JPH0758098A - Formation of silicon oxide film - Google Patents

Abstract

PURPOSE:To prevent mixing of impurities and to form a silicon oxide film only on the required part of a silicon substrate selectively at a low temperature. CONSTITUTION:A silicon substrate 1 is provided in a vacuum container 5. Silicon depositing gas 9 and oxygen 10 are introduced into the container. The surface of the silicon substrate 1 is irradiated with electron beams 4 to form a silicon oxide film on the silicon substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxide film such as a gate oxide film of a field effect transistor or a film for protecting a device from the external environment on a silicon substrate in a semiconductor integrated circuit in a high vacuum at low temperature and selectively. The present invention relates to a method for forming a silicon oxide film that can be formed on a substrate.

[0002]

2. Description of the Related Art Conventionally, thermal oxidation is known as a method for forming an oxide film on a silicon substrate. Examples of this thermal oxidation method include (1) steam oxidation, (2) dry oxidation, and (3) wet oxidation. In each case, an oxide film is formed on the entire surface of the silicon substrate by the reaction between the silicon substrate surface and oxygen molecules. Is the way. FIG. 5 shows a conventional method for forming a silicon oxide film by thermal oxidation. In a reaction container (not shown), the silicon substrate 1 is heated 3 from below by a heating device to form the silicon oxide film 2 on the entire surface of the substrate. The state of making is shown.

[0003]

According to the conventional thermal oxidation method described above, the oxide film is formed by raising the substrate temperature to 1000 ° C. or higher in order to increase the film formation rate. In order to avoid a change in film quality of other layers, production at such a temperature is not preferred and lowering of the temperature is required. Further, since the degree of vacuum in the reaction container is low (several Torr to several tens Torr), impurities may be mixed in the film. Furthermore, since various conventional oxide film forming methods form a film on the entire surface of the substrate, partial and selective film formation cannot be performed, and a separate etching process such as lithography is required.

The present invention is intended to provide a method for forming a silicon oxide film which can solve the above problems.

[0005]

The present invention focuses on the fact that gas and solid are partially and efficiently excited by an electron beam, and a silicon substrate is installed in a vacuum container to deposit silicon in the vacuum container. A silicon oxide film is formed on the silicon substrate by introducing a working gas and an oxygen-containing gas and irradiating the surface of the silicon substrate with an electron beam.

[0006]

[Function] A silicon substrate is installed in a vacuum container, and a silicon deposition gas such as SiH ₄ , Si ₂ H ₆ and Si ₂ Cl ₂ H ₄ and an oxygen-containing gas such as O ₂ are introduced into the vacuum container to form a silicon substrate. By irradiating the surface with an electron beam, a silicon oxide film is formed only on the surface of the silicon substrate and the portion on the silicon substrate where the source gas is excited and irradiated with the electron beam.

[0007]

EXAMPLE FIG. 1 schematically shows a film forming apparatus used in an example of the present invention. An electron gun 6 having a differential pumping 7 is provided in the vacuum container 5. The silicon substrate 1 is installed in the vacuum container 5, and an infrared light heating device 11 is provided below the vacuum container 5 to heat the silicon substrate 1. A silicon deposition gas (disilane S) is formed on the upper portion of the vacuum container 5 toward the silicon substrate 1.
A gas dozer 8 capable of introducing i ₂ H ₆ ) 9 is provided, and a pipe 12 for introducing oxygen 10 is opened at a side portion of the vacuum container 5.

In this embodiment, the silicon substrate 1 is placed in the infrared heating device 1 in a vacuum container 5 which is evacuated to 10 ^-10 Torr.
1 to heat from room temperature to 400 ° C. Disilane (Si ₂ H ₆ ) gas 9 and oxygen (O ₂ ) gas 10 are used as raw material gases, the disilane gas 9 is introduced into the vacuum container 5 from the gas dozer 8, and the oxygen gas 10 is introduced into the vacuum container 5 from the pipe 12. Introduce. An electron beam 4 with an accelerating voltage of 5 to 17 keV is emitted from the electron gun 6 that has been differentially pumped 7 onto the surface of the silicon substrate by 2-3
Irradiation is carried out at an incident angle of °, and as shown in FIG. 2, the heated silicon oxide film 2 is formed on the portion irradiated with the electron beam 4.

FIG. 3 shows the mixing ratio of the source gases (Si ₂ H ₆ /
O ₂ ) is 0.4, and the total pressure in the vacuum container after gas introduction is 4.
The cross-sectional shape of the silicon oxide film when the substrate temperature is 100 ° C. and the electron beam accelerating voltage is changed to ^5, 10 and 17 keV is shown as 9 × 10 ⁻⁵ Torr. Also, in FIG. 4, the acceleration voltage is 17 ke
The cross-sectional shape of the silicon oxide film when V is set and the silicon substrate temperature is changed to 28, 80, and 100 ° C. is shown. As a result, the silicon oxide film grew to a maximum of about 0.65 μm. Further, as shown in FIG. 3, it was confirmed that the shape of the formed silicon oxide film was in good agreement with the Gaussian distribution which is generally approximated to the electron density distribution of the electron beam.

The mixing ratio of the raw material gases is 0.1 to 0.1.
2.0, the acceleration voltage is several eV or more, and the silicon oxide film can be produced. The temperature of the silicon substrate is room temperature to 200.
It is better to set it around ℃.

As described above, in the present embodiment, since the silicon oxide film can be formed in the high-vacuum vacuum container 5, it is possible to suppress the mixing of impurities and to lower the temperature of the manufacturing process. Moreover, the silicon oxide film is selectively formed only on the portion irradiated with the electron beam 4, and the etching step in the manufacturing process of the integrated circuit or the like can be omitted.

[0012]

The present invention can bring the following effects. (1) Since the silicon oxide film can be formed in a high vacuum, it is possible to suppress the mixing of impurities. (2) The temperature of the manufacturing process can be lowered. (3) The silicon oxide film can be selectively formed only on the electron beam irradiation portion, and the etching step in the manufacturing process of the integrated circuit or the like can be omitted.

[Brief description of drawings]

FIG. 1 is a schematic view of a film forming apparatus used in an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a production state of a silicon oxide film according to the same example.

FIG. 3 is a graph showing the shape of the film thickness of the silicon oxide film produced in the same example when the acceleration voltage was changed.

FIG. 4 is a graph showing the shape of a silicon oxide film manufactured by the same example when the temperature of the silicon substrate is changed.

FIG. 5 is an explanatory diagram of a conventional method for forming a silicon oxide film by thermal oxidation.

[Explanation of symbols]

 1 Silicon Substrate 4 Electron Beam 5 Vacuum Container 6 Electron Gun 8 Gas Dozer 9 Gas for Silicon Deposition (Disilane) 10 Oxygen 11 Infrared Light Heating Device

Claims (1)

[Claims] 1. A silicon substrate is installed in a vacuum container, a silicon deposition gas and an oxygen-containing gas are introduced into the vacuum container, and the surface of the silicon substrate is irradiated with an electron beam to form a silicon oxide film on the silicon substrate. A method for forming a silicon oxide film, which comprises manufacturing the same.