JPH03252175A - Manufacture of gallium nitride compound semiconductor - Google Patents

Abstract

PURPOSE:To obtain an N-type GaN compound semiconductor in which its resistivity can be controlled by controlling mixture ratio of gas containing silicon to other raw gas. CONSTITUTION:A sapphire board 1 is vapor etched, an AlN buffer layer 2 is formed, a high carrier concentration layer 3 made of GaN is formed, and then an N<+> type low carrier concentration layer 4 made of GaN is formed. When the layer 3 is formed by vapor growth, H2, NH3 as other raw gas and H2 in which TMG held at -25 deg.C are bubbled are fed to control flow rate of silane (SiH4) gas diluted with H2 is controlled as gas containing silicon.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for manufacturing an N-type gallium nitride-based compound semiconductor with controlled conductivity, and is particularly effective in improving the luminous efficiency of a blue-emitting gallium nitride-based compound semiconductor light-emitting device.

[Prior art]

Conventionally, a GaN-based compound semiconductor has been used for blue light emitting diodes. The GaN-based compound semiconductor is attracting attention because it has high luminous efficiency due to direct transition, and because it emits blue light, which is one of the three primary colors of light. A light emitting diode using such a GaN-based compound semiconductor is produced by growing an N layer made of an N-type GaN-based compound semiconductor on a sapphire substrate directly or with a buffer layer made of aluminum nitride interposed therebetween. P on top of the layer
It has a structure in which a single layer of I-type GaN-based compound semiconductor is grown by adding type impurities (Japanese Unexamined Patent Publication No. 1983-1999).
119196, JP-A-63-188977).

[Problem to be solved by the invention]

When manufacturing a light emitting diode with the above structure, one layer and N
Bonding with layers is used. When manufacturing a GaN-based compound semiconductor,
Normally, even without intentionally doping impurities, the G
aN-based compound semiconductors have N conductivity type, and on the other hand, unlike semiconductors such as silicon, l (In5ulator)
To obtain a type of semiconductor, it was doped with zinc. Also, N
When obtaining type GaN, it has been difficult to control its conductivity. However, in the process of manufacturing the above-mentioned GaN light emitting diode, the present inventor has established a vapor phase growth technique for GaN semiconductor using organometallic compound vapor phase epitaxy, and it has become possible to obtain a high-purity GaN vapor phase growth film. did it. As a result, N-type GaN with low resistivity was conventionally obtained without doping with impurities, but with the establishment of vapor phase growth technology by the present inventors, N-type GaN with high resistivity was obtained without doping with impurities. type GaN was obtained. On the other hand, in the future, in order to improve the characteristics of the GaN light emitting diode mentioned above, it is necessary to use N-type G, whose conductivity can be controlled intentionally.
It has become necessary to obtain a vapor-phase grown film of an aN-based compound semiconductor. Therefore, an object of the present invention is to establish a manufacturing technique for an N-type GaN-based compound semiconductor whose resistivity can be controlled.

[Means to solve the problem]

The present invention is a method for manufacturing a gallium nitride-based compound semiconductor (AIlxGa+-xN; containing X=O) by an organometallic compound vapor phase epitaxy method. In the phase growth process, an N-type gallium nitride compound semiconductor (including X=0 in AlxGa+-) with controlled conductivity is produced by controlling the mixing ratio of silicon-containing gas and other raw material gases. It is characterized by obtaining.

[Operation and effects of the invention]

In the present invention, in the vapor phase growth process of a gallium nitride-based compound semiconductor, a gas containing silicon and other raw material gases are simultaneously flowed, and the mixing ratio of both gases is controlled. As a result, silicon is incorporated into the vapor-grown film of the gallium nitride-based compound semiconductor, and the silicon acts as a donor. The conductivity of the N-type vapor phase grown film can be changed by controlling the mixing ratio of the silicon-containing gas and other source gases.

【Example】

The present invention will be described below based on specific examples. A light emitting diode 10 having the structure shown in FIG. 1 was manufactured using the manufacturing method of the present invention. In FIG. 1, a light emitting diode 10 has a sapphire substrate 1, and 500 A
An IN buffer layer 2 is formed. On top of the buffer layer 2, G
High carrier concentration N+ layer 3 made of aN and a film thickness of 1.5μ
A low carrier concentration N layer 4 made of GaN of s is formed. Furthermore, on the low carrier concentration N layer 4, a film with a thickness of 0.2
One layer 5 made of 4 GaN is formed. and,
An electrode 7 made of aluminum connected to the first layer 5 and an electrode 8 made of aluminum connected to the high carrier concentration N+ layer 3 are formed. Next, a method for manufacturing the light emitting diode 10 having this structure will be described. The light emitting diode 10 was manufactured by vapor phase growth using an organometallic compound vapor phase epitaxy method (hereinafter referred to as rMOVPE J). The gases used were NH3, carrier-poor H2, and trimethyl gallium (Ga(CHs)s) (hereinafter referred to as rTMGJ).
) and trimethylaluminum (At(cns)s
) (hereinafter referred to as rTMAJ), silane (SiH, ), and diethylzinc (hereinafter referred to as rDEZJ). First, a single-crystal sapphire substrate 1 having an a-plane main surface that has been cleaned by organic cleaning and heat treatment is mounted on a susceptor placed in a reaction chamber of a MOVPE apparatus. Next, while flowing H2 into the reaction chamber at a flow rate of 2 A/min, a temperature of 1
The sapphire substrate 1 was subjected to vapor phase etching at 200° C. for 10 minutes. Next, the temperature was lowered to 400°C and the H2 flow rate was 20°C.
1/min, NH5 flow rate 1o1/min, T maintained at 15°C
H2 bubbled with MA was supplied at a rate of 50 cc/min to form a buffer layer 2 of AIN to a thickness of approximately 500 mm. Next, the supply of TMA is stopped, the temperature of the sapphire substrate 1 is maintained at 1150°C, and 2 is set to 201! /min, NH as other raw material gas at 101/min, and H2 bubbled with TMG kept at -15°C at 100 cc1.
0.86p with H2 as a gas containing silicon.
Silane (SiH4) diluted to pm at 200mf/
Flowing for 30 minutes, film thickness 2.2 m, carrier concentration 1
．． A high carrier concentration 81 layer 3 made of GaN of 5×101=/cIIl was formed. Subsequently, the temperature of the sapphire substrate 1 was maintained at 1150°C, and 100 cc of H3 was bubbled with TMG held at -15°C at 201/min of H2 and 101/min of NH6.
/min for 20 minutes to form a low carrier concentration N layer 4 made of GaN with a film thickness of 1.5 m1 and a carrier concentration of lXl0"/cl or less. Next, the sapphire substrate 1 was heated to 900°C and heated with H2 20
1/min, NH, 101/min, TMG 1.7X10-
One layer 5 of GaN having a thickness of 0.2 mm was formed by supplying DEZ at a rate of 1.5 x 10 -'-t mol/min. In this way, a multilayer structure as shown in FIG. 2 was obtained. Next, as shown in FIG. 3, a 5iO=layer 11 with a thickness of 2,000 layers was formed on the layer 5 by sputtering. Next, a photoresist 12 is applied on the 5th layer 02 layer 11.
was coated, and the photoresist 12 was formed into a pattern by removing the photoresist at the electrode formation site for the high carrier concentration N layer 3 using a photorin graph. Next, as shown in FIG. 4, the SiO□ layer 11 not covered with the photoresist 12 was removed using a hydrofluoric acid etching solution. Next, as shown in FIG.
1 layer 5 in a portion not covered by the iOa layer 11, a low carrier concentration N layer 4 below it, and a high carrier concentration N'' layer 3
A part of the upper surface of the
．． 44W/cat, CCf2F, gas was supplied at a rate of 10 d/min for dry etching, and then dry etching was performed at 8[deg.]. Next, as shown in FIG.
02 layer 11 was removed with hydrofluoric acid. Next, as shown in FIG.
was formed by vapor deposition. Then, a photoresist 14 is coated on the A1 layer 13, and the photoresist 14 is formed into a high carrier concentration 81 layer 3 by photolithography.
Then, a pattern was formed in a predetermined shape so that an electrode portion for one layer 5 remained. Next, as shown in FIG. 7, using the photoresist 14 as a mask, the exposed portion of the lower A1 layer 13 is etched with a nitric acid-based etching solution, and the photoresist 14 is removed with acetone, and the high carrier concentration 81 layer is etched. 3 electrode 8.1 layer 5 electrode 7 was formed. In this way, the old S (Meta
l-1nsulator-Semiconductor
) structure can be manufactured. In the above manufacturing process, when the high carrier concentration N'' layer 3 is grown in a vapor phase, H2 is bubbled for 2017 minutes, NH as another raw material gas is bubbled for 101 minutes, and TMG maintained at -15°C is bubbled. H2 was flowed at 100cc/min, and silane (SiH4) diluted to 0.86 ppm with H2 was flowed as a silicon-containing gas at 10cc/min to 300cc.
By controlling within the range of c7 minutes, high carrier concentration N
The resistivity of layer 3 is 3X10 as shown in FIG.
-'Ω 4 to 8X 10-'' The resistivity may be changed by controlling the ratio. In addition, although silane was used as the Si dopant material in this example, an organic compound containing Si such as tetraethylsilane (S r (C2H5) 4) may be used with H2. Bubbling gas may also be used. In this way, the high carrier concentration N4 layer 3 and the low carrier concentration N layer 4 could be formed in a state where the resistivity could be controlled. As a result, the above method Manufactured light emitting diode 10
The 0 emission intensity is Q, 2mcd, and the conventional single layer and N
The luminous intensity was four times higher than that of a light emitting diode composed of two layers. Furthermore, when the light emitting surface was observed, it was also observed that the number of light emitting points was increasing.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the structure of a light emitting diode according to a specific embodiment of the present invention, FIGS. 2 to 7 are cross-sectional views showing the manufacturing process of the light emitting diode of the same embodiment, and FIG. The figure is a measurement diagram showing the relationship between the flow rate of silane gas and the electrical characteristics of the N layer grown in a vapor phase. 10 Light emitting diode 1゛Sapphire substrate 2 Buffer layer 3-゛High carrier concentration N layer 4゛Low carrier concentration N layer 5-4 layer 7.8 Electrode

Claims (1)

[Claims] Gallium nitride-based compound semiconductor by organometallic compound vapor phase growth method (Al_xGa_1_-_xN; including X=0)
In the process of vapor phase growth by flowing a silicon-containing gas simultaneously with other raw material gases, the conductivity is increased by controlling the mixing ratio of the silicon-containing gas and the other raw material gases. controlled N-type gallium nitride compound semiconductor (Al_xGa_1_-_x
A manufacturing method characterized by obtaining a vapor-phase grown film of N; including X=0).