JPH0574750A - Cleaning method for semiconductor substrate - Google Patents

Abstract

PURPOSE:To provide a method capable of removing a surface oxide film on a silicon substrate by a treatment of a low temperature of 800 deg.C or lower in regard to a method of cleaning the surface of the silicon substrate. CONSTITUTION:1) A silicon substrate 1 is heated while an energy line is emitted on the surface of the substrate 1 in a vacuum, 2) after the energy line is emitted on the surface of the substrate 1 in the vacuum the substrate 1 is heated and 3) the substrate is constituted so that the energy line is an electron beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a surface of a silicon (Si) substrate. High-temperature heat treatment of the substrate is performed as a pre-growth substrate treatment on the Si substrate, but the process temperature is required to be lowered with the miniaturization of device formation and higher density.

The present invention can be used as a method to meet this demand.

[0003]

2. Description of the Related Art Conventionally, a method of cleaning a pre-growth substrate such as Si molecular beam epitaxy (MBE) before growth involves heating a substrate to 800 ° C. or higher to remove a natural oxide film formed on the substrate by solution cleaning. The method of evaporation was taken.

FIG. 2 is a sectional view for explaining a conventional example. In the figure, 1 is a Si substrate and 2 is a natural oxide film. In the conventional method, the native oxide film 2 is removed by heating the substrate 1 to 800 ° C or higher in a vacuum.

For this reason, it is known that SiO 2 is released into a vacuum due to a reaction between a substrate and an oxide film.

[0006]

In the conventional example, in order to completely remove the surface oxide film, it is necessary to heat it at a high temperature of 800 ° C. or higher. However, there was a problem that the heat treatment during the process diffused in the vertical and horizontal directions to hinder the densification.

An object of the present invention is to provide a method capable of removing a surface oxide film on a substrate by a low temperature treatment of 800 ° C. or lower.

[0008]

Means for Solving the Problems To solve the above problems, 1) a method for cleaning a semiconductor substrate in which the surface of a silicon substrate is heated while irradiating the surface of the silicon substrate with energy rays in vacuum, or 2) a silicon substrate in vacuum This is achieved by a method for cleaning a semiconductor substrate, which comprises heating the substrate after irradiating the surface with an energy ray, or 3) the method for cleaning a semiconductor substrate according to 1) or 2), wherein the energy ray is an electron beam.

[0009]

According to the present invention, the temperature of the natural oxide film removing process can be reduced from the following two facts. (1) In the conventional method of heating and evaporating the native oxide film, Si and SiO ₂ react at the interface between the substrate and the native oxide film to produce SiO, and the produced SiO is released into the vacuum.

Therefore, evaporation at low temperature can be expected by increasing the portion where Si and SiO ₂ are in contact with each other. (2) On the other hand, it is known that by irradiating the oxide film with an electron beam, metallic Si is deposited on the surface of the oxide film.

From the facts of (1) and (2) above, it can be seen that the natural oxide film can be removed at a lower temperature than the conventional method by heating the oxide film while irradiating it with an electron beam in a vacuum.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view for explaining an embodiment of the present invention. In the figure, 1 is a Si substrate and 2 is a natural oxide film.

After forming a thin oxide film on the substrate by washing with a hydrochloric acid solution, irradiating it with an electron beam in a vacuum,
The substrate was heated at 500 ° C. At this time, the hydrochloric acid solution was washed under the following conditions.

Hydrochloric acid solution (HCl: H ₂ O ₂ : H ₂ 0 = 1: 1: 4)
Soak in and boil for 10 minutes. In this case, Si of the electron beam irradiation was deposited on the surface of the oxide film because SiO is generated reacts with SiO _2, it was possible to remove the natural oxide film at a temperature lower 300 ° C. than the conventional example.

The electron beam irradiation of the embodiment was performed under the following conditions using an electron gun of AES (Auger electron spectroscopy) system. Acceleration voltage: Radiation current from electron gun at irradiation of 500 eV: 100 μA Diameter of irradiated part: 400 μm The inspection that the oxide film was removed was conducted as follows.

In the epitaxial growth of Si, if the pretreatment is insufficient and the removal of the native oxide film on the surface of the Si substrate is incomplete, polycrystalline is deposited on the incomplete portion and the native oxide film is completely removed. The single crystal grows in the part where there is actually a trace of 0 or C left.

Utilizing this property, the above pretreatment was locally performed on the Si substrate by electron beam irradiation, and then epitaxial growth was performed. As a result of observing the surface with an interference microscope,
A single crystal grew in the irradiated area and a polycrystal was deposited in the unirradiated area.

From this result, it was confirmed that the irradiation part was cleaned. In addition to the conventional example of the present invention, a cleaning method by hydrogen reduction is also used, but since it is performed at a high temperature of 850 ° C or higher, it cannot be used as a low temperature treatment method.

In the example, the surface of the Si substrate was heated while being irradiated with an electron beam, but even if the substrate was irradiated with an electron beam at room temperature, the Si substrate was heated.
Since it is possible to deposit on the SiO ₂ , it was confirmed by the above inspection method that the same effect can be obtained by heating the substrate at a low temperature after irradiating the substrate with an electron beam.

Although the electron beam is used as the energy beam in the embodiment, any energy beam can be used as long as it can excite electrons in SiO ₂ , and therefore light having an energy of 10 eV or more, higher than the vacuum ultraviolet region. It may be light with energy.

[0021]

EFFECT OF THE INVENTION A method has been obtained in which the surface oxide film on the substrate can be removed by a low temperature treatment at 800 ° C. or lower. As a result, the substrate processing temperature was lowered and the diffusion of impurities introduced into the substrate was suppressed, which contributed to the miniaturization of the device.

[Brief description of drawings]

FIG. 1 is a sectional view illustrating an embodiment of the present invention.

FIG. 2 is a sectional view illustrating a conventional example.

[Explanation of symbols]

 1 Si substrate 2 Natural oxide film

Claims (3)

[Claims] 1. A method of cleaning a semiconductor substrate, which comprises heating the surface of a silicon substrate in vacuum while irradiating the surface with energy rays. 2. A method for cleaning a semiconductor substrate, which comprises heating the substrate after irradiating the surface of the silicon substrate with energy rays in vacuum. 3. The method for cleaning a semiconductor substrate according to claim 1, wherein the energy beam is an electron beam.