasive supply amount is set to 0, Ol to 0.
If it is in the range of 2CG/crl·min, no damage will occur and a surface roughness of 10 Å or less can be obtained.

Note that the surface roughness was measured using a three-dimensional surface roughness meter. In addition, the damage can be measured by oxidizing the wafer surface after polishing and using lighttetch (l!lighttetch).
I checked the pits using defect detection etch.

By using this polishing method in this way, the wafer (5
) can be finished to a mirror finish without scratches or damage, and with a surface roughness of 10 Å or less.
Therefore, it is possible to produce semiconductor devices with ultra-fine patterns or highly reliable bonded wafers.

〔Effect of the invention〕

According to the method of polishing a semiconductor substrate according to the present invention, by specifying conditions such as the pH of the alkaline solution of the polishing agent, the particle size of the abrasive grains contained, the supply amount of the polishing agent, and the polishing pressure,
Mirror polishing with a surface roughness of 10 Å or less can be performed.

Therefore, by using this polishing method, it is possible to create semiconductor devices with ultra-fine patterns, and even in bonded wafers, it is possible to obtain highly reliable bonding with no air bubbles between the wafers. be.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an example of a polishing apparatus according to the present invention, and FIG.
The figure is a graph showing the relationship between the grain size of abrasive grains (SiO It is a graph showing the relationship between roughness and damage. (1) is a polishing device, (2) is a polishing plate, (5) is a semiconductor substrate, and (8) is a polishing agent. Agent Hidemori Matsukuma 1 Tomorrow Apparatus Figure 2 Figure 3 Procedural Amendment 1, Indication of Case) V Command 1 Year Patent Application No. 224063 2 Q Ming (7) Name S Semiconductor Base 1, Method 3,
Relationship with the case of the person making the 1ili correction Patent applicant address: 6-7-35, Kitashinyo, Tokyo Parts Store Name (2
18) Sony Corporation Representative Director Norio Ohga 4, Agent

Claims (1)

[Scope of Claims] A method for polishing a semiconductor substrate, in which a semiconductor substrate is brought into contact with a polishing plate, and a polishing agent is supplied to polish the surface of the semiconductor substrate, wherein a particle size of 100 to 300 Å is added to an alkaline solution having a pH of 11.0 or less.
Using an abrasive containing abrasive grains, the supply amount of the abrasive is 0.01 to 0.2 cc/cm^2.
A method for polishing a semiconductor substrate, comprising polishing at a polishing pressure of 100 to 200 g/cm^2.