JPH08115880A - Method for manufacturing p-type gallium nitride compound semiconductor - Google Patents

Abstract

(57) [Summary] [Object] To provide a method for manufacturing a low-resistance p-type gallium nitride-based compound semiconductor that can be used for a double heterojunction of a light emitting device by MOVPE growth. [Structure] After a gallium nitride-based semiconductor doped with p-type impurity Mg was deposited by a vapor phase growth method using ammonia as a nitrogen source, the cooling atmosphere was cooled from ammonia to hydrogen in a temperature range of 600 ° C or higher during cooling. Alternatively, switch to a mixed atmosphere of nitrogen. According to this method, the supply of atomic hydrogen supplied from ammonia can be avoided by switching the cooling atmosphere in the temperature range of 600 ° C or higher, so that hydrogen-passivation does not occur and a low-resistance p-type gallium nitride-based compound semiconductor is obtained. To be

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blue or violet light emitting semiconductor laser diode, a method for manufacturing a blue or violet light emitting diode device, and a method for manufacturing a p-type gallium nitride-based compound semiconductor used in the light emitting device, The present invention relates to a method of manufacturing a p-type gallium nitride-based compound semiconductor having a low resistance wholly or partially by vapor phase growth.

[0002]

2. Description of the Related Art A blue light emitting device is expected as a light source for a full color display or an optical disk capable of high density recording, and is a II-VI group compound semiconductor such as ZnSe or III such as SiC or GaN.
-Research is actively conducted using group V compound semiconductors.

In particular, a blue light emitting diode has recently been realized by using AlGaN, GaN, etc., and a light emitting element using a gallium nitride-based compound semiconductor has attracted attention. As a stacking method for gallium nitride-based compound semiconductors, metal organic chemical vapor deposition (MOVPE
Method) and molecular beam epitaxy method (MBE method) are generally used.

For example, a growth method using the MOVPE method will be described. A reaction furnace equipped with a sapphire substrate is supplied with hydrogen gas such as trimethylgallium (TMG), trimethylaluminum (TMA), and ammonia which are organic metals as a carrier gas. Then, after stacking a buffer layer such as GaN or AlN at a low temperature of about 600 ° C, GaN or AlG at a high temperature of about 1000 ° C.
A gallium nitride compound semiconductor such as aN is deposited. At this time, if necessary, impurities are doped to form p-type, i-type, and n-type layers to form a device structure such as a double hetero structure. p
Mg and Zn are known as type impurities.

However, it is not possible to obtain a p-type gallium nitride compound semiconductor having a low resistance by the conventional MOVPE growth, and even if Mg or Zn is doped, only a semi-insulating layer having a high resistance can be obtained. Therefore, for example, a high-resistance Mg-doped p-type gallium nitride compound semiconductor substrate is irradiated with an electron beam with an accelerating voltage of about 6 to 30 kV, or decomposition of a gallium nitride compound semiconductor as disclosed in JP-A-5-183189. A low-resistance p-type gallium nitride compound semiconductor was produced by annealing at 400 ° C or higher in a nitrogen atmosphere pressurized above the pressure. In order to manufacture a p-type gallium nitride-based compound semiconductor having such a low resistance, a step of performing some treatment after MOVPE growth is necessary.

[0006]

As described above, p having a low resistance is used.
In order to obtain a type gallium nitride-based compound semiconductor, annealing is performed after crystal growth, so that an additional step is required.

Further, electron beam irradiation is used to obtain a p-type gallium nitride-based compound semiconductor having a low resistance. However, in this method, only the extreme surface where electrons can enter has a low resistance, and a portion irradiated with an electron beam is used. However, in order to reduce the resistance of the entire substrate, it was necessary to uniformly irradiate the substrate with an electron beam, and thus the uniformity was poor.

Further, a defect may occur on the surface due to damage caused by electron beam irradiation, and there is a problem of deterioration of crystallinity.

On the other hand, by annealing in a nitrogen atmosphere, a low resistance p-type gallium nitride compound semiconductor can be obtained over the entire substrate, but a low resistance layer cannot be selectively obtained, and the degree of freedom in device fabrication is small.

Therefore, the first object of the present invention is to manufacture a low resistance p-type gallium nitride compound semiconductor layer by MOVPE growth itself in order to simplify the process for obtaining a low resistance p-type gallium nitride compound semiconductor. The second object is to provide a method for manufacturing a p-type gallium nitride compound semiconductor layer having a low resistance selectively at a certain position of the substrate not only on the surface but also over the entire thickness without impairing the crystallinity. It is in.

[0011]

According to a first growth method of the present invention, a p-type gallium nitride compound semiconductor layer is deposited on a substrate by vapor phase growth via a buffer layer, and then a vapor phase atmosphere is applied during cooling. It is characterized in that a low resistance p-type gallium nitride compound semiconductor layer is grown by switching.

More specifically, this growth method is a method in which a source gas is supplied into the reaction furnace by a vapor phase growth method to epitaxially grow a p-type gallium nitride compound semiconductor, and Ga _x Al _{1-x is formed} on a sapphire substrate. After growing a buffer layer represented by N (0 ≦ x ≦ 1) at 600 ° C., a gallium nitride-based compound semiconductor doped with p-type impurities such as Mg and Zn is epitaxially grown at around 1000 ° C.

When ammonia is used as the nitrogen source,
The supply of ammonia is stopped in a temperature range of 600 ° C. or higher during cooling after vapor phase growth, and at a temperature lower than that, it is cooled to room temperature in a hydrogen or nitrogen atmosphere that is a carrier gas of the raw material.

In the second growth method of the present invention, when ethyl azide is used as a nitrogen source and hydrogen is used as a carrier gas, the carrier gas is changed from hydrogen to nitrogen in a temperature range of 600 ° C. or higher during cooling after vapor phase growth. In the temperature range below that, cool to room temperature in a nitrogen atmosphere, and
A gallium nitride-based compound semiconductor layer is manufactured.

In the third growth method of the present invention, a p-type gallium nitride compound semiconductor layer is deposited on a substrate by vapor phase growth via a buffer layer, and then a dielectric film is selectively deposited on the epitaxial growth layer. Then, after heat-treating this in an organic nitrogen atmosphere having a hydride gas of 600 ° C. or higher or hydrogen as a carrier gas, it is cooled to room temperature in the above atmosphere.

More specifically, like the first growth method, this growth method is a method of supplying a source gas into the reaction furnace by a vapor phase growth method to epitaxially grow a p-type gallium nitride-based compound semiconductor. On board
After growing the buffer layer represented by Ga _x Al _1-x N (0 ≤ x ≤ 1) at 600 ℃, p-type gallium nitride compound semiconductor doped with p-type impurities such as Mg and Zn at around 1000 ℃ Epitaxially grow a single layer. The method of supplying the source gas at the time of cooling the vapor phase growth does not necessarily have to be the same as the first growth method. For example, when ammonia is used as the nitrogen source, it may be cooled while being supplied to room temperature.

Next, SiO ₂ on the epitaxial growth layer,
A dielectric film made of SiN or the like is selectively deposited to a thickness of about 400 nm.
Next, heat treatment is performed at 600 ° C. or higher in any one of hydride gases such as ammonia, arsine, and phosphine or a mixed atmosphere thereof, and the temperature is kept to be cooled to room temperature.

A fourth growth method of the present invention is a method of growing a p-type gallium nitride compound semiconductor substrate having the dielectric film deposited thereon at 600 ° C.
As described above, the heat treatment is performed in an ethyl azide atmosphere using hydrogen as a carrier gas, and the atmosphere is maintained and the temperature is cooled to room temperature.

A fifth growth method of the present invention is a method of supplying a source gas into a reaction furnace by a vapor phase growth method to epitaxially grow a p-type gallium nitride-based compound semiconductor, which is Ga _x Al _1- After growing the buffer layer represented by _x N (0 ≤ x ≤ 1) at 600 ℃, p of p-type gallium nitride compound semiconductor doped with p-type impurities such as Mg and Zn at around 1000 ℃.
Type epitaxial layer, an undoped i-layer, and an n-type layer doped with an n-type impurity such as Si or Sn after epitaxial growth of a double heterostructure, using ammonia as a nitrogen source during cooling of vapor phase growth. While cooling to room temperature, SiO ₂ , on the epitaxial growth layer,
A dielectric film made of SiN or the like is selectively deposited to a thickness of about 400 nm.
Next, it is characterized in that it is heat-treated at 600 ° C. or higher in any one of hydride gases such as ammonia, arsine, phosphine, or a mixed atmosphere thereof, and cooled to room temperature while keeping the atmosphere as it is.

A sixth growth method of the present invention is the p-type gallium nitride compound semiconductor p-type semiconductor in which the dielectric film is selectively deposited.
Type layer, an undoped i layer, and a substrate including a double heterostructure consisting of an n type layer doped with an n type impurity such as Si or Sn are heat-treated at 600 ° C. or higher in an ethyl azide atmosphere using hydrogen as a carrier gas, It is characterized by cooling to room temperature while maintaining the same atmosphere.

[0021]

The reason why a low resistance p-type gallium nitride compound semiconductor is obtained by the present invention is presumed to be as follows. That is, in vapor phase growth of ordinary p-type gallium nitride compound semiconductors, ammonia (NH ₃ ) is generally used as the nitrogen source.
Is used, and during the growth, this ammonia decomposes and atomic hydrogen penetrates into or is released from the crystal.

If ammonia is continuously supplied to room temperature during the cooling after the growth, the bond between nitrogen and atomic hydrogen becomes stable around the p-type impurities Mg and Zn at around 600 ° C., and the NH bond is formed, so that the hole is formed. As a result, the p-type gallium nitride compound semiconductor with high resistance is obtained (hydrogen passivation). That is, it is considered that the high resistance of the p-type gallium nitride compound semiconductor during vapor phase growth is mainly determined by the cooling process after vapor phase growth. Therefore, during cooling after vapor phase growth, NH bonds adjacent to Mg and Zn are unstable and dissociated. The supply of atomic hydrogen is stopped at 600 ° C or higher, and hydrogen gas or hydrogen that does not easily decompose at 600 ° C is released. It is considered that when cooled to room temperature in a nitrogen gas atmosphere containing no hydrogen, atomic hydrogen is diffused and released from the crystal into the gas phase, and a low-resistance p-type gallium nitride compound semiconductor is obtained.

Therefore, according to the growth method of the present invention, when ammonia is used as a nitrogen source in vapor phase growth of a p-type gallium nitride compound semiconductor, if the supply of ammonia is stopped at 600 ° C. or more during cooling, the crystal Hydrogen inside is released to the outside and the resistance is lowered.

Further, in order to avoid intrusion of atomic hydrogen during vapor phase growth, ethyl azide (EtN ₃ ) as a raw material containing no direct bond between hydrogen and nitrogen can be considered. However, this raw material can contribute to crystal growth by reacting with hydrogen, which is a carrier gas of the raw material, and therefore hydrogen passivation occurs when it is cooled to room temperature in the hydrogen atmosphere with ethyl azide.

Therefore, according to the growth method of the present invention, by changing the carrier gas from hydrogen to nitrogen in the temperature range of 600 ° C. or higher in the cooling process after vapor phase growth, atomic hydrogen can be released from the crystal, so that the resistance is low. A p-type gallium nitride-based compound semiconductor is obtained.

The reason why the p-type gallium nitride-based compound semiconductor having a low resistance is selectively obtained by the present invention is as follows. When ammonia was continuously supplied to room temperature during the cooling process after vapor phase growth, NH bonds in the p-type gallium nitride compound semiconductor were stable at around 600 ° C and N in the ammonia in the gas phase was stable.
It is considered that hydrogen passivation occurs because the -H bond is decomposed. Decomposition of ammonia occurs by a catalytic reaction on the surface of the gallium nitride-based compound semiconductor. Therefore, if a dielectric film such as SiO ₂ or Si ₃ N ₄ is deposited on the surface of the gallium nitride-based compound semiconductor, this catalytic effect disappears and the decomposition efficiency of ammonia is drastically reduced. Therefore, at around 600 ° C., the supply of atomic hydrogen from the gas phase atmosphere is stopped and a low resistance p-type gallium nitride compound semiconductor is obtained. Therefore, according to the growth method of the present invention, when the mask of the dielectric film is selectively deposited on the substrate and cooled to room temperature with a hydride gas such as ammonia, arsine, or phosphine, the mask portion has low resistance and is otherwise A high resistance p-type gallium nitride compound semiconductor is obtained.

According to the growth method of the present invention, the mask of the dielectric film is selectively deposited on the p-type gallium nitride compound semiconductor substrate, and heat treatment is performed at a temperature of 600 ° C. or higher with ethyl azide as a carrier gas. When it is carried out, at 600 ° C or higher, hydrogen penetrates into the crystal due to the reaction of the raw material, and when this atmosphere is cooled to room temperature and cooled, there is no penetration of hydrogen at the part where the mask is deposited, so that the resistance becomes low, and at other parts. High resistance due to hydrogen passivation.

According to the manufacturing method of the present invention, a dielectric mask is selectively deposited on a substrate having a double hetero structure containing a p-type gallium nitride compound semiconductor, and a hydride gas such as ammonia, arsine, phosphine, etc. is deposited. When cooled to room temperature, the catalytic effect works for the same reason as described above to increase the resistance except for the dielectric mask, so that the current flows only in the portion where the dielectric mask is deposited, and the current is constricted. According to the growth method of the present invention, when a substrate having a double hetero structure containing a p-type gallium nitride compound semiconductor selectively deposited with the dielectric film is heat-treated at 600 ° C. or higher in an ethyl azide and hydrogen atmosphere, the raw material is The reaction produces atomic hydrogen. If the NH bond becomes stable at 600 ° C or less when cooled to room temperature while maintaining this atmosphere, the reaction is suppressed in the region where the dielectric film is deposited, and otherwise the catalyst effect of the substrate accelerates the reaction. The p-type gallium nitride-based semiconductor layer other than the region where the is deposited has a high resistance, and when a current is injected into the device, the current is constricted.

[0029]

EXAMPLES The present invention will be described in detail below with reference to examples.

Example 1 First, a sapphire substrate is placed on a susceptor in a reaction furnace and evacuated, and then heated at 1150 ° C. for 10 minutes in a hydrogen atmosphere at atmospheric pressure to clean the substrate. Next, cool to 600 ° C. and add TMA at 3 μmol /
, NH ₃ at 1.3 l / min and carrier hydrogen at 2.5 l / min to grow an AlN buffer layer of about 40 nm. Next, after stopping only the supply of TMA and raising the temperature to 1030 ° C, TMG is added at 60 μmol /
, CP2Mg of 5 μmol / min and the Mg-doped GaN layer
Grow with a film thickness of 1 μm.

Next, after stopping the supply of TMG and CP ₂ Mg to complete the growth, the heater is turned off and the mixture is naturally cooled in a mixed atmosphere of ammonia and hydrogen. When the temperature reaches 600 ° C, the supply of ammonia is stopped, the atmosphere is switched to hydrogen only, and the temperature is cooled to room temperature.

FIG. 1 shows the results of measuring the resistivity of the Mg-doped GaN layer while changing the temperature at which the mixed atmosphere of ammonia and hydrogen is switched to the atmosphere containing only hydrogen during cooling after vapor phase growth. By stopping the supply of ammonia at 600 ℃ or higher, p-type GaN with a resistivity of 1.5 Ωcm and extremely low resistance was obtained.

Similarly, an experiment was conducted to measure the resistivity of the Mg-doped GaN layer by changing the temperature at which the mixed atmosphere of ammonia and hydrogen was switched to nitrogen or the mixed atmosphere of nitrogen and hydrogen during cooling after vapor phase growth. , Similar to the experiment of switching from ammonia to hydrogen, a rapid change occurs between 400 ° C and 600 ° C, and by switching from the mixed atmosphere of ammonia and hydrogen to nitrogen or the mixed atmosphere of nitrogen and hydrogen at 600 ° C or higher, In each case, p-GaN having a resistivity as low as 1.0 Ωcm was obtained.

As described above, low resistance was obtained when the supply of ammonia was stopped at 600 ° C. or higher in any atmosphere. From the above results, when cooling after vapor phase growth, stopping the supply of ammonia at 600 ° C or higher and cooling to room temperature in an inert gas such as hydrogen, nitrogen, or argon alone or in a mixed atmosphere, low resistance p-type nitriding is performed. It was found that a gallium compound semiconductor can be obtained.

In this example, the cooling atmosphere was switched at 600 ° C. or higher at which the maximum effect was obtained in order to obtain a p-type nitride compound semiconductor having a low resistance. If it is more than the above, the effect of lowering the resistance can be obtained although there is a degree of difference.

Further, according to the present invention, N-
Since the supply of atomic hydrogen is stopped above the temperature at which the H bond becomes stable, it is not limited to p-type GaN, but AlGaN, AlGaInN, InGaN
It is clear that it is effective in reducing the resistance of all p-type nitride compound semiconductors.

(Example 2) First, a sapphire substrate was placed on a susceptor in a reaction furnace and evacuated, and then heated at 1150 ° C for 10 minutes in a hydrogen atmosphere at atmospheric pressure to clean the substrate. Next, cool to 600 ° C. and add TMA at 3 μmol /
, NH ₃ at 1.3 l / min and carrier hydrogen at 2.5 l / min to grow an AlN buffer layer of about 40 nm.

Next, after stopping the supply of TMA, the temperature is set to 700 ° C.
Then, the ammonia supply is stopped and ethyl azide (EtN ₃ ) is supplied at 6 mmol / min. Next, TMG is 60 μmol /
, CP2Mg of 5 μmol / min and the Mg-doped GaN layer
Grow with a film thickness of 1 μm. Next, after stopping the supply of TMG and CP ₂ Mg to complete the growth, the heater is turned off and the mixture is naturally cooled in a mixed atmosphere of ethyl azide and hydrogen. When the temperature reaches 600 ° C., the supply of carrier hydrogen is stopped, nitrogen is supplied as a carrier gas, and the mixture is cooled to room temperature in a mixed atmosphere of ethyl azide and nitrogen. When GaN is epitaxially grown using ethyl azide, ethyl azide reacts with carrier hydrogen to decompose ethyl azide and grow. Therefore, atomic hydrogen exists inside and outside the crystal during the growth. Before the NH bond becomes stable in the crystal during cooling, that is, when the carrier gas is switched from hydrogen to nitrogen at 600 ° C or higher, the decomposition of ethyl azide is suppressed and the hydrogen atom does not exist in the gas phase. Emitted and low resistance p-type GaN
Is obtained.

FIG. 2 shows the results of plotting the resistivity of the Mg-doped GaN layer against the carrier gas switching temperature during cooling when p-type GaN was epitaxially grown using ethyl azide. As is clear from the results, by lowering the resistance of the Mg-doped GaN layer by switching the carrier gas from hydrogen to nitrogen at 400 ° C or higher, hydrogen passivation can be almost completely avoided at 600 ° C or higher.

In the present invention, N- in the crystal is also used.
Since the supply of atomic hydrogen is stopped above the temperature at which the H bond becomes stable, it is not limited to p-type GaN, but AlGaN, AlGaInN, InGaN
It is clear that it is effective in reducing the resistance of all p-type nitride compound semiconductors.

Further, the nitrogen source is not limited to ethyl azide, and the same effect can be obtained if it is an organic nitrogen source such as hydrazine (N ₂ H ₄ ).

Example 3 As shown in FIG. 3, 10 μ × was formed on the Mg-doped p-GaN 2 epitaxially grown as in Example 1 or Example 2 by photolithography.
A 10 μ square SiO ₂ film 1 is selectively deposited at intervals of 10 μ. S
The thickness of the iO ₂ film is 400 nm. Next, the substrate is placed on a susceptor in a reaction furnace, vacuum exhausted, and then ammonia and hydrogen are supplied to bring to atmospheric pressure. Ammonia is supplied at a rate of 1.3 l / min. Next, raise the temperature in the furnace to 1000 ° C,
Keep at constant temperature for 30 minutes. Finally, while supplying ammonia and hydrogen continuously, it is naturally cooled to room temperature.

It is well known that Mg-doped p-GaN is passivated by hydrogen supplied by ammonia, but this hydrogen passivation is performed after growth or cooling after heat treatment as shown in Example 1. Occurs, especially in the temperature range of 400-600 ℃. Therefore, SiO on Mg-doped p-GaN
_When a dielectric film such as ₂ or SiN is deposited, the decomposition efficiency of ammonia on the film is lowered and hydrogen atoms do not penetrate into the crystal, so that hydrogen passivation does not occur and the resistance of p-GaN can be reduced.

FIG. 4 is a graph showing the total surface area of 4000 Å on the Mg-doped p-GaN 2 epitaxially grown as in Example 1.
Samples with SiO ₂ film 1 deposited (with SiO ₂ ) and samples without SiO ₂ film deposited (without SiO ₂ ) were heat treated in a mixed atmosphere of ammonia and hydrogen at atmospheric pressure, and then ammonia was supplied during cooling. The results of observing the resistivity at that time are shown by changing the temperature at which to stop. Ammonia supply
It was performed at a rate of 1.3 l / min. The sample with the SiO ₂ film deposited has a low resistivity under all conditions, whereas the sample without the SiO ₂ film has a high resistance when the ammonia is continuously supplied to 600 ° C or lower, and the resistivity becomes higher at 400 ° C. You can see that you are almost at the limit. When the supply amount of ammonia is increased and the partial pressure is increased, the resistance is further lowered in the sample in which the SiO ₂ film is not deposited. Therefore, if a SiO ₂ film is selectively deposited and heat treatment is performed in an atmosphere of hydride gas such as ammonia, the resistance can be increased to an arbitrary degree at an arbitrary place. Further, in the present invention, since only the temperature range of 400-600 ° C. during cooling of growth or heat treatment is a problem, the Mg-doped p-
GaN does not necessarily have to have low resistance as in Example 1 or Example 2, and even a high-resistance film does not have a problem because the NH bond is broken by once raising the temperature to 600 ° C. or higher.

Next, another method for selectively increasing the resistance of p-GaN will be described. The wafer on which a SiO ₂ film is selectively deposited is placed on a susceptor in a reaction furnace, vacuum exhausted, and then ethyl azide and hydrogen are supplied to attain atmospheric pressure. Ethyl azide is fed at a rate of 6 mmol / min. Next, the temperature inside the furnace is raised to 700 ° C and kept at a constant temperature for 30 minutes. Finally, while continuously supplying ethyl azide and hydrogen, the mixture is naturally cooled to room temperature. During the heat treatment at 700 ° C, ethyl azide reacts with hydrogen to form intermediate products such as NH and NH ₂ . On the GaN on which the SiO ₂ film is not deposited, these are further decomposed due to the catalytic reaction to form hydrogen atoms, and hydrogen passivation of the Mg acceptor occurs. On the other hand, in the region where the SiO ₂ film is deposited, the decomposition efficiency of intermediate products such as NH and NH ₂ is lowered, and hydrogen passivation is suppressed. Therefore, by selectively depositing a SiO ₂ film, a high resistance layer and a low resistance layer can be obtained at arbitrary positions on GaN.

In this embodiment, p-GaN is used, but p-type
Not only GaN but also AlGaN, AlGaInN, InGaN, and all other p-type nitride-based compound semiconductors are clearly effective in reducing the resistance.

Further, the nitrogen raw material is not limited to ethyl azide, and the same effect can be obtained if it is an organic nitrogen raw material such as hydrazine (N ₂ H ₄ ).

Although the SiO ₂ film is used in this embodiment, the same effect can be obtained with a dielectric such as SiN or another semiconductor as long as the film reduces the decomposition efficiency of the hydride gas and the organic nitrogen raw material. It is obvious that

(Embodiment 4) First, the sapphire substrate 3 is placed on a susceptor in a reaction furnace and evacuated, and then heated at 1150 ° C. for 10 minutes in a hydrogen atmosphere at atmospheric pressure to clean the substrate. Next, it is cooled to 600 ° C., TMA is flowed at 3 μmol / min, NH ₃ is flown at 1.3 l / min, and carrier hydrogen is flown at 2.5 l / min to flow Al.
The N buffer layer 4 is grown to about 40 nm. Next, only the supply of TMA is stopped and the temperature is raised to 1030 ° C., then TMG is supplied at 60 μmol / min and SiH 4 is supplied at 1 μmol / min to deposit the n-GaN layer 5. Furthermore, TMA was added at a rate of 60 μmol / min to add n-Al _0.1 Ga.
After depositing _0.9 N6, the temperature is lowered to 800 ° C. in a mixed atmosphere of ammonia and hydrogen, and the flow rate of ammonia is increased to 10 l / min. Next, after supplying TMG at 60 μmol / min and TMI at 500 μmol / min to deposit an undoped In _0.1 Ga _0.9 N layer 7, TMG, TMI
Supply was stopped, the flow rate of ammonia was reduced to 1.3 l / min and the temperature was raised to 1030 ° C, and then CP2Mg was further added at 5 μmol / min.
, TMG at 60 μmol / min and TMA at 60 μmol / min to grow the Mg-doped p-Al _0.1 Ga _0.9 N layer 8. Next, the supply of TMA is stopped and the p-GaN layer 9 is grown.

Next, after stopping the supply of TMG and CP ₂ Mg to complete the growth, the heater is turned off and the mixture is naturally cooled in a mixed atmosphere of ammonia and hydrogen. When the temperature reached 600 ° C, the supply of ammonia was stopped, the atmosphere was switched to hydrogen only, and the temperature was cooled to room temperature (Fig. 5a). Next, a photolithography technique is used to form a SiO ₂ stripe 10 having a thickness of 4000 Å and a width of 5 μm.
It is deposited at 350 μm intervals (Fig. 5b). Next, the substrate is placed on a susceptor in a reaction furnace, vacuum exhausted, and then ammonia and hydrogen are supplied to bring to atmospheric pressure. Ammonia supply is 1.3 l
/ Min. Next, the temperature inside the furnace is raised to 1000 ° C and kept at a constant temperature for 30 minutes. Finally, while supplying ammonia and hydrogen continuously, it is naturally cooled to room temperature.

By the final heat treatment, the p-type layer (R region) other than the SiO ₂ stripe 10 is made highly resistive by hydrogen passivation (FIG. 5c). Therefore, after heat treatment, SiO ₂ is removed, positive and negative electrodes are attached, and the wafer is disassembled into semiconductor laser chips with a resonant structure.
When electrons are supplied from aN, current flows through the stripe-shaped low resistance and holes are supplied to the active layer, current confinement occurs, and a lateral mode control type blue semiconductor laser can be manufactured.

Even if the heat treatment is performed using ethyl azide and hydrogen as in the case of Example 3, the p-type layer other than the SiO ₂ stripe can have a high resistance, and the same effect can be obtained. The nitrogen raw material is not limited to ethyl azide, and similar effects can be obtained as long as it is an organic nitrogen raw material such as hydrazine (N ₂ H ₄ ).

Although the SiO ₂ film is used in this embodiment, the same effect can be obtained with a dielectric such as SiN or another semiconductor as long as the film reduces the decomposition efficiency of the hydride gas or the organic nitrogen raw material. What can be done is clear as in the third embodiment.

[0054]

As described above, according to the manufacturing method of the present invention, in order to obtain a p-type gallium nitride compound semiconductor having a low resistance as in the conventional case, after the vapor phase growth the substrate is cooled to room temperature and then annealed. The p-type gallium nitride-based compound semiconductor having low resistance can be obtained by a simple process of only switching the cooling atmosphere after vapor phase growth without performing the complicated process of performing.

Further, since the production of atomic hydrogen due to the thermal decomposition of the raw material can be selectively controlled by utilizing the catalytic effect of the substrate, the depth direction of the epitaxial growth layer, which was not possible by conventional electron beam irradiation or annealing, can be controlled over the entire depth direction. It is possible to selectively manufacture the low resistance portion and the high resistance portion on the substrate. Therefore, since the resistance can be selectively changed with respect to the substrate having the double hetero structure, the current confinement of the blue semiconductor laser becomes possible.

[Brief description of drawings]

[FIG. 1] Changing the temperature at which the mixed atmosphere of ammonia and hydrogen is switched to the atmosphere containing only hydrogen during cooling after vapor phase growth
Diagram showing the results of measuring the resistivity of the Mg-doped GaN layer

FIG. 2 is a diagram showing the results of measuring the resistivity of a Mg-doped GaN layer by performing epitaxial growth of p-type GaN using ethyl azide and changing the temperature at which hydrogen in the carrier gas is switched to nitrogen during cooling.

[Fig. 3] 10 on p-GaN by photolithography technology
Diagram showing selective deposition of μ × 10 μ square SiO ₂ films at intervals of 10 μ

FIG. 4 shows a sample in which a 4000 Å SiO ₂ film is deposited on the entire surface of Mg-doped p-GaN and a sample in which no SiO ₂ film is deposited are heat-treated in a mixed atmosphere of ammonia and hydrogen at atmospheric pressure.
Diagram showing the results of observing the resistivity at that time by changing the temperature at which the supply of ammonia is stopped during cooling

FIG. 5A is a cross-sectional view of a nitride blue semiconductor laser device, showing one step of a manufacturing method in which heat treatment is performed using an SiO ₂ film to confine current. FIG. 5B is a nitride blue semiconductor laser device. performing current constriction was heat-treated with SiO ₂ film in a single step diagram (c) the element cross-sectional view of a nitride based blue semiconductor laser manufacturing method for performing current constriction was heat-treated with SiO ₂ film in cross section Manufacturing process

[Explanation of symbols]

1 SiO ₂ 2 p-GaN 3 Sapphire substrate 4 AlN 5 n-GaN 6 n-AlGaN 7 InGaN 8 p-AlGaN 9 p-GaN 10 SiO ₂

Claims (14)

[Claims] 1. A p-type which is characterized in that an atmosphere containing a hydride gas is switched to an atmosphere of hydrogen or nitrogen at a temperature of 400 ° C. or more during vapor phase growth cooling of a gallium nitride-based compound semiconductor doped with p-type impurities. Method of manufacturing gallium nitride compound semiconductor. 2. The method for producing a p-type gallium nitride-based compound semiconductor according to claim 1, wherein the hydride gas is ammonia. 3. A carrier gas from hydrogen to nitrogen at a temperature of 400 ° C. or higher during vapor phase growth cooling of a gallium nitride-based compound semiconductor doped with a p-type impurity using an organic group V raw material containing no bond between nitrogen and hydrogen. A method of manufacturing a p-type gallium nitride-based compound semiconductor, characterized by switching to an atmosphere. 4. The method for producing a p-type gallium nitride-based compound semiconductor according to claim 3, wherein the organic group V raw material is ethyl azide (EtN ₃ ). 5. A step of selectively depositing a dielectric film on a portion of a gallium nitride-based compound semiconductor doped with p-type impurities, and a step of performing heat treatment in a temperature range of 400 ° C. or higher. A method for manufacturing a p-type gallium nitride-based compound semiconductor. 6. The method for producing a p-type gallium nitride based compound semiconductor according to claim 5, wherein the heat treatment atmosphere is a hydride gas or an organic group V containing hydrogen as a carrier gas. 7. The hydride gas is ammonia and the organic group V is ethyl azide (EtN ₃ ).
The method for producing a p-type gallium nitride-based compound semiconductor according to item 1. 8. The method for producing a p-type gallium nitride-based compound semiconductor according to claim 6, wherein the hydride gas is arsine or phosphine. 9. The method for producing a p-type gallium nitride compound semiconductor according to claim 5, wherein the dielectric film is SiO ₂ . 10. A step of selectively depositing a dielectric film on a portion of a substrate having a double hetero structure composed of a gallium nitride compound semiconductor layer having a gallium nitride compound semiconductor layer doped with a p-type impurity as a cladding layer. And a step of performing heat treatment in a temperature range of 400 ° C. or higher, p
Type gallium nitride compound semiconductor manufacturing method. 11. The method for producing a p-type gallium nitride-based compound semiconductor according to claim 10, wherein the heat treatment atmosphere is a hydride gas or an organic group V containing hydrogen as a carrier gas. 12. The method for producing a p-type gallium nitride compound semiconductor according to claim 11, wherein the hydride gas is ammonia and the organic group V is ethyl azide (EtN ₃ ). 13. The method for producing a p-type gallium nitride compound semiconductor according to claim 10, wherein the dielectric film is SiO ₂ . 14. An atmosphere containing a hydride gas at a temperature of 400 ° C. or higher is switched to a gas atmosphere that does not generate hydrogen atoms during vapor phase growth cooling of a gallium nitride-based compound semiconductor doped with p-type impurities. A method of manufacturing a p-type gallium nitride compound semiconductor.