JPH0380197A - Production of single crystal of semiconductor sic - Google Patents

Abstract

PURPOSE:To easily obtain the doped single crystal of semiconductor SiC by introducing a doping element into the system and doping the this element into an SiC crystal at the time of using SiO2 and C as raw materials and producing the single crystal of the SiC by a CVD method. CONSTITUTION:A high-temp. part 2 and a low-temp. part 3 are provided in a reaction vessel 1. A vessel 5 contg. a mixture 4 formed by mixing the raw materials SiO2 and C at about equal molar ratio is disposed in the high-temp. part 2 and a base material 6 is disposed in the low temp. part 3. The compd. (e.g. B4C, Si3N4) contg. the element (e.g. B, N) to be doped is added into the raw material SiO2. After a high vacuum is maintained in the reaction vessel 1, the high-temp. part 1 is heated to about 1700 to 2000 deg.C and the low-temp. part 3 to about 1600 to 1800 deg.C. The gas 7 generated from the high-temp. part 1 is allowed to arrive at the base material 6 to deposit the doped single crystal of the semiconductor SiC on the surface of the base material 6. The doping of various kinds of dopants is possible in this way.

Description

[Detailed description of the invention] [Industrial use! I! [The present invention relates to a method of manufacturing a semiconductor SiC single crystal used for LEDs (visible light emitting diode 1"), ICs, etc. by doping ('1') epitaxial growth using the CVD method.

[Conventional technology]

Conventionally, methods for obtaining doped SiC single crystals include sublimation of SiC on the surface of a claw-shaped crystal of hexagonal SiC synthesized by the Acheson method, or e.g. Method for epitaxially growing SiC using M (JP-A-1108200 Schiff et al.)-1
133998, or SiC on the Si single crystal surface.
A method of growing in a superlattice structure (+988, Autumn Society of Applied Physics, Proceedings, 61)-Z-11) is known.

[Invention or problem to be solved]

However, in the former case, SiC nail-shaped crystals must be used as the base material for the hair. by the way,
It is difficult to produce these nail-shaped crystals with good reproducibility.
The size is about 1 cm, which not only makes it impossible to make large pieces, but also makes it difficult to handle due to the ability to open the arms, and the latter has problems such as the process being complicated and requiring time and effort.

The inventors of the present invention have conducted extensive research to solve the problems mentioned in 2.1 and to find a method that can easily produce semiconductor SIC single crystals with good reproducibility. 611. /II+, 2+1 Yariya, and SL cubic 3C type, each with a forbidden band width of 2 to 3 eV (Band G
ap), so! -I thought it would be possible to use epitaph growth with pigs as an excuse.

The invention is based on the above idea, and therefore provides a method for producing a semiconductor SiC single crystal in which hexagonal or cubic SiC is intentionally produced with good reproducibility, and doping is performed during production. The purpose is to

[Means to solve the problem]

In order to achieve the above object, in the method of the present invention, using 5in2 and C as raw materials, SC
When producing a single crystal, a 1-Pick element is introduced into the system and doped into the SiC crystal.

The CVD method used in the present invention uses Sin as a raw material.

This is a method according to the following reaction formula, in which a mixture of SiC and C is formed into a scum and precipitated as SiC on a substrate.

Casing reaction in the high temperature section S io, -1-c->s i○lCO Precipitation reaction in the low temperature section is 5iO-1-2C->5i when the base material is carbon
Whether the C-1-C0 reaction mainly occurs or because SiC is produced even if the base material is not carbon, the CO gas produced at the high temperature part is fI (2C (1>CI Co at the high part).

As a result, C precipitates out, which results in 2Si○+2C→2SiC+02 It is assumed that this reaction is also occurring.

The raw material Sin is Sin for optical fiber.

By using high-purity graphite as a C source, high-purity SiC can be precipitated at the station.

FIG. 1 shows an example of a reaction apparatus used in the method of misfire 11JJ, and the reference numeral 1 in the figure is a reaction vessel.

The reaction vessel 1 consists of a high temperature section (cassation section) 2 and a low temperature section (precipitation section) 3, which are heated from the outside.

A graphite container 5 containing a mixture 4 obtained by combining raw materials Si○2 and C at a molar ratio of 11±05 is arranged in the Jl high vortex part 2, and a graphite container 5 containing a mixture 4 in which raw materials Si○2 and C are combined at a molar ratio of 11±05 is placed, and in the low temperature part 3, Sl○ scum is placed. The base material 6 is supported and placed by a support stand or a support rod 6a at a position determined depending on the flow, altitude, waste concentration, etc.

After that, the inside of the reaction volume a'rs I was set to 0. ] ~l O
While reducing the pressure to Torr, the Hatake 1iA section 2 was heated to 170 Torr.
0~2000°C1 low vortex part 3, 1600~1800°
When heated to C, Jj sufu generated from high temperature section 2 becomes L
(The material 6 is reached and SiC is deposited on the surface.

The crystal system that is generated becomes a hole depending on the temperature of the precipitation part 3,]
In the case of 600 to 1800°C, it becomes cubic system 3C, and in the case of 1800 to 2000°C, it becomes hexagonal system, 6H
14H12+-1, 21 shaku, etc. are generated in large numbers.

These crystals each have a different BandGap, for example, 3C has a band gap of 2.2 eV, 61-1 has a band gap of 2.86 eV,
2I] is 3.3 eV. For blue LED, the B and Gap needs to be around 2.8eV, so
The city where the crystal having this has priority is important, and the required BandGap can be prioritized by temperature adjustment.

” 1. As the base material 6, graphite or already produced Si
C single crystal is used.

When graphite is used as the base material 6, the epitaxial layer grows parallel to the surface of the base material because it grows in a 5iC11i shape with a diameter of 05 to 1 mm.

Therefore, after removing the graphite base material, the precipitated portion may be cut.

Further, when an existing SiC single crystal is used as the base material 6, the crystal grows on each side in the direction of increasing the diameter of the crystal. Therefore, it is advantageous to cut out and use the SiC that will become the base material 6 so that a large amount of the surface can be removed.

Further, in order to perform doping, a compound which is a high-performance 11-point compound and does not contain any elements that cause disturbance during doping is added to the raw material S]02.

For example, in the P type, B, A&, Ca, etc. are 1-pulled, but in this case, B, CXA LC, CaClB
, H6 is added to the raw material 5iO-, and in the n-type, N
, P, etc. or Si, H4, PH,, NH3. At this time, P I-1, etc. may be supplied in gaseous form into the reaction vessel 1 from the outside.

Also, in the case of a p-n junction, is it necessary to switch between 1 and - bands, or is it necessary to change the scum formation rate to lj7+i?
j and the previous 1・-bread l-/l)? After i'i is lost, the next 1-Punt is added S i Op to high/! 51 parts, or add the following 1.-Bread I. or Sin, and C prepared separately in advance.
This may be done by replacing the graphite container containing the 7iiA compound.

``The dopant of the above dopant is usually 1017~10'' atoms/cc or added to the raw material;/
By adjusting the amount of s+1-1-compound, the doping level can be freely adjusted.

〔Example〕

Next, the present invention will be explained with reference to Examples.

Example 1 Using the apparatus shown in Fig. 1, the size of approximately Q
, 5 mm single crystal SiC grains were arranged on a graphite base material with a gap of about 2 to 3 mm between grains, and the purity was 99.9 mm.
5102500g of 999% or more, 500g of C and Si○ as a dopant, Q, 1wt% of 51
The raw material to which 3N4 was added was stored in a graphite container and used.

The inside of the reaction vessel was maintained at 0.2 Torr, the temperature of the casing part was 2000°C, the temperature of the precipitation part was 1900'C,
An approximately 50 μm hexagonal epitaxial growth layer was obtained as the epitaxial growth interlayer 511r, and the conductivity and the like of this precipitate were measured.

Example 2 A hexagonal growth layer of 50 μm was obtained in the same manner as in Example 1, except that 0.05 wt% B4C was used instead of Si3N as the dopant added to the raw material, and the conductivity etc. It was measured.

Example 3 The dopant added to the raw material was 513N- instead of 513N-.
A 50 μm hexagonal SiC epitaxial long layer was obtained in the same manner as in Example 1 except that AQ4C3 containing 1 wt% of O and IO2 was used, and its conductivity and the like were measured.

Example 4 Q, 1 wt% 5 for SiO2, C and Si○
13N+ added raw material stored in a graphite container,
5107, Q for C and Sin, 1 wt% B
, stored in a graphite container doped with C, were prepared in advance, and first, Si3N4 was prepared as 1-17XH71~2,5
Perform hr epitaaxial growth, and then perform the following 1. ) The same method as in Example 1 except that epitaxial growth was performed for 2.5 hours on 3°C 1''-pan 1.
A hexagonal growth layer was obtained.

This grown layer was measured by electron spectroscopy (AES), and it was confirmed that the first half of the deposition contained N and the second half contained 4'' of B.

Example 5 Using the apparatus shown in Fig. 1, a 5 cm square, 5 mm thick high-purity graphite (ash content: Oppm or less) was used as the system material, and the temperature of the precipitation part was 17.
The same process as in Example 2 was carried out except that the temperature was 00°C, a cubic crystal growth layer was obtained, and the conductivity etc. were determined as H1l+.

A summary of the results of Examples 1 to 5 is shown in Table 1.

Table [Effects of the Invention] As described above, the method of the present invention allows easy doping of various dopants using CVDK using SiO2.C as a raw material, and facilitates the production of semiconductor SiC single crystals. I can do it.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of an apparatus for carrying out the method of the present invention. 1. Reaction container, 2. Takabatake part (casing part), 3 low n1 part (precipitated part) 11s compound (S ○2-1 C) 5. Graphite container, L (material, a support joint or support rod, generated from a high temperature part)J

Claims (2)

[Claims] (1) Production of a semiconductor SiC single crystal characterized by introducing a doping element into the system and doping it into the SiC crystal when producing the SiC single crystal by the CVD method using SiO_2 and C as raw materials. Law. (2) The method for producing a semiconductor SiC single crystal according to claim (1), wherein the doping element is a group III or group V element.