JP2006253617A - SiC SEMICONDUCTOR AND ITS MANUFACTURING METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor having 3C-SiC single crystal thin film with a surface of reduced irregularity and curvature as well as excellent crystalline and high quality surface orientation (111), and a SiC semiconductor capable of forming 3C-SiC single crystal thin film with surface orientation (111) on an Si single crystal substrate surely and easily by reducing lattice mismatching and preventing etching. <P>SOLUTION: The SiC semiconductor is fabricated in a method to carry out vapor phase epitaxy of the 3C-SiC low temperature growth layer 2 including hydrogen with a volume of 10<SP>19</SP>atoms/cm<SP>3</SP>or more under a condition of reduced pressure atmosphere of 300 Torr or less and a temperature range of 780 to 950°C using organic compound gas on the Si single crystal substrate 1 with surface orientation (110), then form the 3C-SiC single crystal layer 3 with surface orientation (111) on the layer 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention comprises a β-SiC (cubic silicon carbide) single crystal thin film formed on a Si (silicon, silicon) single crystal substrate, a next-generation electronic device, an electronic device capable of high-speed and high-temperature operation, a photovoltaic power generation device, etc. The present invention relates to a SiC semiconductor (including the use of a SiC semiconductor substrate) that is expected to be applied as a semiconductor device and a manufacturing method thereof.

SiC has excellent characteristics such as a wide band gap, high electron mobility, and high heat resistance, is rich in the amount of constituent elements, and has little concern about environmental pollution. It is a material expected to be applied as a compound semiconductor in next-generation electronic devices, electronic devices capable of high-speed and high-temperature operation, solar power generation devices, and the like.
In particular, the SiC thin film formed on the Si single crystal substrate can inherit the current silicon technology, and therefore, its practical use is required also from the advantage in the development cost of industrial technology.

As a method of forming the SiC thin film as described above, various CVD methods, sputtering methods, various MBE methods and the like are used.
In order to obtain a SiC film having excellent crystallinity by these methods, the bond between Si and C is a covalent bond, and both the chemical bond formation energy and the diffusion energy for epitaxial crystal growth are large. In the CVD method, a high temperature condition of 1200 ° C. or higher is required. Further, in the sputtering method and the MBE method, it must be grown in a high vacuum atmosphere.

  Furthermore, Si and SiC have a large lattice mismatch of about 20% in lattice constant, and it is extremely difficult to continuously grow a high-quality SiC film on a Si single crystal substrate. A method of forming a very thin SiC single crystal layer by heat-treating the surface of the single crystal substrate in a hydrocarbon atmosphere has been adopted.

In addition, since 3C-SiC having the same plane orientation as that of the Si single crystal substrate is usually epitaxially grown on the Si single crystal substrate, a 3C-SiC single crystal layer having a plane orientation (111) is obtained. Used a Si single crystal substrate with a plane orientation (111).
However, when a 3C-SiC single crystal layer with a plane orientation (111) is formed on a Si single crystal substrate with a plane orientation (111), compared to the case of growing on a Si single crystal substrate with a plane orientation (001), Twice or more warping occurred, and there was a problem that later handling was difficult.

On the other hand, Non-Patent Document 1 discloses that 3C-SiC single crystals with different plane orientations (111) grow when a Si single crystal substrate with plane orientations (110) is used.
T. Nishiguchi, Y. Mukai, S. Ohshima and S. Nishino, “physica. Status Solidi (c)”, (USA), 2003, Vol. 0, No. 7, p.2585-2588

  Also in the method described in Non-Patent Document 1, a thin SiC layer is formed by introducing a hydrocarbon gas and carbonizing the surface of the Si single crystal substrate to alleviate lattice mismatch between the Si single crystal substrate and the SiC single crystal. Is forming.

However, when the concentration of the introduced hydrocarbon gas is low, etching of the surface of the Si single crystal substrate occurs when the temperature exceeds about 800 ° C. due to an impurity gas such as H ₂ O or O ₂ .
On the other hand, if the concentration of hydrocarbon gas to be introduced is too high, the supplied C becomes excessive rather than the progress of the carbonization reaction on the surface of the Si single crystal substrate. There is a case where abnormal growth of SiC occurs and huge carbonized SiC grains are formed.
In particular, when the temperature is raised by introducing a hydrocarbon gas from a temperature lower than the temperature at which etching is performed, if the temperature rise rate is larger than the formation rate of the SiC carbide layer, etching also occurs in this case. Strict control such as adjustment of hydrocarbon gas concentration is required.

  In the CVD method, when the surface of the Si single crystal substrate is etched, the unevenness caused by this etching becomes a defect factor, which adversely affects the subsequent growth of the SiC single crystal. Etch pit voids remain at the SiC / Si interface or many defects occur, making it difficult to use as a so-called SiC on Si device having a SiC single crystal on a Si single crystal substrate.

In addition, as for the growth surface of the 3C-SiC single crystal, when grown under normal pressure atmosphere, the diffusion layer becomes narrow and abnormal growth increases, so that the unevenness becomes intense. Growth under reduced pressure is used.
However, when a 3C-SiC single crystal with a plane orientation (111) is grown on a Si single crystal substrate with a plane orientation (110), as described above, it is grown in a reduced pressure atmosphere in order to suppress unevenness of the growth surface. Then, the 3C-SiC single crystal takes over the orientation of the Si single crystal substrate, and the (110) orientation becomes dominant.

  Therefore, there has been a demand for a method capable of forming a high-quality plane orientation (111) 3C-SiC single crystal on a Si single crystal substrate without causing defects or etching due to lattice mismatch. .

  The present invention has been made to solve the above technical problem, and includes a high-quality plane orientation (111) 3C-SiC single crystal thin film with reduced surface irregularities and warpage and excellent crystallinity. 3C-SiC single crystal thin film having a plane orientation (111) can be reliably and easily formed on a semiconductor and Si single crystal substrate by relaxing lattice mismatch and preventing etching. It aims at providing the manufacturing method of a SiC semiconductor.

The SiC semiconductor according to the present invention has a surface orientation (111) 3C-SiC single layer via a 3C-SiC layer containing hydrogen of 10 ¹⁹ atoms / cm ³ or more on a surface orientation (110) Si single crystal substrate. A crystal layer is formed.
Thus, by interposing the 3C-SiC layer containing hydrogen at 10 ¹⁹ atoms / cm ³ or more between the Si single crystal substrate and the 3C-SiC single crystal layer, high-quality 3C with few defects and warpage. A SiC single crystal layer can be obtained.

In addition, in the method for producing an SiC semiconductor according to the present invention, an organic compound gas is used on a Si single crystal substrate having a plane orientation (110) in a reduced pressure atmosphere of 300 Torr or less at 780 to 950 ° C. and hydrogen is 10 ^19. A 3C—SiC low-temperature growth layer contained in atoms / cm ³ or more is vapor-phase grown, and then a 3C—SiC single crystal layer having a plane orientation (111) is formed thereon.
As described above, by forming a 3C-SiC low-temperature growth layer on an Si single crystal substrate with a plane orientation (110) using an organic compound gas, lattice mismatch is alleviated even in a reduced-pressure atmosphere. In addition, it is possible to grow a 3C—SiC single crystal layer having a high-quality plane orientation (111) with no surface unevenness without causing etching.

In the said manufacturing method, it is preferable that the thickness of a 3C-SiC low temperature growth layer shall be 10-750 nm.
The 3C-SiC low temperature growth layer preferably has a thickness in the above range from the viewpoint of the effect of relaxation of lattice mismatch and the maintenance of crystallinity of the 3C-SiC single crystal layer grown on the 3C-SiC low temperature growth layer.

The 3C—SiC single crystal layer is preferably formed at 1100 ° C. or higher.
In order to obtain the surface of the 3C—SiC single crystal layer in a smooth state, it is preferably formed at a high temperature in consideration of growth surface migration.

According to the manufacturing method of the SiC semiconductor according to the present invention, the lattice mismatch with the Si single crystal substrate is relaxed, and the etching at the interface is prevented, so that the 3C-SiC having the plane orientation (111) can be surely and easily obtained. A single crystal layer can be formed.
Further, the SiC semiconductor according to the present invention obtained by the above manufacturing method has a high-quality 3C-SiC single crystal layer with reduced surface irregularities and warpage and excellent crystallinity, and as a high-power electronic device or the like Not only can it be used, but it can also be used as a substrate for crystal growth of hexagonal compound semiconductors such as 4H—SiC, 6H—SiC, and GaN based on this.

Hereinafter, the present invention will be described in more detail.
In FIG. 1, the outline of the process of the manufacturing method of the SiC semiconductor which concerns on this invention is shown.
In the manufacturing method according to the present invention, a 3C-SiC low-temperature growth layer 2 is vapor-phase grown on an Si single crystal substrate 1 (FIG. 1A) having a plane orientation (110) using an organic compound gas (FIG. 1). 1 (b)), and a 3C-SiC single crystal layer 3 having a plane orientation (111) is formed thereon (FIG. 1 (c)).
That is, in the method of manufacturing an SiC semiconductor according to the present invention, the 3C-SiC low-temperature growth layer 2 formed using an organic compound gas is interposed between the Si single crystal substrate 1 and the 3C-SiC single crystal layer 3. It is characterized by.
Thereby, it is possible to grow a 3C-SiC single crystal layer having a surface orientation (111) in a reduced pressure atmosphere on a Si single crystal substrate having a surface orientation (110), and high quality 3C with reduced surface irregularities. -A SiC single crystal can be obtained.

Therefore, according to the manufacturing method according to the present invention as described above, the plane orientation is obtained via the 3C—SiC layer containing hydrogen of 10 ¹⁹ atoms / cm ³ or more on the Si single crystal substrate having the plane orientation (110). The SiC semiconductor according to the present invention in which the (111) 3C—SiC single crystal layer is formed is obtained.
This SiC semiconductor is obtained by crystal-growing 3C-SiC having a plane orientation (111) on a Si single crystal substrate having a plane orientation (110). Compared with the case where 3C-SiC with the same plane orientation and (111) plane orientation is grown on the surface, the lattice mismatch rate is reduced from 20% to 2%, and the surface is formed as a high-quality crystal with few defects and warpage. 3C-SiC with the orientation (111) can be obtained.

In the manufacturing method according to the present invention, first, a 3C—SiC low-temperature growth layer 2 is formed on a Si single crystal substrate 1 having a plane orientation (110) (see FIG. 1B).
The 3C-SiC low temperature growth layer 2 is formed by vapor phase growth at 780 to 950 ° C. in a reduced pressure atmosphere of 300 Torr or less using an organic compound gas.

The Si single crystal substrate 1 in the present invention is not limited to those manufactured by the CZ (Czochralski) method, but those manufactured by the FZ (floating zone) method, and these Si single crystal substrates are vapor-phased. An epitaxially grown Si single crystal layer (Si epi substrate) or the like may be used, but a crystal plane orientation (110) is used.
The Si single crystal can be easily manufactured as a large bulk, and since the wafer processing technology is mature, it can be suitably used as a substrate for element formation.
The Si single crystal substrate 1 is etched before the formation of the 3C-SiC low-temperature growth layer 2, and the natural oxide film is removed by heat treatment at 1000 to 1350 ° C. in a hydrogen atmosphere to clean the surface. It is preferable to keep it.

The organic compound gas used in the vapor phase growth is preferably a gas that can generate SiC at a relatively low temperature, such as organosilane.
If an organosilane gas containing both elements of Si and C is used, etching does not occur because it is not necessary to supply Si from the Si single crystal substrate in order to form SiC.
Therefore, a low temperature vapor phase growth using such a gas forms a 3C-SiC layer containing 10 ¹⁹ atoms / cm ³ or more of hydrogen, thereby setting severe conditions as in the conventional carbonized layer formation. Therefore, it is possible to alleviate lattice mismatch and prevent etching.

When the hydrogen concentration in the 3C-SiC low temperature growth layer 2 is less than 10 ¹⁹ atoms / cm ³ , the lattice mismatch with the Si single crystal substrate 1 cannot be sufficiently relaxed and etching cannot be sufficiently prevented.
Incidentally, in 3C-SiC growth that requires carbonization and a high temperature of 1000 ° C. or higher, it is difficult to form a 3C—SiC layer containing hydrogen of 10 ¹⁹ atoms / cm ³ or more, and etching is performed because it exceeds the etching temperature of the Si substrate. It cannot be prevented.

The vapor phase growth of the 3C-SiC low temperature growth layer 2 is performed in a reduced pressure atmosphere to reduce unevenness of the growth surface, and is performed at 300 Torr or less, more preferably 100 Torr or less.
Moreover, it is preferable that the formation temperature of the said 3C-SiC low temperature growth layer 2 shall be 780 degreeC or more and 950 degrees C or less.
When the formation temperature is lower than 780 ° C., the amorphous composition increases, and then the crystallinity of the 3C—SiC single crystal layer 3 grown at a high temperature is deteriorated. On the other hand, when the said temperature exceeds 950 degreeC, decomposition | disassembly of organosilane gas etc. is accelerated | stimulated and the ratio which Si precipitates increases rather than SiC being formed.

The thickness of the 3C—SiC low temperature growth layer 2 is preferably 10 to 750 nm.
When the thickness is less than 10 nm, the effect of relaxation of lattice mismatch is not sufficiently obtained, and thereafter the crystallinity of the 3C—SiC single crystal layer 3 grown at a high temperature is deteriorated or polycrystallized. In addition, etching of the Si single crystal substrate 1 is likely to occur.
On the other hand, since the 3C-SiC low temperature growth layer is inferior in crystallinity to that grown at a high temperature, even if it is too thick, the subsequent crystallinity is deteriorated. Therefore, it is not preferable that the thickness exceeds 750 nm.

Next, a 3C-SiC single crystal layer 3 having a plane orientation (111) is formed on the 3C-SiC low-temperature growth layer 2 (see FIG. 1C).
Specifically, the 3C-SiC single crystal layer is formed by using, for example, a mixed gas of silane and propane as a source gas and hydrogen gas as a carrier gas, under a reduced pressure atmosphere of about 1150 to 1350 ° C. and 300 Torr or less. It can be formed by vapor growth to a desired thickness by the method.
If it is on the 3C-SiC low temperature growth layer 2 formed as described above, the 3C-SiC single crystal layer having a plane orientation (111) different from the plane orientation (110) of the Si single crystal substrate in a reduced pressure atmosphere. Can be grown as a high quality crystal with reduced surface irregularities without causing defects and etching due to lattice mismatch.

  The 3C-SiC single crystal layer 3 is preferably grown until a sufficient film thickness can be secured for smoothing the surface, and the growth temperature is as high as 1100 ° C. or higher in consideration of growth surface migration. It is preferable to do.

EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not restrict | limited by the following Example.
[Example 1]
The surface of the Si single crystal substrate having a surface orientation (110) whose surface was chemically etched was cleaned at 1100 ° C. in a reduced pressure atmosphere of 50 Torr using hydrogen (H ₂ ) as a carrier gas.
The temperature of the Si single crystal substrate was lowered to 830 ° C., and MMS (monomethylsilane: SiH ₂ CH ₃ ) was used to supply a gas flow rate ratio of MMS: H ₂ = 1: 10000, and the thickness was increased by CVD for 10 minutes. A 3C-SiC low temperature growth layer having a thickness of about 30 nm was formed.
Next, the supply of MMS is stopped, and the temperature is raised to 1200 ° C. while supplying only the carrier gas (H ₂ ), and then SiH ₄ and C ₃ H ₈ are converted into a gas flow rate ratio of SiH ₄ : C ₃ H ₈ : H. ₂ = 1: 2: 10000, and a 3 C—SiC single crystal layer having a thickness of 10 μm was vapor-phase grown in 8 hours.

As a result of X-ray diffraction analysis, the 3C-SiC single crystal on the Si (110) substrate obtained has a very sharp peak in the plane orientation (111), and the interface with the Si single crystal substrate is etched. It wasn't.
Further, the surface of the 3C—SiC single crystal layer was smooth, and the surface roughness was about half that when the 3C—SiC single crystal layer was grown at normal pressure.

[Comparative Example 1]
A carbonized SiC layer was formed on the surface of the Si single crystal substrate with the plane orientation (111) by carbonization of the surface of the Si single crystal substrate using C ₃ H ₈ .
A 3C—SiC single crystal layer was grown on the carbonized SiC layer in the same manner as in Example 1.

  As a result of X-ray diffraction analysis, the 3C-SiC single crystal layer was in the plane orientation (111) and the crystallinity was good as in Example 1, but the warpage was large and the thickness grew to 1 μm or more. When cracked, cracks occurred.

[Comparative Example 2]
A carbonized SiC layer was formed on the Si single crystal substrate having a plane orientation (110) by carbonization of the surface of the Si single crystal substrate using C ₃ H ₈ at normal pressure.
A 3C—SiC single crystal layer was grown on the carbonized SiC layer in the same manner as in Example 1.

As a result of X-ray diffraction analysis, the peak of the 3C—SiC single crystal layer had a half-value width similar to that of Example 1 and the crystallinity was good, but 5 × 10 ^{3 at} the interface with the Si single crystal substrate. Etch pits of about 1 piece / cm ² existed.

[Comparative Example 3]
A carbonized SiC layer was formed by carbonizing the surface of the Si single crystal substrate using C ₃ H ₈ in a reduced pressure atmosphere on the Si single crystal substrate having the plane orientation (110).
A 3C—SiC single crystal layer was grown on the carbonized SiC layer in the same manner as in Example 1.

  The growth surface was not a mirror surface, and as a result of X-ray diffraction analysis, it was confirmed that the growth surface was 3C-SiC polycrystal having a strong plane orientation (110) orientation.

It is sectional drawing which shows the outline of the process of the manufacturing method of the SiC semiconductor which concerns on this invention.

Explanation of symbols

1 Si single crystal substrate 2 3C-SiC low temperature growth layer 3 3C-SiC single crystal layer

Claims (4)

A 3C-SiC single crystal layer having a plane orientation (111) is formed on a Si single crystal substrate having a plane orientation (110) via a 3C-SiC layer containing hydrogen of 10 ¹⁹ atoms / cm ³ or more. SiC semiconductor characterized by this. 3C-SiC low-temperature growth layer containing 10 ¹⁹ atoms / cm ³ or more of hydrogen at 780 to 950 ° C. in a reduced-pressure atmosphere of 300 Torr or less using an organic compound gas on a Si single crystal substrate having a plane orientation (110) A method for producing an SiC semiconductor, comprising: vapor-phase-growing a silicon nitride film and forming a 3C-SiC single crystal layer having a plane orientation (111) thereon.   3. The method of manufacturing an SiC semiconductor according to claim 2, wherein the thickness of the 3C-SiC low temperature growth layer is 10 to 750 nm.   4. The method of manufacturing an SiC semiconductor according to claim 2, wherein the 3C—SiC single crystal layer is formed at 1100 ° C. or higher. 5.

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