JP2000091640A - Manufacture of gallium nitride compound semiconductor light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a light emitting element using a gallium nitride compound semiconductor having controlled conductivity and electron density. SOLUTION: An AlN buffer layer 2 having a film thickness of 500 Å, a higher carrier-density N+-type silicon-doped GaN layer 3 having a film thickness of bout 2.2 μm and an electron density of 1.5×1018/cm3, a lower carrier-density N-type GaN layer 4 having a film thickness of about 1.5 μm and an electron density of <=1×1015/cm3, and an I-type GaN layer 5 having a film thickness of about 0.2 μm are successively formed on a sapphire substrate 1. In addition, aluminum electrodes 7 and 8 are respectively formed on the I-type layer 5 and N+-type layer 3 and connected to the layers 5 and 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a method for manufacturing a light emitting device having a gallium nitride based compound semiconductor of the type, and is particularly effective for improving the luminous efficiency of a gallium nitride based compound semiconductor light emitting device which emits blue light.

[0002]

2. Description of the Related Art Heretofore, GaN-based compound semiconductors have been used for blue light emitting diodes. The GaN-based compound semiconductor has attracted attention because of its direct transition, high luminous efficiency, and the use of blue, one of the three primary colors of light, as the luminescent color.

A light-emitting diode using such a GaN-based compound semiconductor is an N-type Ga-type semiconductor device directly on a sapphire substrate or with a buffer layer of aluminum nitride interposed therebetween.
An N-layer composed of an N-type compound semiconductor is grown, and a P-type impurity is added on the N-layer to grow an I-layer composed of an I-type GaN-based compound semiconductor. Akira
62-119196, JP-A-63-188977).

[0004]

In manufacturing a light emitting diode having the above structure, a junction between an I layer and an N layer is used. When a GaN-based compound semiconductor is manufactured, the GaN-based compound semiconductor is usually of N conductivity type without intentionally doping impurities. To obtain an (Insulator) type semiconductor, zinc was doped. Also, when obtaining N-type GaN, it was difficult to control its conductivity.

However, in the process of manufacturing the above-mentioned GaN light emitting diode, the present inventor has established a technique for vapor-phase growth of a GaN semiconductor by a metalorganic compound vapor-phase epitaxy method, and has produced a high-purity GaN vapor-phase grown film. I got it. As a result, conventionally, when doping of impurities is not performed,
Although low resistivity N-type GaN was obtained, high resistivity GaN was obtained without doping with impurities due to the establishment of the vapor growth technique of the present inventors.

On the other hand, in the future, in order to improve the characteristics of the GaN light emitting diode, it has become necessary to intentionally obtain a GaN-based compound semiconductor vapor grown film whose conductivity can be controlled. Therefore, an object of the present invention is to provide an electric conductivity (1).
An object of the present invention is to establish a manufacturing technique for a GaN-based compound semiconductor capable of controlling the (/ resistivity) or electron concentration, and to obtain a gallium nitride-based compound semiconductor having controlled conductivity or electron concentration. In particular, in a light emitting device having a GaN-based compound semiconductor layer,
By obtaining a gallium nitride-based compound semiconductor whose conductivity (1 / resistivity) or electron concentration can be controlled by silicon doping, the luminous efficiency of a light emitting element is improved.

[0007]

According to a first aspect of the present invention, there is provided a method of manufacturing a light emitting device having a gallium nitride-based compound semiconductor (Al _x Ga _{1 -X} N; including X = 0). In order to set the electrical conductivity (1 / resistivity) of the gallium-based compound semiconductor to a desired value, in the vapor phase growth process of the gallium nitride-based compound semiconductor, the mixing ratio between the gas containing silicon and other source gases is A gallium nitride-based compound semiconductor is obtained by setting the value of the gallium nitride-based compound semiconductor to a value that increases in substantially direct proportion to the electrical conductivity (1 / resistivity) of the gallium nitride-based compound semiconductor and flowing a gas containing silicon simultaneously with other raw material gases. And a method for manufacturing a gallium nitride-based compound semiconductor light emitting device.

According to a second aspect of the present invention, there is provided a method of manufacturing a light emitting device having a gallium nitride-based compound semiconductor (Al _x Ga ₁ -XN; including X = 0). In order to set the concentration to a desired value, in the vapor phase growth process of the gallium nitride-based compound semiconductor, the mixing ratio between the gas containing silicon and the other source gas is substantially reduced to the electron concentration of the obtained gallium nitride-based compound semiconductor. A method for manufacturing a gallium nitride-based compound semiconductor light emitting device, characterized in that a gallium nitride-based compound semiconductor is obtained by setting a value in a range that increases in direct proportion and flowing a gas containing silicon simultaneously with another source gas, to obtain a gallium nitride-based compound semiconductor. is there.

A third aspect of the present invention is characterized in that the gallium nitride-based compound semiconductor is GaN. The invention described in claim 4 is characterized in that the conductivity is 3.3 / Ωcm or more.

According to a fifth aspect of the present invention, the electron concentration is 6
× 10 ¹⁶ / cm ³ or more. Claim 6
In the invention described in the above, the electric conductivity is 3.3 / Ωcm or more to 1.3 ×
It is characterized by 10 ² / Ωcm. In the invention according to claim 7, the gallium nitride-based compound semiconductor has an electron concentration of:
It is a desired value in a range of 6 × 10 ¹⁶ / cm ^{3 to} 3 × 10 ¹⁸ / cm ³ .

The invention according to claim 8 is characterized in that the gallium nitride-based compound semiconductor is formed on a buffer layer formed on a sapphire substrate. The invention according to claim 9 is characterized in that the buffer layer is formed at a temperature lower than the growth temperature of the gallium nitride-based compound semiconductor on the sapphire substrate by a metalorganic compound vapor deposition method.

According to a tenth aspect of the present invention, a gallium nitride-based compound semiconductor (Al _x Ga
_1- XN; including X = 0), the gallium nitride-based compound is used to set the conductivity (1 / resistivity) of the gallium nitride-based compound semiconductor to a desired value. In the vapor phase growth process of the semiconductor, the supply ratio of silicon (Si) to the reaction chamber with respect to gallium (Ga) is changed to gallium (Ga).
About trimethylgallium (TM
G) is converted to a flow rate of bubbling hydrogen, and silicon (Si) is converted to a flow rate of a gas diluted to 0.86 ppm, which is a value in the range of 0.1 to 3. Is a method for manufacturing a gallium nitride-based compound semiconductor light emitting device.

[0013] The invention according to claim 11 is a method for preparing a gallium nitride-based compound semiconductor (Al _x Ga
_1- XN; including X = 0), the gallium nitride-based compound is used to set the conductivity (1 / resistivity) of the gallium nitride-based compound semiconductor to a desired value. In the vapor phase growth process of the semiconductor, the supply ratio of silicon to the reaction chamber with respect to NH ₃ is 8.6 × 10 ^{−10 to} 2.6 ×.
A method for producing a gallium nitride-based compound semiconductor light emitting device, characterized in that the value is in the range of 10 ^-8 .

[0014]

According to the first or second aspect of the present invention, there is provided a method for manufacturing a light emitting device having a gallium nitride-based compound semiconductor (Al _X Ga _{1 -X} N; including X = 0). In order to set the conductivity (1 / resistivity) or the electron concentration of the gallium nitride-based compound semiconductor to a desired value, the gas containing silicon and another source gas are mixed in the vapor phase growth process of the gallium nitride-based compound semiconductor. The mixing ratio is set to a value that increases in substantially direct proportion to the conductivity (1 / resistivity) of the obtained gallium nitride-based compound semiconductor or the electron concentration, and the gas containing silicon flows simultaneously with the other source gases. Thus, a gallium nitride-based compound semiconductor is obtained. Thereby, the conductivity or the electron concentration is controlled, and a gallium nitride-based compound semiconductor having a desired value can be obtained accurately.

According to the third aspect of the invention, since the gallium nitride-based compound semiconductor is GaN, a low-resistivity layer having a large forbidden band width can be obtained, and the n-type clad layer and the n-type clad layer having improved functions can be obtained. A contact layer can be obtained. According to the fourth aspect of the present invention, since the conductivity of the gallium nitride-based compound semiconductor is 3.3 / Ωcm or more, a highly conductive gallium nitride-based compound semiconductor layer can be obtained.
Therefore, a high-quality contact layer and clad layer can be obtained. According to the fifth aspect of the present invention, the electron concentration of the gallium nitride-based compound semiconductor is 6 × 10 ¹⁶ / cm ³ or more. A semiconductor layer can be obtained. Therefore, a high-quality contact layer and clad layer can be obtained. In the inventions of claims 6 and 7, similarly, a highly conductive gallium nitride-based compound semiconductor layer can be obtained. Therefore, a high-quality contact layer and clad layer can be obtained.

According to the present invention, the buffer layer is formed on the sapphire substrate or the buffer layer is formed on the sapphire substrate at a temperature lower than the growth temperature of the gallium nitride compound semiconductor. Since it is formed by the phase growth method, a layer having high resistance and high crystallinity can be obtained when silicon is not added. Therefore, control of conductivity (1 / resistivity) and electron concentration by addition of silicon is achieved. The performance is improved.

According to the tenth aspect of the present invention, the reaction of silicon (Si) with gallium (Ga) during the vapor phase growth of a gallium nitride-based compound semiconductor (including Al _X Ga _{1 -X} N; X = 0). -15 ° C for gallium (Ga)
In the above, the value converted to the flow rate of hydrogen obtained by bubbling trimethylgallium (TMG), and the value of silicon (Si) converted to the flow rate of a gas diluted to 0.86 ppm, a value in the range of 0.1 to 3 By doing so, the conductivity (1 /
Resistivity) or electron concentration can be controlled favorably.

Similarly, in the invention according to claim 11, in a vapor phase growth process of a gallium nitride-based compound semiconductor (including Al _X Ga _{1 -X} N; X = 0), the silicon is reacted to a reaction chamber of NH ₃ . The conductivity (1 / resistivity) or the electron concentration can be satisfactorily controlled by setting the supply ratio of 8.6 × 10 ^{−10 to} 2.6 × 10 ⁻⁸ .

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific embodiments. The light emitting diode 10 having the structure shown in FIG. 1 was manufactured by using the manufacturing method of the present invention.

In FIG. 1, a light emitting diode 10 has a sapphire substrate 1 and 50
An AlN buffer layer 2 of 0 ° is formed. On the buffer layer 2, a high carrier concentration N ⁺ layer 3 made of GaN with a thickness of about 2.2 μm and a low carrier concentration N layer 4 made of GaN with a thickness of about 1.5 μm are formed in this order. Further, an I layer 5 made of GaN having a thickness of about 0.2 μm is formed on the low carrier concentration N layer 4. Then, an electrode 7 made of aluminum connected to the I layer 5 and a high carrier concentration N ⁺
An electrode 8 made of aluminum connected to the layer 3 is formed.

Next, a method of manufacturing the light emitting diode 10 having this structure will be described. The light emitting diode 10 includes:
It was manufactured by vapor phase growth by metal organic compound vapor phase epitaxy (hereinafter referred to as "M0VPE").

The gases used were NH ₃ and carrier gas H ₂
Trimethyl gallium _{(Ga (CH 3) 3)} ( hereinafter referred to as "TMG") and trimethylaluminum _{(Al (CH 3) 3)} ( hereinafter "TMA
), Silane (SiH ₄ ) and diethylzinc (hereinafter “DEZ
").

First, a single-crystal sapphire substrate 1 whose main surface is the a-plane cleaned by organic cleaning and heat treatment is mounted on a susceptor placed in a reaction chamber of an MOVPE apparatus. Then H ₂
At a flow rate of 2 l / min (because it is difficult to distinguish
(Liter / minute)) while flowing into the reaction chamber at a temperature of 1200
The sapphire substrate 1 was subjected to gas phase etching at 10 ° C. for 10 minutes.

Next, the temperature was lowered to 400 ° C., and H ₂ was supplied at a flow rate of 20 liter / min, NH ₃ was supplied at a flow rate of 10 liter / min, and H ₂ bubbled with TMA maintained at 15 ° C. was supplied at a flow rate of 50 cc / min. Supply
The AlN buffer layer 2 was formed to a thickness of about 500 °.

Next, the supply of TMA is stopped, the temperature of the sapphire substrate 1 is maintained at 1150 ° C., and H ₂ is set at 20 liter / min.
10 liter / min of NH ₃ as other source gas and -15
Flushed ℃ of H ₂ which was bubbled TMG held in at 100 cc / min, silane diluted (SiH ₄₎ and 30 shunted 200ml / min as a gas containing silicon with H ₂ up to 0.86 ppm, a thickness of about 2.
GaN with 2 μm, carrier concentration (electron concentration) 1.5 × 10 ¹⁸ / cm ³
, A high carrier concentration N ⁺ layer 3 was formed.

Subsequently, the temperature of the sapphire substrate 1 is set to 1150 ° C.
And hold the H_Two20 liter / min, NH _ThreeTo 10 liter /
Min, bubbled TMG at -15 ° C_TwoTo 100
Flow at cc / min for 20 minutes, thickness about 1.5μm, carrier concentration
(Electron concentration) 1 × 10^Fifteen/cm^ThreeLow carrier consisting of the following GaN
A concentration N layer 4 was formed.

Next, the sapphire substrate 1 is heated to 900 ° C.
H ₂ 20 liter / min, NH ₃ 10 liter / min, TMG 1.7
X10 ^-4 mol / min and DEZ were supplied at a rate of 1.5 × 10 ^-4 mol / min to form an I layer 5 made of GaN having a thickness of 0.2 μm. Thus, a multilayer structure as shown in FIG. 2 was obtained. Next, as shown in FIG. 3, an SiO ₂ layer 11 was formed to a thickness of 2000 ° on the I layer 5 by sputtering.
Next, a photoresist 12 is applied on the SiO ₂ layer 11, and the photoresist 12 is applied by photolithography.
Was formed in a pattern in which the photoresist at the electrode formation site for the high carrier concentration N ⁺ layer 3 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 etchant. Next, as shown in FIG. 5, a part of the upper surface of the I layer 5 which is not covered by 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 thereunder. Was dry-etched by supplying a CCl ₂ F ₂ gas at a vacuum degree of 0.04 Torr, high-frequency power of 0.44 W / cm ² and CCl ₂ F ₂ gas at 10 ml / min, and then dry-etching with Ar. next,
As shown in FIG. 6, the SiO ₂ layer 11 remaining on the I layer 5 was removed with hydrofluoric acid.

Next, as shown in FIG.
The Al layer 13 was formed by vapor deposition. And the Al layer 13
A photoresist 14 is applied on the
The photoresist 14 has a high carrier concentration N
⁺A predetermined shape so that the electrode portions for the layer 3 and the I layer 5 remain.
A pattern was formed. Next, as shown in FIG.
Exposure of lower Al layer 13 using photoresist 14 as a mask
Part is etched with nitric acid based etchant,
Are removed with acetone, and a high carrier concentration N ⁺Layer 3
The electrode 8 and the electrode 7 of the I layer 5 were formed.

As described above, the MIS (Me
A gallium nitride-based light emitting device having a (ta-l-insulator-semiconductor) structure can be manufactured. In the above manufacturing process, when the high carrier concentration N ⁺ layer 3 is vapor-phase grown,
H ₂ at 20 liter / min, NH ₃ as other source gas at 10 lit
er / min and H bubbled with TMG maintained at -15 ° C
₂ flowed at 100 cc / min, 0.8 with H ₂ as a gas containing silicon
Silane (SiH ₄ ) diluted to 6 ppm with 10 cc / min to 300 cc /
In this case, the resistivity (= 1 / conductivity) of the high carrier concentration N ⁺ layer 3 is controlled as shown in FIG.
It can be changed from × 10 ⁻¹ Ωcm to 8 × 10 ⁻³ Ωcm. Similarly, the carrier concentration of the high carrier concentration N ⁺ layer 3 (electron concentration), as shown in FIG. 8, 3 to 6 × 10 ¹⁶
It can be changed up to × 10 ¹⁸ / cm ³ .

In the above method, silane (SiH ₄ ) is controlled. However, the flow rate of another source gas may be controlled, and the mixing ratio of the two is controlled to control the resistivity (= 1 / conductivity). May be changed. In this embodiment, silane is used as the Si dopant material. However, a gas in which an organic compound containing Si, for example, tetraethylsilane (Si (C ₂ H ₅ ) ₄ ) or the like is bubbled with H ₂ may be used. In this manner, the high carrier concentration N ⁺ layer 3 and the low carrier concentration N layer 4 were formed in a state where the conductivity (1 / resistivity) was controllable.

As a result, the light-emitting intensity of the light-emitting diode 10 manufactured by the above method was 0.2 mcd, which was four times higher than the light-emitting intensity of the conventional light-emitting diode having the I layer and the N layer. When the light emitting surface was observed, it was also observed that the number of light emitting points increased.

[Brief description of the 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 sectional view showing a manufacturing process of the light emitting diode of the embodiment.

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

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

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

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

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

FIG. 8 is a measurement diagram showing the relationship between the flow rate of a silane gas and the electrical characteristics of a vapor-grown N layer.

[Explanation of symbols]

DESCRIPTION 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 ... I layer 7, 8 ... Electrode

 ──────────────────────────────────────────────────続 き Continuing from the front page (71) Applicant 396020800 Japan Science and Technology Agency 4-1-8, Honcho, Kawaguchi-shi, Saitama (72) Inventor Michinari Saga 1 Ochiai-Ochiai, Kasuga-cho, Nishikasugai-gun, Aichi Prefecture Toyoda Gosei Inside (72) Inventor Katsuhide Shinbe 1 Ochiai Nagahata, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside Toyoda Gosei Co., Ltd. In-house (72) Kuki Kato, Inventor 1 at Nagata, Ochiai, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside Toyoda Gosei Co., Ltd. ) Inventor Isamu Akasaki Naoichi-shi, Nagoya

Claims (11)

[Claims] 1. A gallium nitride-based compound semiconductor (Al _X Ga _{1 -X} N; X
0 is included). In order to set the electrical conductivity (1 / resistivity) of the gallium nitride-based compound semiconductor to a desired value, the gaseous phase of the gallium nitride-based compound semiconductor is In the growth process, the mixing ratio of the gas containing silicon and the other source gas is set to a value in a range that increases substantially directly in proportion to the conductivity (1 / resistivity) of the obtained gallium nitride-based compound semiconductor. A method of manufacturing the gallium nitride-based compound semiconductor light emitting device, wherein the gallium nitride-based compound semiconductor is obtained by flowing the gas containing silicon simultaneously with the other source gas. 2. A gallium nitride-based compound semiconductor (Al _X Ga _{1 -X} N; X
= 0) (including 0), in order to set the electron concentration of the gallium nitride based compound semiconductor to a desired value, in the vapor phase growth process of the gallium nitride based compound semiconductor, silicon The mixing ratio between the gas containing the other source gas and the other source gas is set to a value in a range that increases substantially directly in proportion to the electron concentration of the gallium nitride-based compound semiconductor to be obtained. A method for manufacturing a gallium nitride-based compound semiconductor light emitting device, wherein the gallium nitride-based compound semiconductor is obtained by flowing the gallium nitride-based compound semiconductor simultaneously. 3. The gallium nitride-based compound semiconductor comprises Ga
3. The method for manufacturing a gallium nitride-based compound semiconductor light-emitting device according to claim 1, wherein the light-emitting device is N 2. 4. The electric conductivity (1 / resistivity) is 3.3 /
4. The method according to claim 1, wherein the resistance is not less than Ωcm.
3. The method for producing a gallium nitride-based compound semiconductor light-emitting device according to item 1. 5. The method for manufacturing a gallium nitride-based compound semiconductor light emitting device according to claim 2, wherein the electron concentration is 6 × 10 ¹⁶ / cm ³ or more. 6. The electric conductivity (1 / resistivity) is 3.3 /
4. The method for manufacturing a gallium nitride-based compound semiconductor light emitting device according to claim 1, wherein the resistance is from Ωcm to 1.3 × 10 ² / Ωcm. 5. 7. The electron concentration of the gallium nitride-based compound semiconductor is a desired value in a range of 6 × 10 ¹⁶ / cm ^{3 to} 3 × 10 ¹⁸ / cm ^3. 3
3. The method for producing a gallium nitride-based compound semiconductor light-emitting device according to item 1. 8. The gallium nitride-based compound semiconductor according to claim 1, wherein the gallium nitride-based compound semiconductor is formed on a buffer layer formed on a sapphire substrate. A method for manufacturing a compound semiconductor light emitting device. 9. The nitride according to claim 8, wherein the buffer layer is formed on a sapphire substrate by a metalorganic chemical vapor deposition at a temperature lower than a growth temperature of the gallium nitride-based compound semiconductor. A method for manufacturing a gallium compound semiconductor light emitting device. 10. A method for manufacturing a light-emitting device having a gallium nitride-based compound semiconductor (Al _x Ga ₁ -XN; including X = 0) by an organometallic compound vapor deposition method, wherein the gallium nitride-based compound semiconductor In order to set the conductivity (1 / resistivity) to a desired value, in the vapor phase growth process of the gallium nitride-based compound semiconductor, the supply ratio of silicon (Si) to gallium (Ga) to the reaction chamber is gallium
For (Ga), the value was converted to the flow rate of hydrogen obtained by bubbling trimethylgallium (TMG) at -15 ° C, and for silicon (Si), the value was converted to the flow rate of a gas diluted to 0.86 ppm. A method for producing a gallium nitride-based compound semiconductor light emitting device, wherein the value is in the range of 1-3. 11. A method for manufacturing a light-emitting device having a gallium nitride-based compound semiconductor (Al _x Ga ₁ -XN; including X = 0) by an organometallic compound vapor deposition method, wherein the gallium nitride-based compound semiconductor In order to set the electrical conductivity (1 / resistivity) of the GaN to a desired value, the supply ratio of silicon to NH _{3 in} the reaction chamber during the vapor phase growth of the gallium nitride-based compound semiconductor is 8.6 × 10 ^{−. 10-2.}
A method for producing a gallium nitride-based compound semiconductor light emitting device, wherein the value is in the range of 6 × 10 ⁻⁸ .