JPH0782098A - Silicon substrate having silicon carbide-embedded layer and its production - Google Patents

Abstract

PURPOSE:To form a single crystal silicon carbide layer having same crystal direction as a single crystal silicon as thickly as possible to a definite depth from the surface of a silicon substrate. CONSTITUTION:In a silicon substrate having silicon carbide-embedded layer, this silicon substrate has a single crystal silicon layer on the surface and has a single crystal silicon carbide layer having same crystal direction as the single crystal silicon as an intermediate layer under the single crystal silicon layer. In a method for synthesizing silicon carbide by injecting carbon ion into the silicon substrate, carbon ions to which >=20keV energy is given are injected into the single crystal silicon substrate heated and kept to 800-1300 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon substrate having a silicon carbide embedded layer and a method for manufacturing the same.

[0002]

2. Description of the Related Art Silicon carbide has a large energy band gap of 2.4 eV at 3 C and 3.0 eV at 6 H and has high thermal conductivity. It is used as etc.
In this case, if a silicon carbide layer as thick as possible can be formed in the silicon substrate, the utility value in various fields can be further enhanced.

As a method for forming a single crystal bulk of silicon carbide, there are a sublimation method, a liquid phase method and the like, and a silicon carbide substrate is manufactured by slicing and polishing the single crystal bulk formed by these methods.

However, it is difficult to synthesize a large single crystal by the above-mentioned method for synthesizing silicon carbide of single crystal bulk. Further, since silicon carbide has many crystal polymorphs and the properties thereof greatly vary, it is necessary to make a crystal form according to the purpose, but it is extremely difficult to control it by the above synthesis method.

On the other hand, as a method for forming a silicon carbide thin film, methods such as chemical vapor deposition, sputter vapor deposition, and ion implantation are known. For example, energy of 180 keV, 135 keV and 90 keV is applied to a silicon substrate heated to 860 ° C. There is an example in which a carbon carbide thin film is implanted to form a silicon carbide thin film on a silicon substrate.

However, in the above conventional ion implantation method,
Due to low energy and the like, the silicon carbide layer is limited to a very surface portion (about 0 to 0.5 μm), and a large amount of ions cannot be implanted. Moreover, while increasing the implantation region allows silicon carbide to be formed over a large area, amorphous silicon carbide is formed, and even if it is heat-treated, it cannot be made into a single crystal, so that it remains as a polycrystalline body.

[0007]

SUMMARY OF THE INVENTION The main object of the present invention is to form a single crystal silicon carbide layer having the same crystal orientation as that of single crystal silicon to a certain depth from the surface of a silicon substrate as thick as possible. .

[0008]

The inventors of the present invention have made extensive studies in view of the above-mentioned problems of the prior art. As a result, in the ion implantation method, carbon ions having a certain energy are held at a specific temperature. When injecting into the substrate,
The inventors have found that a single crystal silicon carbide layer can be formed as an intermediate layer at a certain depth from the surface while holding the single crystal silicon layer on the surface thereof, and completed the present invention.

That is, the present invention provides the following silicon substrate having a silicon carbide burying layer and a method for manufacturing the same. 1. A silicon substrate having a silicon carbide layer, having a single crystal silicon layer on the surface thereof, and having a single crystal silicon carbide layer having the same crystal orientation as that of single crystal silicon as an intermediate layer under the single crystal silicon layer. A silicon substrate having a silicon carbide buried layer. 2. In the method of synthesizing silicon carbide by implanting carbon ions into a silicon substrate, 200 keV is applied to a single crystal silicon substrate heated and held at 800 to 1300 ° C.
A method of manufacturing a silicon substrate having a silicon carbide burying layer, which comprises implanting carbon ions given the above energy.

The present invention will be described in detail below.

The substrate of the present invention has a single crystal silicon layer on its surface, and a single crystal silicon carbide layer having the same crystal orientation as the substrate under the single crystal silicon layer.

The manufacturing method will be described below. First, as the silicon substrate that can be used in the present invention, a substrate manufactured by a known manufacturing method can be used.

Then, the above silicon substrate is covered with 800 to 13
Heat and hold at 00 ° C. If it exceeds 1300 ° C., there is a possibility that the crystal polymorphic form will be 6H, which is not preferable. Moreover, it is desirable to perform heating and holding in a vacuum. Then, a silicon carbide layer is formed by implanting carbon ions into the heated silicon substrate. Carbon ions are accelerated by giving energy of 200 keV or more. Since carbon ions in a high energy state are used in this way, etching of the surface of the silicon substrate by sputtering can be avoided, and as a result, a large amount of carbon ions up to the same concentration as the substrate silicon can be implanted. in this case,
The upper limit of the energy to be accelerated may be appropriately adjusted depending on the desired depth and thickness of the silicon carbide burying layer, but is usually about 1 GeV. As a device for accelerating carbon ions, a known accelerator can be used, and examples thereof include a tandem accelerator, a high frequency quadrupole accelerator, and a cyclotron. The operation method and conditions other than the above in the ion implantation may be according to the method based on the ordinary ion implantation method.

Thus, by implanting carbon ions into the high temperature substrate, the surface layer has a single crystal structure having the same crystal orientation as the silicon substrate while maintaining the original silicon single crystal state. The layers can be formed to a constant depth.

[0015]

According to the manufacturing method of the present invention, the silicon substrate surface is not etched by sputtering, that is, the surface layer has the same crystal orientation as the silicon single crystal while maintaining the original silicon single crystal state. A silicon substrate having a silicon carbide burying layer made of single crystal as an intermediate layer can be obtained. Moreover, it is also possible to freely control the depth and thickness of the silicon carbide burying layer by adjusting the energy applied to the carbon ions.

Therefore, the silicon substrate of the present invention having such a peculiar structure is particularly useful for various electronic device materials and the like. For example, when an electronic element having a SiC-Si heterojunction is created, the conventional semiconductor process can be applied as it is because the surface portion is a silicon single crystal layer. Further, in the case of forming an oxide film (SiO ₂ ) on silicon carbide, conventionally, silicon carbide was directly oxidized by a thermal oxidation method, whereas in the substrate of the present invention, only the surface layer of silicon is directly oxidized. Therefore, the oxide film can be formed at a lower temperature and at a higher speed.

[0017]

EXAMPLES Examples and comparative examples will be shown below to further clarify the features of the present invention.

Example 1 Carbon single ions having an energy of 1.5 MeV were implanted into a silicon single crystal substrate kept at 880 ° C. in a vacuum using a tandem accelerator at 1.5 × 10 ¹⁸ cm ^-2 , The substrate of the present invention was obtained.

FIG. 1 shows the result of measuring the concentration distribution of carbon in the depth direction in the substrate thus obtained by using the Rutherford backscattering method. As is clear from FIG. 1, carbon does not exist on the surface of the substrate, and the silicon carbide layer is formed at a constant depth from the surface.

The results of analyzing the above silicon carbide by X-ray diffraction analysis are shown in FIGS. 2 and 3. From this result,
Only cubic silicon carbide (3C type) is formed,
Moreover, the silicon substrate (400) surface and the silicon carbide (200)
It can be seen that the crystal orientations are the same because the orientations in which the diffraction of the planes occur are the same.

[Brief description of drawings]

FIG. 1 is a diagram showing a carbon concentration distribution by Rutherford backscattering method showing a state of a buried silicon carbide layer in a silicon substrate obtained by the method of the present invention.

FIG. 2 is a positive pole figure of X-ray diffraction from a silicon (400) plane in a silicon substrate obtained by the method of the present invention.

FIG. 3 is a positive pole figure of X-ray diffraction from a silicon carbide (200) plane in a silicon substrate obtained by the method of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Kinomura 4-1-33 Nishikoji, Minoh City, Osaka Prefecture

Claims (2)

[Claims] 1. A silicon substrate having a silicon carbide layer, which has a single crystal silicon layer on its surface, and an intermediate layer of a single crystal silicon carbide layer having the same crystal orientation as that of the single crystal silicon under the single crystal silicon layer. And a silicon substrate having a silicon carbide burying layer. 2. A method of synthesizing silicon carbide by implanting carbon ions into a silicon substrate, which comprises 800 to 13
20 for single crystal silicon substrate heated and held at 00 ℃
A method of manufacturing a silicon substrate having a silicon carbide burying layer, which comprises implanting carbon ions having an energy of 0 keV or more.