JPS60144940A - Method of producing silicon oxide - Google Patents

Abstract

PURPOSE:To obtain SiO2 added with F on the surface to be formed, by providing a mixture of silicon fluoride gas and silicon oxide gas with electric energy together with thermal energy through thermal energy or light (with a wavelength of 300nm or less). CONSTITUTION:An Si substrate 2 is put in a quartz tube 1. Ar, NO2 or N2O and SiF2 are introduced into the quartz tube 1 from valves 9, 10 and 7, respectively, such that SiF2/O2 is about 0.3. The substrate 2 is heated to 1,050 deg.C at 2Torr and an SiO2 film is formed on the substrate 2 by the vacuum CVD method. Alternatively, the substrate 2 is heated to 300 deg.C while electric energy (13.56 MHz) is supplied at 2Torr so as to convert the reactive gas into plasma, whereby an SiO2 film is deposited on the substrate from SiF4 and N2O. Alternatively, the optical CVD method may be used with radiation of light having a wavelength of 300nm or less. SiO2 produced by any one of these methods contains no residual H2 or OH, and an excellent protective film can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to silicon oxide doped with fluorine by a vapor phase reaction method using heat, light or plasma chemical reaction (hereinafter referred to as CVD method), such as quartz as a raw material for optical fibers, and semiconductors. The present invention relates to a method of making a passivation film for electronics.

The present invention relates to a method for producing silicon oxide to which fluorine is added and has a 5t-F bond, and in which hydrogen remains in an amount less than 1/1000 of fluorine.

The present invention relates to a method of reacting a fluoride of silicon with oxygen or a nitride of oxygen to form a silicon oxide film at a temperature of 1200°C or less, preferably 100 to 400°C, for example 300°C.

Conventionally, in order to produce a silicon oxide film, silane (SiH,
, ) and - dinitrogen oxide (NtO) are reacted, 200
The coating was produced at a substrate temperature of ~400°C. However, such a silicon oxide film generates residual charges due to residual silicon dangling bonds and silicon clusters remaining within the film.

And because of this charge, the final voltage of MOS, IC, etc.
It could not be used as a coating.

Furthermore, in this method, hydrogen or 011 remains in the produced silicon oxide. For this reason, a method for producing a silicon oxide film that does not use hydrogen at all has been sought in practice.

The present invention aims to produce silicon oxide for this purpose, that is, by using a fluoride of silicon, such as SiF.

The main reaction formula is 2SiFL+ Q & → Sin, + SiF.

It is.

For this reason, SiF or Si% is used as a fluorinated silicide gas.
For example, it is characterized by the use of Si'PL.

The present invention will be described below according to the drawings.

FIG. 1 shows an outline of the CVD apparatus used in the present invention.

In the drawing, the reaction vessel (vacuum vessel) (1) is made of quartz. The substrate (2) is placed in a quartz tube (1) surrounded by a heater (3) and heated to a temperature of room temperature to 1200°C, preferably 2
Heating is carried out at 00 to 400°C, for example 300°C.

The doping system consists of a flow meter (6) and a valve (7), and an inert gas such as helium or argon is supplied from (9).

Oxygen or nitrogen oxygenate gas is supplied from (10), and silicon fluoride is supplied from (11). The silicon fluoride is supplied with Si- from (8), and the metal silicon (purity of 9N or more x 17) in the quartz tube is heated to 100% by heater (15).
It was heated to ~1250° C. and 5iFL was prepared according to the following formula.

S i F4 + S i → 2SiF2 These reactive gases are introduced into the reaction vessel through (11), and then the pressure regulating valve (12-input stop valve (1)) is introduced through the exhaust port (7).
3) and was evacuated using a vacuum pump (14). An electrical energy supply device (5) for plasma chemical reaction is provided.

A resistance heater (3) is provided surrounding this high frequency energy supply coil (4).

Examples are shown below.

Example 1 In this example, silicon oxide was produced in a quartz tube by a reaction between SiF and oxygen.

In FIG. 1, a silicon substrate is disposed on the inner wall of a quartz tube disposed within a heater (13). More valves (7)
Open S i F, and OL S LFL/Oa
It was introduced as Company O.3. The pressure inside the reaction vessel is 0.1~
The range is 10 torr, for example, 2 torr. The temperature was 1050°C. Then, silicon oxide could be obtained in the reaction tube at a growth rate of 4.3 persons/second using a low pressure CVD method by supplying only thermal energy. This film growth rate is 1
If torr+o, 1 torr, 3.2 people/second, 0
．． The number of people per second decreased to 7 people/second.

When this product was examined by IR (infrared absorption spectrum) with a thickness of 5 mm, it was found that it had a thickness of 2000 to 3500 cm.
No absorption was observed at all. Due to this,
Even though there is a 5i-F bond in this silicon oxide, this absorption is 980 cm', which is in the near-infrared region (for optical fibers).
It was found that there were no extra impurities that absorbed any light in the wavelength region longer than 1300 cm'.

Example 2 In this example, a silicon oxide film was formed on a single crystal silicon substrate by a reaction between Sil and dinitrogen monoxide.

The same apparatus as in Example 1 was used. The substrate temperature is 300℃,
Pressure 2 torr, electrical energy (13,56Ml1z
By supplying No. 3, the reactive gas was turned into plasma (plasma density: 13 mW/cal).

A counter electrode was formed on this silicon oxide to form a diode structure, and the C-■ characteristics were measured. As a result, the interface state density was less than 3 × 10"cm"2, and when a DC electric field was applied to the silicon oxide film, hysteresis characteristics were observed for the first time at I It was found that there were few charge trapping centers in silicon oxide due to the presence of silicon clusters.The reaction method with gas was found to be extremely effective as a passivation film for semiconductors. It has been found that this Example 2 is effective as a gate insulator for MIS and FET, and that it is better to use each separately depending on the purpose.

In the present invention, it goes without saying that a thermal CVD method, a plasma CVD method, or a photo-CVD method using irradiation with light energy of 300 nm or less may be used.

[Brief explanation of drawings]

FIG. 1 shows an outline of a CVD apparatus for carrying out the method of the present invention. patent applicant

Claims (1)

[Claims] 1. By applying thermal energy or thermal energy and light or electrical energy with a wavelength of 300 nm or less to a mixed reactive gas of a silicon fluoride gas and an oxygenate gas, fluorine is formed on the surface to be formed. 1. A method for producing silicon oxide, comprising producing silicon oxide to which is added. 2. In claim 1, SiF Yoto0JI
A method for producing silicon oxide, characterized in that silicon oxide is produced on a surface to be formed by adding thermal energy or thermal energy and light or electrical energy with a wavelength of 300 nm or less to a gas mixture of NO□ or N, 0. .