JPH11279534A - Surface polishing liquid composition for semiconductor product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface polishing liquid composition for semiconductor products, having excellent polishing efficiency and exhibiting stable good polishing performances. SOLUTION: The surface polishing liquid composition comprises an alkaline silica sol containing a water-soluble organic amine such as aminoethylethanolamine, monoethanolamine, monomethylamine, hydrazine, ethylenediamine, diethylenetriamine, or tetramethylammonium hydroxide, particularly desirably, such an alkaline silica sol having a low metal content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing composition for a semiconductor product surface suitable for polishing and flattening the surface of a semiconductor product such as an LSI. The process of flattening, for example, an insulating oxide film on the surface of a semiconductor product such as an LSI is performed by using
A method of selecting a source having excellent leveling property in the D (chemical vapor deposition) method to obtain an insulating oxide film having high flatness;
After once obtaining an insulating oxide film without considering the flatness much,
There is a method of planarizing this insulating oxide film by chemical mechanical polishing, and the present invention is a polishing liquid composition used for the latter method.

[0002]

2. Description of the Related Art Conventional chemical mechanical polishing methods include:
Polishing is performed by dropping an abrasive slurry (polishing liquid) onto a polishing cloth surface attached to a polishing board and pressing it against a silicon wafer surface with an insulating oxide film while applying a constant load. At this time, in polishing the silicon-based insulating oxide film,
Usually, a polishing process is performed using a slurry containing silica-based abrasive grains as a component. As a specific process, a silicon wafer with an insulating oxide film is attached to the polishing block,
This polishing block is pressed with an appropriate pressure against a polishing cloth (polisher) adhered to a rotary polishing machine to mainly adjust the pH to 9
By dropping a polishing liquid of ultrafine silica dispersed in about 12 to about water, the polishing liquid and the insulating oxide film cause a mechanochemical action, and the polishing proceeds.

[0003]

However, since the conventional polishing liquid is mainly an ultrafine silica-based slurry liquid, it tends to cause secondary aggregation in the liquid and is not satisfactory in terms of dispersion stability. There is a need for a system such as adding a stirring step to maintain dispersibility. On the other hand, as a method for improving the dispersion stability, JP-A-63-285112,
Japanese Patent Application Laid-Open Nos. 2-278822 and 4-2606 disclose abrasives for semiconductors containing a silica sol component. However, the silica sol-based abrasive mentioned above deteriorates the working environment due to the volatilization of ammonia and the polishing liquid changes with time, so that it is difficult to obtain stable and good polishing.

Accordingly, it is an object of the present invention to provide a polishing composition for a semiconductor product surface having excellent polishing efficiency and stably giving good polishing properties.

[0005]

That is, the present invention relates to a polishing composition for a semiconductor product surface comprising an alkaline silica sol containing an organic water-soluble amine, and in particular, the alkaline silica sol has a low metal content. It is a polishing composition for semiconductor product surfaces.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The alkaline silica sol used in the present invention preferably contains silica having an average particle diameter of 15 to 100 nm as silica in terms of polishing efficiency and polishing accuracy. This is an alkaline silica sol prepared by adjusting the pH of an alkaline silica sol solution prepared as described above or a commercially available alkaline silica sol with an organic water-soluble amine as described below.

It is preferable that the alkaline silica sol solution has a low metal content to a level which is conventionally known as one which can be used for surface polishing of semiconductor products. Therefore, the organic water-soluble amine which is an alkaline agent for adjusting pH is also low. Preferably, it is a metal content.

[0008] The term "low metal content" as used herein refers to those having a low content of metal ions (semiconductor grade in commercial transactions and the like). Since a large amount of metal ions has a chemical adverse effect on a material constituting a semiconductor product, it is preferable to minimize the content of metal ions, but it is particularly preferable to make Na ions less than 15 ppm.

In order to remove the metal component of the general-purpose silica sol (also referred to as colloidal silica), it may be treated with a cation exchange resin. Examples of the cation exchange resin include Amberlite IR-116 and IR-120B (manufactured by Rohm and Haas), Duolite C-20, and C-26.
Polystyrenesulfonic acid type such as (manufactured by Sumitomo Chemical Co., Ltd.) can be used as a representative one. Also, IRA-400, IR
The degree of purification can be further increased by the combined use with an anion exchange resin such as A-410 (manufactured by Rohm and Haas).

When a water-insoluble or poorly water-soluble metal compound or the like (including a simple substance) is contained, it has little chemical adverse effect as in the case of the above-mentioned metal ions. If the particle size is larger than the silica particles in the silica sol, physical adverse effects may occur. Therefore, it is better to filter those having a particle size of about 150% or more of the silica particle size.

Incidentally, a surfactant having a low metal content can be added to improve the cleaning property after polishing.

The alkaline silica sol solution used in the present invention may have a silica solid content of 10 to 55% by weight, but is 20 to 50% by weight in order to exhibit good polishing efficiency and stable polishing. Is preferred.

The organic water-soluble amine used in the present invention is a linear, branched or cyclic amine having 1 to 6 carbon atoms, for example, N, N-diethylethanolamine, aminoethylethanolamine, Ethanolamine, monomethylamine, monoethylamine, hydrazine, ethylenediamine, diethylenetriamine, benzylamine, 1-aminoethylpiperazine and the like can be exemplified, and from the viewpoint of solution stability, alkanol is more preferable as the organic water-soluble amine. Amines and alkylamines are preferred, and particularly preferred are aminoethylethanolamine, monoethanolamine, monomethylamine, hydrazine, ethylenediamine, diethylenetriamine, and tetramethylammonium hydroxide.

The alkaline silica sol preferably has a pH of 9 to 12, but from the viewpoint of stability and polishing efficiency, the pH is preferably 9 to 12.
More preferably, it is adjusted to 9.6 to 11.5. Organic water-soluble amines, alkaline silica sol as described above
It may be appropriately added so as to have a pH range, but for example, 0.1 to 5% by weight based on the whole composition.

[0015]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited to these examples. Example 1 An alkaline silica sol solution having an average particle diameter of 25 nm and a silica solid content of 30% by weight [Adeleite EX-30N: manufactured by Asahi Denka Kogyo KK, pH 10.
5 (adjusted to 5) as a component (the metal component in the solution is Fe
0.4 ppm, Al 25 ppm, Ca 0.2 ppm,
The silicon wafer with the insulating oxide film was polished under the following conditions using 0.3 ppm of Mg and 10 ppm of Na).

Polishing machine: LPH-15 manufactured by Lappmaster
Improved polishing machine diameter: 15 inches Polishing machine rotation speed: 90 rpm Polishing sample: 6-inch wafer with thermal oxide film (thickness: 1 μm) × 10 Pressure: 180 g / cm ² Polishing fluid temperature: 30 ° C. Abrasive supply: 100 ml / Min Polishing time: 3 minutes

The polished removal amount of the oxidized film on the wafer surface after polishing is measured at 24 points on the wafer surface using a polarization analyzer (manufactured by Mizojiri Optical Industrial Co., Ltd.), and the average value of 10 polished wafers is used as the polishing efficiency. Was observed with a microscope. The result is that the polishing efficiency is 2
At 700 ° / min, the surface condition of the wafer was free of scratches (scratch) and evaluated by centrifugation (3500 rpm × 30 minutes). As a result, no precipitate was generated and good stability was exhibited.

Example 2 A polishing liquid was prepared in the same manner as in Example 1 except that aminoethylethanolamine was used as an alkali for pH adjustment, and a silicon wafer with an insulating oxide film was polished.
As a result, the polishing efficiency was 2650 ° / min, the surface condition was free of scratches, the stability of the polishing solution was good, and no precipitate was found.

Comparative Example 1 A slurry of ultrafine silica (manufactured by Nippon Aerosil Co., Ltd.) having an average particle diameter of 25 nm and a silica solid content of 12% was adjusted to pH 10.5 with diethylenetriamine to prepare a polishing solution, and the same conditions as in Example 1 were used. Was used to polish a silicon wafer with an insulating oxide film. As a result, although there was no scratch on the surface state, the stability of the polishing liquid was measured by a centrifugal separation method, and as a result, generation of a precipitate was observed. The polishing efficiency was as low as 2300 ° / min because the polishing liquid partially caused secondary aggregation.

Comparative Example 2 Alkaline silica sol solution having an average particle diameter of 12 nm and a silica solid content of 30% by weight [Adelite AT-30N: manufactured by Asahi Denka Kogyo KK, adjusted to pH 10.5 with ammonia]
Using a polishing liquid (polishing stock solution) having the following composition, a silicon wafer with an insulating oxide film was polished under the same conditions as in Example 1. As a result, the polishing efficiency was as low as 2250 ° / min because the liquid composition changed due to the volatilization of ammonia.
There were no scratches on the surface, and the polishing liquid was measured by centrifugation to find no precipitate.

[0021]

According to the present invention, there is provided a polishing composition for a semiconductor product surface having excellent polishing efficiency and stably giving good polishing properties.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/304 622 H01L 21/304 622A 21/308 21/308 G

Claims (3)

[Claims] 1. A polishing composition for a semiconductor product surface comprising an alkaline silica sol containing an organic water-soluble amine. 2. The polishing composition according to claim 1, wherein the alkaline silica sol has a low metal content. 3. The organic water-soluble amine is at least one selected from the group consisting of aminoethylethanolamine, monoethanolamine, monomethylamine, hydrazine, ethylenediamine, diethylenetriamine and tetramethylammonium hydroxide. 2
3. The polishing composition for semiconductor product surfaces according to item 1.