JP2003012400A - Apparatus and process for growing group iii nitride compound crystal and group iii nitride compound crystal and its semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To grow a high quality group III nitride compound crystal of a desired size by continuously and stably feeding a group III material to the reaction vessel. SOLUTION: A pump (feed pump) 108 is arranged between a first feed pipe 107 and a second feed pipe 109 in order to feed a group III raw material stored in a vessel 110 continuously and stably to a reaction vessel 101 via the feed pipes 107 and 109. The type of the pump 108 is such that the rotational motion of a motor is converted into a translatory motion of a rod, and the translating rod pushes a liquid group III raw material (a substance at least including a group III metal), for example liquid Ga metal, into the reaction vessel from the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blue-violet light source for optical disks, an ultraviolet light source (LD or LED), a blue-violet light source for electrophotography, a group III nitride electronic device, a group III nitride which can be used for LED lighting equipment and the like. The present invention relates to a device crystal growth apparatus, a group III nitride crystal growth method, a group III nitride crystal, and a semiconductor device.

[0002]

2. Description of the Related Art InGaAlN (group III nitride) devices currently used as light sources of purple to blue to green are
Most of them are M on a sapphire substrate or SiC substrate.
It is produced by crystal growth using an O-CVD method (metal organic chemical vapor deposition method), MBE method (molecular beam crystal growth method), or the like. When sapphire or SiC is used as the substrate, there are many crystal defects due to a large difference in thermal expansion coefficient or lattice constant with the group III nitride. For this,
There are problems that the device characteristics are poor, for example, it is difficult to extend the life of the light emitting device, and the operating power is increased.

Further, since the sapphire substrate is insulative, it is impossible to take out the electrode from the substrate side as in the conventional light emitting device, and the electrode from the crystal-grown group III nitride semiconductor surface side is not possible. It needs to be taken out. As a result, there is a problem that the device area becomes large, leading to high cost. Also, it was fabricated on a sapphire substrate.
In the group III nitride semiconductor device, chip separation by cleavage is difficult, and it is not easy to obtain the cavity end face required for a laser diode (LD) by cleavage. For this reason, currently, cavity end face formation by dry etching,
Alternatively, after the sapphire substrate is polished to a thickness of 100 μm or less, the resonator end face is formed in a shape close to the cleavage, but in this case also, the resonator end face and the chip separation as in the conventional LD are separated by a single step. Therefore, it is impossible to easily carry out the process, and the process becomes complicated and the cost becomes high.

In order to solve these problems, it has been proposed to reduce the crystal defects by selectively laterally growing a group III nitride semiconductor film on a sapphire substrate or by taking other measures.

For example, the document “Japanese Journal of Applie
d Physics Vol.36 (1997) Part 2, No.12A, L1568-157
1 "(hereinafter referred to as the first conventional art) shows a laser diode (LD) as shown in FIG. Figure 4
In the laser diode of, the GaN low temperature buffer layer 2 and the GaN layer 3 are sequentially grown on the sapphire substrate 1 by an MO-VPE (metal organic chemical vapor deposition) apparatus, and then S for selective growth is used.
The iO ₂ mask 4 is formed. The SiO ₂ mask 4 is formed through a photolithography and etching process after depositing a SiO ₂ film by another CVD (chemical vapor deposition) device. Then, again on the SiO ₂ mask 4, M
By growing the GaN film 3 ′ having a thickness of 20 μm by the O-VPE apparatus, GaN is selectively grown in the lateral direction, and crystal defects are reduced as compared with the case where the selective lateral growth is not performed. Furthermore, by introducing a modulation-doped strained superlattice layer (MD-SLS) 5 formed thereabove, crystal defects are prevented from extending to the active layer 6. As a result, it becomes possible to prolong the device lifetime as compared with the case where the selective lateral growth and the modulation-doped strained superlattice layer are not used.

In the case of the first conventional technique, it is possible to reduce the crystal defects as compared with the case where the GaN film is not selectively laterally grown on the sapphire substrate. However, by using the sapphire substrate, The aforementioned problems with insulation and cleavage still remain. Furthermore, the crystal growth by the MO-VPE apparatus is required twice between the SiO ₂ mask forming steps, which causes a new problem that the steps become complicated.

As another method, for example, the document "Appl
ied Physics Letters, Vol.73, No.6, p.832-834 (199
8) ”(hereinafter referred to as the second related art), it is proposed to apply a GaN thick film substrate. In the second conventional technique, after the selective lateral growth of 20 μm in the first conventional technique described above, a GaN thick film of 200 μm is grown by an H-VPE (hydride vapor phase epitaxy) apparatus, and thereafter, The GaN film grown to a thickness of 150 μm is polished from the sapphire substrate side so that the GaN film has a thickness of 150 μm.
Make a substrate. By using the MO-VPE apparatus to sequentially perform the crystal growth necessary for an LD device on this GaN substrate to produce an LD device, it becomes possible to reduce crystal defects and use a sapphire substrate. It is possible to solve the above-mentioned problems relating to insulation and cleavage due to Incidentally, Japanese Patent Laid-Open No. 11-4048 has been proposed as the same as the second prior art, and FIG. 5 shows a semiconductor laser of Japanese Patent Laid-Open No. 11-4048.

However, the second conventional technique has more complicated steps than the first conventional technique, and the cost is further increased. Further, when a GaN thick film having a thickness of about 200 μm is grown by the method of the second conventional technique, stress due to a difference in lattice constant and a difference in thermal expansion coefficient with sapphire, which is a substrate, becomes large, so that the substrate A new problem occurs that warpage and cracks occur.

In order to avoid this problem, Japanese Unexamined Patent Publication No. 10-
No. 256662 proposes that the thickness of the original substrate (sapphire and spinel) for thick film growth be 1 mm or more. As described above, by using the substrate having a thickness of 1 mm or more, even if the GaN film having a thick film of 200 μm is grown, the substrate is not warped or cracked. However, such a thick substrate has a high cost for the substrate itself and requires a lot of time for polishing, which leads to an increase in the cost of the polishing process. That is, when using a thick substrate, the cost is higher than when using a thin substrate. When a thick substrate is used, the substrate does not warp or crack after the thick GaN film is grown, but the stress is relaxed in the polishing process, and warping or cracks occur during polishing. Therefore, even if a thick substrate is used, a GaN substrate with high crystal quality cannot be easily manufactured in a large area.

On the other hand, the document “Journal of Crystal Growth,
Vol.189 / 190, p.153-158 (1998) "(hereinafter referred to as the third conventional technique), it is proposed to grow a GaN bulk crystal and use it as a homoepitaxial substrate. This third conventional technique is based on 1400 to 1700.
This is a method of crystal-growing GaN from liquid Ga at a high temperature of ° C and an ultrahigh pressure of several tens of kbar. In this case, using this bulk-grown GaN substrate, it becomes possible to grow a group III nitride semiconductor film necessary for a device. Therefore, the GaN substrate can be provided without complicating the process as in the first and second conventional techniques.

However, in the third conventional technique, there is a problem that the crystal growth at high temperature and high pressure is required, and the reaction container that can withstand the growth becomes extremely expensive. In addition, even with such a growth method, the size of the crystal obtained is at most about 1 cm, which is a problem that the device is too small for practical use.

As a method for solving the problem of GaN crystal growth at high temperature and high pressure, the document "Chemistry of Mater" is used.
ials Vol.9 (1997) p.413-416 ”(hereinafter referred to as the fourth prior art) describes GaN using Na as a flux.
Crystal growth methods have been proposed. In this method, sodium azide (NaN ₃ ) and metallic Ga are used as raw materials, and a stainless steel reaction vessel (inside vessel size; inner diameter = 7.5 mm, length = 100 mm) is sealed in a nitrogen atmosphere, and the reaction vessel is sealed at 600 The GaN crystal is grown by holding at a temperature of ~ 800 ° C for 24 to 100 hours. In the case of the fourth conventional technique, crystal growth is possible at a relatively low temperature of about 600 to 800 ° C., and the pressure inside the container is at most 1.
The feature is that the pressure can be lowered to about 00 kg / cm ² as compared with the third conventional technique. However, the problem with the fourth conventional technique is that the size of the obtained crystal is 1 mm.
This is a small point that is less than. This size is too small for practical use of the device as in the third prior art.

Further, Japanese Patent Application Laid-Open No. 2000-327495 (hereinafter referred to as "fifth prior art") proposes a technology in which the above-mentioned fourth conventional technology and an epitaxial method using a substrate are combined. In the fifth conventional technique, a substrate on which GaN or AlN is previously grown is used as a substrate, and a GaN film is epitaxially grown on the substrate by using the fourth conventional technique. However, the fifth conventional technique is basically epitaxial growth and cannot solve the problem of crystal defects as in the first and second conventional techniques. Furthermore, since the GaN film or AlN film is grown on the substrate in advance, the process becomes complicated and the cost is increased.

Further, recently, Japanese Patent Laid-Open Nos. 2000-12900 and 2000-22212 (hereinafter, referred to as sixth prior art) propose a method of manufacturing a GaN thick film substrate using a GaAs substrate. There is. 6 and 7 show a method of manufacturing a GaN thick film substrate according to the sixth conventional technique. First, referring to FIG. 6, (111) Ga
As in the first conventional technique, the GaN film 63 is 70 μm thick on the As substrate 60 using the SiO ₂ film or the SiN film as the mask 61.
~ Selectively grow to a thickness of 1 mm (Fig. 6 (1) ~
(3)). This crystal growth is performed by H-VPE. After that, the GaAs substrate 60 is removed by etching with aqua regia, and the GaN free-standing substrate 63 is manufactured (FIG. 6 (4)). Based on this GaN free-standing substrate 63, a GaN crystal 64 having a thickness of several 10 mm is vapor-grown again by H-VPE (FIG. 7 (1)). The GaN crystal 64 having a thickness of several tens of mm is cut into a wafer by using a slicer to manufacture a GaN wafer (FIGS. 7 (2) and 7 (3)).

In the sixth conventional technique, a GaN free-standing substrate 63 is obtained, and a GaN crystal 64 having a thickness of several tens mm is further provided.
Can be obtained. However, the sixth conventional technique has the following problems. That is, SiN film or Si
Since the O ₂ film is used as a mask for selective growth, its manufacturing process becomes complicated, resulting in high cost. Also, H-V
When growing a GaN crystal with a thickness of several tens of millimeters by PE, a GaN crystal (single crystal or polycrystal) of similar thickness or amorphous GaN also adheres to the inside of the reaction vessel, which increases mass productivity. There's a problem. Moreover, since the GaAs substrate is etched and removed as a sacrificial substrate at each growth,
This leads to higher costs. Also, regarding the crystal quality, basically, it comes from the crystal growth on a heterogeneous substrate called GaAs.
There remains the problem of high defect density due to lattice mismatch and difference in thermal expansion coefficient.

[0016]

SUMMARY OF THE INVENTION The present invention does not complicate the steps, which are the problems of the first, second, fifth or sixth prior art, and the problems of the third prior art. A high-performance light-emitting diode, LD, or other device is manufactured without using an expensive reaction container and without reducing the crystal size, which is a problem of the third and fourth conventional techniques. Group III nitride crystal growth apparatus, Group III nitride crystal growth method, and Group III nitride crystal capable of growing a high-quality Group III nitride crystal at a practical size for low cost And to provide a semiconductor device.

Further, according to the present invention, the Group III raw material is continuously and stably supplied into the reaction vessel, and a high quality II of desired size is obtained.
An object of the present invention is to provide a group III nitride crystal growth apparatus, a group III nitride crystal growth method, a group III nitride crystal and a semiconductor device capable of growing a group I nitride crystal.

[0018]

In order to achieve the above object, the invention according to claim 1 is characterized in that in a reaction vessel, an alkali metal and a substance containing at least a Group III metal form a mixed melt, From the mixed melt and a substance containing at least nitrogen,
In a group III nitride crystal growth apparatus for growing a group III nitride crystallized from a group III metal and nitrogen, a rotary motion of a motor is converted into a linear motion of a rod, and at least the group III metal is converted by the linear motion rod. It is characterized in that it is provided with a pump for feeding the contained substance from the outside of the reaction vessel into the reaction vessel.

The invention according to claim 2 is the same as that of claim 1.
In the Group III nitride crystal growth apparatus, a check valve is provided in the pump for feeding a substance containing at least a Group III metal into the reaction vessel, and the check valve is provided at least from the reaction vessel to the pump. It is characterized by having a ball made of a predetermined material for preventing backflow of a substance containing a Group III metal.

According to a third aspect of the present invention, in the group III nitride crystal growth apparatus according to the second aspect, the density of the material of the balls is higher than the density of the substance containing at least the group III metal. Is characterized by.

Further, the invention according to claim 4 is characterized in that in the reaction vessel, a mixed melt of an alkali metal and a substance containing at least a Group III metal forms a mixed melt, and the mixed melt and a substance containing at least nitrogen, In a group III nitride crystal growth method for growing a group III nitride composed of a group III metal and nitrogen, a substance containing at least a group III metal is transferred from the outside of the reaction vessel into the reaction vessel by using a predetermined pump. It is characterized by sending in.

The invention according to claim 5 is the method for growing a group III nitride crystal according to claim 4, wherein at least III
The substance containing a group metal is characterized in that it is fed into the reaction container from the outside of the reaction container in a liquid state.

Further, the invention according to claim 6 is the method for growing group III nitride crystals according to claim 5, wherein the substance containing at least a group III metal fed into the reaction vessel from outside the reaction vessel is in a liquid state. It is characterized by being metallic Ga (gallium).

The invention according to claim 7 is characterized by being manufactured by the group III nitride crystal growth method according to any one of claims 4 to 6.

The invention according to claim 8 is characterized in that it is produced by using the group III nitride crystal according to claim 7.

Further, the invention according to claim 9 is the semiconductor device according to claim 8, wherein the semiconductor device is 4
It is characterized in that it is a light emitting device that emits light at a wavelength shorter than 00 nm.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a group III nitride crystal growth apparatus according to the present invention.

Referring to FIG. 1, in a reaction vessel 101, a mixed melt holding vessel for holding a mixed melt 103 of an alkali metal (eg, Na) and a substance containing at least a group III metal (eg, Ga). 102 is installed.

The alkali metal (for example, Na) may be supplied from the outside or may be present in the reaction vessel 101 from the beginning.

The reaction vessel 101 is made of stainless steel, for example. In addition, the mixed melt holding container 102
Is, for example, BN (boron nitride) or AlN,
Alternatively, it is formed of pyrolytic BN.

Further, in the group III nitride crystal growth apparatus of FIG. 1, a nitrogen supply pipe 104 for supplying a substance containing at least nitrogen (for example, nitrogen gas, ammonia gas or sodium azide) into the reaction vessel 101. Is provided. The term "nitrogen" as used herein means a nitrogen molecule or atomic nitrogen produced from a nitrogen molecule or a compound containing nitrogen, and an atomic group or molecular group containing nitrogen, and in the present invention, nitrogen means Let's say that

Further, the nitrogen supply pipe 104 is provided with a pressure adjusting mechanism 105 for adjusting the pressure of nitrogen gas. The pressure adjusting mechanism 105 is composed of a pressure sensor, a pressure adjusting valve, and the like.

In addition, the reaction vessel 101 has a temperature at which a group III nitride (eg, GaN) can be grown on the reaction vessel 10.
A first heating device 106 for controlling the inside of the device 1 is provided. That is, the temperature control function of the first heating device 106 raises the temperature in the reaction vessel 101 to a temperature at which crystal growth is possible, lowers it to a temperature at which crystal growth is stopped, and keeps those temperatures for an arbitrary time. It is possible to do.

Further, in the group III nitride crystal growth apparatus of FIG. 1, a substance containing at least a group III metal (hereinafter referred to as a group III raw material) is supplied from outside the reaction vessel 101 to the reaction vessel 101.
In order to supply the gas to the reactor, a container 110 for containing a group III raw material is provided outside the reaction container 101. Specifically, the amount of the group III metal consumed in the reaction container 101 (for example, the amount of Ga consumed when crystallizing GaN from Ga and N) to be consumed in the reaction container 101 is sufficiently large. The group III raw material (for example, metal Ga) is stored. Here, the group III raw material (for example, metal Ga) contained in the container 110 is the second heating device 112 described later.
It can be made into a liquid state.

Then, the container 110 and the reaction container 101
Is connected by a first supply pipe 107 and a second supply pipe 109, and the group III raw material is supplied to the mixed melt holding container 102 in the reaction container 101 through the supply pipes 107 and 109. It is possible.

Further, in order to continuously and stably supply the group III material housed in the container 110 into the reaction container 101 through the supply pipes 107 and 109, the group III nitride crystal growth apparatus of FIG. A pump (liquid feeding pump) 108 is provided between the first supply pipe 107 and the second supply pipe 109. The pump 108 converts the rotational motion of the motor into a linear motion of the rod, and a group III raw material in a liquid state (a substance containing at least a Group III metal), for example, a metallic Ga in a liquid state of the reaction vessel is converted by the linearly moving rod. A type that is fed into the reaction vessel from the outside is used.

FIG. 2 is a diagram showing a configuration example of the pump 108. In addition, in FIG. 2, the container 110 is located on the upstream side of the second supply pipe 109 (on the right side in this figure), and the reaction container 101 is on the downstream side of the first supply pipe 107 (in this figure). It is located on the left side of).

Referring to FIG. 2, inside the pump 108,
The motor 201 is provided, and the motor 201 is
The electric signal is converted into rotary motion and transmitted to the rotary shaft 202. The rotating shaft 202 is coupled to the cam 203 at a position (eccentric) displaced from the center of the cam 203. Here, the plane shape of the cam 203 is an ellipse. The rod 204 is always in contact with the side surface of the cam 203. In such a configuration, the motor 201
As a result, the rotating shaft 202 rotates and the cam 203 rotates, so that the rod 204 moves straight in the direction of arrow A1 or A2.

The rod 204 is a third T-shaped member.
Is inserted in one tube portion 205a of the supply tube 205 of FIG. Then, the other pipe portion 2 of the third supply pipe 205
05b and 205c are the first check valves 206 and 205, respectively.
It is connected to the second check valve 207. The downstream side of the first check valve 206 (left side in this figure) is connected to the first supply pipe 107, and the upstream side of the second check valve 207 (right side in this figure) is It is connected to the second supply pipe 109.

The first check valve 206 and the second check valve 207
Inside, springs 208 and 209 and balls 210 and 2
11 are installed respectively. First check valve 206, second
As shown in FIG. 2, the internal structure of the check valve 207 is such that the springs 208 and 209 are at the downstream portion (left side in this figure) and the balls 210 and 211 are at the upstream portion (right side in this figure).
The springs 208 and 209 bias the balls 210 and 211 from the downstream direction to the upstream direction. As a result, the balls 210 and 211 move the check valve 20.
The structure is such that it stops on the upstream side of 6,207.
The balls 210 and 211 are the openings 20 of the first check valve 206.
6a, when the second check valve 207 is in contact with the opening 207a of the second check valve 207, the downstream side and the upstream side are shut off so that the liquid group III raw material does not flow from the downstream side to the upstream side (backflow). Is designed to prevent).

In the pump 108 having such a structure, when the rod 204 moves in the direction of the arrow A2 (pulling direction), the inside of the third supply pipe 205 is in a depressurized state, and the inside of the third supply pipe 205 enters. The group III raw material in a liquid state is drawn from the container 110. At this time, the first check valve 206 prevents the backflow by moving the ball 210 in the upstream direction, and the ball 211 of the second check valve 207 moves in the downstream direction, and the container 11
It is possible to draw liquid Group III raw materials from 0.

On the contrary, when the rod 204 moves in the direction of arrow A1 (pushing direction), the inside of the third supply pipe 205 is in a pressurized state and is in a liquid state drawn from the container 110. Group III raw material downstream (reaction vessel 101 side)
Will be pushed out to. At this time, the first check valve 206
The ball 210 moves in the downstream direction and the group III raw material in the liquid state can be supplied toward the reaction vessel 101, and the ball 211 of the second check valve 207 moves in the upstream direction, so that the liquid state It is possible to prevent backflow of the group III raw material.

When such a pump 108 is provided, by adjusting the moving speed of the rod 204, that is, the rotation speed of the motor 201, the liquid group III raw material from the outside of the reaction vessel 101 into the reaction vessel 101 is adjusted. It is possible to control the liquid feeding speed of

In this way, the pump 108 is provided, the liquid supply rate of the group III raw material in the liquid state into the reaction vessel 101 is controlled, and the group III raw material can be stably supplied into the reaction vessel 101. .

Here, the inventors of the present application experimentally confirmed that the material of the balls 210 and 211 of the check valves 206 and 207 is important. That is, the check valve 20
It was confirmed that the density of the material of the balls 210 and 211 of 6,207 needs to be higher than the density of the group III raw material to be fed. In fact, experiments were carried out using stainless steel (having a density of 8 g / cm ³ ), sapphire and glass (having a density of 4 g / cm ³ ) as the material of the balls 210 and 211. The density of the group III raw material (for example, the density of metallic Ga) is 6
It is about g / cm ³ . As a result of this experiment, ball 21
By using stainless steel having a density higher than that of the group III raw material as the material of the check valves 206, 2
It was confirmed that 07 works without problems as described above. On the other hand, when sapphire, glass, or the like having a density lower than that of the group III raw material is used as the material of the balls 210 and 211, the check valves 206 and 207 do not operate, and the liquid group III raw material flows backward. I found out that I would do it.

In the present invention, the ball includes not only a spherical shape but also a three-dimensional shape such as an ellipse or a polygon.

In addition, the group III nitride crystal growth apparatus of FIG. 1 includes a second heating device 112 for heating and controlling the first supply pipe 107, the second supply pipe 109, the pump 108, and the container 110. It is provided. This second heating device 112
The first supply pipe 107, the second supply pipe 109,
The temperature of the pump 108 and the container 110 can be set to about 40 ° C., and in this case, the temperature is stored in the container 110.
Group III raw material (substance containing at least Group III metal), and container 110 to second supply pipe 109, pump 10
8. The group III raw material (the substance containing at least the group III metal) before being sent to the reaction vessel 101 through the first supply pipe 107 is in a liquid state.

In the group III nitride crystal growth apparatus of FIG. 1, the temperature inside the reaction vessel 101 and the effective nitrogen partial pressure are set to the conditions under which group III nitride crystals grow.
Crystal growth of the group nitride can be initiated.

Specifically, the nitrogen pressure in the reaction vessel 101 is set to 50 atm, and the temperature in the reaction vessel 101 is raised to a temperature of 750 ° C. at which crystal growth starts. By maintaining this growth condition for a certain period of time, a Group III nitride crystal (for example, Ga
N crystal) 111 grows in the mixed melt holding container 102.

At this time, in the group III nitride crystal growth apparatus of FIG. 1, the group III metal (eg, Ga) consumed to supplement the group III nitride crystal (eg, GaN) 111 by crystal growth is supplemented. The group III raw material (for example, Ga) is supplied from the inside of the container 110 to the second supply pipe 1 using the pump 108.
09, the liquid can be supplied into the reaction vessel 101 through the first supply pipe 107. Further, nitrogen for supplementing the consumed nitrogen can be supplied in the state of nitrogen gas through the nitrogen gas supply pipe 104.

As described above, after the growth of the group III nitride crystal is started, the group III raw material (the substance containing at least the group III metal) is fed into the reaction vessel 101 to continuously produce II.
Group I nitride crystals can be grown.

In this way, the pump 108 is provided to control the liquid feeding speed of the group III raw material into the reaction vessel 101,
By stably supplying the group raw material into the reaction vessel 101,
A group III nitride crystal (for example, GaN crystal) 111 can be continuously and stably grown, and a large size III
Group nitride crystals (GaN crystals) can be grown.

As described above, in the group III nitride crystal growth apparatus and group III nitride crystal growth method of the present invention, the reaction vessel 1
In 01, a mixed melt of an alkali metal and a substance containing at least a group III metal is formed, and a group III nitride composed of a group III metal and nitrogen is formed from the mixed melt and a substance containing at least nitrogen. Since the crystal is grown, it is possible to obtain a high-quality group III nitride crystal at low cost without requiring a complicated process as in the first or second prior art.

Further, since the crystal growth of the group III nitride is possible under the condition that the growth temperature is as low as 1000 ° C. or less and the pressure is as low as 100 atm or less, the ultrahigh pressure as in the third prior art, There is no need to use an expensive reaction vessel that can withstand ultrahigh temperatures. As a result, it becomes possible to produce a group III nitride crystal at low cost.

Further, in the present invention, a pump 108 is provided which converts the rotational movement of the motor into the linear movement of the rod and sends the substance containing at least the group III metal from the outside of the reaction vessel into the reaction vessel by the linearly moving rod. By controlling the liquid feed rate of the group III raw material into the reaction vessel 101 and stably supplying the group III raw material into the reaction vessel 101, II
The group I nitride crystal (for example, GaN crystal) 111 can be continuously and stably grown, and a large-sized group III nitride crystal (GaN crystal) can be grown.

Group III nitride crystal growth apparatus of the present invention, III
The group III nitride crystal grown by the group nitride crystal growth method is of high quality, and the group III nitride semiconductor device produced by using this group III nitride crystal has good characteristics. Will have.

Specifically, in the prior art, the emission from the deep order of the emission spectrum of the GaN film is dominant, and
Although there is a problem that device characteristics are poor at wavelengths shorter than 0 nm, the present invention can provide a light emitting device having good characteristics even in the ultraviolet region.

FIG. 3 is a diagram showing a structural example of a semiconductor device manufactured using the group III nitride crystal of the present invention. The semiconductor device in FIG. 3 is configured as a semiconductor laser. The semiconductor laser of FIG. 3 is an n-type GaN substrate 30 using a group III nitride crystal growing apparatus and a group III nitride crystal growing method of the present invention.
1, n-type AlGaN cladding layer 302, n-type GaN
Guide layer 303, InGaN MQW (multiple quantum well)
Active layer 304, p-type GaN guide layer 305, p-type AlG
aN cladding layer 306, p-type GaN contact layer 307
Are sequentially crystal-grown and laminated.

The crystal growth method is MO-VPE.
A thin film crystal growth method such as a (metal organic chemical vapor deposition) method or an MBE (molecular beam epitaxy) method can be used.

Then, such GaN, AlGaN,
A ridge structure is formed on the InGaN laminated film, and SiO ₂
An insulating film 308 is formed with holes only at the contact layer 307, and a p-side ohmic electrode (Au / Ni) 309 and an n-side ohmic electrode (Al / Ti) 310 are formed on the upper and lower portions, respectively. There is.

In this semiconductor laser, by injecting a current from the p-side ohmic electrode 309 and the n-side ohmic electrode 310, laser oscillation occurs and laser light is emitted in the direction of the arrow in FIG.

Since this semiconductor laser uses the group III nitride crystal (GaN crystal) of the present invention as a substrate, it has few crystal defects in the semiconductor laser device, and has a large output operation and a long life. . In addition, the GaN substrate is n
Since it is a mold, it is possible to form electrodes directly on the substrate, and unlike the first conventional technique (FIG. 4), it is not necessary to take out the two electrodes on the p-side and the n-side only from the surface, and the cost is low. Can be realized. Furthermore, it becomes possible to form the light emitting end face by cleavage, and together with the separation of the chip,
It is possible to realize a high quality device at low cost.

In the above example, the InGaN MQW is used.
Although the active layer 304 is made of AlGaN MQW, the active layer 304 may be made of AlGaN MQW to shorten the emission wavelength. That is, in the present invention, since the number of defects and impurities in the GaN substrate is small, the light emission from the deep order is small, and a highly efficient light emitting device is possible even if the wavelength is shortened.

Further, in the above-mentioned example, the case where the present invention is applied to the optical device has been described, but the present invention can also be applied to the electronic device. That is, by using a GaN substrate with few defects, the GaN-based thin film epitaxially grown thereon has few crystal defects, and as a result, leakage current can be suppressed, the carrier confinement effect in the case of a quantum structure can be enhanced, and A high-performance device can be realized.

That is, the group III nitride crystal of the present invention is
As described above, it is a high quality crystal with few crystal defects. A high-performance device can be realized by producing a device by using this group III nitride crystal or by producing a device as a substrate or from thin film growth. The high performance referred to here is, for example, in the case of a semiconductor laser or a light emitting diode, high output and long life which have not been realized conventionally, and in the case of an electronic device, low power consumption, low noise, high speed operation, It can operate at high temperature and has low noise and long life as a light receiving device.

[0066]

As described above, according to the first to sixth aspects of the invention, the alkali metal and the substance containing at least a Group III metal form a mixed melt in the reaction vessel, From the mixed melt and a substance containing at least nitrogen,
Since a group III nitride composed of a group III metal and nitrogen is crystal-grown, complicated steps such as those of the first, second, fifth or sixth conventional techniques are not required,
It is possible to realize a high-quality Group III nitride crystal at low cost and a semiconductor device using the same.

Furthermore, since the group III nitride crystal can be grown under the condition that the growth temperature is as low as 1000 ° C. or less and the pressure is as low as about 100 atm or less, the ultrahigh pressure as in the third prior art, It is not necessary to use an expensive reaction container that can withstand ultrahigh temperatures, and as a result, it is possible to realize a low cost group III nitride crystal and a semiconductor device using the same.

Further, according to the first to sixth aspects of the invention, the rotational motion of the motor is converted into the linear motion of the rod, and the linearly moving rod is used to transfer the substance containing at least a group III metal from the outside of the reaction vessel. By providing the pump for feeding into the reaction vessel, the substance containing at least the group III metal can be continuously fed into the reaction vessel by using the pump. Therefore, it becomes possible to continuously and stably grow the group III nitride crystal, and a high quality group III nitride crystal having a desired size can be obtained.

In particular, in the inventions according to claims 2 and 3, in the group III nitride crystal growth apparatus according to claim 1, the inside of the pump for feeding the substance containing at least the group III metal into the reaction vessel is reversed. A check valve is provided, and since the check valve has a ball made of a predetermined material for preventing backflow of a substance containing at least a Group III metal from the reaction vessel to the pump, at least a Group III metal is provided. It is possible to prevent the backflow of the substance containing the metal, and it is possible to continuously feed the substance containing at least the group III metal into the reaction vessel.

Further, according to the invention of claim 7, a group III nitride produced by the method of growing a group III nitride crystal according to any one of claims 4 to 6. Since it is a crystal, it is possible to provide a group III nitride crystal having high crystal quality and large enough to make a device at low cost.

According to the eighth and ninth aspects of the present invention, the semiconductor device is characterized by being produced by using the group III nitride crystal according to the seventh aspect, and is therefore a high-performance semiconductor. The device can be provided at low cost.

In particular, according to the invention described in claim 9, in the semiconductor device according to claim 8, the semiconductor device is a light emitting device which emits light at a wavelength shorter than 400 nm, and has a high wavelength range shorter than 400 nm. A light emitting device that efficiently emits light can be provided. That is,
By using the group III nitride crystal of the present invention as a substrate, a group III nitride semiconductor device with few crystal defects and impurities can be realized, and as a result, light emission from a deep order can be suppressed and highly efficient light emission characteristics can be achieved. Can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a Group III nitride crystal growth apparatus according to the present invention.

FIG. 2 is a diagram showing a configuration example of a pump.

FIG. 3 is a diagram showing a configuration example of a semiconductor device according to the present invention.

FIG. 4 is a diagram showing a conventional laser diode.

FIG. 5 is a diagram showing a conventional semiconductor laser.

FIG. 6 is a diagram showing a method of manufacturing a GaN thick film substrate according to a sixth conventional technique.

FIG. 7 is a diagram showing a method of manufacturing a GaN thick film substrate according to a sixth conventional technique.

[Explanation of symbols]

101 Reaction Container 102 Mixed Melt Holding Container 103 Mixed Melt 104 Nitrogen Supply Pipe 105 Pressure Adjustment Mechanism 106 First Heating Device 107 First Supply Pipe 108 Pump 109 Second Supply Pipe 110 Container 111 Group III Nitride Crystal 112 Second heating device 201 Motor 202 Rotating shaft 203 Cam 204 Rod 205 Third supply pipe 206 First check valve 207 Second check valve 208, 209 Spring 210, 211 Ball 301 n-type GaN substrate 302 n-type AlGaN clad layer 303 n-type GaN guide layer 304 InGaN MQW active layer 305 p-type GaN guide layer 306 p-type AlGaN clad layer 307 p-type GaN contact layer 308 SiO ₂ insulating film 309 p-side ohmic electrode 310 n-side ohmic electrode

Continued front page    F-term (reference) 4G077 AA02 BE15 CC05 CC06 EG26                 5F041 AA04 AA44 CA40 CA63 CA65                       CA66 CA85                 5F053 AA50 DD20 FF04 GG01 LL01                       RR11 RR13                 5F073 AA04 AA45 AA74 CA07 CB02                       CB22 DA04 DA06 DA07 DA32                       EA24 EA28

Claims (9)

[Claims] 1. A reaction vessel, in which an alkali metal and a substance containing at least a group III metal form a mixed melt, and the mixed melt and a substance containing at least nitrogen are used to form a group III metal and nitrogen. Growth of group III nitrides III
The group-nitride crystal growth apparatus is provided with a pump for converting the rotational movement of the motor into the linear movement of the rod, and for feeding the substance containing at least the group III metal from the outside of the reaction vessel into the reaction vessel by the linearly-moving rod. A group III nitride crystal growth apparatus characterized by: 2. The group III nitride crystal growth apparatus according to claim 1, wherein a check valve is provided in the pump for feeding a substance containing at least a group III metal into the reaction vessel, and the check valve is provided. At least II from the reaction vessel to the pump
A group III nitride crystal growth apparatus having a ball made of a predetermined material for preventing backflow of a substance containing a group I metal. 3. The group III nitride crystal growth apparatus according to claim 2, wherein the ball has a material density higher than that of a substance containing at least a group III metal. Crystal growth equipment. 4. A reaction vessel, in which an alkali metal and a substance containing at least a group III metal form a mixed melt, and the mixed melt and a substance containing at least nitrogen constitute a group III metal and nitrogen. Growth of group III nitrides III
In the Group III nitride crystal growth method, a Group III nitride crystal growth method is characterized in that a substance containing at least a Group III metal is fed into the reaction vessel from outside the reaction vessel using a predetermined pump. 5. The group III nitride crystal growth method according to claim 4, wherein the substance containing at least a group III metal is fed into the reaction vessel from outside the reaction vessel in a liquid state. Nitride crystal growth method. 6. The group III nitride crystal growth method according to claim 5, wherein the substance containing at least a group III metal fed into the reaction vessel from the outside of the reaction vessel is liquid metal Ga (gallium). And a method for growing a group III nitride crystal. 7. A group III nitride crystal produced by the group III nitride crystal growth method according to claim 4. 8. A semiconductor device manufactured by using the group III nitride crystal according to claim 7. 9. The semiconductor device according to claim 8, wherein the semiconductor device is a light emitting device that emits light with a wavelength shorter than 400 nm.