JP2004039766A - 3C-SiC SEMICONDUCTOR OR GaN SEMICONDUCTOR AND ITS MANUFACTURING METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a 3C-SiC or GaN semiconductor and the manufacturing method of the same which can avoid the dry area of a substrate. <P>SOLUTION: Upon the epitaxial growth of 3C-SiC or GaN which is effected on a substrate of Si, multi-layered (2 layered) epitaxial growth film is formed of an organic metall material. In this case, the epitaxial growth film of SiC or GaN is formed of a buffer layer and a main body layer. The buffer layer is formed by the epitaxial growth at a comparatively low temperature at a slow speed. In the case of SiC, the epitaxial growth of the buffer layer is effected at a temperature of 500-900°C at a speed of 0.1-1μm/h. The epitaxial growth of the main body layer is effected on the buffer layer at a temperature of 1000-1300°C at a speed of 1-15μm/h. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a SiC semiconductor or a GaN semiconductor having a better semiconductor function than Si, and a method for manufacturing the same.
[0002]
[Prior art]
A cubic silicon carbide (3C-SiC) semiconductor or a GaN semiconductor is mainly manufactured by epitaxially growing SiC or GaN on a Si substrate.
[0003]
[Problems to be solved by the invention]
There is a lattice mismatch between Si serving as a substrate and SiC grown thereon.
As a result, a large number of crystal defects due to misfit dislocations occur, which is a problem during device fabrication.
[0004]
In order to suppress crystal defects due to a difference in lattice constant, there is known a method of carbonizing the surface of a Si substrate with a hydrocarbon gas and growing SiC using the carbonized gas as a buffer layer. According to this conventional method, a phenomenon in which Si atoms in the substrate are carried away to the substrate surface by the carbonization treatment, and as a result, holes are generated in the Si substrate and the Si substrate is roughened.
[0005]
In epitaxial growth, the film formation layer inherits the crystallinity of the substrate. Therefore, in order to obtain a high-quality crystal, the roughness of the substrate should be avoided.
[0006]
An object of the present invention is to provide a 3C—SiC or GaN semiconductor that can avoid such substrate roughness, and a method for manufacturing the same.
[0007]
[Means for Solving the Problems]
An example of the solution of the present invention is as follows.
[0008]
(1) When 3C—SiC or GaN is epitaxially grown on a Si substrate, a buffer layer of SiC or GaN is first epitaxially grown by changing both or one of the temperature and the speed of the epitaxial growth, and then the SiC or GaN is grown. A method for producing a 3C-SiC semiconductor or a GaN semiconductor, wherein a body layer is epitaxially grown.
[0009]
(2) The method for producing a 3C-SiC semiconductor or GaN semiconductor described above, wherein the buffer layer is epitaxially grown at a relatively low temperature and at a low speed, and the main body layer is epitaxially grown at a relatively high temperature and at a high speed.
[0010]
(3) The 3C-SiC semiconductor described above, wherein the buffer layer is epitaxially grown at a temperature of 500 to 900 ° C. and at a rate of 0.1 to 1 μm / h, or at a temperature of 300 to 700 ° C. and 0.1 The method of manufacturing a GaN semiconductor described above, wherein the GaN buffer layer is epitaxially grown at a speed of about 1 μm / h.
[0011]
(4) The above-mentioned 3C-SiC semiconductor or the main body layer is grown at a temperature of 800 to 1100 ° C. and at a temperature of 1 to 15 μm / h. The method of manufacturing a GaN semiconductor described above, wherein the epitaxial growth is performed at a rate of 15 μm / h.
[0012]
(5) A buffer comprising a Si substrate, a 3C-SiC or GaN buffer layer formed on the Si substrate by epitaxial growth, and a 3C-SiC or GaN body layer formed on the buffer layer by epitaxial growth. A 3C-SiC or GaN semiconductor, wherein the layer and the main layer form a multilayer structure formed by epitaxial growth.
[0013]
(6) The 3C-SiC or GaN semiconductor described above, wherein the buffer layer is formed of a single material of an organic metal, and the main layer is formed of two types of materials. Production method.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention selects an organometallic raw material of SiC or GaN as a suitable substance which does not cause the roughening of the Si substrate, thereby forming an epitaxially grown film, and forming the epitaxially grown film on a multilayer (two-layer) comprising a buffer layer and a main body layer. Above).
[0015]
First, a method for manufacturing a SiC semiconductor will be described.
[0016]
A typical example of the organometallic raw material used for the SiC film formation is monomethylsilane (CH ₃ SiH ₃ ). Monomethylsilane already has a Si-C bond. Therefore, monomethylsilane is a convenient raw material for forming a SiC film.
[0017]
Normally, when performing heteroepitaxial growth of 3C—SiC on a Si substrate, it is necessary to carbonize the substrate in advance. This is to alleviate the lattice mismatch between Si and SiC.
[0018]
However, when monomethylsilane is used as a raw material, 3C—SiC can be heteroepitaxially grown on a Si substrate at a relatively low temperature of 1000 ° C. or less. However, even when the temperature is lower than 1000 ° C., if heteroepitaxial growth is performed at a temperature higher than 900 ° C., polycrystallization tends to occur. If the growth is performed at a relatively low temperature, the growth rate tends to be slow. Typically, the growth rate is 1 μm / h. This results in poor production efficiency.
[0019]
In growing 3C-SiC, SiH ₄ or SiH ₂ Cl ₂ is used as a Si source, and C ₂ H ₂ or C ₃ H ₈ is used as a C source. The growth temperature is 1000 ° C. or more, and the growth rate is 1 μm / h or more. Then, a single crystal is obtained by growing in a C-rich state. In the case of Si-rich, polycrystallization may occur.
[0020]
Since monomethylsilane has a 1: 1 ratio of Si and C, raising the growth temperature to increase the growth rate is disadvantageous in obtaining a single crystal.
[0021]
Thus, a 3C-SiC layer is formed on a Si substrate at a relatively low temperature of 900 ° C. or less with a thickness of about 1 μm or less using monomethylsilane as a raw material, and first, a buffer layer is formed. Thereafter, a 3C-SiC crystal is grown relatively quickly at 1000 ° C. or higher using SiH ₄ or SiH ₂ Cl ₂ and C ₃ H ₈ or C ₂ H ₂ to form a main body layer. Thus, it is preferable to increase the production efficiency.
[0022]
Next, a method for manufacturing a GaN semiconductor will be described.
[0023]
Representative examples of organometallic raw materials used for GaN film formation include trimethylgallium and ammonia or monomethylhydrazine.
[0024]
When diethyl gallium azide (C ₂ H ₅ ) ₂ GaN ₃ having a Ga—N bond in a molecular structure is used as a raw material, GaN can be heteroepitaxially grown on a Si substrate at a relatively low temperature of 800 ° C. or less. It is possible. However, even when the temperature is 800 ° C. or less, polycrystallization tends to occur when heteroepitaxial growth is performed at a temperature higher than 700 ° C. Since the growth is performed at a relatively low temperature, the growth rate is low. Typically, the growth rate is 1 μm / h. This results in poor production efficiency.
[0025]
Normally, for the growth of GaN, trimethylgallium “(CH ₃ ) ₃ Ga” or the like is used as a Ga source, and ammonia “NH ₃ ”, monomethylhydrazine “CH ₃ NHNH ₂ ” or the like is used as an N source. The growth temperature is 800 ° C. or more, and the growth rate is 1 μm / h or more. Then, a single crystal is obtained by growing in an N-rich state. In the case of Ga-rich, polycrystallization may occur.
[0026]
Therefore, first, a buffer layer is formed by providing a GaN layer with a thickness of about 1 μm or less on a Si substrate at a relatively low temperature of 700 ° C. or less using diethyl gallium azide as a raw material. Thereafter, a crystal of GaN is grown relatively rapidly at 800 ° C. or higher using trimethylgallium and ammonia or monomethylhydrazine to form a main body layer. Thus, it is preferable to increase the production efficiency.
[0027]
【Example】
FIG. 1A shows an example of a procedure for manufacturing a 3C-SiC semiconductor according to the present invention, and FIG. 1B shows an example of a procedure for manufacturing a GaN semiconductor according to the present invention. In the embodiment of FIG. 1, the thickness of the substrate 1, the buffer layer 2, and the main body layer 3 are 0.7 mm, 500 nm, and 5 μm, respectively, in both cases (A) and (B). The relative thicknesses of the substrate 1, buffer layer 2 and body layer 3 shown in FIG. 1 are not accurate.
[0028]
Each of the 3C-SiC semiconductor shown at the bottom of FIG. 1A and the GaN semiconductor shown at the bottom of B has an epitaxially grown film formed on the Si substrate 1, and this epitaxially grown film is 3C-SiC. Or, it has a multilayer structure of the buffer layer 2 and the main body layer 3 made of GaN. Since the Si substrate 1 is not carbonized, no holes are generated in the substrate 1 and there is no roughness. Therefore, the good crystallinity of the substrate 1 without roughness is successfully inherited by the buffer layer 2. Further, the main layer 3 also inherits the good crystallinity of the buffer layer 2.
[0029]
The buffer layer 2 is a film formed by epitaxial growth at a relatively low temperature and at a low speed, and has a structural characteristic that the buffer layer 2 is distorted including amorphous because it is directly grown on Si having a different lattice constant. .
[0030]
The main body layer 3 is a film formed by epitaxial growth at a relatively high temperature and at a high speed, and its structural feature is that the buffer layer surface is already in a lattice-relaxed state and thus has no distortion. It is.
[0031]
As described above, when the buffer layer 2 is interposed between the Si substrate 1 and the main layer 3 of 3C-SiC or GaN, the lattice mismatch between the Si that becomes the substrate 1 and the main body layer 3 to be grown thereon is formed. Crystal defects due to differences in lattice constant and lattice constant are effectively suppressed by the buffer action of the buffer layer 2. When the buffer layer is 3C-SiC, the main body layer may be GaN, and when the buffer layer is GaN, the main body layer may be 3C-SiC.
[0032]
Hereinafter, Examples 1 and 2 of the present invention will be specifically described.
[0033]
<Example 1>
An example of manufacturing a 3C-SiC semiconductor will be described.
[0034]
(1) The natural oxide film on the substrate surface is removed by heating the substrate Si (100) in a hydrogen atmosphere at a temperature of 1000 ° C. or higher.
[0035]
(2) Monomethylsilane is flowed into the reaction tube as the first source gas, and a 3C-SiC layer is formed as a buffer layer on the substrate at a temperature of about 500 to 900 ° C. and a growth rate of about 0.1 to 1 μm / h. The buffer layer is formed by growing with a thickness.
[0036]
(3) At the end of the growth of the buffer layer, the supply of the first source gas is stopped, and the temperature is raised to 1000 to 1300 ° C.
[0037]
(4) When the growth temperature reaches 1000 to 1300 ° C., supply of SiH ₄ gas and C ₃ H ₈ gas as the second source gas is started, and the required film thickness is reduced to 3C at a rate of about 1 to 15 μm / h. -Crystal growth of the SiC layer is performed to form a main body layer.
[0038]
<Example 2>
An example of manufacturing a GaN semiconductor will be described.
[0039]
(1) The natural oxide film on the substrate surface is removed by heating the substrate Si (100) in a hydrogen atmosphere at a temperature of 1000 ° C. or higher.
[0040]
(2) Diethyl gallium azide is flowed into the reaction tube as the first source gas, and a GaN layer is formed as a buffer layer on the substrate at a temperature of about 300 to 700 ° C. and a growth rate of 0.1-1 μm / h and a thickness of about 500 nm or less. To form a buffer layer.
[0041]
(3) At the end of the growth of the buffer layer, the supply of the first source gas is stopped, and the temperature is raised to 1000 to 1300 ° C.
[0042]
(4) When the growth temperature reaches 1000 to 1300 ° C., supply of trimethylgallium and ammonia or monomethylhydrazine is started as the second source gas, and the GaN layer is grown to a required thickness at a rate of about 1 to 15 μm / h. Crystal growth is performed to form a main body layer.
[0043]
【The invention's effect】
The 3C-SiC semiconductor and the GaN semiconductor according to the present invention can prevent the substrate from being roughened, and can suppress misfit dislocation due to lattice defects as compared with the case where the main layer of the epitaxial growth film is directly grown without the low-temperature buffer layer. Therefore, high quality crystals can be obtained.
[Brief description of the drawings]
FIGS. 1A and 1B are longitudinal sectional views showing, in an enlarged scale, a manufacturing procedure of a Si substrate, a buffer layer and a main body layer of a 3C-SiC semiconductor and a GaN semiconductor manufactured by one preferred method of the present invention. Area view. The relative relationship between the thicknesses of the Si substrate, the buffer layer, and the body layer is not accurate.
[Explanation of symbols]
1 substrate 2 buffer layer 3 body layer

Claims (6)

When epitaxially growing 3C-SiC or GaN on a Si substrate, by changing both or one of the temperature and the speed of the epitaxial growth, first a buffer layer of SiC or GaN is epitaxially grown, and then a main layer of SiC or GaN is formed. A method for producing a 3C-SiC semiconductor or a GaN semiconductor, comprising epitaxially growing. The method for producing a 3C-SiC semiconductor or a GaN semiconductor according to claim 1, wherein the buffer layer is epitaxially grown at a relatively low temperature and at a low speed, and the main body layer is epitaxially grown at a relatively high temperature and at a high speed. . The 3C-SiC semiconductor according to claim 1 or 2, wherein the SiC buffer layer is epitaxially grown at a temperature of 500 to 900 ° C and at a rate of 0.1 to 1 µm / h, or at a temperature of 300 to 700 ° C. 3. The method according to claim 1, wherein the GaN buffer layer is epitaxially grown at a rate of 0.1 to 1 [mu] m / h. The 3C-SiC semiconductor according to any one of claims 1 to 3, wherein the main body layer is epitaxially grown at a temperature of 1000 to 1300C and at a rate of 1 to 15 m / h. The method for producing a GaN semiconductor according to claim 1, wherein the epitaxial growth is performed at a temperature of 1100 ° C. and at a rate of 1 to 15 μm / h. An Si substrate, a buffer layer of 3C-SiC or GaN formed on the Si substrate by epitaxial growth, and a main layer of 3C-SiC or GaN formed on the buffer layer by epitaxial growth. A 3C-SiC or GaN semiconductor, wherein the layers constitute a multilayer structure formed by epitaxial growth. The 3C-SiC semiconductor or the GaN semiconductor according to claim 4, wherein the buffer layer is formed of a single organic metal material, and the main body layer is formed of two types of raw materials. Manufacturing method.

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