JP2004273869A - METHOD FOR FORMING SILICON OXIDE FILM BY LIGHT IRRADIATION OF COMPOUND CONTAINING Si-O-Si BOND - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a silicon oxide film of fine quality free from carbon mixture on an optional base in order to manufacture an optical integrated circuit or the like based on an SiO<SB>2</SB>optical waveguide. <P>SOLUTION: Organic polysiloxane 10 is arranged in a vacuum container 1 as a compound containing the Si-O-Si bond, a silicon substrate 20 is arranged as a base, the organic polysiloxane 10 is irradiated with light from a light source 30 including light of 200nm wavelength or less, and the silicon substrate 20 is also irradiated with light. Consequently, gas (a gas-like silicon compound and oxygen) is radiated from an exposure part of the organic polysiloxane 10, and a silicon oxide film is chemically deposited on the silicon substrate 20 which is irradiated with light by using the gas. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for forming a silicon oxide film by irradiating a compound containing a Si—O—Si bond with light for the purpose of photonics, and particularly relates to a method for forming a compound containing a Si—O—Si bond (eg, polysiloxane). The present invention relates to a method for forming a silicon oxide film by chemical vapor deposition using a gas emitted from a light source including a light having a wavelength of 200 nm or less and utilizing a gas released from the compound. It is also possible to form a film on an easy substrate (polymer material, biomaterial, low melting point material, material that easily diffuses heat, etc.), and its use is useful not only in electricity and electronics but also in all fields.
[0002]
[Prior art]
There are many methods for forming a silicon oxide film, but a silicon substrate is mainly placed in a high-temperature electric furnace and thermally oxidized in an atmosphere such as oxygen gas or water vapor, or introduced into a decompression vessel. The reaction gas is thermally decomposed on a heated substrate to form a film.
[0003]
[Problems to be solved by the invention]
In any of the conventional methods, since a high temperature is required for forming a silicon oxide film, the use of the substrate is limited. That is, it has been difficult to form a film on a substrate that is easily affected by heat (such as a polymer material, a biomaterial, a low melting point material, or a material that is easily thermally diffused). When the film is formed at a low temperature, defects and impurities are mixed in the film, and it is difficult to obtain a high-quality film. Further, in order to form a film in an arbitrary pattern, a chemical or physical etching step is required.
[0004]
In view of the above, the present invention provides a method for forming a silicon oxide film by irradiating a compound containing a Si-O-Si bond with which a high-quality silicon oxide film free of carbon contamination can be formed at room temperature (normal temperature). The purpose is to do.
[0005]
Other objects and novel features of the present invention will be clarified in embodiments described later.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a method for forming a silicon oxide film by irradiating light to a compound containing a Si-O-Si bond according to the invention of claim 1 of the present application comprises the steps of: The method is characterized in that a compound containing a bond is exposed by a light source containing light having a wavelength of 200 nm or less, and a silicon oxide film is chemically deposited using a gas released from the compound.
[0007]
The method of forming a silicon oxide film according to the invention of claim 2 of the present application is characterized in that, in claim 1, the silicon oxide film is formed on a substrate at normal temperature.
[0008]
According to a third aspect of the present invention, there is provided a method for forming a silicon oxide film according to the first or second aspect, wherein the silicon oxide film is formed in a predetermined pattern.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a method for forming a silicon oxide film by irradiating a compound containing a Si—O—Si bond according to the present invention with light will be described with reference to the drawings.
[0010]
FIG. 1 shows an embodiment of a method for forming a silicon oxide film by irradiating a compound containing a Si-O-Si bond with light according to the present invention. In this figure, reference numeral 1 denotes a vacuum vessel as a depressurized vessel, which is evacuated by a vacuum pump 2. A light transmitting window 3 made of MgF ₂ is formed in the vacuum vessel 1. In the vacuum vessel 1, an organic polysiloxane 10 (for example, in the form of a plate) is disposed as a compound containing a Si-O-Si bond, and a silicon substrate 20 (a base for depositing a silicon oxide film) is disposed. Have been. A light source 30 (containing light having a wavelength of 200 nm or less) is provided outside the light transmitting window 3 of MgF ₂ , and the laser light is applied to the organic polysiloxane 10 through the light transmitting window 3 and the silicon substrate is irradiated with the laser light. The arrangement is also such that irradiation is also made to 20. When a silicon oxide film having a predetermined pattern is formed on the silicon substrate 20, the metal mask 21 is disposed on the front side of the substrate 20.
[0011]
The light for irradiating the organic polysiloxane 10 needs to include light having a wavelength of 200 nm or less because a gas for forming SiO ₂ cannot be generated at a wavelength exceeding 200 nm. It is necessary to include light having a wavelength of 200 nm or less that can completely remove the side chain constituting the siloxane by photocleavage. For example, a laser device capable of generating laser light having a wavelength of vacuum ultraviolet or less can be suitably used.
[0012]
In the configuration shown in FIG. 1, an F ₂ laser device is used as a light source 30, an organic polysiloxane 10 is placed in a vacuum vessel 1 which is substantially reduced to a vacuum, and vacuum ultraviolet F ₂ laser light (wavelength 157 nm) is applied to the surface thereof. Irradiation was performed at an ablation threshold (about 140 mJ / cm ² ) or less. At that time, the optical path portion of the F ₂ laser beam was placed perpendicular to the laser light metal mask 21 of silicon substrate 20 is brought into close contact with (30 [mu] m mesh). At that time, the laser energy density on the substrate 20 was about 9 mJ / cm ² , the pulse repetition frequency was 20 Hz, and the irradiation time was 15 minutes. As a result, a gas (a gaseous silicon compound and oxygen) is released from the exposed portion of the organic polysiloxane 10, and a silicon oxide film is formed on the silicon substrate 20 placed in the optical path of the laser beam by using the gas. Chemical vapor deposition. That is, silicon oxide was deposited as a film by photolysis of the gas near the silicon substrate 20. In this chemical vapor deposition, heating or cooling of the silicon substrate 20 is not required, and the chemical vapor deposition can be performed at room temperature (normal temperature).
[0013]
FIG. 2 shows an atomic force microscope photograph of the silicon oxide film formed on the silicon substrate. It can be seen that the silicon oxide film was formed only on the light irradiated portion (30 × 30 μm ² ) transmitted through the metal mask (30 μm mesh) provided in close contact with the silicon substrate, and the surface was extremely smooth.
[0014]
In FIG. 1, the silicon substrate 20 is arranged perpendicular to the optical axis of the laser light. However, even when the silicon substrate is installed in the optical path of the laser light and inclined or parallel to the optical axis, Similar silicon oxide film formation was confirmed. This is advantageous when it is desired to increase the area for forming a silicon oxide film on a silicon substrate.
[0015]
Furthermore, it was found that a similar silicon oxide film could be formed even when the silicon substrate was replaced with a germanium substrate. This indicates that a silicon oxide film can be formed on a substrate of any material.
[0016]
FIG. 3 is an analysis result of the formed film by Fourier transform infrared spectroscopy (FT-IR), and is a Fourier transform infrared absorption spectrum. In FIG. 3, curve (a) is a film deposited on a silicon substrate, and curve (b) is a film deposited on a germanium substrate. In each case, an absorption peak indicating a Si—O—Si bond was determined at 1060 to 1070 cm ⁻¹ . This peak position coincides with the case of the thermal silicon oxide film (SiO ₂ ). Therefore, it was found that the formed film was SiO ₂ having a stoichiometric composition.
[0017]
When the formed film was analyzed by X-ray photoelectron spectroscopy (XPS), it was found that the XPS spectrum of Si 2p had a peak at 103.2 to 103.3 eV. Also in this case, the spectrum coincided with the spectrum of the thermal silicon oxide film (SiO ₂ ).
[0018]
FIG. 4 is an X-ray photoelectron spectroscopy spectrum showing the result of analysis of the formed film in the depth direction by XPS. The substrate used is a silicon substrate. The horizontal axis in FIG. 4 indicates the sputtering time (time when the formed film was cut by sputtering; that is, the depth) by the argon gas, and the vertical axis indicates the atomic concentration. The atomic concentrations of oxygen and silicon in the formed film were uniform in the depth direction, and the ratio was about 2: 1. Therefore, it was found that the chemical composition of the formed film was SiO ₂ also in the depth direction. In addition, from the XPS spectrum of C1s, no carbon was mixed in the formed film.
[0019]
Raman spectroscopy was performed to further confirm the presence or absence of carbon in the formed film. As a result, two broad peaks of 1350 cm ^-1 and 1580 cm ^-1 indicating the presence of carbon was observed. Therefore, it was found that the formed film was carbon-free SiO ₂ .
[0020]
According to this embodiment, the following effects can be obtained.
[0021]
(1) By exposing the organic polysiloxane 10 placed in the vacuum vessel 1 which has been substantially reduced to a vacuum to a light source 30 including light having a wavelength of 200 nm or less, and utilizing gas released from the organic polysiloxane 10 A high-quality silicon oxide film can be chemically deposited on a substrate placed in the optical path of the light source 30.
[0022]
(2) When performing chemical vapor deposition of the silicon oxide film, heating or cooling of the substrate is not required, and the silicon oxide film can be formed on a substrate at room temperature (normal temperature). Therefore, it is possible to form a film on a substrate that is easily affected by heat (a polymer material, a biomaterial, a low-melting material, a material that easily diffuses heat, and the like), which has been considered difficult.
[0023]
(3) A silicon oxide film having a desired pattern can be formed on a substrate by providing a mask having a predetermined pattern for transmitting light from the light source 30 in close contact with the substrate. Therefore, a high quality silicon oxide film for manufacturing an optical integrated circuit based on the SiO ₂ optical waveguide can be formed.
[0024]
In the embodiment of the present invention, FIG. 1 illustrates a flat substrate as the substrate 20 on which the silicon oxide film is deposited. However, the substrate 20 is not limited to the flat substrate and may be oxidized on a substrate having a curved surface or the like. It is possible to deposit a silicon film.
[0025]
In addition, in the configuration of FIG. 1, both the organic polysiloxane 10 as the compound containing a Si—O—Si bond and the silicon substrate 20 are simultaneously irradiated with light from the light source 30. After irradiating the light of the light source 30 to release a gas (a gaseous silicon compound and oxygen), the light of the light source 30 may be applied to a substrate such as a silicon substrate. Further, the light from the light source 30 may be reflected and applied to the base.
[0026]
Although the embodiments of the present invention have been described above, it will be obvious to those skilled in the art that the present invention is not limited to the embodiments and various modifications and changes can be made within the scope of the claims.
[0027]
【The invention's effect】
As described above, according to the method of forming a silicon oxide film by irradiating a compound containing a Si—O—Si bond according to the present invention with a desired pattern on an arbitrary substrate without being restricted by heat. A high quality silicon oxide film can be formed. Since an optical waveguide, a photonic crystal, and the like can be formed using this silicon oxide film, it is an indispensable technique for shifting from the present integrated circuit to the future optical integrated circuit. The present invention is very applicable to these photonics fields.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of a method for forming a silicon oxide film by irradiating a compound containing a Si—O—Si bond according to the present invention with light.
FIG. 2 shows an atomic force micrograph of a silicon oxide film patterned into a 30 μm square by simultaneously irradiating a vacuum ultraviolet F ₂ laser beam to an organic polysiloxane and a silicon substrate in an embodiment of the present invention. FIG.
FIG. 3 is a Fourier transform infrared absorption spectrum showing the relationship between the wave number and the transmittance when the substrate is made of silicon and germanium in the formed film according to the embodiment of the present invention.
FIG. 4 is an X-ray photoelectron spectroscopy spectrum showing the relationship between the sputtering time and the atomic concentration in the formed film for the formed film according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Vacuum pump 3 Light transmission window 10 Organic polysiloxane 20 Silicon substrate 21 Mask 30 Light source

Claims (3)

Exposing a compound containing a Si-O-Si bond installed in a depressurized container to a light source containing light having a wavelength of 200 nm or less, and chemically depositing a silicon oxide film using a gas released from the compound. A method for forming a silicon oxide film. The method for forming a silicon oxide film according to claim 1, wherein the silicon oxide film is formed on a substrate at room temperature. The method for forming a silicon oxide film according to claim 1, wherein the silicon oxide film is formed in a predetermined pattern.

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