JPH06151962A - Nitrogen-iii compound semiconductor luminous element and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the luminous intensity of blue color and the crystallinity of GaN. CONSTITUTION:The title luminous element consists of a sapphire substrate 1, and a light-emitting section; the light-emitting section consists of a plurality of layers composed of nitrogen-III compound semiconductor (including AlXGaYIn1-X-YN; X=0, Y=0, X=Y=0). The luminous element includes an amorphous (AlXGa1-XN; Xnot equal to 0) buffer layer 2 with a thickness of 100Angstrom -500Angstrom formed at a temperature of 400 deg.C-800 deg.C, and the layers 3, 4 and 5 of the light- emitting section are formed on the buffer layer 2. The presence of the buffer layer 2 improves the crystallinity of GaN formed thereon, resulting in improved the luminous intensity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blue light-emitting nitrogen-group III compound semiconductor light-emitting device.

[0002]

2. Description of the Related Art Conventionally, as a blue light emitting diode, one using a GaN compound semiconductor has been known. Its GaN
Attention has been paid to the fact that the compound semiconductors of the type have high emission efficiency because they are direct transitions, and that blue, which is one of the three primary colors of light, is the emission color.

A light emitting diode using such a GaN compound semiconductor has a buffer layer made of aluminum nitride or gallium nitride on a sapphire substrate,
growing an n-layer made of n-type GaN-based compound semiconductor,
A p-type impurity is added on the n-layer to form a semi-insulating i-type
It has a structure in which an i layer made of a GaN-based compound semiconductor or a p-layer made of a p-type GaN-based compound semiconductor is grown by heat treatment or electron beam irradiation (JP-A-62-119196, JP-A-62-119196). 63-188977, JJAP Vol.30, No.12A, 199
Dec. 9, pp.L1998-L2008, JJAP Vol.31, Part2, No.2B,
February 1992, pp.L139-L142).

[0004]

However, the light emission intensity of the light emitting diode having the above structure is not yet sufficient, and improvement is desired. As a result of repeated research, the inventors of the present invention have found that a high-quality nitrogen group-3 element compound semiconductor (Al _x Ga) is formed on a sapphire substrate.
_Y In _1-XY N; including X = 0, Y = 0, X = Y = 0) was obtained. As a result, the emission brightness was improved. The present invention solves this problem, and an object thereof is to improve blue light emission intensity.

[0005]

The present invention relates to a sapphire substrate and a nitrogen-3 group element compound semiconductor (Al _x Ga _Y In _1-XY N; X =
0, Y = 0, X = Y = 0 inclusive), in a light emitting device having a light emitting portion composed of a plurality of layers, on a sapphire substrate,
Amorphous Al _X Ga _1-X N at temperatures of 400 ° C to 800 ° C
X ≠ 0 has a buffer layer formed to have a thickness of 100Å to 500Å, and each layer of the light emitting portion is formed on the buffer layer.

Another invention is a nitrogen-group-3 compound semiconductor (Al _x Ga _Y In _1-XY N; X = 0, Y = 0, X = Y = on a sapphire substrate.
(Including 0) in a method of epitaxially growing a layer of 400 ℃ ~ 800 ℃ on a sapphire substrate
, Amorphous Al _X Ga _{1-X with} a thickness of 100Å to 500Å
A buffer layer consisting of N; X ≠ 0 is grown, and a nitrogen-3 group element compound semiconductor (Al _x Ga _Y In _{1 -XY} N; X = 0, Y = 0) is grown on the buffer layer at a temperature of 1000 ° C to 1200 ° C. , Including X = Y = 0) is epitaxially grown.

[0007]

FUNCTION AND EFFECT OF THE INVENTION As described above, the thickness of 100 Å on the sapphire substrate at the temperature of 400 ° C to 800 ° C.
As a result of the formation of an amorphous buffer layer consisting of ~ 500Å Al _X Ga _1-X N; X ≠ 0, a nitrogen-group 3 compound semiconductor (Al _x Ga _Y In _1-XY N) epitaxially grown thereon is formed. ; X = 0, Y =
(Including 0, X = Y = 0) could be improved.
As a result, the emission brightness of the light emitting element was improved.

[0008]

EXAMPLES The present invention will be described below based on specific examples. First Embodiment In FIG. 1, a light emitting diode 10 has a sapphire substrate 1, and the sapphire substrate 1 has an Al _X G of 500 Å.
The buffer layer 2 of a _1-X N (X = 0.1) is formed. On the buffer layer 2, a high carrier concentration n ⁺ layer 3 made of GaN having a film thickness of about 2.2 μm and a low carrier concentration n layer 4 made of GaN having a film thickness of about 1.5 μm are sequentially formed. ,
On the low carrier concentration n-layer 4, an i-layer 50 made of GaN having a film thickness of about 0.2 μm is formed. Further, a p-type portion 5 exhibiting p-type is formed in a predetermined region of the i layer 50.

From the upper surface of the i layer 50, a hole 15 is formed which penetrates the i layer 50 and the low carrier concentration n layer 4 to reach the high carrier concentration n ⁺ layer 3. An electrode 52 made of aluminum bonded to the high carrier concentration n ⁺ layer 3 through the hole 15 is formed on the i layer 50. Further, an electrode 51 made of aluminum for the p-type portion 5 is formed on the upper surface of the p-type portion 5. High carrier concentration n
^The electrode 52 for the ⁺ layer 3 is the i layer 50 for the p-type portion 5.
It is insulated and separated by.

Next, a method of manufacturing the light emitting diode 10 having this structure will be described. 2 to 8 showing the manufacturing process
Is a sectional view of only one element on a wafer,
Actually, the following manufacturing process is performed on the wafer in which the elements shown in the drawing are repeatedly formed. Then, finally, the wafer is cut to form each light emitting element.

The light emitting diode 10 was manufactured by vapor phase epitaxy by a metal organic compound vapor phase epitaxy method (hereinafter referred to as "M0VPE"). The gas used was NH ₃ , carrier gas H _2, and trimethylgallium (Ga (CH ₃ ) ₃ ) (hereinafter “TMG”).
) And trimethylaluminum (Al (CH ₃ ) ₃ ) (hereinafter referred to as “TMA”), silane (SiH ₄ ), and biscyclopentadienyl magnesium Mg (C ₅ H ₅ ) ₂ (hereinafter referred to as “CP ₂ Mg ]).

Each layer is laminated in the structure shown in FIG. The procedure will be described. A single-crystal sapphire substrate 1 whose main surface is the A surface, which has been cleaned by organic cleaning and heat treatment, is mounted on a susceptor placed in the reaction chamber of the M0VPE apparatus. Next, while flowing H ₂ at a normal pressure at a flow rate of 2 litre / min into the reaction chamber, the temperature 11
The sapphire substrate 1 was vapor-phase etched at 00 ° C. next,
The temperature is reduced to 400 ° C and H ₂ is 20 litre / min, NH ₃
10 liter / min, TMA 1.8 × 10 ^-5 mol / min, TMG 1.6
The buffer layer 2 of Al _X Ga _{1 -X} N (X = 0.1) was formed at a thickness of about 500 Å by supplying at a ^{dose of} × 10 ^-4 mol / min.

Next, the temperature of the sapphire substrate 1 is maintained at 1150 ° C., H ₂ is 20 litre / min, NH ₃ is 10 litre / min, and TMG is used.
Silane (SiH ₄ ) diluted to 1.7 × 10 ^-4 mol / min and 0.86 ppm with H ₂ at a rate of 200 ml / min for 30 minutes to obtain a film thickness of approx.
A high carrier concentration n ⁺ layer 3 of 2.2 μm and a carrier concentration of 1.5 × 10 ¹⁸ / cm ^{3 made} of GaN was formed.

Then, the temperature of the sapphire substrate 1 is set to 1150 ° C.
Hold at 20 litre / min for H ₂ , 10 litre / min for NH ₃ , TMG
For 20 minutes at a rate of 1.7 × 10 ^-4 mol / min,
A low carrier concentration n layer 4 made of GaN having a carrier concentration of 1 × 10 ¹⁵ / cm ^{3 and having} a thickness of 1.5 μm was formed. Next, the sapphire substrate 1 is heated to 900 ° C., H ₂ is 20 litre / min, and NH ₃ is 10 lit.
re / min, TMG 1.7 × 10 ^-4 mol / min, CP ₂ Mg 3 × 10 ^-6
GaN with a film thickness of 0.2 μm is supplied at a rate of mol / min for 3 minutes.
An i-layer 50 was formed. In this state, the i layer 50
Is an insulator.

As shown in FIG. 3, a SiO ₂ layer 11 having a thickness of 2000 Å was formed on the i layer 50 by sputtering. Next, a photoresist 12 was applied on the SiO ₂ layer 11. Then, by photolithography, the photoresist of the electrode forming portion A corresponding to the hole 15 formed in the i layer 50 to reach the n layer 4 was removed.

Next, as shown in FIG. 4, the SiO ₂ layer 11 not covered with the photoresist 12 was removed with a hydrofluoric acid-based etching solution. Next, as shown in FIG.
A part of the upper surface of the i layer 50 which is not covered with the photoresist 12 and the SiO ₂ layer 11 and the low carrier concentration n layer 4 and the high carrier concentration n ⁺ layer 3 under the i layer 50 are vacuumed to 0.04 Torr.
r, high frequency power 0.44 W / cm ² , and BCl ₃ gas were supplied at a rate of 10 ml / min to perform dry etching, and then dry etching was performed using Ar. In this step, the hole 15 for taking out the electrode for the high carrier concentration n ⁺ layer 3 was formed.

Next, as shown in FIG. 6, the SiO ₂ layer 11 remaining on the i layer 50 was removed with hydrofluoric acid. next,
As shown in FIG. 7, the p-type portion 5 of the p-type semiconductor was formed by irradiating only a predetermined region of the i layer 50 with an electron beam using a reflected electron beam diffraction apparatus. Electron beam irradiation conditions are acceleration voltage
10KV, sample current 1μA, beam moving speed 0.2mm / sec,
The beam diameter is 60 μmφ and the degree of vacuum is 2.1 × 10 ^-5 Torr. By this electron beam irradiation, the i layer 50 changed from an insulator having a resistivity of 10 ⁸ Ωcm or more to a p-type semiconductor having a resistivity of 35 Ωcm.

At this time, the portion other than the p-type portion 5, that is, the portion not irradiated with the electron beam, remains the i-layer 50 of the insulator. Therefore, the p-type portion 5 forms a pn junction with the low carrier concentration n layer 4 in the vertical direction, but in the horizontal direction, the p-type portion 5 is electrically connected to the surroundings by the i layer 50. Electrically isolated.

Next, as shown in FIG. 8, an Al layer 20 was formed by vapor deposition on the high carrier concentration n ⁺ layer 3 through the upper surface of the p-type portion 5, the i layer 50 and the hole 15. And that Al
A photoresist 21 was applied on the layer 20, and the photoresist 21 was patterned into a predetermined shape by photolithography so that the electrode portion for the high carrier concentration n ⁺ layer 3 and the p-type portion 5 remained.

Next, using the photoresist 21 as a mask, the exposed portion of the lower Al layer 20 was etched with a nitric acid-based etching solution, and the photoresist 21 was removed with acetone. Thus, as shown in FIG. 1, the electrode 52 of the high carrier concentration n ⁺ layer 3 and the electrode 51 of the p-type portion 5 were formed. After that, the wafer formed as described above was cut into each element.

The crystal structure of the Al _x Ga _{1 -X} N buffer layer seems to be a state in which polycrystalline or microcrystals are mixed in the amorphous structure. In such a crystalline state, the crystallinity of the GaN layer grown on that layer will be improved. In order to improve the crystallinity of the GaN layer, the existence ratio of polycrystals or microcrystals in the Al _x Ga _{1 -X} N buffer layer is 1 to 90.
%, And its size should be 0.1 μm or less.

Second Embodiment In the light emitting diode of the first embodiment having the structure shown in FIG. 1, a high carrier concentration n ⁺ layer 3, a low carrier concentration n layer 4,
The i layer 50 and the p-type portion 5 were made of Al _0.2 Ga _0.5 In _0.3 N, respectively. The high carrier concentration n ⁺ layer 3 is formed by adding silicon to an electron concentration of 2 × 10 ¹⁸ / cm ³ , and the low carrier concentration n layer 4 is formed.
Was formed to have an electron concentration of 1 × 10 ¹⁶ / cm ³ without any impurities. i
The layer 50 is formed by adding magnesium (Mg), and then the p-type portion 5 is irradiated with an electron beam in a predetermined region to have a hole concentration of 1 × 10 ¹⁶ / c.
formed to m ³ .

Next, the light emitting diode 10 having this structure can be manufactured similarly to the light emitting diode of the first embodiment. Trimethylindium (In (CH ₃ ) ₃ ) was used in addition to TMG, TMA, silane, CP ₂ Mg gas. The generation temperature and gas flow rate are the same as in the first embodiment. The flow rates of the other gases are the same as those in the first embodiment except that trimethylindium is supplied at 1.7 × 10 ⁻⁴ mol / min.

The light emission intensity of the light emitting diode 10 thus manufactured was measured and found to be 10 mcd, and the light emission life was 10 ⁴ hours.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of a light emitting diode according to a specific embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of the light emitting diode of the same embodiment.

FIG. 3 is a cross-sectional view showing a manufacturing process of the light emitting diode of the embodiment.

FIG. 4 is a cross-sectional view showing a manufacturing process of the light emitting diode of the same embodiment.

FIG. 5 is a cross-sectional view showing the manufacturing process of the light emitting diode of the same embodiment.

FIG. 6 is a cross-sectional view showing a manufacturing process of the light emitting diode of the embodiment.

FIG. 7 is a sectional view showing a manufacturing process of the light emitting diode of the embodiment.

FIG. 8 is a cross-sectional view showing a manufacturing process of the light emitting diode of the embodiment.

[Explanation of symbols]

10 ... Light emitting diode 1 ... Sapphire substrate 2 ... Buffer layer 3 ... High carrier concentration n ⁺ layer 4 ... Low carrier concentration n layer 5 ... P-type part 50 ... i layer 51, 52 ... Electrode 15 ... Hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhide Mabe Aichi Prefecture Kasuga Town Kasuga Town Ochiai character No. 1 Nagahata Toyoda Gosei Co., Ltd. (72) Inventor Norikazu Koide Kasuga Town Nishi Kasugai County Aichi Prefecture Ochiai letter Nagahata No. 1 in Toyoda Gosei Co., Ltd. (72) Inventor Masami Yamada Ochiai, Kasuga-cho, Nishikasugai-gun, Aichi Prefecture Nagahata No. 1 Toyoda Gosei Co., Ltd. (72) Inventor Kuki Kato Nishi-Kasuga-cho, Aichi Ochiai 1 Nagachihata Address: Toyoda Gosei Co., Ltd. (72) Inventor, Isamu Akasaki, 1-1, Jyoshin, Nishi-ku, Nagoya-shi, Aichi Prefecture 38-805 (72) Inventor, Hiroshi Amano 2--21, Kamioka-cho, Meito-ku, Nagoya-shi, Aichi Nijigaoka-higashichi 19 Building No. 103

Claims (2)

[Claims] 1. A sapphire substrate and a plurality of layers composed of a nitrogen-3 group compound semiconductor (Al _x Ga _Y In _1-XY N; including X = 0, Y = 0, X = Y = 0) A light emitting device having a light emitting part formed on the sapphire substrate at a temperature of 400 ° C. to 800 ° C. with an amorphous Al _X Ga _1-X N; X ≠ 0 having a thickness of 100Å to 50.
A gallium nitride-based compound semiconductor light-emitting device having a buffer layer formed in 0Å, wherein each layer of the light-emitting portion is formed on the buffer layer. 2. A method of epitaxially growing a layer made of a nitrogen-3 group compound semiconductor (Al _x Ga _Y In _{1 -XY} N; including X = 0, Y = 0, X = Y = 0) on a sapphire substrate. In the above, on the sapphire substrate, at a temperature of 400 ° C. to 800 ° C., an amorphous Al _X Ga _1-X N; X having a thickness of 100 Å to 500 Å.
A buffer layer consisting of ≠ 0 is grown, and a nitrogen-group 3 compound semiconductor (Al _x Ga _Y In _1-XY N; X = 0, Y = 0, X = is formed on the buffer layer at a temperature of 1000 ° C. to 1200 ° C. A method for manufacturing a semiconductor in which (including Y = 0) is epitaxially grown.