JP2004273822A - GaN SEMICONDUCTOR AND ITS MANUFACTURING METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a GaN semiconductor that can be suppressed in crystal defect to such a degree that the semiconductor can be used for electronic devices. <P>SOLUTION: In the GaN semiconductor, a single-crystal c-GaN film 5 having a thickness of about 1-10 μm is formed on a single-crystal Si substrate 1 through a single-crystal c-BP layer 3 having a thickness of about 50 nm to 1 μm and a single-crystal GaP layer 4 having a thickness of about 1-10 nm in this order. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is superior to a semiconductor function as compared with Si (silicon), is composed of a single crystal film formed on a Si single crystal substrate, and is used for a short wavelength LED (light emitting diode), a short wavelength LD (laser diode), and the like. The present invention relates to a GaN (potassium nitride) semiconductor and a method for manufacturing the same.
[0002]
[Prior art]
Conventionally, as a GaN semiconductor of this type, a c-BP (cubic boron phosphide) single crystal layer is interposed as a buffer layer for relaxing lattice mismatch between Si and GaN on a Si single crystal substrate. One in which a cubic gallium nitride) single crystal film is formed is disclosed (for example, see Patent Documents 1 and 2).
[0003]
[Patent Document 1]
JP 2000-349335 A
[Patent Document 2]
JP-A-2000-351592
Here, c-BP has a lattice constant (4.538 angstroms) which is mismatched by 16.4% as compared with that of Si (5.431 angstroms). And a mismatch of only 0.6% with the lattice constant of c-GaN (4.52 angstroms).
Therefore, it is considered that a c-GaN single crystal film having a close lattice constant can be grown by using c-BP as the buffer layer.
[0006]
The GaN semiconductor is obtained by epitaxially growing a c-BP single crystal layer on a Si single crystal substrate at a temperature of 900 to 1150 ° C. to a thickness of about 5 μm, and then forming a temperature of 700 to 1100 ° C. on the c-BP single crystal layer. This is manufactured by epitaxially growing a c-GaN single crystal film to a thickness of about 4 μm.
[0007]
[Problems to be solved by the invention]
However, in a conventional GaN semiconductor, a c-GaN single crystal film in which defects are suppressed to such an extent that it can be used for an electronic device has not been obtained.
The reason for this is considered to be that the ionicity of c-BP is as low as 0.006, whereas that of c-GaN is relatively high at 0.5, which is a difference (polarity mismatch) between the two. .
[0008]
Therefore, an object of the present invention is to provide a GaN semiconductor which can be suppressed to crystal defects to such an extent that it can be used for an electronic device, and a method for manufacturing the same.
[0009]
[Means for Solving the Problems]
In order to solve the above problem, the first GaN semiconductor of the present invention includes a c-BP single crystal layer having a thickness of about 50 nm to 1 μm and a GaP single crystal layer having a thickness of about 1 to 10 nm on a Si single crystal substrate in order. A c-GaN single crystal film having a thickness of about 1 to 10 μm is formed therebetween.
[0010]
In the second GaN semiconductor, the low-temperature c-BP growth layer having a thickness of about 2 to 50 nm is interposed between the Si single crystal substrate and the c-BP single crystal layer in the first GaN semiconductor. It is characterized by the following.
[0011]
On the other hand, the first method for manufacturing a GaN semiconductor is to epitaxially grow a c-BP single crystal layer to a thickness of about 50 nm to 1 μm on a Si single crystal substrate at a temperature of 850 to 1000 ° C. A GaP single crystal layer is epitaxially grown on the layer at a temperature of 750 to 950 ° C. to a thickness of about 1 to 10 nm, and thereafter, a c-GaN single crystal film is formed on the GaP single crystal layer at a temperature of 700 to 900 ° C. It is characterized by epitaxially growing to a thickness of about 10 to 10 μm.
[0012]
Further, the second method for manufacturing a GaN semiconductor is the same as the first method, except that the c-BP is grown at a temperature of 350 to 450 ° C. on the Si single crystal substrate at a low temperature before the epitaxial growth of the c-BP single crystal layer. The layer is deposited to a thickness of the order of 2 to 50 nm.
[0013]
[Action]
In the first GaN semiconductor and the method of manufacturing the same according to the present invention, GaP (gallium phosphide) single having a relatively high ionicity of 0.32 is provided between the c-BP single crystal layer and the c-GaN single crystal film. A crystal layer is interposed.
[0014]
In addition, in the second GaN semiconductor and the method of manufacturing the same, the crystal defects of the c-BP single crystal layer, and thus the GaP single crystal layer and the c-GaN single crystal film, are reduced in addition to the actions of the first one and the method. You.
[0015]
If the thickness of the c-BP single crystal layer is less than 50 nm, the influence of the lattice of Si cannot be canceled. On the other hand, if it exceeds 1 μm, the surface of the C-BP single crystal layer becomes rough.
The thickness of the c-BP single crystal layer is preferably from 80 to 800 nm.
If the thickness of the GaP single crystal layer is less than 1 nm, the ionic effect of GaP is not clear. On the other hand, if it exceeds 10 nm, a lattice mismatch with the c-GaN single crystal occurs.
The thickness of the GaP single crystal layer is preferably from 1 to 4 nm.
If the thickness of the GaN single crystal layer is less than 1 μm, it may not function as a device. The thickness may be sufficient, but if it exceeds 10 μm, the effect does not change even though the production takes time.
If the thickness of the low-temperature growth layer of c-BP (formed at a temperature at which no crystal grows) is less than 2 nm, the crystal growth layer becomes polycrystalline. On the other hand, if it exceeds 50 nm, the crystallinity of the crystal growth layer decreases.
The thickness of the low-temperature growth layer of c-BP is preferably 5 to 20 nm.
[0016]
On the other hand, if the temperature at the time of epitaxial growth of the c-BP single crystal layer is lower than 850 ° C., C-BP becomes polycrystalline. On the other hand, when the temperature exceeds 1000 ° C., it is no longer cubic.
The temperature during the epitaxial growth of the c-BP single crystal layer is preferably 900 to 950 ° C.
B ₂ H ₆ (diborane) and PH ₃ (phosphine) are used as raw materials for epitaxial growth of the c-BP single crystal layer.
If the temperature at the time of epitaxial growth of the GaP single crystal layer is lower than 750 ° C., polycrystallization occurs. On the other hand, when the temperature exceeds 950 ° C., polycrystallization occurs.
The temperature during the epitaxial growth of the GaP single crystal layer is preferably from 780 to 920 ° C.
As raw materials for epitaxial growth of the GaP single crystal layer, Ga (CH ₃ ) ₃ (trimethylgallium) and PH ₃ are used.
When the temperature at the time of epitaxial growth of the c-GaN single crystal film is lower than 700 ° C., the film becomes polycrystalline. On the other hand, when it exceeds 900 ° C., it becomes a wurtzite type.
The temperature during the epitaxial growth of the c-GaN single crystal film is preferably from 720 to 900C.
The raw material for the epitaxial growth of c-GaN single crystal film, Ga _{(CH 3)} 3 and _(CH 3) NHNH _{2 (monomethyl} hydrazine) is used.
If the temperature at the time of epitaxial growth of the low-temperature growth layer of c-BP is lower than 350 ° C., the surface of the c-BP single crystal layer becomes rough. On the other hand, when the temperature exceeds 450 ° C., the surface of the c-BP single crystal layer similarly becomes rough.
The temperature at the time of epitaxial growth of the low-temperature growth layer of c-BP is preferably 380 to 420C.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a conceptual sectional view showing an example of an embodiment of a GaN semiconductor according to the present invention.
[0018]
This GaN semiconductor is formed on a (100) Si single crystal substrate 1 at a low temperature growth layer 2 of c-BP having a thickness of about 2 to 50 nm, a c-BP single crystal layer 3 having a thickness of about 50 nm to 1 μm, and a thickness A c-GaN single crystal film 5 having a thickness of about 1 to 10 μm is formed with a GaP single crystal layer 4 of about 1 to 10 nm interposed therebetween in order.
[0019]
In the GaN semiconductor, a GaP single crystal film having a relatively high ionicity of 0.32 is interposed between the c-BP single crystal layer and the c-GaN single crystal film, and a c-BP single crystal film is formed. The crystal defects of the layers, that is, the GaP single crystal layer and the c-GaN single crystal film are reduced.
[0020]
In order to manufacture the above-described GaN semiconductor, first, the natural oxide film was removed by heating the (100) plane Si single crystal substrate 1 in an H ₂ (hydrogen gas) atmosphere at a temperature of 1000 ° C. or more (FIG. 2 (a)).
Next, in order to provide a low-temperature growth layer 2 of c-BP, was lowered to 350 to 450 ° C., supplying PH ₃ to the partial pressure of PH ₃ is greater than or equal to 1 Torr, _and, PH 3 / _{B 2} B ₂ H ₆ was supplied so that the supply ratio of H ₆ became 100 or more, and the low-temperature growth layer 2 of c-BP was deposited to a thickness of about 2 to 50 nm (see FIG. 2B).
Next, the supply of B ₂ H _{6 is} temporarily stopped, and the temperature is raised to about 850 to 1000 ° C., which is the growth temperature of the c-BP single crystal, and then B ₂ H ₆ is supplied again to supply the c-BP single crystal layer 3. Was epitaxially grown to a thickness of about 50 nm to 1 μm, and then supply of B ₂ H ₆ was stopped (see FIG. 2C).
[0021]
Next, while maintaining the temperature at about 750 to 950 ° C., Ga (CH ₃ ) ₃ is supplied together with PH ₃ (partial pressure of 1 Torr or more) to make the GaP single crystal layer 4 to a thickness of about 1 to 10 nm. It was epitaxially grown (see FIG. 2D).
Next, the supply of Ga (CH ₃ ) ₃ and PH ₃ is stopped, and after the temperature is increased to about 700 to 900 ° C., which is the growth temperature of the c-GaN single crystal, 50% of the carrier gas is changed to N (nitrogen gas). At the same time, an organic nitrogen raw material such as Ga (CH ₃ ) ₃ and (CH ₃ ) NHNH ₂ was supplied to epitaxially grow the c-GaN single crystal film 5 to a thickness of 1 to 10 μm (see FIG. 2E). ).
[0022]
In the above-described embodiment, the case where the low-temperature growth layer of c-BP is interposed between the Si single crystal substrate and the c-BP single crystal layer has been described. However, the present invention is not limited to this. The c-BP single crystal layer may be provided directly on the Si single crystal substrate without providing the low temperature growth layer of c-BP.
[0023]
【The invention's effect】
As described above, according to the first GaN semiconductor and the method for manufacturing the same of the present invention, the ionicity between the c-BP single crystal layer and the c-GaN single crystal film is relatively high at 0.32. Since the GaP single crystal layer is interposed, not only the lattice matching between the Si single crystal substrate and the GaN single crystal film but also the polarity matching can be improved, and the crystal defects are reduced to such an extent that the GaN semiconductor can be used for an electronic device. Can be suppressed.
[0024]
Further, according to the second GaN semiconductor and the method for manufacturing the same, in addition to the effects of the first and the second methods, the crystal defects of the c-BP single crystal layer, and eventually the GaP single crystal layer and the GaN single crystal film, are reduced. Therefore, crystal defects of the GaN semiconductor can be further suppressed.
[Brief description of the drawings]
FIG. 1 is a conceptual sectional view showing an example of an embodiment of a GaN semiconductor according to the present invention.
2 (a) to 2 (e) are explanatory views showing respective steps of a method for manufacturing the GaN semiconductor of FIG. 1.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 Si single crystal substrate 2 Low temperature growth layer of c-BP 3 c-BP single crystal layer 4 GaP single crystal layer 5 GaN single crystal film

Claims (4)

A c-GaN single crystal film having a thickness of about 1 to 10 μm with a c-BP single crystal layer having a thickness of about 50 nm to 1 μm and a GaP single crystal layer having a thickness of about 1 to 10 nm interposed in this order on a Si single crystal substrate 1 A GaN semiconductor, characterized in that GaN is formed. 2. The GaN semiconductor according to claim 1, wherein a low-temperature growth layer of c-BP having a thickness of about 2 to 50 nm is interposed between the Si single crystal substrate and the c-BP single crystal layer. After a c-BP single crystal layer is epitaxially grown on a Si single crystal substrate at a temperature of 850 to 1000 ° C. to a thickness of about 50 nm to 1 μm, a GaP single crystal is formed on the c-BP single crystal layer at a temperature of 750 to 950 ° C. A crystal layer is epitaxially grown to a thickness of about 1 to 10 nm, and thereafter, a c-GaN single crystal film is epitaxially grown to a thickness of about 1 to 10 μm on a GaP single crystal layer at a temperature of 700 to 900 ° C. GaN semiconductor manufacturing method. Before the epitaxial growth of the c-BP single crystal layer, a low temperature growth layer of c-BP is deposited on the Si single crystal substrate at a temperature of 350 to 450 ° C. to a thickness of about 2 to 50 nm. Item 4. The method for producing a GaN semiconductor according to Item 3.

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