JPH02267935A - Pretreatment of semiconductor substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] This invention relates to a method for pre-processing a semiconductor substrate in a semiconductor device manufacturing process.

The aim is to obtain an ideal semiconductor substrate with no irregularities on the surface.

A process of oxidizing the surface of the semiconductor substrate to form a sacrificial oxide film, a process of removing contaminants on the surface of the semiconductor substrate that adhered during polishing by peeling off this sacrificial oxide film, and a process of oxidizing the semiconductor substrate at high temperature in a vacuum. The method is configured to include a step of removing unevenness and flattening the surface of the semiconductor substrate by heat treatment.

[Industrial application field]

The present invention relates to a method for preprocessing a semiconductor substrate, and particularly to a method for preprocessing a semiconductor substrate in a semiconductor device manufacturing process.

In recent years, as semiconductor devices have become more integrated and faster,
2. Description of the Related Art In the manufacturing process of semiconductor devices, there is a need to minimize irregularities on the surface of a semiconductor substrate used.

[Conventional technology]

Taking the manufacture of a semiconductor device using a silicon substrate as an example, the conventional pretreatment of a semiconductor substrate is as follows.

By forming a sacrificial oxide film on a silicon mill and peeling it off by etching, contaminants adhering to the surface of the silicon substrate were removed.

[Problem to be solved by the invention]

In the conventional method, the interface between the sacrificial oxide film and the silicon substrate surface reflects the unevenness of the silicon substrate before RII conversion.
Since approximately 10 irregularities remain, there is a problem in that it is not possible to eliminate the irregularities on the silicon substrate surface simply by forming a sacrificial oxide film on the silicon substrate and peeling it off by etching.

For this reason, when a gate insulating film of a MOS FET is formed on this silicon substrate, the gate insulating film also has unevenness,9 and the film thickness varies locally.
There was also the problem.

The present invention solves the above problems and makes it possible to obtain an ideal semiconductor substrate with no unevenness on its two surfaces. An object of the present invention is to provide a method for preprocessing a semiconductor substrate.

[Means to solve the problem]

In order to achieve the above objects, the semiconductor substrate pretreatment method according to the present invention includes a step of oxidizing the surface of the semiconductor substrate to form a sacrificial oxide film, and a step of peeling off the sacrificial oxide film during polishing. The method is structured to include a step of removing adhered contaminants from the surface of the semiconductor substrate, and a step of flattening the surface of the semiconductor substrate by subjecting the semiconductor substrate to high-temperature heat treatment in a vacuum.

[For production]

In the semiconductor substrate pretreatment method according to the present invention, first, the surface of the semiconductor substrate is oxidized to form a sacrificial oxide film.

By peeling off this sacrificial oxide film, contaminants on the surface of the semiconductor substrate that adhered during polishing are removed.

Next, this semiconductor substrate is subjected to high temperature heat treatment in a vacuum. As a result, the atoms constituting the semiconductor substrate diffuse into the surface, eliminating unevenness on the surface of the semiconductor substrate.

The surface of the semiconductor substrate is planarized.

In order to more completely planarize the surface of the semiconductor substrate,
In order not to inhibit the diffusion of atoms that make up the semiconductor substrate when performing high-temperature heat treatment on the semiconductor substrate in vacuum,
This must be done in an ultra-high vacuum.

When a semiconductor substrate is subjected to high temperature heat treatment in an ultra-high vacuum.

The reason why the surface of the semiconductor substrate is planarized is considered to be secondary.

■By subjecting the semiconductor substrate to high-temperature heat treatment in an ultra-high vacuum, the atoms that make up the semiconductor substrate can easily diffuse on the surface.
These atoms migrate on the surface of the semiconductor substrate.

(2) The migrated atoms fill in the convex portions on the surface of the semiconductor substrate, and as a result, the surface of the semiconductor substrate becomes smooth and flat.

For high-temperature heat treatment of semiconductor substrates in ultra-high vacuum.

If contaminants are not present on the semiconductor substrate so as not to inhibit the diffusion of atoms constituting the semiconductor substrate on the surface of the semiconductor substrate, the surface of the semiconductor substrate can be more completely flattened.

〔Example〕

FIGS. 1 to 4 are nine diagrams illustrating each process of an embodiment of the present invention.

In FIGS. 1 to 4, 1 is a silicon substrate.

2 is a sacrificial oxide film, 3 is a dip bath, 4 is an etching liquid,
5 is a chamber, 6 is a heater, and 7 is a surface atom.

8 is a protective oxide film.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

(Step 1. See FIG. 1) A sacrificial oxide film 2 is formed by thermally oxidizing the surface of the silicon substrate l.

(Step 2. See Figure 2) The silicon substrate 1 with the sacrificial oxide film 2 formed on its surface is etched in a dip bath 3 filled with an etching solution 41, for example, an HF solution.
The sacrificial oxide film 2 formed on the surface of the silicon substrate 1 in step 1 (FIG. 1) is peeled off.

At this time, 9 contaminants from polishing the silicon substrate 1 are removed.

(Step 3. See Figure 3) Set the silicon substrate 1 in the chamber 5,
The interior is brought to an ultra-vacuum of 1X10-s or less, and the silicon substrate 1 is heated by the heater 6 to 100°C or higher, preferably 100°C to 1200°C.

In this way, the surface atoms 7 of the silicon substrate 1 are easily diffused into the surface, and the surface of the semiconductor substrate 1 is migrated. Then, the migrated surface atoms 7 fill the convex portions on the surface of the silicon substrate 1, and as a result, the surface of the silicon substrate 1 becomes flat without any unevenness.

Note that at this time, silicon atoms can be vapor-deposited or supplied in a gaseous state to flatten the surface at a lower temperature.

(Step 4. See FIG. 4) For example, by introducing ozone, the inside of the chamber 5 is made into an oxidizing atmosphere, and the surface of the silicon substrate 1 is coated with a thickness of 15 mm.
Forms a natural oxide film of ~20 people.

This is referred to as a protective oxide film 8.

Protective oxide film 8 maintains the flatness of silicon substrate 1.

It also plays a role in preventing pollution.

〔Effect of the invention〕

According to the semiconductor substrate pretreatment method according to the present invention, on the surface,
It is possible to obtain an ideal semiconductor substrate having irregularities of only about 1 atom-hide.

[Brief explanation of drawings]

Figures 1 to 4 are diagrams showing each process of an embodiment of the present invention. It is. In Figures 1 to 4 1: Silicon substrate 2: Sacrificial oxide film 3: Dip tank etching liquid chamber heater surface atoms protective oxide film Superintendent Nio 1 ? i1 country

Claims (1)

[Claims] A process of oxidizing the surface of the semiconductor substrate (1) to form a sacrificial oxide film (2), and peeling off the sacrificial oxide film (2) removes the semiconductor substrate (1) that adhered during polishing. ) and a step of removing contaminants from the surface of the semiconductor substrate (1) and flattening the surface of the semiconductor substrate (1) by subjecting the semiconductor substrate (1) to high-temperature heat treatment in a vacuum. Pretreatment method for semiconductor substrates.