KR20020065892A - Method of fabricating group-ⅲ nitride semiconductor crystal, method of fabricating gallium nitride-based compound semiconductor, gallium nitride-based compound semiconductor, gallium nitride-based compound semiconductor light-emitting device, and light source using the semiconductor light-emitting device - Google Patents

Abstract

The present invention provides a method for depositing a Group 3 metal particle using a metal material on a substrate surface in an atmosphere including a nitrogen source but no metal material, and the Group 3 nitride semiconductor crystal on the substrate surface on which the particles are deposited. It relates to a method for producing a group 3 nitride semiconductor crystal film comprising the step of growing a.

Description

A method for producing a group III nitride semiconductor crystal, a gallium nitride-based compound semiconductor manufacturing method, a gallium nitride-based compound semiconductor, a gallium nitride-based compound semiconductor light emitting device, and a light source using a semiconductor light emitting device {METHOD OF FABRICATING GROUP-III NITRIDE SEMICONDUCTOR CRYSTAL, METHOD OF FABRICATING GALLIUM NITRIDE-BASED COMPOUND SEMICONDUCTOR, GALLIUM NITRIDE-BASED COMPOUND SEMICONDUCTOR, GALLIUM NITRIDE-BASED COMPOUND SEMICONDUCTOR LIGHT-EMITTING DEVICE, AND LIGHT SOURCE USING V

Group III nitride semiconductors are used in LEDs and LDs because they have direct-transition bandgap energy that extends from visible light to ultraviolet light where high efficiency light can be emitted. At the heterojunction boundary of aluminum gallium nitride (AlGaN) and gallium nitride (GaN), due to the unique piezoelectric effect of group III nitride semiconductors, electrons on the two-dimensional layer are obtained in conventional group 3-4 compound semiconductors. One of the potential semiconductor properties that cannot be achieved.

However, the nitrogen separation pressure that can reach 2000 atm at the single crystal growth temperature makes it difficult to grow the Group 3 compound semiconductor single crystal. Therefore, at present, it is difficult to use a single crystal substrate of such a group III nitride semiconductor as a substrate for epitaxial growth of another compound semiconductor of group 3-5. Therefore, as the epitaxial growth substrate, another substrate, for example, a substrate composed of sapphire (Al ₂ O ₃ ) single crystal or silicon carbide (SiC) single crystal is used.

There is a large lattice mismatch between this substrate and the Group 3 nitride compound semiconductor crystals epitaxially grown on the substrate. For example, there is a lattice mismatch of 16% between sapphire and gallium nitride and between 6% between SiC and gallium nitride. In general, such a large mismatch makes it difficult for crystals to epitaxially grow directly on a substrate, and even if such growth occurs, the crystallinity is not good. Metal-organic chemical vapor deposition (MOCVD) methods are used to epitaxially grow group III nitride semiconductor crystals on single crystal substrates composed of sapphire or SiC, as shown in JP-C 3,026,087 and JP-A Hei 4-297023. In general, a commonly used method includes first depositing on a substrate called a low temperature buffer layer composed of aluminum nitride (AlN) or AlGaN, and then epitaxially growing a group III nitride semiconductor crystal on the buffer layer. Steps.

In the case of a sapphire substrate, the above-mentioned low temperature buffer layer is formed as follows. First, the sapphire substrate is heated to 1000 ° C to 1200 ° C in a MOCVD epitaxial growth apparatus to remove all surface oxide films and the like. Next, the temperature of the system is reduced to 400-600 ° C. and the metal-organic material and nitrogen source are simultaneously provided to the substrate formed by the low temperature buffer layer. Next, the supply of the metal-organic material is stopped and the temperature is raised again to perform a heat treatment for crystallizing the low temperature buffer layer. Thereafter, the target group III nitride semiconductor crystal is epitaxially grown.

The temperature of 400 ° C. to 600 ° C. at which the low temperature buffer layer is formed by deposition is not sufficient to thermally decompose the ammonia used in the metal-organic material or nitrogen source, in particular the nitrogen source. Thus, in the deposited state, the low temperature buffer layer contains many defects. In addition, since the material reacts at a low temperature, a polymerization reaction occurs with an alkyl group of a metal-organic material and a nitrogen source that does not decompose to generate a large amount of impurities in the low temperature buffer layer.

The above-mentioned heat treatment crystallization of the low temperature buffer layer is performed to remove such defects and impurities. Impurities and defects in the low temperature buffer layer are removed by heat treatment at a high temperature close to the temperature at which group III nitride semiconductor crystals are epitaxially grown on the low temperature buffer layer.

As noted above, the low temperature buffer layer requires depositing a buffer layer material at low temperature and crystallizing the layer at high temperature. Manufacturing conditions for these steps should be optimized to obtain a high quality buffer layer. In the case of cold deposition of the buffer layer material, for example, the ratio between the metal-organic material and the nitrogen source, the deposition temperature, the flow rate of the carrier gas and these other factors all influence the properties of the buffer layer. Also, in the crystallization step, factors affecting the characteristics of the buffer layer include the temperature at which the heat treatment is performed, the length of the heat treatment, and the rate of temperature rise. The effect of these conditions on a low temperature buffer layer composed of aluminum nitride was tested by Ito et al. In the publication Crystal Growth, 205 (1999), 20-24.

In order to obtain a high quality low temperature buffer layer, each of these conditions must be carefully considered and these effects are optimized. In addition, there is a general need to adjust these conditions for each MOCVD apparatus used. A set of optimized conditions from one device to another requires a lot of time and effort.

During the temperature rise in the heat treatment used to crystallize the low temperature buffer layer, the layer is deformed through sublimation and recrystallization, resulting in a structure in which the crystal nuclei of gallium nitride are intermittently dispersed on the surface of the sapphire substrate. Obtained. Gallium nitride-based compound semiconductor crystals are grown from these nuclei and, under appropriate nuclear distribution density, these crystals bond to form a crystal film. That is, a gallium nitride-based compound semiconductor layer having good crystallinity can be formed by appropriately controlling the distribution density of crystal nuclei.

However, the distribution structure of the crystal nuclei is incidentally determined only by the thermal history during the heating step and by the composition of the carrier gas during the growth of the gallium nitride semiconductor layer. Since it is difficult to freely control the density, morphology, size and other properties of the crystal nucleus, the crystallinity of the obtained gallium nitride-based compound semiconductor is limited.

The present invention provides a method of manufacturing a group III nitride semiconductor crystal, a gallium nitride-based compound semiconductor, a gallium nitride-based compound semiconductor, which can be used to manufacture light emitting diodes (LEDs), laser diodes (LDs), electronic devices, and the like. The present invention relates to a gallium nitride-based compound semiconductor, a gallium nitride-based compound semiconductor light emitting device, and a light source using a semiconductor light emitting device.

1 is a growth mechanism of forming a gallium nitride-based compound semiconductor layer on a substrate in accordance with the present invention.

2 is an embodiment of a heating pattern used during the formation of a gallium nitride-based compound semiconductor layer on a substrate.

3 is a step of a sixth embodiment of the present invention.

4 is a step of a seventh embodiment of the present invention.

5 shows the steps of the eighth and ninth embodiments.

6 is a short structure of the semiconductor light emitting device manufactured according to the fourth, tenth and eleventh embodiments of the present invention.

7 is a plan view of the light emitting device of FIG. 6.

8 is a cross-sectional structure of a semiconductor light emitting device manufactured according to twelfth and fifteenth embodiments of the present invention.

9A-9G illustrate examples of growth conditions in each step of forming a gallium nitride-based compound semiconductor layer on a substrate using a mask layer.

10 (a) to 10 (f) show examples of growth conditions in each step of forming a gallium nitride-based compound semiconductor layer on a substrate using a mask layer.

SUMMARY OF THE INVENTION An object of the present invention is to provide a simplified method of manufacturing Group 3 nitride semiconductor crystals capable of forming high quality Group 3 nitride semiconductor crystals instead of the above-described method using a low temperature buffer layer where many manufacturing conditions should be optimized. It is. In particular, it is an object of the present invention to provide a method for producing a group III nitride semiconductor crystal which allows epitaxial growth of high quality group III nitride semiconductor crystals on a sapphire substrate by a simplified method (hereinafter, 3 The nitride semiconductor of the group is represented by In _x Ga _y Al _z N, where x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1).

Another object of the present invention is to allow the density, morphology, size and other properties of the crystal nuclei constituting the layer provided on the substrate to be freely controlled to provide good crystallinity to the substrate, and to be superior to the crystal layer formed by depositing on the substrate. It is to provide a method of manufacturing a gallium nitride-based compound semiconductor that allows crystallinity to be provided.

Another object of the present invention is to provide a light emitting device and a light source having good emission efficiency, low decay rate and low power consumption rate, which is also low cost and requires replacement with a low frequency.

A first step of depositing Group 3 metal particles on the substrate surface, a second step of nitriding the particles in a nitrogen source containing atmosphere, and In _x Ga _y Al _z N (x A first aspect comprising a third step of using a vapor phase growth method for growing a group III nitride semiconductor represented by + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) The above object of the present invention is achieved by providing a method for producing a nitride semiconductor crystal of Group 3 according to the present invention.

The method includes the case where the substrate is a sapphire (Al ₂ O ₃ ) substrate.

The method includes the case where the Group 3 metal is In _u Ga _v Al _w (u + v + w = 1, 0 ≦ u ≦ 1, 0 ≦ v ≦ 1, 0 ≦ w ≦ 1).

The method includes the case where the Group 3 metal particles are deposited by thermal decomposition of the metal-organic material.

The method includes the case where the first step is carried out at a temperature above the boiling point of the Group 3 metal in an atmosphere in which there is no nitrogen source.

The method includes the case where the second step is carried out in an atmosphere in which there is no metal material above the temperature used in the first step.

The method includes the case where the third step is performed above the temperature used in the second step.

The method includes the case where the group III nitride semiconductor crystal is formed by a metal-organic chemical vapor deposition method.

The method includes the case where the Group 3 metal particles nitrified in the second step are polycrystalline and / or amorphous Group III nitrides and have an unreacted metal.

According to a second aspect of the present invention, the above object is also an In _u Ga _v Al _w (u +) consisting of one or more selected from In, Ga and Al at a temperature T1 above the boiling point of the metal, in an atmosphere not containing a nitrogen source. at least one metal element selected from In, Ga, and Al for depositing a metal represented by v + w = 1, 0 ≦ u ≦ 1, 0 ≦ v ≦ 1, 0 ≦ w ≦ 1) on the sapphire substrate A first step utilizing thermal decomposition of the metal-organic material, a second step of nitriding the deposited metal to a temperature T2 (T2 ≧ T1) in an atmosphere that does not include the metal-organic material and includes a nitrogen source, and Preparation of group III nitride semiconductor crystals comprising a third step in which a metal-organic chemical vapor deposition method is used to epitaxially grow group III nitride semiconductor crystals on a metal-deposited sapphire substrate at a temperature T3 (T3≥T2). Obtained by the method.

The method includes the case where the sapphire substrate has a (0001) plane having a vertical axis inclined in a specific direction from <0001>.

The method includes the case where the specific direction of the sapphire substrate is <1-100> and the inclination angle from <0001> is 0.2 ° to 15 °.

The method includes the case where the temperature T1 is at least 900 ° C and the temperature T3 is at least 1000 ° C.

The method includes in the first step, thermal decomposition of the metal-organic material occurs in a hydrogen atmosphere.

The method includes the case where the metal is deposited on the sapphire substrate as particles rather than as a layer having a height of 50 kPa or more and 1000 kPa or less.

In the second step, the method comprises a region where the stoichiometric ratio of nitrogen to metal is not 1: 1, i.e., In _u Ga _v Al _w N _k (u + v + w = 1, 0 ≦ u, v, w ≦ 1 And the case where the nitrided metal has polycrystals present in the region 0 <k <1).

According to a third aspect, a method of manufacturing a group III nitride semiconductor crystal provides a group 3 metal material on a heated substrate, and deposits the group 3 metal material on the substrate and / or decomposes the product, nitrogen. A second step of heat-treating the substrate in an atmosphere containing the source, and a third step of using a Group 3 metal material and a nitrogen source to grow the Group 3 nitride semiconductor crystals on the substrate by a vapor phase method.

The method includes the case where the group III nitride semiconductor crystals grown on the substrate have a (0001) plane having a vertical axis inclined in a specific direction from <0001>.

The method includes the case where the specific tilt direction is <11-20> and the tilt angle from <0001> is 0.2 ° to 15 °.

The above object of the present invention is achieved by providing a method for producing a gallium nitride-based compound semiconductor by growing a gallium nitride-based compound semiconductor crystal layer on a substrate. According to a first aspect, the method comprises a first step of attaching a metal nucleus to a substrate, a second step of annealing the metal nucleus, a third step of growing the nucleus by nitriding the annealed metal nucleus, and gallium nitride— And a fourth step of growing a gallium nitride-based compound on a substrate having a growth nucleus forming a base compound semiconductor crystal layer.

The method includes the case where the substrate is sapphire and the case where the metal nucleus is attached to the heated substrate by flowing a source gas comprising metal-organic vapor that does not contain a nitrogen source in the first step.

The method includes the case where the water vapor of the metal-organic material has at least one member selected from gallium-containing metal-organic materials, aluminum-containing metal-organic materials and indium-containing metal-organic materials.

The method includes, in a second step, annealing of the metal nucleus by carrying only a carrier gas containing neither a nitrogen source nor water vapor of the metal-organic material.

The method includes, in a third step, the metal nucleus being nitrided by flowing a gas containing a nitrogen source but not containing water vapor of the metal-organic material.

The method includes, in a fourth step, a gallium nitride-based compound semiconductor crystal being grown by flowing a gas containing both a nitrogen source and a metal-organic material using a metal-organic chemical vapor deposition method.

In the method, the temperature at which the second step is performed is at least a temperature at which the first step is performed, the temperature at which the third step is performed is at least a temperature at which the second step is performed, and the temperature at which the fourth step is performed is at a third temperature. And when the step is above the temperature at which it is performed.

The method may be carried out after the first step and the second step have been alternately performed two or more times, or after the third step is carried out alternately two or more times, after the fourth step is carried out. Is performed.

The method comprises a first state step in which the first stage flows a vapor-containing gas of at least one member selected from an aluminum containing metal-organic material, a gallium containing metal-organic material and an indium containing metal-organic material, and the metal of the first state step A case having two stages, a second state stage of flowing a vapor-containing gas of the substance different from the organic substance.

The method includes the case where the second step is performed after the first and second state steps of the first step are alternately performed two or more times.

The method includes the case where the growth nucleus is a substantially trapezoidal nitride semiconductor crystal having flat vertices parallel to the substrate and flat and horizontal sides.

The method includes the case where each gallium nitride-based compound semiconductor crystal layer is grown on the gallium nitride-based compound semiconductor formed in the fourth step.

According to a second aspect, a method of manufacturing a gallium nitride-based compound semiconductor includes a first step of attaching a metal nucleus to a substrate, the first step being an aluminum containing metal-organic material, a gallium containing metal-organic material, and indium. A first state step of flowing a vapor-containing gas of at least one member selected from the containing metal-organic material, and a second state step of flowing a vapor-containing gas of the material different from the metal-organic material of the first state step; A second step of forming a growth nucleus by nitriding a metal nucleus, and a third step of growing a gallium nitride-based compound on a substrate having a growth nucleus forming a gallium nitride-based compound semiconductor crystal layer. do.

The method includes the case where the substrate is a sapphire substrate.

The method comprises a second step performed after the first state step and the second state step of the first step are alternately performed two or more times and a third step after the first and second steps are alternately performed two or more times. Includes cases where it is performed.

The method includes, in a first step, a metal nucleus attached to a heated substrate by flowing a gas containing metal-organic material water vapor but no nitrogen source.

The method includes, in a second step, the metal nucleus being nitrided by flowing a gas containing a nitrogen source but no metal-organic material vapor.

The method includes, in a third step, a gallium nitride-based compound semiconductor crystal being grown by flowing a gas containing both a nitrogen source and a metal-organic material using a metal-organic chemical vapor deposition method.

The method includes the case where the temperature at which the second step is performed is at least the temperature at which the first step is performed, and the temperature at which the third step is performed is at least the temperature at which the second step is performed.

The method includes the case where the growth nuclei are substantially trapezoidal group III nitride semiconductor crystals having flat vertices and flat sides parallel to the substrate.

The method includes the case where each gallium nitride-based compound semiconductor crystal layer is grown on the gallium nitride-based compound semiconductor crystal layer formed in the third step.

The present invention also provides a gallium nitride-based compound semiconductor produced by the gallium nitride-based compound semiconductor manufacturing method according to the first, second and third aspects of the present invention.

The present invention also provides a gallium nitride-based compound semiconductor light emitting device manufactured using the above-mentioned gallium nitride-based compound semiconductor.

The present invention also provides a light source manufactured using the above-described gallium nitride-based compound semiconductor light emitting device.

The above-described gallium nitride-based compound semiconductor manufacturing method according to the first and second aspects also forms a mask layer on the substrate to grow the gallium nitride-based compound semiconductor at a low growth rate, whereby gallium nitride Selectively growing the base compound semiconductor.

The method includes a mask layer forming step performed in the same epitaxial growth apparatus in which the gallium nitride-based compound semiconductor is grown.

The method includes forming a mask layer on a heated substrate by flowing a Si containing gas material.

The method includes forming a mask layer on a heated substrate by simultaneously flowing a Si containing gaseous material and ammonia.

The method includes forming a mask layer such that a portion of the substrate is covered by a material that constitutes the mask layer and the portion of the substrate is exposed.

The method includes, in the first step, flowing a gaseous material containing a group 3 component and a Si-containing gaseous material simultaneously.

The method also includes forming a mask layer on a substrate, the mask layer comprising a portion composed of a material having a low growth rate of a gallium nitride-based compound semiconductor and a portion composed of a material having a high growth rate of a gallium nitride-based compound semiconductor. Include.

These and other features of the present invention will become apparent from the specification described with reference to the drawings.

A method for producing a group III nitride semiconductor crystal according to the first aspect of the present invention is now started.

Group 3 nitride semiconductor crystal manufacturing method according to the first aspect is sequentially a first step of depositing the Group 3 metal particles on the substrate surface, the second step of nitriding the particles in a nitrogen source containing atmosphere, and Group 3 And a third step of growing the nitride semiconductor crystals.

A nitride semiconductor crystal of Group 3 having excellent crystallinity can be formed on the substrate by a manufacturing method composed of three steps. In addition, high quality group III nitride semiconductor crystals can be easily produced by this method without strict control of the manufacturing conditions required by the conventional method using a low temperature buffer layer. The nitride semiconductor crystal of Group 3 of the present invention is represented by In _x Ga _y Al _z N (x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1).

The substrate used in the above-described manufacturing method may be glass, SiC, Si, GaAs, sapphire, or such a substrate. The use of a sapphire substrate AL ₂ O ₃ provides the advantage of obtaining high quality crystals and materials at low cost. In the case of sapphire, the faces that can be used include m, a, and c faces. It is preferable to use the c plane (the (0001) plane), and it is also preferable that the vertical axis of the substrate surface is inclined from the <0001> direction. It is also preferred that the substrate is organic cleaned or etched or pre-treatment prior to the cleaning in a first step, since the substrate surface can be kept constant by this step.

In the first step, the Group 3 metal particles deposited on the substrate may be particles such as Al, Ga, In, or the like. In the present invention, it is preferable to use In _u Ga _v Al _w (u + v + w = 1, 0 ≦ u ≦ 1, 0 ≦ v ≦ 1, 0 ≦ w ≦ 1) particles. The advantage of using In _u Ga _v Al _w is that In _u Ga _v Al _w has an excellent affinity with the nitride semiconductor of the Group 3 which is formed next. Impurities that can be added to the Group 3 metal particles include Si, Be, Mg, and metals other than Group III. When a method of decomposing a metal compound is used to deposit a Group 3 metal, the Group 3 metal particles may contain impurities such as carbon, hydrogen, and halogen, but these particles may also be used as metal particles.

The particles can be deposited by various methods such as thermal decomposition of metal-organic materials or metal halide compounds, vapor deposition, and sputtering. Preference is given to using a thermal decomposition method of the metal-organic material to deposit the Group 3 metal particles. As the metal-organic material, compounds such as trimethyl gallium (TMG), triethyl gallium (TEG), trimethyl aluminum (TMA), trimethyl indium (TMI), and bicyclopentadiethyl indium (Cp ₂ In) may be used. . The advantage of the in situ deposition can be achieved by the method of thermal decomposition of metal-organic materials to deposit Group 3 metal particles.

If the first step is carried out in an atmosphere containing a nitrogen source such as ammonia, problems such as suppression of surface migration can occur. For this reason, it is preferable to perform the first step in an atmosphere containing no nitrogen source. N ₂ gas, which is commonly used as an inert carrier gas, is not considered a nitrogen source in the present invention. N ₂ gas does not produce an effective nitrogen source, since the decomposition temperature of nitrogen gas is higher than that of a common nitrogen gas such as ammonia or hydrazine. Therefore, in the first step using this method, the result is not suppressed by containing N ₂ gas in the atmosphere. Usable gases include hydrogen, rare gases and nitrogen. It is preferable to perform the first step at a temperature above the boiling point of the Group 3 metals, because performing the first step at this temperature facilitates the movement of metal atoms on the substrate.

Group 3 metal particles deposited on the substrate surface in the first step are deposited as a discontinuous distribution. The particles can be bound in place. The deposition state of the particles on the substrate surface can be observed using atomic force microscopy (AFM). Viewed vertically from above, the Group 3 metal particles formed in the first step have a height of about 50 kPa to 1000 kPa and a length from end to end of about 100 kPa to 10000 kPa, and the surface density of the particles is about 1 × 10 ⁶ cm ^-2 to 1 × 10 ¹⁰ cm ⁻² .

Since the crystallinity of the group III nitride semiconductor crystals grown in the third step will be reduced if the second step is performed in an atmosphere containing a metal material, the second step should be performed in an atmosphere not containing a metal material. In the second step, an atmosphere containing ammonia or hydrazine as the nitrogen source can be used. It is preferable to carry out the second step under atmospheric pressure of 1000 to 1 × 10 ⁵ Pa. Cross-sectional analysis using tunneling electron microscopy (TEM) shows that the Group III metal particles nitrided in the second step have polycrystalline and / or amorphous structures and contain unreacted metals.

It is preferred to carry out the second step above the temperature at which the first step is carried out. The experiment carried out by the inventor enables the production of nitride semiconductor crystals of group 3 having excellent crystallinity by performing the step at the above temperature. In order to promote the nitriding reaction of the particles, it is preferred to carry out the second step at a temperature of at least 700 ° C, more preferably at least 900 ° C. Nitriding the Group 3 metal particles in the second step may be performed by maintaining the particles deposited on the substrate for 1 to 10 minutes at a temperature of about 700 ° C. or more in an atmosphere containing a nitrogen source.

It is preferred to carry out the third step above the temperature at which the second step is carried out. This is advantageous in that it provides a grown high quality group III nitride semiconductor. In particular, it is preferred to carry out the third step at a temperature of at least 700 ° C, more preferably at least 900 ° C.

In the third step, the nitride semiconductor crystals of Group 3 are produced by various vapor growth methods including metal-organic chemical vapor deposition (MOCVD) method, molecular beam epitaxy (MBE) method and vapor phase epitaxy (VPE) method. Can be formed. Particular preference is given to using the MOCVD method to form group III nitride semiconductor crystals, since the method can be used to grow thin films. It can be used to grow a layer in a gas containing a metal-organic material and a nitrogen source under a pressure of 1000 to 1 × 10 ⁵ Pa. It is known that gallium nitride-based compound semiconductors with good crystallinity can be obtained when the third step is performed using the MOCVD method at temperatures in excess of 1000 ° C. This is thought to be due to the fact that, unlike other temperatures, the growth mode of the gallium nitride-based compound semiconductor becomes a substantially horizontal growth mode above 1000 ° C. In this case, it is possible to form a crystal layer having an excellent surface shape with low displacement.

In the method for producing a group III nitride semiconductor crystal according to the second aspect of the present invention, in the first step of the atmosphere containing no nitrogen source, a metal-organic compound comprising at least one metal element selected from In, Ga and Al The thermal decomposition of the material is a metal 1 consisting of at least one selected from In, Ga and Al at a temperature above the boiling point of metal 1 (in _u Ga _v Al _w , where u + v + w = 1, 0 ≦ u ≦ 1, 0 ≦ v ≦ 1, 0 ≦ w ≦ 1) are used to deposit on the sapphire substrate. Next, a second step of nitriding the metal 1 deposited at a temperature T2 (T2? T1) in an atmosphere containing no metal-organic material and containing a nitrogen source is performed. Next, the metal-organic chemical vapor deposition method is a group III nitride semiconductor (In _x Ga _y Al _z N is represented on the sapphire substrate on which the metal 1 is deposited, x + y + z = 1, 0≤x≤1 A third step is used, which is used to epitaxially grow crystals of 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, at temperature T3 (T3 ≧ T2).

By the above method, group 3 nitride semiconductor crystals having excellent crystallinity can be epitaxially grown on a sapphire substrate. In addition, high quality Group III nitride semiconductor crystals can be easily produced by this method without strict control of the manufacturing conditions required by conventional methods using low temperature buffer layers.

In the present invention, a sapphire substrate having a (0001) plane in which the preferred step-flow growth of the group III nitride semiconductor crystal is inclined in a specific direction from the <0001> direction of the (0001) plane is provided. It has been found to be enhanced by use. Step-flow growth is maximized when the specific direction of the vertical axis inclination is <1-100> and the inclination angle from <0001> is 0.2 ° to 15 °, resulting in high quality Group III nitride semiconductor crystals. Can be used as conditions.

For effective thermal decomposition of the metal-organic material, it is preferred that the temperature T1 is at least 200 ° C. and also at least the boiling point of metal 1. T1 of 900 ° C. or higher may more preferably close to 100% of the metal-organic material so that the deposited metal 1 dissolves. The temperature T3 at which Group III nitride semiconductor crystals are epitaxially grown should be at least 700 ° C, more preferably at least 900 ° C, which allows for proper decomposition of the nitrogen source.

Since metal 1 was deposited at a temperature above the boiling point, surface tension was confirmed by atomic microscope observation that the metal was formed on the sapphire substrate as particles rather than as a layer. Particles of metal 1 retain their shape even after the second stage of nitriding. Since epitaxial growth of group 3 nitride semiconductor crystals is processed using the particles as nuclei, it is considered that group 3 nitride semiconductor crystals having excellent crystallinity can be obtained.

Cross-sectional analysis using tunneling electron microscopy showed that the group III metal particles treated in the second step were polycrystalline, and the stoichiometric ratio of nitrogen to metal was not 1: 1 (the composition of the region was In _u Ga _v Al _w) . It is shown that polycrystals are present at u + v + w = 1, 0 ≦ u, v, w ≦ 1, 0 <k <1). This is between the growth mode in the case of the prior art in which the metal-organic material and the nitrogen source are simultaneously supplied to form a low temperature buffer layer by high temperature heat treatment after low temperature deposition to crystallize the layer and the method of nitriding metal 1 according to the present invention. It seems to be difference based on difference.

According to a third aspect, a method of manufacturing a nitride semiconductor crystal of Group 3 includes a first method of supplying a Group 3 metal material to a heated substrate, depositing a Group 3 metal material and / or decomposing a product of the material on the substrate. A second step of heat-treating the substrate in an atmosphere containing a nitrogen source, and then a third step of using a Group 3 metal material and a nitrogen source to grow a group III nitride semiconductor on the substrate by a vapor phase method It includes.

The metal-organic material included in the atmosphere used in the first step may be a metal-organic compound, a metal halide compound or a metal. Among these, it is preferable to use a metal-organic compound. In the first step, the metal-organic compounds of the Group III elements that can be used are trimethyl gallium (TMG), triethyl gallium (TEG), trimethyl aluminum (TMA), trimethyl indium (TMI), and biclopentadienyl indium ( Cp ₂ In). Silane (SiH ₄ ), disilane (Si ₂ H ₆ ), biclopentadienyl magnesium (Cp ₂ Mg), and the like may be added to the atmosphere to dope with elements other than Group III metals such as Si or Mg.

In the first step, it is also preferred that the atmosphere does not contain a nitrogen source. If a nitrogen source such as ammonia is included in the first step, the grown gallium nitride-based compound semiconductor will not have the shape of the mirror surface. This is disclosed in the prior art of JP-C 3026087 and JP-A-PH 4-297023. N ₂ is widely used as an inert carrier gas, but is not considered as a nitrogen source in the present invention. N ₂ gas is not an effective nitrogen source because the decomposition temperature of N ₂ is higher than that of a common nitrogen source such as ammonia or hydrazine. Therefore, in the first step of the method, the effect is not greatly suppressed by containing N ₂ gas in the atmosphere. Gases that may be used include hydrazine, nitrogen and rare gases.

Experiments conducted by the inventors can produce group III nitride semiconductor crystals having good crystallinity by performing the second step above the temperature at which the first step is performed. In particular, in order to accelerate the nitriding reaction of the particles, it is preferred to carry out the second step at a temperature of at least 700 ° C, more preferably at least 900 ° C. Very good crystallinity can be obtained at temperatures above 1000 ° C. It is preferable to use the MOCVD method of growing the group III nitride semiconductor in the third step. By using this method the same epitaxial reactor can be used during the first to third steps. When the MOCVD method is used, 1000 ° C or higher is the ideal temperature to be used for the third step. It is even preferable to use a temperature of 1100 ° C. or higher because mirror crystals can be easily obtained at a temperature of 1000 ° C. or higher. It is preferable to carry out the third step in a hydrogen containing atmosphere, because in this atmosphere it is easier to control the crystallinity and surface morphology.

As mentioned above, sapphire forms an ideal substrate. It is preferable to use a sapphire substrate having a (0001) plane whose vertical axis is inclined in a specific direction from the <0001> direction. As mentioned above, the preferred tilt direction of this vertical axis is <1-100> and the preferred tilt angle from the <0001> direction is 0.2 ° to 15 °.

When a sapphire substrate having a (0001) plane whose vertical axis is inclined from the <0001> direction to the <1-100> direction is used, the group III nitride semiconductor crystals grown on the substrate are moved from the <0001> direction to the specific direction. It has a (0001) plane with an inclined vertical axis. In the present invention, the specific direction of the surface inclination of the group III nitride semiconductor crystal is <11-20> because the crystal is grown by being rotated by 30 ° compared with the surface direction of the substrate. When the inclination angle <0001>, which can be used as a condition for producing high quality Group 3 nitride semiconductor crystals, is 0.2 ° to 15 °, step-flow growth is enhanced.

The manufacturing method may comprise a known heat treatment step prior to the first step known as thermal annealing. Widely used thermal annealing when sapphire substrates are used is a form of cleaning treatment performed in an epitaxial reactor. The method generally includes heating the substrate to 1000 ° C. to 1200 ° C. in a hydrogen or nitrogen containing atmosphere.

In the production method, the first step can also be divided into a number of steps in the form of metal-organic materials contained in the atmosphere, the mixing ratio and composition of the materials being changed each time. Other conditions such as substrate processing temperature and length may also vary. When the first step is divided into a number of steps, the atmosphere in the first step preferably comprises a metal-organic material comprising Al. This is because, among the Group 3 metals, Al has a high boiling point and is easily bonded to the substrate.

The annealing step in the atmosphere containing neither metal material nor nitrogen source may be included between the first and second steps and / or between the second and third steps. The annealing step promotes the distribution of metal particles. All these annealing steps must be carried out at temperatures above the boiling point of the Group 3 metal particles. The temperature should be at least 900 ° C, more preferably at least 1000 ° C. The annealing step must also be carried out in a hydrogen atmosphere.

The second step can be performed while the temperature of the substrate is changing. Even in this case, the second step must be carried out above the decomposition temperature of the nitrogen source. The second step should be carried out at 700 ° C. or higher, more preferably at least 900 ° C. and most preferably at least 1000 ° C. The starting temperature of the second stage should be higher than the ending temperature. The second step may begin at the same temperature as the temperature used in the first step and may end at the same temperature as the third step is performed. When the temperature changes during the second step, the temperature change may involve changes in flow rate and reactor pressure and the carrier gas type used.

The gallium nitride-based compound semiconductor manufacturing method according to the present invention will now be described in detail with reference to the drawings.

1 illustrates the growth mechanism in the step of forming a gallium nitride-based compound semiconductor layer, and FIG. 2 illustrates an embodiment of a heating pattern used during formation of the gallium nitride-based compound semiconductor layer.

The next step is used to form a gallium nitride-based compound semiconductor layer on the substrate. As shown in Fig. 1 (a), in step a (first step), a metal nucleus (small droplet) Sa of a metal element, preferably a Group 3 metal element, is attached to the substrate 1. In this step, the metal nucleus Sa does not need to be insulated, and the metal nucleus Sa, which is a non-continuous particle, may be in liquid form covering the surface. Next, in step b (second step), the metal nucleus Sa is annealed (Fig. 1 (b)). If, in the first step, the particles are not in the state required for complete insulation, they are annealed. Next, in step c (third step), the annealed metal nucleus Sa1 is nitrided to form a growth nucleus Sb (Fig. 1 (c)). Regardless of the shape of the growth nucleus Sb, if appropriately distributed, the growth nucleus Sb is considered to function as a growth nucleus. However, through experiments, the inventors have confirmed that the shape of the growth nucleus (Sb) affects the crystal properties of the gallium nitride-based compound semiconductor layer. Preferably, the group III nitride semiconductor crystals should be trapezoidal with a plate top parallel to the substrate 1 and a plate side with any angle to the substrate 1. The growth nucleus Sb can be obtained, for example, by appropriately treating the gas, reactor pressure, substrate temperature and substrate heating pattern used during the nitriding treatment.

In step d (fourth step), the gallium nitride-based compound semiconductor layer is grown on the substrate 1 having the growth nucleus Sb (FIG. 1 (d)). The growth proceeds horizontally, mainly involving displacement and obtaining an appropriate layer depth (eg 2 μm), whereby the flat plate of the gallium nitride-based compound semiconductor 2 (FIG. 1 (e)), Provide a horizontal layer.

Steps a through d are continued to be used in the epitaxial growth apparatus by the MOCVD method. Before performing step a, for example, the sapphire device is thermally cleaned in the MOCVD device at a temperature of 1000 ° C. to 1200 ° C. (showing that a temperature of 1170 ° C. is used), as shown in FIG. 2. . This is done to remove all oxide films and the like from the substrate surface. The temperature of the epitaxial growth apparatus is reduced, for example, from 5 ° C. to 200 ° C. and maintained at this temperature (1100 ° C. in FIG. 2). Steps a, b and c are carried out at this temperature. During the formation of the growth nucleus Sb by the nitriding treatment of step c, the temperature of the growth apparatus is raised and maintained at an elevated level (1160 ° C. in FIG. 2): Step d is gallium on the growth nucleus Sb. It is carried out at this temperature for further growth of the nitride-based compound.

The steps described above and shown in FIG. 1 are one embodiment of the method of the present invention, which is not limited thereto. For example, thermal cleaning can be used where necessary. Similarly, the heating pattern is not limited to that shown in FIG. 2, which preferably uses conditions appropriate for the type of epitaxial reactor, type of metal-organic material, nitrogen source and carrier gas, flow rate used and other factors. Because. Different temperatures may be used for each of steps a, b and c, or different temperatures may be used for steps a and b and steps b and c. In addition, step d may be affected at lower temperatures, or at the same temperature, than steps a to c.

Thus, in this embodiment of the present invention, the first metal nucleus Sa is attached to the substrate 1 which forms the basis of the growth nucleus Sb used to grow the gallium nitride-based compound. The growth of the metal nucleus Sa attached to the substrate 1 controls the flow rate of the metal-organic gas, the length of time the gas flows, the processing temperature used, and the like, whereby the growth of the metal nucleus Sa on the substrate 1 is achieved. It can be controlled by controlling the density.

The vertical size of the metal nucleus Sa is increased as a result of agglomerates generated by wetting to the substrate by the annealing of the metal nucleus (Sa1 in FIG. The adhesion is reduced by generating water vapor, and the substrate surface is formed in the exposed space between the portions to which Sa1 is attached. Thereby, the density of the growth nucleus Sb obtained from the nitriding treatment can be controlled to a desired state. In particular, the gases and temperatures, pressures, cycles and other conditions used during annealing are all effective in controlling the density. These conditions should be appropriately selected depending on the type of metal used for the metal nucleus Sa attached to the substrate, the type of reactor, and the like. According to the experiments carried out by the inventors, it is considered that the gas used should be hydrogen, the temperature should be at least 900 ° C., and the annealing cycle should be at least 5 minutes.

Next, the metal nucleus Sa1 is nitrided to transform the nucleus into a growth nucleus Sb forming a nitride semiconductor. As described above, the growth nucleus Sb should be trapezoidal in shape with a plate top and plate side parallel to the substrate 1. The shape of the growth nucleus Sb can be controlled by controlling the conditions used during the nitriding treatment. In particular, gases used during the nitriding treatment as well as temperature, pressure and other conditions are effective in controlling their form. These conditions should be appropriately selected depending on the type of metal used for the metal nucleus Sa attached to the substrate, the nitrogen material used for the nitriding treatment, the type of reactor, and the like. According to the experiments carried out by the inventors, it is considered that the gas used is hydrogen, the temperature is above 900 ° C. and the temperature must be raised between the nitriding treatment steps.

More gallium nitride-based compound semiconductors are grown on growth nuclei Sb so that the gallium nitride-based compounds fill the space between adjacent growth nuclei Sb to form a horizontal layer. As a result, a gallium nitride-based compound semiconductor layer having a desired thickness and crystallinity can be formed.

The surface of this gallium nitride-based compound semiconductor layer is covered by the gallium nitride-based compound so that very good lattice matching properties with the top layer can be maintained. Thus, by the gallium nitride-based compound semiconductor 2, gallium nitride-based compound semiconductor layers each having excellent crystallinity can be formed on the substrate 1. This improves the emission characteristics of semiconductor light emitting devices produced using gallium nitride-based compound semiconductors. The semiconductor light emitting element manufactured by the above-described method can also be used as electronic light source, vehicle, traffic signal and the like as a light source having excellent brightness and other emission characteristics.

Substrates used in the methods described above may be glass, SiC, Si, GaAs, sapphire and the like. By using a sapphire (Al203) substrate, high quality crystals are obtained and the material can be obtained at low cost. In the case of sapphire, it can be used among the m, a and c planes. Of course, it is preferable to use the c plane (the (0001) plane). It is also desirable to organically clean or etch the substrate or pre-treat the substrate prior to the clean or etch in the first step, since the substrate surface can be kept constant.

Metals that can be used for the metal nuclei attached to the substrate in the first step include Al, Ga and In. In the present invention, it is preferable to use a Group 3 metal nucleus represented by In _u Ga _v Al _w (u + v + w = 1, 0 ≦ u ≦ 1, 0 ≦ v ≦ 1,0 ≦ w ≦ 1). In _u Ga _v Al _w has the advantage of good affinity with the gallium nitride-based compound semiconductor formed next. Impurities that may be added to dope Group 3 metal particles include Si, Be, Mg, and metals other than Group 3. When decomposition of a metal compound is used to deposit a metal of Group 3, the Group 3 metal particles may include impurities such as carbon, hydrogen, and halogen, and the metal particles may also be used as metal nuclei.

The metal nucleus may be attached to the substrate by a variety of methods, including thermal decomposition of metal-organic materials or metal halide compounds, vapor deposition, and sputtering. In the case of the present invention, it is preferred to use thermal decomposition of the metal-organic material, since it is easy to control the density and form of the metal nucleus. Metal-organic materials that can be used include trimethyl gallium (TMG), triethyl gallium (TEG), trimethyl aluminum (TMA), trimethyl indium (TMI), biclopentadienyl indium (Cp ₂ In). By using such metal-organic materials comprising gallium, aluminum or indium, metal nuclei of Group 3 metals such as In _u Ga _v Al _w can be attached.

Performing the first step in an atmosphere containing a nitrogen source, such as ammonia, may cause problems such as suppressing the surface migration of metal atoms. Therefore, it is preferable to perform the first step in an atmosphere containing no nitrogen source. In the present invention, N ₂ gas which is widely used as an inert carrier gas is not observed as a nitrogen source. N ₂ gas does not produce effective nitrogen gas because the decomposition temperature of the N ₂ gas is higher than that of a common nitrogen source such as ammonia or hydrazine. Therefore, in the first step of this method, the effect is suppressed by including N ₂ gas in the atmosphere. Gases that can be used include hydrogen, rare gas and nitrogen.

The first step must be carried out at a temperature above the boiling point of the metal nucleus, as this facilitates the movement of metal atoms on the substrate. In the first step, the metal nuclei deposited on the substrate surface are deposited in a discontinuous distribution. The particles can be bound in place. The deposition state of the metal nuclei on the substrate surface can be observed using atomic force microscopy (AFM). It is observed from the vertical top that the metal nucleus formed in the first stage has a height of about 50 kPa to 1000 kPa and a length of about 100 kPa to 10000 kPa from end to end, and the surface density of the particles is 1 × 10 ⁶ cm ^-2 to 1 × 10 ^It represents the range of ¹⁰ cm <^-2> .

Regarding the annealing step, it is preferable to anneal the metal nucleus using a carrier gas containing neither a nitrogen source nor a metal-organic material, since the nuclei are efficiently agglomerated thereby. Hydrogen, rare gas and nitrogen are all gases which can be used as carrier gases, but it is most preferable to use hydrogen which has the effect of removing oxides from the metal nucleus surface. Annealing of the metal nucleus should be carried out at a temperature which is not above the boiling point of the metal nucleus, and also at a temperature of 700 ° C. or higher, since the nuclei are efficiently agglomerated.

Annealing should be carried out above the temperature at which the first step is carried out. Experiments performed by the inventors make it possible to prepare gallium nitride-based compound semiconductor crystals having good crystallinity. Even when annealing is performed at the same temperature used in the first step, good crystallinity is obtained, which makes it easier to use a system apparatus for controlling the conditions inside the reactor.

If the step of nitriding the metal nucleus is carried out in an atmosphere containing a metal material, the crystallinity of the gallium nitride-based compound semiconductor grown in the next step will be reduced. Therefore, the nitriding treatment step should be carried out in an atmosphere free of metallic substances. In the case of the present invention, as the nitrogen source containing atmosphere in which the metal nucleus is nitrided, ammonia or hydrazine containing atmosphere can be used. This step should be carried out under a pressure of 1000 to 1 × 10 ⁵ Pa. Cross-sectional analysis using a tunneling microscope (TEM) shows that the growth nuclei formed by nitrification of the metal nuclei in the nitriding treatment step described above are polycrystalline and / or amorphous and contain non-reactive metals.

In order to promote the nitriding reaction of the metal nucleus, the nitriding treatment step should be carried out at 700 ° C. or higher, more preferably at least 900 ° C. to produce gallium nitride-based compound semiconductor crystals having good crystallinity. Formation of the growth nucleus by nitriding treatment of the metal nucleus can be performed by holding the substrate deposited for 1 to 10 minutes at 700 ° C. or higher in an atmosphere in which the metal nucleus contains a nitrogen source.

The nitriding treatment step must be carried out above the temperature of the annealing step, because gallium nitride-based compound semiconductor crystals with good crystallinity can be produced thereby. Even when the nitriding treatment is performed at the same temperature as the annealing, a gallium nitride-based compound semiconductor having good crystallinity is obtained, and the use of a system apparatus for controlling the conditions inside the reactor is facilitated.

The step of growing the gallium nitride-based compound semiconductor on the substrate with a growth nucleus at 700 ° C. or higher, more preferably at 900 ° C. or higher is that a high quality gallium nitride-based compound semiconductor can be grown. This is the advantage. The growth step of the gallium nitride-based compound semiconductor is performed by various vapor growth methods including metal-organic chemical vapor deposition (MOCVD) method, molecular beam epitaxy (MBE) method and vapor phase epitaxy (VPE) method. Can be. Particular preference is given to using the MOCVD method since it can be used for thin film growth. In the present invention, the known MOCVD method can be used to grow a semiconductor in an atmosphere containing a metal-organic compound and a nitrogen source under a pressure of 1000 to 1 × 10 ⁵ Pa.

The growth step of the gallium nitride-based compound semiconductor should be carried out above the temperature at which the nitriding treatment step is performed. Experiments conducted by the inventors show that gallium nitride-based compound semiconductor crystals with good crystallinity can be produced thereby. Even when the growth step of the compound semiconductor is carried out at the same temperature as the nitriding treatment step, excellent crystallinity is obtained to facilitate the use of the system apparatus for controlling the conditions inside the reactor.

The above description has been made with reference to attaching the metal nucleus Sa on the substrate 1 and annealing the metal nucleus Sa. However, the repeated attaching step of the metal nucleus Sa can be used instead of the annealing step. An iterative attachment step of the metal nucleus Sa can be used to control the density of the growth nucleus Sb formed in step c. In this case, in the first step of attaching the first metal nucleus and in the second step of attaching the second metal nucleus, the density and shape of the growth nucleus Sb selects the material flowing according to the adhesion to the substrate 1. It becomes easy by doing this. In the present invention, the step of flowing at least one water vapor-containing gas selected from an aluminum-containing metal-organic material, a gallium-containing metal-organic material, and an indium-containing metal-organic material is used as the first state step, and Preference is given to using the step of flowing the water-containing gas of different metal-organic materials as the second state step. In this case, in the first state step, for example, to form a metal nucleus Sa on the substrate at a predetermined density, a material containing Al that is well bonded to the substrate can be flowed, and the second state In a step, a material such as Ga or In that is not well bonded can be flowed to produce a metal nucleus (Sa), creating a structure in which Ga or In is present around Al. The first state step and the second state step may be changed each time, but it is preferable to change the two or more times.

Next, nitriding treatment is used to form growth nuclei without using any annealing. Also in the present invention, the well-shaped growth nucleus Sb can be formed by appropriate control of the nitriding treatment in the same manner as when annealing is used to control the density of the metal nucleus Sa1. In the case of annealing, the gas, temperature and pressure used during the nitriding treatment are conditions that affect shape control. These conditions should be appropriately selected depending on the metal core (Sa) material, the nitrogen material used for the nitriding treatment, the reactor type and the like. According to the experiments carried out by the inventors, the gas used should be hydrogen, the temperature should be at least 900 ° C. and the temperature should be increased during the nitriding treatment step.

Even in this case, the growth step of the gallium nitride-based compound semiconductor must be carried out above the nitriding treatment temperature. Experiments conducted by the inventors show that gallium nitride-based compound semiconductor crystals with good crystallinity can be produced thereby. Even when gallium nitride-based compound semiconductor crystals are grown at the same temperature used for the nitriding treatment, good crystallinity is still obtained, and it becomes easy to use a system apparatus for controlling the conditions inside the reactor.

As described above, in the gallium nitride-based compound semiconductor manufacturing method according to the present invention, the metal nucleus is attached to the substrate and grown. The film having excellent crystalline properties can be formed by using a sapphire substrate on which a mask layer having a low growth rate of gallium nitride-based compound semiconductor crystals is formed to selectively grow a gallium nitride-based compound semiconductor.

9 (a) to 9 (g) will be used to describe the mechanism for forming a gallium nitride-based compound semiconductor having good crystallinity.

As shown in Fig. 9 (a), the Si-containing source gas 3 and the ammonia gas 4 are silicon nitride film 5 on the sapphire substrate 1 heated to a predetermined temperature by reacting two compounds. Flows to form. Since the formation of the film 5 begins with active points scattered across the substrate, the film 5 does not initially cover the entire substrate uniformly. The growth time is controlled such that the region 6 covered by the silicon nitride film 5 and the region 6 exposed by sapphire exist on the substrate 1 (Fig. 9 (b)). Subsequently, after flowing the group 3 substance gas 3 ', the droplet-shaped particles 7 of the group 3 element are supplied to the region 6 (Fig. 9 (c)), ammonia is flowed to the region 6 Influence on the reaction to form group III nitride 8 (FIG. 9 (d)). Therefore, the growth nucleus of the region covered by the silicon nitride film 5 does not grow, whereas the crystal 9 is grown from the sapphire exposed region 6, the growth being the silicon nitride film 5 Proceeds horizontally above (Fig. 9 (f)). As a result, the crystal 9 covers the entire surface of the sapphire substrate 1 (Fig. 9 (g)). The growth direction of threading displacements caused by the lattice constant difference between sapphire and gallium nitride-based compound semiconductors can be controlled so that most of the displacements do not point upwards and form a closed loop. This reduces the density of the threading displacement, so that a good quality crystal is obtained.

The mask layer may be prepared by the method in which the Si source gas is simultaneously flowed with a nitrogen source gas such as ammonia, and the method in which the ammonia is preflowed to partially nitrate the sapphire surface, and then used to form the mask layer. Si source gas is flowed to produce a single scattered single layer of silicon nitride film. When the silicon oxide layer is used as the mask layer, thermal cleaning can be used to activate oxygen atoms on the sapphire substrate, followed by flowing Si source gas to form one monolayer of silicon oxide.

An effective way to form layers on sapphire substrates at different growth rates is to flow ammonia gas after simultaneously flowing a Si source gas and a Group 3 source gas onto the heated sapphire substrate. 10 (a) to 10 (f) show the growth treatment in the case of this method. First, the Si source gas 3 and the group 3 material gas 3 'flow on the heated substrate 1 (Fig. 10 (a)). The gases are decomposed, and the silicon atom population 10 and the droplet-shaped particles 7 of the Group 3 metal are attached to the sapphire substrate 1 at set intervals (Fig. 10 (b)). Next, the silicon atoms and the particles are each nitrided by flowing ammonia gas 4, so that the low-growth portion 5 of silicon oxide and the high-growth portion 8 of the gallium nitride-based compound semiconductor A mask layer consisting of) is formed on the substrate 1. When the gallium nitride-based compound semiconductor 9 is grown on this mask layer, crystals are selectively grown on the gallium nitride-based compound semiconductor film 8, as in the case of the embodiment of FIG. This selective growth improves crystallinity.

In the case of the method described with reference to FIGS. 9 and 10, the treatment and growth after growth of the mask layer should be performed at a temperature of 1000 ° C. or higher. This is because at a low temperature of about 600 ° C., the movement will be insufficient while the Group 3 metal particles 7 and the gallium nitride-based compound semiconductor film 8 are formed. As a result, growth nuclei will also begin to grow in the substrate 1 region and in the buffer layer covered with silicon oxide and silicon nitride, reducing the selective growth characteristics. Even when the gallium nitride-based compound semiconductor layer 9 is formed on this mask layer, at low temperatures, such as 600 ° C., the movement during the initial growth phase is insufficient, so that the growth nuclei are formed in the substrate 1 region and silicon oxide. And also start growing in a buffer layer covered with silicon nitride, reducing the selective growth properties. Silanes (SiH ₄ ) and disilanes (Si ₂ H ₄ ) may be used as the Si source gas. The mask layer forming step may be performed in a growth apparatus used for the next growth of the gallium nitride-based compound semiconductor.

As described above, according to the present invention, a semiconductor crystal film having a crystallinity sufficiently good for semiconductor device applications can be obtained by including a metal-organic material on a heated substrate, whereby gallium nitride on the substrate -The base compound semiconductor is grown. Thus, the obtained film has better crystallinity than the film obtained by the flat mirror surface and the low temperature buffer layer method. Current leakage from pit defects increased during crystal growth, reduction in emission density caused by displacement, and other phenomena which are disadvantages of semiconductor devices can be suppressed, so that emission output can be improved.

Next, a specific embodiment of a method of manufacturing a group 3 nitride semiconductor crystal and a gallium nitride-based compound semiconductor is described. However, the present invention is not limited to this embodiment. The following examples each use a method of forming a gallium nitride-based compound semiconductor layer using a sapphire substrate.

Example 1

An embodiment of a group 3 nitride semiconductor crystal manufacturing method will now be described. The substrate used is a sapphire single crystal substrate having a (0001) plane. The substrate is organically cleaned with acetone and placed on a silicon carbide (SiC) susceptor and then placed in a MOCVD apparatus. RF induction heating systems are used to control the temperature in the MOCVD apparatus. The thermocouple sealed in the quartz tube is inserted into the susceptor so that the growth temperature can be measured in the device.

After the substrate is placed in the apparatus, it is heated to 1180 ° C. in a hydrogen atmosphere and maintained at that temperature for 10 minutes to remove all oxide films from the substrate surface. At this time, the temperature is reduced to 1100 ° C. and in the same hydrogen atmosphere containing no nitrogen source, metal-organic trimethyl aluminum (TMA) is supplied to the substrate for 1 minute at a flow rate of 12 μmol / minute. Thus, the TMA is thermally reduced so that Al is deposited on the sapphire substrate. After blocking the TMA, the temperature is raised to 1180 ° C. and upon formation of ammonia (NH ₃ ) a nitrogen source is supplied for 3 minutes at a flow rate of 0.2 mol / minute to nitrate Al. Next, the flow rate of NH ₃ remains unchanged and the temperature is maintained at 1180 ° C., and trimethyl gallium (TMG), a metal-organic material, is supplied at a flow rate of 140 μmol / minute, and Al deposition provides 1.1 μm of gallium nitride on the substrate. The layer is epitaxially grown. The device can then be cooled to room temperature so that the substrate is removed from the reactor.

The epitaxial wafer thus produced has a mirror surface, and the peak width at half the height of the X-ray locking curve of the epitaxial layer of gallium nitride is 959 seconds. This shows good crystallinity of the epitaxial layer.

Example 2

As in the case of Example 1, the sapphire single crystal substrate having the (0001) plane is organically cleaned and heat treated in the growth apparatus. At this time, while the substrate is maintained at 1180 ° C. in a hydrogen atmosphere containing no nitrogen source, the substrate is supplied with TMA and TMG for 1 minute at a flow rate of 12 μmol / minute to deposit Al and Ga alloys on the sapphire substrate. do. TMA and TMG are blocked, the temperature is maintained at 1180 ° C., and ammonia is supplied for 3 minutes at a flow rate of 0.2 mol / min to nitrate the Al-Ga alloy. Next, ammonia is supplied and the temperature is continuously maintained at 1180 ° C., and a metal-organic substance, trimethyl gallium (TMG), is supplied at a flow rate of 140 μmol / min, and 1.1 μm on the substrate by deposition of an Al-Ga alloy. Epitaxially grow a gallium nitride layer.

Thus, the epitaxial wafers produced have a mirror surface, and the peak width at half the height of the X-ray locking curve of the gallium nitride epitaxial layer is 720 seconds, indicating good crystallinity of the epitaxial layer. Examination of the gallium nitride layer surface by atomic microscopy reveals an atomic-step terrace indicating step-flow growth. Atomic-step terraces exhibit more uniform spacing and parallelism and extend in a specific direction from the center of the epitaxial wafer to the periphery. This means that step-flow growth is enhanced at the (0001) face portion of the wafer periphery where the vertical axis is tilted in a specific direction at <0001>. This direction is <1-100>.

TEM observation of the boundary cross section between the sapphire substrate and the gallium nitride layer of the wafer indicates the nitrided polycrystal of the metal deposited by thermal decomposition of the metal-organic material at the boundary between the substrate and the gallium nitride layer. The crystals are hexagonal and have a height of 5-10 nm. The μ-EDS analysis is a region in which the polycrystalline Al and Ga elements are non-uniform and the nitrogen to metal stoichiometric ratio deviates from 1: 1 (the composition of the region is In _u Ga _v Al _w N _k (u + v + w = 1, 0 ≦ u, v, w ≦ 1 and 0 <k <1).

The following experiment was performed to investigate the crystal growth mechanism of Example 2.

As in Example 1, the sapphire single crystal substrate having the (0001) plane is organically cleaned and heat treated in the growth apparatus. At this time, the substrate is maintained at 1180 ° C in an atmosphere containing no nitrogen source, the substrate is supplied with TMA and TMG to deposit Al and Ga alloy on the sapphire substrate. Next, TMA and TMG are cut off, the temperature is maintained at 1180 ° C., and ammonia is supplied for 3 minutes at a flow rate of 0.2 mol / min to nitrate the Al-Ga alloy. The device can then be cooled at room temperature.

An atomic microscope is used to inspect the wafer surface produced. Nitrided metal particle polycrystals about 50 nm high and about 0.1 μm in diameter are observed. Polycrystals do not cover the entire sapphire substrate: there is a horizontal space between the polycrystals. It is contemplated that epitaxial growth of the gallium nitride layer of Example 2 is treated with polycrystals that act as nuclei.

Similarly, the following experiment is performed to investigate the particle state of the Group 3 metal deposited on the substrate surface.

As in Example 1, the sapphire single crystal substrate having the (0001) plane is organically cleaned and heat treated in the growth apparatus. At this time, using the same conditions as in Example 2, the substrate was maintained at 1180 ° C. in a hydrogen atmosphere containing no nitrogen source, and TMA and TMG were supplied to the substrate to deposit Al and Ga alloys on the sapphire substrate. . Next, the device can be cooled at room temperature and an atomic microscope is used to examine the surface. It is found that the surface has particles of height of about 100 mm 3 and length of about 500 mm 3; The surface density of these particles is 1 × 10 ⁸ cm ⁻² . Some particles are linked together.

Example 3

Using the same method as in Example 1, the sapphire single crystal substrate having the (0001) plane is organically cleaned and heat-treated in the growth apparatus. Subsequently, in a hydrogen atmosphere at a temperature reduced to 1100 ° C. containing no nitrogen source, the substrate contains TMA, TMG and trimethyl indium (TMI), 6 μmol / minute, 18 μmol / minute, and 30 seconds for other metal-organic materials. Each at a flow rate of 18 μmol / min, to form Al, Ga and In alloys on the sapphire substrate. Next, the supply of the metal-organic material is cut off, the temperature is maintained at 1180 ° C., and ammonia is supplied for 3 minutes at a flow rate of 0.2 mol / minute to nitrate the Al / Ga / In alloy. While the supply of ammonia is maintained at the same flow rate and the temperature of the device is maintained at 1180 ° C., the device is supplied with TMG at a flow rate of 140 μmol / minute, giving 1.1 μm of gallium nitride on a substrate with an Al / Ga / In alloy. The layer is grown.

The epitaxial wafer produced at this time had a mirror surface, and the peak width at half height of the X-ray locking curve of the gallium nitride epitaxial layer was 620 seconds. This shows good crystallinity of the epitaxial layer. Examples 1 to 3 describe epitaxial growth of group III nitride semiconductor crystals when forming a gallium nitride layer, but it is also possible to grow group III nitride semiconductors, which are mixed crystals represented by In _X Ga _Y Al ₂ N. .

Example 4

Example 4 will be used to describe a method of manufacturing a gallium nitride-based compound semiconductor light emitting device using a group III nitride semiconductor crystal manufacturing method.

6 shows an epitaxial structure used for a light emitting device manufactured according to Example 4. FIG. A lattice mismatched epitaxial growth method was used to deposit a GaN layer 12 doped with 2-μm Si having an electron concentration of 1 × 10 ¹⁷ cm ⁻³ on the c-plane sapphire substrate 11, followed by 1 ×. 10 ¹⁹ GaN layer 13 and doped with the Si 1-㎛ having an electron concentration of cm ^-3, 1 × 10 of the 100-a having an electron density of ¹⁷ cm ^-3 in _0.1 Ga _0.9 N cladding layer (14 ), A multi-quantum well structure consisting of six 70-A GaN blocking layers 15 and five 20-A undoped In _0.2 Ga _0.8 N well layers 16, beginning and ending with a GaN blocking layer, 30-A Al _0.2 Ga _0.8 N diffusion barrier layer 17, 0.15-μm Mg-doped GaN layer 18 with a hole concentration of 8 x 10 ¹⁷ cm ^-3 and 100- with a hole concentration of 5 x 10 ¹⁸ cm ^-3 A Mg-doped In _0.1 Ga _0.9 N layer 19 of A is formed. 7 is a plan view of the electrode structure of the light emitting device of Example 4;

As described below, the wafer having the epitaxial structure is manufactured by the MOCVD method.

First, the sapphire substrate is placed in a crystal reactor (reactor) disposed inside the RF coil of the induction heater. After the glove box supplied with nitrogen gas is used to place the substrate on the carbon susceptor, nitrogen gas is flowed to purge the reactor interior. After flowing nitrogen gas for 10 minutes, the induction heater is operated to heat the substrate to 1170 ° C. and the temperature is raised for a 10 minute period. At the same time, the pressure inside the reactor is regulated to 50 hPa. While maintaining the temperature of the substrate at 1170 ° C., hydrogen gas and nitrogen gas flowed for 9 minutes to thermally clean the substrate surface. During thermal cleaning, the hydrogen carrier gas is connected to a reactor that starts bubbling and flows through a bubbler comprising trimethyl gallium (TMGa) and trimethyl aluminum (TMAl). A thermobath is used to keep the bubbler at a constant temperature. Until the start of the growth process, TMGa and TMAl water vapor produced by bubbling with a carrier gas is released out of the system through a deharmanizing system. After completion of the thermal cleaning, the nitrogen gas valve is closed so that only hydrogen is supplied to the reactor.

After changing the carrier gas, the substrate temperature is reduced to 1100 ° C. and the reactor pressure is adjusted to 100 hPa. After the temperature has stabilized at 1100 ° C., the TMGa and TMAl valves are operated to supply the reactor with the gas containing TMGa and TMAl steam, and the process of attaching the metal nuclei to the sapphire substrate begins. A flow controller of the bubbling line is used to adjust the molecular ratio between TMGa and TMAl to 2: 1. After 90 seconds, both the TMGa and TMAl valves are operated to stop the movement of the TMGa and TMAl steam-containing gas. After a 10 second pause, an ammonia gas valve is used to begin the movement of ammonia gas into the reactor.

After 10 seconds, ammonia gas continues to flow, and the susceptor temperature rises to 1160 ° C. The flow rate of TMGa is regulated during this temperature rise. In addition, the flow of SiH ₄ begins. Until the formation of the GaN layer doped with Si begins, SiH ₄ continues to flow along with the carrier gas into the dehamaging system to release to the outside. After the susceptor temperature reliably reaches 1160 ° C., the temperature can be stabilized, after which the TMGa and SiH ₄ valves are operated to start the supply of TMGa and SiH ₄ to the reactor. The growth of the GaN layer doped with Si lasts about 75 minutes. Based on previous studies, the flow rate of SiH ₄ is controlled such that the concentration of electrons in the GaN layer is 1 × 10 ¹⁷ cm ⁻³ . In this way, a GaN layer doped with Si having a thickness of 2 mu m is formed.

Next, an n-GaN layer doped with Si is formed on the GaN layer doped with Si. After growing the low doped GaN layer with Si, the supply of TMGa and SiH ₄ to the reactor is stopped for a time period of one minute during which the flow rate of SiH ₄ changes. Based on previous studies, the flow rate of SiH ₄ is controlled to achieve an electron concentration of 1 × 10 ¹⁹ cm ⁻³ in the GaN layer doped with Si. The reactor is continuously fed with ammonia at the same flow rate. After 1 minute, the supply of TMGa and SiH ₄ is resumed and the layer is grown for 45 minutes. This results in a highly doped GaN layer of Si having a thickness of 1 μm.

After the GaN layer doped with Si is formed, the TMGa and SiH ₄ valves are operated to stop the supply of these materials to the reactor. While the carrier gas changes from hydrogen to nitrogen, the flow of ammonia is maintained. The temperature of the substrate is reduced from 1160 ° C. to 800 ° C., while the reactor pressure changes from 100 hPa to 200 hPa. The flow rate of SiH ₄ changes while waiting for the pressure in the reactor to change. Based on previous studies, the flow rate of SiH ₄ is controlled such that an electron concentration of 1 × 10 ¹⁷ cm ⁻³ is achieved in the Si-doped InGaN cladding layer. The reactor is continuously fed with ammonia at the same flow rate. The flow of trimethyl indium (TMIn) and triethyl gallium (TEGa) carrier gas into the bubbler has already begun. Until the start of cladding layer formation, SiH ₄ gas is released out of the system through the dehamanaising system along with the carrier gas along with TMIn and TEGa water vapor produced by bubbling. Next, after giving the reaction time to stabilize, the supply of TMIn, TEGa and SiH ₄ to the reactor is started and maintained for about 10 minutes to form a Si-doped In _0.1 Ga _0.9 N cladding layer to 100 microns thick, Thereafter, the supply of TMIa, TEGa and SiH ₄ to the reactor is stopped.

Next, a multi quantum well structure consisting of a GaN blocking layer and an In _0.2 Ga _0.8 N well layer is prepared. First, a GaN barrier layer is formed on a Si-doped In _0.1 Ga _0.9 N cladding layer. After repeating this step five times to form the required multilayer structure, a sixth GaN barrier layer is formed on the fifth In _0.2 Ga _0.8 N well layer to form a structure having a GaN barrier layer at each end. do.

More specifically, after the formation of the Si-doped In _0.1 Ga _0.9 N cladding layer is completed, it is stopped for 30 seconds, and then while the supply of TEGa to the reactor is started, the same substrate temperature, reactor pressure, carrier gas And the flow rate of the carrier gas is maintained. For seven minutes, the supply of TEGa is stopped, and the formation of the GaN blocking layer composed of the 70 Å thick film is completed.

During the formation of the GaN barrier layer, the molecular flow rate of the flowing TMIn is doubled as compared to the flow rate during the formation of the cladding layer with the dehamaging system. After the GaN barrier layer is completed, the supply of the Group 3 material is stopped for 30 seconds, after which the TEGa and TMIn valves are operated to supply TEGa and TMIn to the reactor, while at the same temperature, reactor pressure and type of carrier gas and flow rate Is maintained. After 2 minutes, the supply of TEGa and TMIn is stopped, and the formation of the In _0.2 Ga _0.8 N well layer is finished. A 20 μm thick In _0.1 Ga _0.9 N cladding layer is formed.

After the formation of the In _0.2 Ga _0.8 N well layer is complete, the supply of group III material is stopped for 30 seconds, after which the supply of TEGa to the reactor begins, the same substrate temperature, reactor pressure, type of carrier gas and The flow rate is maintained so that another GaN blocking layer is grown. This procedure is repeated five times to produce five GaN barrier layers and five In _0.2 Ga _0.8 N well layers. At this time, a GaN blocking layer is formed on the final In _0.2 Ga _0.8 N well layer.

An undoped Al _0.2 Ga _0.8 N diffusion barrier layer 17 is fabricated on the final GaN barrier layer. One minute after stopping the TEGa supply to complete the GaN barrier layer, the same substrate pressure and type and flow rate of the carrier gas are maintained while the reactor pressure changes to 100 hPa. The flow of trimethyl aluminum (TMAl) carrier gas into the bubbler has already begun. Until the diffusion barrier layer forming step begins, the TMAl water vapor produced by bubbling, together with the carrier gas, is released out of the system through the dehamaging system. Next, after the reactor pressure time to stabilize is given, the supply of TEGa and TMAl to the reactor begins. The layer is then grown for about 3 minutes, after which the supply of TEGa and TMAl is stopped to stop the formation of the undoped Al _0.2 Ga _0.8 N diffusion barrier layer. In this way, a 30 Å thick undoped Al _0.2 Ga _0.8 N diffusion barrier layer is formed.

At this time, a Mg-doped GaN layer is prepared on the undoped Al _0.2 Ga _0.8 N diffusion barrier layer. Two minutes after the growth of TEGa and TMAl was stopped and the growth of the undoped Al _0.2 Ga _0.8 N diffusion barrier layer ended, the temperature of the substrate was raised to 1060 ° C. and the reactor pressure was changed to 200 hPa. In addition, the carrier gas is changed to hydrogen. The flow of bicyclopentadienyl magnesium (Cp ₂ Mg) through the bubbler has already begun. Until the Mg-doped GaN layer formation step begins, Cp ₂ Mg water vapor produced with bubbling with the carrier gas is released out of the system through the dehamaging system. After the temperature and pressure change, the reactor pressure is given time to stabilize and the supply of TMGa and Cp ₂ Mg to the reactor begins. The Cp ₂ Mg flow rate has been previously studied and adjusted to achieve a hole concentration of 8 × 10 ¹⁷ cm ⁻³ in the Mg-doped GaN layer. After about 6 minutes of growth, the supply of TMGa and Cp ₂ Mg is stopped to stop the formation of the Mg-doped GaN layer. This process results in a 0.15 μm thick Mg-doped GaN layer.

Next, an Mg-doped InGaN layer is formed on this Mg-doped GaN layer. After the supply of TMGa and Cp ₂ Mg is stopped and growth of the Mg-doped GaN layer is finished, a time of two minutes is used to lower the substrate temperature to 800 ° C. and convert the carrier gas to nitrogen. The reactor is maintained at the same pressure of 200 hPa. The flow rate of Cp ₂ Mg is modified such that the same amount of Mg dopant as the Mg-doped GaN layer is doped into the Mg-doped In _0.1 Ga _0.9 N layer. Based on conventional work, an amount of dopant with a hole concentration of 5 × 10 ¹⁸ cm ⁻³ is provided in the Mg-doped In _0.1 Ga _0.9 N layer. After waiting for the substrate temperature to stabilize, flow to TMIn, TEGa and Cp ₂ Mg into the reactor begins. After 10 minutes of growth time, the supply of TMIn, TEGa and Cp ₂ Mg was stopped to terminate the growth of the Mg-doped In _0.1 Ga _0.9 N layer, resulting in 100 μg thick Mg-doped In _0.1 Ga _0.9 N layers are formed.

After the Mg-doped In _0.1 Ga _0.9 N layer is completed, the induction heater is switched off, whereby the substrate is cooled to room temperature for at least 20 minutes. During this time, the atmosphere of the reactor consists only of nitrogen. After confirming that the substrate has cooled to room temperature, the wafer is taken out of the reactor. According to the above-described procedure, a wafer having an epitaxial structure used in a semiconductor light emitting device is manufactured. Both the Mg-doped GaN layer and the Mg-doped In _0.1 Ga _0.9 N layer show p-type characteristics, although no annealing was used to activate the p-type carrier.

Next, a wafer having the epitaxial structure formed on the sapphire substrate is used to manufacture a light emitting diode, which is one type of semiconductor light emitting device. The In _0.1 Ga _0.9 N layer was formed by forming a p-electrode bonding pad 12 formed of a stack made of titanium, aluminum, and gold, and made of only Au and having a transparent p-electrode 21 attached to the pad 12. A known photolithography process is used to produce the p-side electrode on 18a). Next, dry etching is used to expose the portion 23 of the GaN layer doped with Si to form the n-side electrode, and the n-electrode 22 of Ni and Al is fabricated in the exposed portion. 7 shows the shape of an electrode fabricated on a wafer.

Next, the opposite side of the sapphire substrate is abraded and polished to give mirror finish, and the wafer is cut into 350 micrometer square chips along each side. Next, each chip is mounted on a lead frame having an electrode side surface, and is connected to the lead frame with gold wiring to form a light emitting element. When a 20 mA forward current is applied between the electrodes, the forward voltage is 3.0V. The wavelength of light emitted through the p-side transparent electrode is 470 nm, and the device exhibits an output of 6 cd. The properties of the light emitting diodes can be obtained uniformly with light emitting diodes made from all visible parts of the wafer without any change.

Example 5

Example 5 is an example of a method of preparing a gallium nitride-based compound semiconductor crystal, described below.

The sequence of steps a to d of FIG. 1 is used to form a gallium nitride-based compound semiconductor layer on a sapphire substrate. In step a, metal nuclei are attached to the substrate by flowing a gas containing trimethyl aluminum (TMAl) water vapor and trimethyl gallium (TMGa) water vapor mixed in a 1: 2 molecular ratio. In step b, annealing is performed with hydrogen gas; In step c, a mixture of hydrogen and ammonia is flowed to nitrate the annealed metal nucleus to form the mixture to become a growth nucleus. In step d, TMGa and ammonia are flowed to further grow gallium nitride on the growth nucleus, thereby producing a gallium nitride-based compound semiconductor layer provided with a gallium nitride crystal film on the sapphire substrate.

More specifically, first, a sapphire substrate is disposed in a quartz reactor in which an induction heater RF coil is disposed. The globu-box supplied with nitrogen gas is used to place the substrate on the carbon susceptor, after which nitrogen gas is flowed for 10 minutes to purify the inside of the reactor. Next, the induction heater is activated to raise the substrate temperature to 1170 ° C for at least 10 minutes. The substrate temperature is maintained at 1170 ° C., and hydrogen gas and nitrogen gas are flowed for 9 minutes to thermally clean the substrate surface.

During thermal cleaning, the hydrogen carrier gas is flowed through the trimethyl gallium (TMGa) and trimethyl gallium (TMAl) containing bubblers to start bubbling. A thermal bath is used to keep the bubbler at a constant temperature. Bubbler piping is connected to the reactor. Until the gallium nitride-based compound semiconductor layer growth step begins, bubbling produced TMGa water vapor and TMAl water vapor are released with the carrier gas out of the system through the dehamaging system. After completing the thermal cleaning, the nitrogen gas valve is closed, so that only hydrogen is supplied to the reactor. After changing the carrier gas, the substrate temperature is reduced to 1100 ° C. After confirming that the temperature is stabilized at 1100 ° C., the TMGa and TMAl vapor-containing gas is supplied to the reactor so that the TMGa and TMAl valves are operated to begin attaching metal nuclei to the sapphire substrate. The mass flow controller on the bubbling line is used to adjust the molecular ratio between TMGa and TMAl to 2: 1. After this process for 1 minute 30 seconds, the TMGa and TMAl valves are used to stop the supply of the TMGa and TMAl steam containing gas to the reactor. This state lasts for 3 minutes to anneal the metal nuclei in the hydrogen carrier gas. After annealing for 3 minutes, the ammonia gas line valve is operated to start the transfer of ammonia gas into the reactor for nitriding the annealed metal nucleus so that the metal nucleus becomes a growth nucleus. After flowing gas for 10 seconds, the susceptor temperature is raised to 1160 ° C. The flow rate of TMGa is regulated during this temperature rise. After confirming that the susceptor temperature reaches 1160 ° C., the temperature can be stabilized, after which the TMGa valve is operated to start supply of TMGa to the reactor for further growth of gallium nitride on the growth nucleus.

After the gallium nitride-based compound semiconductor crystal film is grown for one hour, the supply process is terminated by interrupting supply of TMGa to the reactor. After completion of the gallium nitride crystal film formation, the induction heater can be switched off to allow the substrate to cool to room temperature for at least 20 minutes. During this time, the atmosphere of the reactor consists of ammonia, nitrogen and hydrogen, similar to the growth process, but when it is confirmed that the substrate is cooled to 300 ° C., it continues until the ammonia and hydrogen are shut off and the substrate is cooled to room temperature. The nitrogen gas is discharged out of the reactor at this temperature. By the above procedure, a 2 μm thick gallium nitride crystal film 2 is formed on the sapphire substrate. The substrate removed from the reactor is colorless / transparent, and the epitaxial layer has a mirror surface.

XRC measurements of undoped gallium nitride crystals grown in this manner are performed. Using the Cu β line? Line light source, measurements using symmetrical (0002) planes and asymmetrical (10-12) planes are performed. In general, for gallium nitride-based compound semiconductors, the peak width at half height of the (0002) plane XRC spectrum is the flat (mosaic) index and at half the height of the XRC spectrum of the (10-12) plane. The peak width of is the displacement density index. The measurement shows that the (0002) plane has a peak width at half height value of 230 seconds, while the peak width of the (10-12) plane is 350 seconds. Both are good values.

An atomic microscope is used to examine the surface of the top film of gallium nitride crystals. The surface was found to have a good shape and no growth pits were observed at all. In order to measure the etch-pit density of the film, the specimen is immersed in a sulfuric acid and phosphoric acid solution at a temperature of 280 ° C. for 10 minutes. The surface is then irradiated with an atomic microscope to measure an etch-pit density of about 5x10 ⁷ cm ^-2 .

When the sample is removed from the reactor before the gallium nitride crystal film growth step, the wafer can also be manufactured using the same steps to some extent through the above procedure. When the wafer was examined under an atomic microscope, the sapphire substrate was found to have trapezoidal crystal cross-sectional masses of gallium nitride aluminum consisting of growth nuclei.

Example 6

As shown in Fig. 3, in this embodiment, the gallium nitride-based compound semiconductor layer is formed on the sapphire substrate by performing steps c and d after repeating steps a and b three times. In step a, the metal nucleus is attached to the substrate by flowing a trimethyl aluminum (TMAl) vapor containing gas, and in step b, the metal nucleus is annealed with hydrogen gas. After repeating steps a and b three times, in step c, a mixture of hydrogen and ammonia is flowed so that the annealed metal nucleus is nitrided and the metal nucleus becomes a growth nucleus; Then, in step d, TMGa and ammonia are flowed to further grow gallium nitride on the growth nucleus, whereby a gallium nitride-based compound semiconductor layer provided with a gallium nitride crystal film is produced on the sapphire substrate.

First, the substrate surface is thermally cleaned. While this step continues, the hydrogen carrier gas flows through a bubbler containing trimethyl gallium (TMGa) and trimethyl aluminum (TMAl) to start bubbling. Piping of each bubbler is connected to the reactor. Thermal baths are used to keep the bubbler at a constant temperature. Until the growth of the gallium nitride-based compound semiconductor layer begins, TMGa and TMAl water vapor formed by the bubbling and carrier gas are released out of the system through the dehamaging system. After the thermal cleaning step is completed, the nitrogen gas valve is closed, so that only hydrogen gas is supplied to the reactor.

After changing the carrier gas, the substrate temperature is reduced to 1160 ° C. After confirming that the temperature has stabilized at 1160 ° C., the TMAl vapor-containing gas is supplied to the reactor to operate the TMAl valve to attach the metal nuclei on the sapphire substrate.

After this process for 3 minutes, the supply of TMAl-steam containing gas to the reactor is stopped. The state is held for 30 seconds to anneal the metal nuclei in the hydrogen carrier gas. After 30 seconds of annealing, the TMAl line valve is operated to resume the transfer of the TMAl vapor-containing gas to the reactor for attaching the metal nuclei. As with the first, after this process for 3 minutes, the supply of the TMAl water vapor containing gas to the reactor is stopped for 30 seconds to anneal the metal nuclei in the hydrogen carrier gas. These steps are performed once more, and a total of three times of repeating the formation of the metal nucleus and annealing the metal nucleus (step a? Step b) are performed. After the third annealing, the flow of ammonia gas into the reactor begins to nitrate the annealed metal nucleus and the metal nucleus becomes a growth nucleus. After flowing gas for 10 seconds, the TMGa valve is operated to start supply of TMGa to the reactor, resulting in further growth of gallium nitride on the growth nucleus.

After growing the gallium nitride crystal film for 1 hour, the growth process is terminated by interrupting the supply of TMGa to the reactor. Next, the induction heater is switched off and the substrate is cooled to room temperature for at least 20 minutes. During this time, the atmosphere of the reactor consists of ammonia, nitrogen and hydrogen, as during the growth process, but when it is confirmed that the substrate has cooled to 300 ° C., the ammonia and hydrogen are shut off, but the nitrogen gas causes the substrate to be removed from the reactor. It continues to flow until the substrate cools to room temperature, which is the temperature to be removed. By the above procedure, a 2 μm thick gallium nitride crystal film was produced on the sapphire substrate. The substrate removed from the reactor is colorless / transparent, and the epitaxial layer has a mirror surface.

XRC measurements of undoped gallium nitride crystals grown in this manner are performed. Using the Cu β line? Line light source, measurements using symmetrical (0002) planes and asymmetrical (10-12) planes are performed. The measurements indicate that the (0002) plane has a peak width at half height value of 300 seconds, while the peak width of the (10-12) plane is 320 seconds. Both are good values. An atomic microscope is used to examine the surface of the top film of gallium nitride crystals. It has been found that the surface has a good shape and no growth pits are observed at all. In order to measure the etch-pit density of the film, the sample is immersed in a solution of sulfuric acid and phosphoric acid at a temperature of 280 ° C. for 10 minutes. Next, the surface is inspected with an atomic force microscope to measure an etch-pit density of about 7 × 10 ⁷ cm ⁻² .

When the sample is removed from the reactor before the gallium nitride crystal film growth step, the sample can also be prepared using the same step to some extent through the above procedure. When the wafer was examined under an atomic microscope, the sapphire substrate was found to have trapezoidal crystal cross-sectional masses of gallium nitride aluminum consisting of growth nuclei. Thus, in the case of this embodiment, the metal nucleation and annealing steps are repeated, increasing the chance of controlling the density of the metal nuclei on the substrate and the shape of the annealed nuclei. This allows for an increase in process precision and can be given a desired shape and quality for gallium nitride-based compound semiconductor layers based on these metal nuclei.

In Example 6, formation and annealing of the metal nucleus is repeated three times. However, two repetitions or, if necessary, four or more repetitions are also possible.

Example 7

As shown in Fig. 4, in this embodiment, the gallium nitride-based compound semiconductor layer is formed on the sapphire substrate by performing step d after repeating steps a, b and c twice. In step a, the metal nucleus is attached to the substrate by flowing a gas containing trimethyl aluminum (TMAl) water vapor, trimethyl gallium (TMGa) water vapor and trimethyl indium (TMIn) water vapor in a molecular ratio of 1: 2: 4, In step b, the metal nucleus is annealed with hydrogen gas, and in step c, a mixture of hydrogen and ammonia is flowed so that the annealed metal nucleus is nitrided and the metal nucleus becomes a growth nucleus. After repeating steps a, b and c twice, in step d, TMGa and ammonia are flowed to further grow gallium nitride on the growth nucleus, whereby a gallium nitride-based compound provided with a gallium nitride crystal film The semiconductor layer is fabricated on a sapphire substrate.

First, the substrate surface is thermally cleaned and during this step, a hydrogen carrier gas flows through a bubbler containing trimethyl gallium (TMGa), trimethyl aluminum (TMAl) and trimethyl indium (TMIn) to start bubbling. Piping of each bubbler is connected to the reactor, and a thermal bath is used to maintain the bubbler at a constant temperature. Until the growth of the gallium nitride-based compound semiconductor layer begins, TMGa, TMAl, and TMIn water vapor formed by the bubbling and carrier gases are released out of the system through the dehamaging system. After the thermal cleaning step is completed, the nitrogen gas valve is closed, so that only hydrogen gas is supplied to the reactor.

After changing the carrier gas, the substrate temperature is reduced to 900 ° C. After it is confirmed that the temperature is stabilized at 900 ° C, the TMGa, TMAl and TMIn steam valves are operated to supply the reactor with the TMGa, TMAl and TMIn water vapor containing gases to attach metal nuclei to the sapphire substrate. The mass flow controller of the bubbling line is used to control the TMGa, TMAl and TMIn mixtures at a molecular ratio of 2: 1: 4.

After this process for 3 minutes, the supply of TMGa, TMAl and TMIn water vapor containing gases to the reactor is stopped. The state is held for 30 seconds to anneal the metal nuclei in the hydrogen carrier gas. After annealing for 30 seconds, an ammonia line valve is used to nitrate the annealed metal nuclei, and ammonia gas is supplied to the reactor so that the nuclei become growth nuclei. After flowing ammonia gas for 1 minute, a valve is used to stop the flow of ammonia gas to the reactor. After this state lasts for 30 seconds, the valve is used to resume the supply of the TMGa, TMAl and TMIn water vapor containing gases and reattach the metal nuclei to the sapphire substrate. After this process for 3 minutes, the supply of TMGa, TMAl and TMIn water vapor containing gases to the reactor is stopped for 30 seconds to anneal the metal nuclei in the hydrogen carrier gas. After 30 seconds of annealing, an ammonia line valve is used to nitrate the annealed metal nucleus and the supply of ammonia gas to the reactor is started so that the nucleus is a growth nucleus. The sequence of the formation, annealing and nitriding treatment steps (step a? Step b? Step c) is carried out twice.

After flowing gas for 10 seconds, the susceptor temperature is raised to 1160 ° C. The flow rate of TMGa is regulated during this temperature rise. After confirming that the susceptor temperature reaches 1160 ° C. and allowing the temperature to stabilize, the TMGa valve is operated to begin supplying TMGa to the reactor for further growth of gallium nitride on the growth nucleus. After growing the gallium nitride crystal film for 1 hour, the growth process is terminated by interrupting the supply of TMGa to the reactor. The induction heater is then switched off and the substrate is cooled to room temperature for at least 20 minutes. During this time, the atmosphere of the reactor consists of ammonia, nitrogen and hydrogen, as during the growth process, but when it is confirmed that the substrate has cooled to 300 ° C., the ammonia and hydrogen are shut off, but the nitrogen gas causes the substrate to be removed from the reactor. It continues to flow until the substrate cools to room temperature, which is the temperature to be removed.

By the above procedure, a 2 μm thick undoped gallium nitride crystal film was produced on the sapphire substrate. The substrate removed from the reactor is colorless / transparent, and the epitaxial layer has a mirror surface.

XRC measurements of undoped gallium nitride crystals grown in this manner are performed. Using the Cu β line? Line light source, measurements using symmetrical (0002) planes and asymmetrical (10-12) planes are performed. The measurement indicates that the (0002) plane has a peak width at half height value of 250 seconds, while the peak width of the (10-12) plane is 300 seconds, both of which are good values. An atomic microscope is used to examine the surface of the top film of gallium nitride crystals. It has been found that the surface has a good shape and no growth pits are observed at all. In order to measure the etch-pit density of the film, the sample is immersed in a solution of sulfuric acid and phosphoric acid at a temperature of 280 ° C. for 10 minutes. Next, the surface is inspected with an atomic force microscope to measure an etch-pit density of about 3 × 10 ⁷ cm ⁻² .

When the wafer is removed from the reactor before the gallium nitride crystal film growth step, the specimen is also prepared using the same steps to some extent through the above procedure. When the wafer was examined under an atomic microscope, the sapphire surface was found to have trapezoidal crystal cross-section lumps of gallium nitride aluminum consisting of growth nuclei. Thus, for this Example 7, the metal nucleation, annealing and metal nucleation steps are repeated, increasing the chance of controlling the density of the metal nuclei on the substrate and the shape of the annealed nuclei. This allows for an increase in process precision and can be given a gallium nitride-based compound semiconductor layer of the desired shape and quality based on this metal nucleus.

In Example 7, formation and annealing of the metal nuclei are repeated twice. However, if necessary, three or more repetitions are possible.

Example 8

As shown in FIG. 5, in this embodiment in which a gallium nitride-based compound semiconductor layer is formed on a sapphire substrate, step a is divided into two steps, namely step a1 and step a2, followed by step b, c and d follow. In step a1, a trimethyl aluminum (TMA1) containing gas is flowed, and in step a2, a trimethyl gallium (TMGa) water vapor containing gas is flowed to attach a metal nucleus to the substrate. Next, in step b, the metal nucleus is annealed with hydrogen gas, and in step c, a mixture of hydrogen and ammonia is flowed so that the annealed metal nucleus is nitrided and the nucleus is a growth nucleus. In step d, TMGa and ammonia are flowed to further grow gallium nitride on the growth nucleus, thereby producing a gallium nitride-based compound semiconductor layer having a gallium nitride crystal film on the sapphire substrate.

First, the substrate surface is thermally cleaned and during this step a hydrogen carrier gas flows through a bubbler containing trimethyl gallium (TMGa) and trimethyl aluminum (TMAl) to start bubbling. Piping of each bubbler is connected to the reactor, and a thermal bath is used to maintain the bubbler at a constant temperature. Until the growth of the gallium nitride-based compound semiconductor layer begins, TMGa and TMAl water vapor formed by the bubbling and carrier gas are released out of the system through the dehamaging system.

After the thermal cleaning step is completed, the nitrogen gas valve is closed, so that only hydrogen gas is supplied to the reactor. After changing the carrier gas, the substrate temperature is reduced to 1100 ° C. After confirming that the temperature has stabilized at 1100 ° C., the TMAl steam containing gas is supplied to the reactor to start the process of attaching the metal (Al) nuclei to the sapphire substrate by operating the TMAl line valve. After this process for one minute, the use of the valve stops the supply of the TMAl water vapor containing gas to the reactor (step a1). Next, a TMGa steam-containing gas is supplied to the reactor that uses a TMGa valve to start the process of attaching the metal (Ga) nuclei to the sapphire substrate. After annealing for 2 minutes, the valve is used to stop the supply of TMGa steam containing gas to the reactor (step a2). In this way, the step of forming the metal nucleus is carried out in two steps, namely steps a1 and a2.

This state lasts for 5 minutes and the metal nucleus is annealed in the hydrogen carrier gas. After annealing for 5 minutes, an ammonia line valve is used to nitrate the annealed metal nucleus, and the supply of ammonia gas is started so that the nucleus becomes a growth nucleus.

After flowing gas for 10 seconds, the susceptor temperature is raised to 1160 ° C. The flow rate of TMGa is regulated during this temperature rise. After confirming that the susceptor temperature reaches 1160 ° C. and allowing the temperature to stabilize, the TMGa valve is operated to begin supplying TMGa to the reactor for further growth of gallium nitride on the growth nucleus.

After growing the gallium nitride crystal film for 1 hour, the growth process is terminated by interrupting the supply of TMGa to the reactor. The induction heater is then switched off and the substrate is cooled to room temperature for at least 20 minutes. During this time, the atmosphere of the reactor consists of ammonia, nitrogen and hydrogen, as during the growth process, but when it is confirmed that the substrate has cooled down to 300 ° C., the ammonia and hydrogen are shut off, but the nitrogen gas is removed from the reactor. It continues to flow until it cools to room temperature, which is the temperature to be removed.

By the above procedure, a 2 μm thick undoped gallium nitride crystal film was produced on the sapphire substrate. The substrate removed from the reactor is colorless / transparent, and the epitaxial layer has a mirror surface.

XRC measurements of undoped gallium nitride crystals grown in this manner are performed. Using a Cu β line δ line light source, measurements using symmetrical (0002) planes and asymmetrical (10-12) planes are performed. The measurement indicates that the (0002) plane has a peak width at half height value of 180 seconds, while the peak width of the (10-12) plane is 290 seconds. Atomic microscopy was used to examine the surface of the top film of gallium nitride crystals, which was found to have a good shape and no growth pits were observed at all. In order to measure the etch-pit density of the film, the sample is immersed in a solution of sulfuric acid and phosphoric acid at a temperature of 280 ° C. for 10 minutes. Next, the surface is inspected with an atomic force microscope to measure an etch-pit density of about 1 × 10 ⁷ cm ⁻² .

When the wafer is removed from the reactor before the gallium nitride crystal film growth step, the specimen is also prepared using the same steps to some extent through the above procedure. When the wafer was examined under an atomic microscope, the sapphire surface was found to have a trapezoidal crystal cross-section of gallium nitride aluminum composed of growth nuclei.

Thus, in the case of this Example 8, metal nucleation is performed in two steps, and metals in the inverse range can be used to form the nucleus, and the density of the metal nuclei on the substrate can be more accurately controlled. As a result, a gallium nitride-based compound semiconductor layer of desired shape and quality based on this metal nucleus can be given.

In Example 8, the formation of the metal nucleus is performed in two steps, each step being performed once, and the two steps may be repeated two or more times each. In addition, the present invention is not limited to the forming step performed in two steps. Instead, the step may be performed in three or more steps. Due to the number of repetitions and the increase in the number of steps, metal nuclei can be formed more accurately. Further, in Example 8, the metal nucleus is annealed in the hydrogen carrier gas after being carried out in two steps, but this annealing step can be omitted. In this case, however, it is necessary to select a suitable type of material for the metal nucleus and an appropriate gas temperature and pressure for nitriding the nucleus.

Example 9

As in the case of Example 8 (Fig. 5), in Example 9, in which a gallium nitride-based compound semiconductor layer is formed on a sapphire substrate, step a is divided into two steps, namely, step a1 and step a2, This is followed by steps b, c and d. In step a1, a trimethyl aluminum (TMA1) vapor-containing gas is flowed, and in step a2, a mixed trimethyl gallium (TMGa) vapor and trimethyl indium (TMIn) vapor-containing gas are flown in the substrate to a substrate. The metal nucleus is attached. Steps a1 and a2 are performed at different temperatures. In step b, the metal nucleus is annealed with hydrogen gas, and in step c, a mixture of hydrogen and ammonia is flowed to nitrate the annealed metal nucleus to form a growth nucleus. In step d, TMGa and ammonia are flowed to further grow gallium nitride on the growth nucleus, thereby producing a gallium nitride-based compound semiconductor layer having a gallium nitride crystal film on the sapphire substrate.

First, the substrate surface is thermally cleaned and during this step, a hydrogen carrier gas flows through a bubbler containing trimethyl gallium (TMGa), trimethyl aluminum (TMAl) and trimethyl indium (TMIn) to start bubbling. Piping of each bubbler is connected to the reactor, and a thermal bath is used to maintain the bubbler at a constant temperature. Until the growth phase of the gallium nitride-based compound semiconductor layer begins, TMGa, TMAl and TMIn water vapor formed by the bubbling and carrier gas are released out of the system through the dehamaging system. After the thermal cleaning step is completed, the nitrogen gas valve is closed, so that only hydrogen gas is supplied to the reactor.

After changing the carrier gas, the substrate temperature is reduced to 1160 ° C. After confirming that the temperature has stabilized at 1160 ° C., the TMAl steam containing gas is fed to the reactor to start the process of attaching the metal (Al) nuclei to the sapphire substrate by operating the TMAl line valve. After this process for one minute, the valve is used to stop the supply of the TMAl water vapor containing gas to the reactor (step a1). Next, the susceptor temperature is changed to 950 ° C. After waiting for 10 seconds for temperature stabilization, the TMGa and TMIn vapor-containing gas is fed to the reactor, where TMGa and TMIn valves are used to begin the process of attaching metal (Ga and In) nuclei to the sapphire substrate. A mass flow controller in the bubbling line is used to adjust the mixing ratio of TMGa and TMIn in a 1: 2 molecular ratio. After annealing for 2 minutes, the valve is used to stop the supply of TMGa and TMIn water vapor containing gases to the reactor (step a2). The step of forming the metal nucleus is carried out in two steps, namely steps a1 and a2.

This state lasts for 5 minutes to anneal the metal nuclei in the hydrogen carrier gas. After annealing for 5 minutes, an ammonia line valve is used to nitrate the annealed metal nucleus, and the supply of ammonia gas is started so that the nucleus becomes a growth nucleus.

After flowing gas for 10 seconds, the susceptor temperature is raised to 1160 ° C. The flow rate of TMGa is regulated during this temperature rise. After confirming that the susceptor temperature reaches 1160 ° C. and allowing the temperature to stabilize, the TMGa valve is operated to begin supplying TMGa to the reactor to start further growth of gallium nitride on the growth nucleus.

After growing the gallium nitride crystal film for 1 hour, the growth process is terminated by interrupting the supply of TMGa to the reactor. The induction heater is then switched off and the substrate is cooled to room temperature for at least 20 minutes. During this time, the atmosphere of the reactor consists of ammonia, nitrogen and hydrogen, as during the growth process, but when it is confirmed that the substrate has cooled to 300 ° C., while the ammonia and hydrogen are blocked, the nitrogen gas causes the substrate to It continues to flow until it cools to room temperature, which is the temperature removed from.

By the above procedure, a 2 μm thick undoped gallium nitride crystal film was produced on the sapphire substrate. The substrate removed from the reactor is colorless / transparent, and the epitaxial layer has a mirror surface.

XRC measurements of undoped gallium nitride crystals grown in this manner are performed. Using a Cu β line δ line light source, measurements using symmetrical (0002) planes and asymmetrical (10-12) planes are performed. The measurements indicate that the (0002) plane has a peak width at half height value of 190 seconds, while the peak width of the (10-12) plane is 260 seconds. Atomic microscopy was used to examine the surface of the top film of gallium nitride crystals, which was found to have a good shape and no growth pits were observed at all. In order to measure the etch-pit density of the film, the sample is immersed in a solution of sulfuric acid and phosphoric acid at a temperature of 280 ° C. for 10 minutes. Next, the surface is inspected with an atomic force microscope to measure an etch-pit density of about 1 × 10 ⁷ cm ⁻² .

When the wafer is removed from the reactor before the gallium nitride crystal film growth step, the specimen is also prepared using the same steps to some extent through the above procedure. When the specimen was examined under an atomic microscope, the sapphire surface was found to have trapezoidal crystal cross-sections of gallium nitride aluminum composed of growth nuclei.

Thus, in the case of this Example 9, metal nucleation is performed in two steps, each step being set at a different temperature. Metals above the inverse range may be used to form the nucleus, and more precise temperatures may be set for the metal used with respect to the attachment of the metal nucleus. In addition, the density of the metal nuclei on the substrate can be controlled more accurately. As a result, a gallium nitride-based compound semiconductor layer of desired shape and quality based on this metal nucleus can be given.

In Example 9, the formation of the metal nucleus is carried out in two steps, after the nucleus is annealed in a hydrogen atmosphere, this annealing step can be omitted. In this case, the metal nucleation and nitriding treatment steps may each be performed in two or more steps.

Comparative Example 1

Comparative wafer specimens are prepared for comparison with specimens prepared according to Examples 1-3 and 5-9, respectively. As described in JP-A Hei 4-297023 described above, comparative samples were prepared using conventional low temperature buffer layer methods. This method is used to produce an undoped film of 2 μm thick gallium nitride crystals on a substrate. Thus, the specimen is colorless / transparent, and the epitaxial layer has a mirror surface.

XRC measurements of the undoped gallium nitride crystal film grown by the aforementioned conventional method indicate that the (0002) and (10-12) planes have peak widths at half values of 400 seconds and 500 seconds, respectively. When the surface of the top layer of gallium nitride crystals was examined under an atomic microscope, the surface was shown to have a large number of displacements, and was found to have scattered growth pits and terraces with short arches. In order to measure the etch-pit density, a specimen was prepared using the same process as in Example 5. The example using an atomic microscope shows an etch-pit density of 2 × 10 ⁹ cm ⁻² .

Example 10

In Example 10, the method described with reference to Example 8 is used to form a gallium nitride-based compound semiconductor layer on a substrate, with another gallium nitride layer on the substrate to fabricate a semiconductor light emitting device. Is formed.

6 illustrates a cross-sectional structure of a semiconductor light emitting device manufactured according to Example 10. FIG. In Example 10, the MOCVD method is used to form a multilayer structure for a semiconductor light emitting device using the following procedure. A metal nucleus is formed on the substrate 11 heated at a high temperature by flowing trimethyl aluminum (TMAl) steam containing gas and then flowing trimethyl gallium (TMGa) steam containing gas. Next, the metal nucleus is nitrided with hydrogen and ammonia. The next layer is a GaN layer 12 doped with 2 μm Si having an electron concentration of 1 × 10 ¹⁷ cm ⁻³ ; A GaN layer 13 heavily doped with 1 μm Si having an electron concentration of 1 × 10 ¹⁹ cm ⁻³ ; 100 In In _0.1 Ga _0.9 N cladding layer 14 with an electron concentration of 1 × 10 ¹⁷ cm ⁻³ ; A multi quantum well structure consisting of six 70-kV GaN blocking layers 15 and five 20-kV undoped In _0.2 Ga _0.8 N well layers 16, starting with GaN blocking layer 15 and ending with GaN blocking layer; 0.15 μm Mg-doped GaN layer 18 with a hole concentration of 8 × 10 ¹⁷ cm ⁻³ ; And 100 μs Mg-doped In _0.1 Ga _0.9 N layer 19 having a hole concentration of 5 × 10 ¹⁸ cm ⁻³ . A sapphire structure and a wafer composed of the multilayer structure are used for manufacturing a light emitting diode.

The wafer having the epitaxial structure described above is manufactured by the MOCVD method using the following steps.

First, the sapphire substrate 11 is placed in a quartz reactor inside the RF coil of the induction heater. Using a glove box supplied with nitrogen gas, the substrate is placed on a carbon susceptor, after which nitrogen gas is used to purify the interior of the reactor. After flowing nitrogen gas for 10 minutes, the induction heater is activated to heat the substrate to 1170 ° C. and the temperature is raised for at least 10 minutes. At the same time, the pressure inside the reactor is regulated to 50 hPa. While the substrate temperature is maintained at 1170 ° C., hydrogen gas and nitrogen gas are flowed for 9 minutes to thermally clean the substrate surface.

During the thermal cleaning process, hydrogen carrier gas is flowed through a bubbler containing trimethyl gallium (TMGa) and trimethyl aluminum (TMAl) connected to the reactor to start bubbling. Thermal baths are used to keep the bubbler at a constant temperature. By the beginning of the growth process, TMGa and TMAl water vapor formed by the bubbling and carrier gases are released out of the system through the dehamaging system. After the thermal cleaning is completed, the nitrogen gas valve is closed, so that only hydrogen is supplied to the reactor.

After changing the carrier gas, the substrate temperature is reduced to 1100 ° C. and the reactor pressure is adjusted to 100 hPa. After confirming that the temperature has stabilized to 1100 ° C., the TMAl valve is operated to supply the TMAl water vapor-containing gas to the reactor to start the process of attaching the metal (Al) nucleus to the sapphire substrate. After one minute of this process, the TMAl valve is used to stop supplying the TMAl water vapor containing gas. Next, the TMGa valve is operated to supply the TMGa steam-containing gas to the reactor and to resume the process of attaching a metal (Ga) nucleus to the sapphire substrate. After this process for two minutes, the TMGa valve is used to stop the supply of the TMGa steam containing gas. In this way, the formation of metal nuclei is divided into two stages.

This state lasts for 5 minutes to anneal the metal nuclei formed in the hydrogen carrier gas. After annealing for 5 minutes, an ammonia line valve is used to nitrate the annealed metal nuclei and start the supply of ammonia gas to the reactor to form into a growth nucleus. The procedure up to this point is the same as in Example 4.

After flowing ammonia for 10 seconds, the susceptor temperature is raised to 1160 ° C. The line flow of TMGa is regulated during this temperature rise and the flow of SiH ₄ begins. During the time until the growth of the GaN layer doped with Si begins, SiH ₄ is released to the outside through the dehamaging system. After confirming that the susceptor temperature has reached 1160 ° C. and allowing the temperature to stabilize, the TMGa and SiH ₄ valves are operated to initiate the formation of TMGa and SiH _{4 in} the reactor to begin the formation of a low doped GaN layer. Feeding begins and lasts for about 75 minutes. Based on previous studies, the flow rate of SiH ₄ is controlled to achieve an electron concentration of 1 × 10 ¹⁷ cm ^{−3 in} the GaN layer. In this way, a GaN layer 12 doped with Si having a thickness of 2 mu m is formed.

Next, an n-GaN layer doped with Si is grown on the GaN layer doped with Si. In particular, after growing the GaN layer 12 doped with Si, the TMGa and SiH ₄ to the reactor Feeding is interrupted for 1 minute, during which time the flow rate of SiH ₄ changes. Based on conventional work, the flow rate of SiH ₄ is controlled to achieve an electron concentration of 1 × 10 ¹⁹ cm ⁻³ in the GaN layer doped with Si. The same flow rate of ammonia is continuously supplied to the reactor. After one minute of interruption of supply, the supply of TMGa and SiH ₄ is resumed and layer formation continues for 45 minutes, forming a GaN layer doped with Si having a thickness of 1 μm.

After forming the GaN layer 13 doped with Si, valves of TMGa and SiH ₄ are used to stop the supply of these materials to the reactor, and the carrier gas is transferred from hydrogen to nitrogen while the flow of ammonia gas is maintained. Change. At this time, the temperature of the substrate is reduced from 1160 ° C. to 800 ° C., and at the same time the reactor pressure is changed from 100 hPa to 200 hPa.

The flow rate of SiH ₄ changes while waiting for the temperature inside the reactor to change. Based on conventional work, the flow rate of SiH ₄ is controlled to achieve an electron concentration of 1 × 10 ¹⁷ cm ^{−3 in} the Si-doped InGaN cladding layer. The same flow rate of ammonia is continuously supplied to the reactor. The flow of trimethyl indium (TMIn) and trimethyl gallium (TEGa) carrier gas into the bubbler has already begun. Until the formation of the cladding layer begins, the SiH ₄ gas and the TMIn and TEGa water vapor formed by bubbling are released with the carrier gas out of the system through the dehamaging system. After the reaction time to stabilize is given, the supply of TMIn, TEGa and SiH ₄ to the reactor is started and maintained for about 10 minutes to form a 100 micron thick Si-doped In _0.1 Ga _0.9 N cladding layer 14, Thereafter the supply of TMIn, TEGa and SiH ₄ to the reactor is stopped.

Next, a multi quantum well structure composed of a GaN blocking layer 15 and an In _0.2 Ga _0.8 N well layer 16 is fabricated. First, a GaN blocking layer 15 is formed on a Si-doped In _0.1 Ga _0.9 N cladding layer 14, after which an In _0.2 Ga _0.8 N well layer 16 is formed on the GaN blocking layer. After repeating this procedure five times to form the required multilayer structure, a sixth GaN barrier layer 15 is formed on the sixth In _0.2 Ga _0.8 N well layer 16, blocking GaN at each end. Form a structure with a layer.

To form the first GaN layer, after the formation of the Si-doped In _0.1 Ga _0.9 N cladding layer is completed, it is stopped for 30 seconds, after which the same substrate temperature, reactor, while the supply of TEGa to the reactor starts The pressure, the type of carrier gas and the flow rate of the carrier gas are maintained. For seven minutes, the supply of TEGa is stopped, and the formation of the 70-nm thick GaN blocking layer is completed.

During the formation of the GaN barrier layer, the molecular flow rate of TMIn flowing into the dehamaging system is doubled compared to the flow rate used during the formation of the cladding layer 14. After the GaN blocking layer 15 is completed, the supply of the Group 3 material is stopped for 30 seconds, after which the TEGa and TMIn valves are operated to supply TEGa and TMIn to the reactor, while at the same temperature, reactor pressure and carrier gas The type and flow rate are maintained. After 2 minutes, the supply of TEGa and TMIn is stopped, and the formation of a 20 μm thick In _0.2 Ga _0.8 N well layer 16 is finished.

After the formation of the In _0.2 Ga _0.8 N well layer 16 is complete, the supply of group III material is stopped for 30 seconds, after which the supply of TEGa to the reactor begins, while the same substrate temperature, reactor pressure, carrier gas The type and flow rate of is maintained so that another GaN blocking layer is grown. This procedure is repeated five times to produce five GaN blocking layers 15 and five In _0.2 Ga _0.8 N well layers 16. Finally, a GaN blocking layer 15 is formed on the final In _0.2 Ga _0.8 N well layer 16.

The following procedure is used to fabricate an undoped Al _0.2 Ga _0.8 N diffusion barrier layer 17 on the final GaN barrier layer 15. One minute after the TEGa supply is stopped to complete the GaN barrier layer 15, the same substrate temperature and type and flow rate of the carrier gas are maintained while the reactor pressure changes to 100 hPa. The flow of trimethyl aluminum (TMAl) carrier gas into the bubbler has already begun. Until the diffusion barrier layer forming step begins, the TMAl water vapor produced by bubbling, together with the carrier gas, is released out of the system through the dehamaging system. Next, after the reactor pressure time to stabilize is given, the supply of TEGa and TMAl to the reactor begins. The layer is then grown for about 3 minutes, after which the supply of TEGa and TMAl is stopped to stop the formation of the undoped Al _0.2 Ga _0.8 N diffusion barrier layer 17, thereby undoping the 30 Å thick undoped Al _0.2 Ga _0.8 N diffusion barrier layer 17 is formed.

At this time, the Mg-doped GaN layer 18 is grown on the undoped Al _0.2 Ga _0.8 N diffusion barrier layer 17. Two minutes after the supply of TEGa and TMAl stopped and the growth of the undoped Al _0.2 Ga _0.8 N diffusion barrier layer 17 ended, the temperature of the substrate was raised to 1060 ° C. and the reactor pressure was changed to 200 hPa. In addition, the carrier gas is changed to hydrogen. The flow of bicyclopentadienyl magnesium (Cp ₂ Mg) carrier gas through the bubbler has already begun. Until the Mg-doped GaN layer formation step begins, Cp ₂ Mg water vapor produced with bubbling with the carrier gas is released out of the system through the dehamaging system. After the temperature and pressure change, the reactor pressure is given time to stabilize and the supply of TMGa and Cp ₂ Mg to the reactor begins. Cp ₂ Mg flow rates have already been studied and are adjusted to achieve hole concentrations of 8 × 10 ¹⁷ cm ⁻³ in the Mg-doped GaN layer. After about 6 minutes of growth, the supply of TMGa and Cp ₂ Mg is stopped to stop the formation of the Mg-doped GaN layer. This process results in a 0.15 μm thick Mg-doped GaN layer 18.

Next, an Mg-doped InGaN layer 19 is formed on this Mg-doped GaN layer 18 as follows. After the supply of TMGa and Cp ₂ Mg is stopped and growth of the Mg-doped GaN layer 18 is complete, a time of two minutes is used to lower the substrate temperature to 800 ° C. and convert the carrier gas to nitrogen. The reactor is maintained at the same pressure of 200 hPa. The flow rate of Cp ₂ Mg is modified such that the same amount of Mg dopant as the Mg-doped GaN layer is doped into the Mg-doped In _0.1 Ga _0.9 N layer. Based on conventional work, an amount of dopant with a hole concentration of 5 × 10 ¹⁸ cm ⁻³ is provided in the Mg-doped In _0.1 Ga _0.9 N layer.

After waiting for the substrate temperature to stabilize, the flow of TMIn, TEGa and Cp ₂ Mg into the reactor begins. After 10 minutes of growth, the supply of TMIn, TEGa and Cp ₂ Mg is stopped to terminate the growth of the Mg-doped In _0.1 Ga _0.9 N layer 19. As a result, a 100 g thick Mg-doped In _0.1 Ga _0.9 N layer 19 is formed.

After the Mg-doped In _0.1 Ga _0.9 N layer 19 is complete, the induction heater is switched off, whereby the substrate is cooled to room temperature for at least 20 minutes. During this time, the atmosphere of the reactor consists only of nitrogen. After confirming that the substrate has cooled to room temperature, the formed wafer is taken out of the reactor. The wafer is pale yellow and transparent, and the epitaxial layer has a mirror surface. According to the above-described procedure, a wafer having an epitaxial structure used in a semiconductor light emitting device is manufactured. Both the Mg-doped GaN layer 18 and the Mg-doped In _0.1 Ga _0.9 N layer 19 exhibit p-type characteristics, although no annealing was used to activate the p-type carrier.

Next, a wafer having the epitaxial structure formed on the sapphire substrate is used to manufacture a light emitting diode. A p-side electrode was fabricated on the surface 18a of an In _0.1 Ga _0.9 N layer 18 of 100 kV by forming a p-electrode bonding pad 20 formed only of gold, a lamination made of titanium, aluminum, and gold. Known photolithography processes are used for this purpose. Next, dry etching is used to expose the portion 131 of the GaN layer 13 doped with Si to form the n-side electrode, and the n-electrode 22 of Ni and Al is exposed ( 131). 7 shows the shape of an electrode fabricated on a wafer.

Next, the opposite side of the sapphire substrate is abraded and polished to complete the mirror surface, and the wafer is cut into chips of 350 mu m ² . Next, the chip is mounted on the lead frame electrode side and forms a light emitting element connected to the lead frame with gold wiring. When 20 mA of forward current is applied between the electrodes, the forward voltage is 3.0V. The light wavelength emitted through the p-side transparent electrode is 470 nm, and the emission output is 6 cd.

Example 11

This embodiment will be described with reference to the steps used to form a gallium nitride-based compound semiconductor and to fabricate a semiconductor light emitting device. The metal nucleus is formed by changing the flow of TMAl (step a1) and the flow of TMGa (step a2) twice, and the metal nucleus is nitrided (step c) without annealing (step b), followed by gallium nitride— A base compound semiconductor layer is formed over the nitrided nucleus (step d). The manufactured device has the same structure as shown in FIG.

Embodiments of the device having the above structure are manufactured by the MOCVD method, as described below. The sapphire substrate 11 is placed in a quartz reactor inside the RF coil of the induction heater. Using a glove box supplied with nitrogen gas, the substrate is placed on a carbon susceptor for heating, after which nitrogen gas is flowed to purify the reactor interior. As in the case of Example 6, the substrate is thermally cleaned prior to attaching the metal nuclei. During the thermal cleaning, the bubbling of the same material used in Example 6 begins, and the formed water vapor is discharged to the outside through the dehamaging system. After the thermal cleaning is completed, the nitrogen carrier gas valve is closed so that only hydrogen gas is supplied to the reactor.

After changing the carrier gas, the substrate temperature is reduced to 1100 ° C. and the reactor pressure is adjusted to 100 hPa. After it is confirmed that the temperature has stabilized to 1100 ° C., a TMAl steam-containing gas begins to be supplied to the reactor to attach an aluminum nucleus to the sapphire substrate using a TMAl valve. After this two minute process, the supply of TMAl to the reactor is stopped. After one second, a TMGa line valve is used to begin supplying the TMGa steam containing gas to the reactor. This starts to attach gallium to the aluminum nucleus on the substrate. After 4 minutes, the supply of TMGa to the reactor is stopped. The feeding operation of TMAl and TMGa to this reactor is repeated twice.

At the same time as stopping the second supply of TMGa water vapor to the reactor, an ammonia gas line valve is used to begin supplying ammonia gas to the reactor, and the nitriding treatment of the metal nucleus begins. After 10 seconds, the flow of ammonia gas is maintained while the susceptor temperature is raised to 1160 ° C. Next, a GaN layer doped with Si is produced. The same procedure described with reference to Example 10 was used to reduce the GaN layer 12 doped with Si, the GaN layer 13 doped with Si, the In _0.1 Ga _0.9 N cladding layer 14, and six GaN blocks. A multi-quantum well structure consisting of layer 15 and five 20-A undoped In _0.2 Ga _0.8 N well layers 16, Al _0.2 Ga _0.8 N diffusion barrier layer 17, Mg-doped GaN layer 18, and Mg-doped In _0.1 Ga _0.9 N layer 19 is grown.

After completion of the Mg-doped In _0.1 Ga _0.9 N layer forming the top layer of the wafer, the induction heater is switched off and the substrate can be cooled to room temperature for at least 20 minutes, during which time the only gas in the reactor is nitrogen. After confirming that the substrate has cooled to room temperature, the wafer is taken out of the reactor. The wafer is pale yellow and transparent and the epitaxial layer has a mirror surface.

According to the above-described procedure, a wafer having a multilayer structure for semiconductor light emitting device application is manufactured. The procedure used in Example 6 was used to form an electrode on the wafer, cut the wafer to fabricate the chip, and mount the chip on the lead frame to form a light emitting device. When a 20 mA forward current is applied between the electrodes of the LED thus produced, the forward voltage is 3.2V. The light wavelength emitted through the p-side electrode is 470 nm, and the device exhibits an output of 5 cd.

Example 12

In this embodiment, the method of the present invention forms a gallium nitride-based compound semiconductor layer on a substrate, forms another gallium nitride-based compound semiconductor layer on the first layer, and constructs a semiconductor substrate and device. Used to form a laminated structure.

Fig. 8 shows a cross-sectional structure of a semiconductor light emitting device manufactured according to Example 12. The MOCVD method is used to form a wafer having a multilayer structure for a semiconductor light emitting device as follows. A metal nucleus is formed on the sapphire substrate 11 heated at a high temperature by flowing a trimethyl aluminum (TMAl) vapor containing gas and then a trimethyl gallium (TMGa) steam containing gas. Next, the metal nucleus is annealed in hydrogen and nitrified in ammonia. The next layer is a GaN layer 12 doped with 2 μm Si having an electron concentration of 1 × 10 ¹⁷ cm ⁻³ ; A GaN layer 13 heavily doped with 1 μm Si having an electron concentration of 1 × 10 ¹⁹ cm ⁻³ ; Multiple quantum consisting of six 70-μs GaN barrier layers 15 and five 20 μs undoped In _0.2 Ga _0.8 N well layers 16, starting with GaN barrier layer 15 and ending with GaN barrier layer 15. Well structure; It is formed on the substrate in the order of 0.15 μm Mg-doped GaN layer 18 having a hole concentration of 8 × 10 ¹⁷ cm ⁻³ . A sapphire substrate and a wafer including the multilayer structure are used to manufacture light emitting diodes.

The wafer with the multilayer epitaxial structure described above is manufactured by the MOCVD method using the following procedure.

First, the sapphire substrate 11 is placed in a quartz reactor inside the RF coil of the induction heater. Using a glove box supplied with nitrogen gas, the substrate is placed on a carbon susceptor for heating, after which nitrogen gas is used to purify the reactor interior. After flowing nitrogen gas for 10 minutes, the induction heater is activated to heat the substrate to 1170 ° C. and the temperature is raised for at least 10 minutes. At the same time, the pressure inside the reactor is regulated to 50 hPa. While the substrate temperature is maintained at 1170 ° C., hydrogen gas and nitrogen gas are flowed for 9 minutes to thermally clean the substrate surface.

During the thermal cleaning process, hydrogen carrier gas is flowed through a bubbler containing trimethyl gallium (TMGa) and trimethyl aluminum (TMAl) connected to the reactor to start bubbling. Thermal baths are used to keep the bubbler at a constant temperature. By the beginning of the growth process, TMGa and TMAl water vapor formed by the bubbling and carrier gases are released out of the system through the dehamaging system. After the thermal cleaning is completed, the nitrogen gas valve is closed, so that only hydrogen is supplied to the reactor.

After changing the carrier gas, the substrate temperature is reduced to 1160 ° C. and the reactor pressure is adjusted to 100 hPa. After confirming that the temperature has stabilized to 1160 ° C, the TMAl valve is operated to supply the TMAl steam-containing gas to the reactor, and the process of attaching the metal (Al) nucleus to the sapphire substrate 11 is started. After this process for 3 minutes, the TMAl valve is used to stop supplying the TMAl water vapor containing gas. Next, the TMGa valve is operated to supply the TMGa steam-containing gas to the reactor, and restart the process of attaching the metal (Ga) nucleus to the sapphire substrate 11. After this process for 3 minutes, the TMGa valve is used to stop the supply of the TMGa steam containing gas. In this way, the formation of metal nuclei is divided into two stages.

This state lasts for 5 minutes so that the metal nuclei formed in the hydrogen carrier gas are annealed. After 5 minutes of annealing, an ammonia line valve is used to nitrate the annealed metal nucleus and a growth nucleus is formed. The mass flow controller of the line of TMGa is used to regulate the flow, and the continued flow of ammonia and the flow of SiH ₄ are initiated. During the time until the growth process of the GaN layer doped with Si is started, SiH ₄ is released to the outside along with the carrier gas through the dehamaging system. The flow rate of TMGa and SiH ₄ is stabilized, after which the supply of TMGa and SiH ₄ to the reactor is started to start the formation of a low doped GaN layer with SiGa and SiH ₄ valves, lasting about 75 minutes do. Based on previous studies, the flow rate of SiH ₄ is controlled to achieve an electron concentration of 1 × 10 ¹⁷ cm ^{−3 in} the GaN layer. In this way, a GaN layer 12 doped with Si having a thickness of 2 mu m is formed.

Next, an n-GaN layer doped with Si is grown on the GaN layer doped with Si. In particular, after growing the low doped GaN layer 12 with Si, the supply of TMGa and SiH ₄ to the reactor is stopped for 1 minute, during which the flow rate of SiH ₄ changes. Based on previous studies, the flow rate of SiH ₄ is controlled to provide an electron concentration of 1 × 10 ¹⁹ cm ⁻³ to the GaN layer doped with Si. The same flow rate of ammonia is continuously supplied to the reactor. After one minute of interruption of supply, the supply of TMGa and SiH ₄ is resumed and layer formation continues for 45 minutes, forming a GaN layer 13 doped with Si having a thickness of 1 탆.

After forming the GaN layer 13 doped with Si, valves of TMGa and SiH ₄ are used to stop the supply of these materials to the reactor, and the carrier gas is transferred from hydrogen to nitrogen while the flow of ammonia gas is maintained. Change. At this time, the temperature of the substrate is reduced from 1160 ° C. to 800 ° C., and at the same time the reactor pressure is changed from 100 hPa to 200 hPa. While waiting for a change in reactor temperature, ammonia is continuously supplied to the reactor at the same flow rate. The flow of trimethyl indium (TMIn) and triethyl gallium (TEGa) carrier gas into the bubbler has already begun. Until the formation of the cladding layer begins, the TMIn and TEGa water vapor formed by bubbling is released with the carrier gas out of the system through the dehamaging system.

Next, a multi quantum well structure composed of a GaN blocking layer 15 and an In _0.2 Ga _0.8 N well layer 16 is fabricated. First, a GaN blocking layer 15 is formed on a Si-doped GaN contact layer 14, after which an In _0.2 Ga _0.8 N well layer 16 is formed on the GaN blocking layer 15. This structure is repeated five times, after which the sixth GaN blocking layer 15 is formed on the sixth In _0.2 Ga _0.8 N well layer 16 to form a structure having a GaN blocking layer 15 at each end. Form.

To form the first GaN layer, a TEGa valve is used to maintain the same substrate temperature, reactor pressure, type of carrier gas, and flow rate while TEGa is supplied to the reactor. For seven minutes, the supply of TEGa is stopped, and the formation of the 70-nm thick GaN blocking layer is completed.

After the GaN blocking layer 15 is completed, the supply of the Group 3 material is stopped for 30 seconds, after which the TEGa and TMIn valves are operated to supply the TEGa and TMIn to the reactor while simultaneously supplying the same substrate temperature, reactor pressure and carrier gas. The type and flow rate of are maintained. After 2 minutes, the supply of TEGa and TMIn is stopped, and the formation of a 20 μm thick In _0.2 Ga _0.8 N well layer 16 is finished. After the formation of the In _0.2 Ga _0.8 N well layer 16 is complete, the supply of group III material is stopped for 30 seconds, after which the supply of TEGa to the reactor begins, while the same substrate temperature, reactor pressure, carrier gas The type and the flow rate of are maintained, so that another GaN blocking layer 15 is grown. This procedure is repeated five times to produce five GaN blocking layers 15 and five In _0.2 Ga _0.8 N well layers 16. Finally, a GaN blocking layer 15 is formed on the final In _0.2 Ga _0.8 N well layer 16.

The following procedure is used to fabricate an undoped Al _0.2 Ga _0.8 N diffusion barrier layer 17 on the final GaN barrier layer 15 of the quantum well structure. One minute after the TEGa supply was stopped to complete the GaN barrier layer 15, the same substrate temperature and type and flow rate of the carrier gas were maintained while the reactor pressure was changed to 100 hPa. The flow of trimethyl aluminum (TMAl) carrier gas into the bubbler has already begun. Until the diffusion barrier layer forming step begins, the TMAl water vapor produced by bubbling, together with the carrier gas, is released out of the system through the dehamaging system. Next, after the reactor pressure time to stabilize is given, the TEGa and TMAl valves are operated to begin supplying TEGa and TMAl to the reactor. The layer is grown for the next about 3 minutes, after which the supply of TEGa and TMAl is stopped to stop the formation of the undoped Al _0.2 Ga _0.8 N diffusion barrier layer 17. The thickness of the obtained undoped Al _0.2 Ga _0.8 N diffusion barrier layer 17 is 30 kPa.

The following procedure is used to grow the Mg-doped GaN layer 18 on the undoped Al _0.2 Ga _0.8 N diffusion barrier layer 17. Two minutes after the growth of TEGa and TMAl was stopped and the growth of the undoped Al _0.2 Ga _0.8 N diffusion barrier layer 17 ended, the temperature of the substrate was raised to 1060 ° C. and the reactor pressure was changed to 200 hPa. Converted to hydrogen. The flow of bicyclopentadienyl magnesium (Cp ₂ Mg) carrier gas through the bubbler has already begun. Until the Mg-doped GaN layer forming step begins, bubbling produced Cp ₂ Mg water vapor is discharged out of the system along with the carrier gas through the dehamaging system.

After the temperature and pressure change, the reactor pressure is given time to stabilize and the supply of TMGa and Cp ₂ Mg to the reactor begins. Cp ₂ Mg flow rates have already been studied and are adjusted to achieve hole concentrations of 8 × 10 ¹⁷ cm ⁻³ in the Mg-doped GaN cladding layer. After about 6 minutes of layer growth, the supply of TMGa and Cp ₂ Mg is stopped to stop the formation of the Mg-doped GaN layer. This process results in a 0.15 μm thick Mg-doped GaN layer 18.

Next, an Mg-doped InGaN layer 19 is formed on the Mg-doped GaN layer 18 as follows. After the supply of TMGa and Cp ₂ Mg is stopped and growth of the Mg-doped GaN layer 18 is complete, a time of two minutes is used to lower the substrate temperature to 800 ° C. and convert the carrier gas to nitrogen. The reactor is maintained at the same pressure of 200 hPa. The induction heater is switched off, whereby the substrate is cooled to room temperature for at least 20 minutes. During this cooling time, the atmosphere of the reactor consists of a mixture of 1% ammonia in nitrogen. After confirming that the substrate has cooled to room temperature, the formed wafer is taken out of the reactor. The wafer is pale yellow and transparent, and the epitaxial layer has a mirror surface. According to the above-described procedure, a wafer having an epitaxial structure used in a semiconductor light emitting device is manufactured. Mg-doped GaN layer 18 exhibits p-type properties, although no annealing is used to activate the p-type carrier.

A wafer having the epitaxial structure formed on the sapphire substrate is used to manufacture a light emitting diode. The surface of the In _0.1 Ga _0.9 N layer 18 of 100 Å was formed by forming a p-electrode bonding pad 20 composed of a stack made of titanium, aluminum, and gold, and a transparent p-side electrode 21 formed only of gold. A known photolithography process is used to produce the p-side electrode on 18a). Next, dry etching is used to expose the portion 131 of the GaN layer 13 doped with Si for the n-side electrode, and the n-electrode 22 of Ni and Al is exposed portion 131. Is manufactured). 7 shows the shape of an electrode fabricated on a wafer.

Next, the opposite side of the sapphire substrate is abraded and polished to complete the mirror surface, and the wafer is cut into chips of 350 mu m ² . Next, the chip is mounted on the lead frame electrode side and forms a light emitting element connected to the lead frame with gold wiring. When 20 mA of forward current is applied between the electrodes, the forward voltage is 3.0V. The light wavelength emitted through the p-side transparent electrode is 472 nm and the emission output is 5.9 cd.

Comparative Example 2

In Comparative Example 2, the wafer is manufactured using a conventional low temperature buffer layer method. This method is used to produce a 2 μm thick gallium nitride film undoped on a substrate. The prepared wafer is colorless and transparent and the epitaxial layer has a mirror surface. In the same manner as in Example 10, p and n side electrodes are formed on the wafer, opposite sides of the sapphire substrate are abraded and polished to form a mirror surface, and the wafer is cut into chips of 350 mu m ² . Next, the chip is mounted on the lead frame electrode side and connected to the lead frame with gold wiring to form a light emitting element. When 20 mA of forward current is applied between the electrodes, the forward voltage is 4.0V. The light wavelength emitted through the p-side transparent electrode is 470 nm, and the emission output is 3 cd.

The high quality gallium nitride-based compound semiconductor layer formed on the substrate according to the method of the present invention improves the crystallinity of the emitting layer, thereby improving the emission quantum yield.

Example 13

Embodiments in which gallium nitride-based compound semiconductor crystals are grown using a slow growth mask layer formed on a substrate will now be described. In this embodiment, the crystal is grown on the substrate according to the steps illustrated in FIG. The MOCVD method produces an epitaxial specimen by flowing ammonia and disilane (Si ₂ H ₆ ), flowing a mixture of TMG and TMA, and then flowing ammonia and covered by silicon nitride on a substrate heated to high temperature. And aluminum nitride and gallium nitride are attached to the sapphire substrate and used to produce a mask layer having a region that forms an undoped GaN layer over the layer.

The MOCVD method is used to prepare a specimen comprising the GaN layer as follows.

The sapphire substrate 11 is placed in a quartz reactor inside the RF coil of the induction heater, and the substrate is mounted on the carbon susceptor for heating. Next, after the air is discharged from the reactor, nitrogen gas flows to purify the inside of the reactor. After nitrogen gas was flowed for 10 minutes, the heater was activated to heat the substrate to 1170 ° C. for at least 10 minutes. While the substrate was held at 1170 ° C. for 9 minutes, hydrogen and nitrogen gas flowed to thermally clean the substrate surface.

During the thermal rinse, the hydrogen carrier gas is connected to the reactor and flowed through a bubbler containing trimethyl gallium (TMG) to start bubbling. Thermal baths are used to maintain the bubbler at a constant temperature. Until the start of the GaN layer growth process, the TMG water vapor generated by bubbling is discharged out of the system through the dehamaging system together with the carrier gas.

After completion of the thermal cleaning, the ammonia and disilane gas valve is used to flow the ammonia and disilane gas over the sapphire substrate for one minute until the supply of ammonia and disilane gas is used to stop. Next, a nitrogen carrier gas valve is used to start supplying nitrogen gas to the reactor. After 1 minute, the TMA and TMG valves are opened to supply the TMA and TMG containing carrier gas to the reactor for 1 minute, after which the supply of TMA and TMG is cut off and the carrier gas valve is used to start flowing nitrogen into the reactor. . After 1 minute, the supply of ammonia to the reactor starts and lasts for 10 minutes, after which the supply is cut off and nitrogen gas is supplied. The mask layer formed by these steps consists of silicon nitride region 5 and gallium nitride aluminum region 8.

After forming the mask layer, the substrate temperature is reduced to 1160 ° C. After confirming that the temperature has stabilized to 1160 ° C, the ammonia gas line valve is operated to start supplying ammonia gas 4 to the reactor. After 1 minute, the TMG line valve is operated so that a TMG steam containing gas is provided to the reactor to grow a GaN layer 9 on the mask layer. After the growth of the GaN layer proceeds for about 2 hours, the TMG supply is cut off and the growth ends. Next, the heater is switched off and the specimen is removed using the procedure used in Example 1. According to the above-described procedure, a mask layer is formed on the sapphire substrate 1 and a 2 μm thick GaN layer is formed on the mask layer for preparing the specimen. The substrate removed from the reactor is colorless and transparent; The epitaxial layer has a mirror surface.

XRC measurements of the undoped GaN layer grown in this manner are performed. Using the Cu β line? Line light source, measurements using symmetrical (0002) planes and asymmetrical (10-12) planes are performed. In general, for gallium nitride-based compound semiconductors, the peak width at half height of the XRC spectrum of the (0002) plane is the flatness index of the crystal and peak at half height of the XRC spectrum of the (10-12) plane. Width is the displacement density index. The measurement shows that the (0002) plane has a peak width at half height value of 280 seconds, while the peak width of the (10-12) plane is 300 seconds.

Irradiation of the top surface of GaN with an atomic microscope was found to have a good surface morphology and no growth pits were observed at all. In order to measure the etch-pit density of the film, the specimen is immersed in a sulfuric acid and phosphoric acid solution at a temperature of 280 ° C. for 10 minutes. The surface is then irradiated with an atomic microscope to measure an etch-pit density of about 9 × 10 ⁶ cm ⁻² .

Example 14

In this embodiment, crystals are grown on the substrate by the steps illustrated in FIG. 10 using the MOCVD method. The sapphire substrate surface is nitrided by flowing ammonia gas at high temperature. By flowing ammonia after flowing the mixture of silane and TMG, a mask layer is formed on the substrate comprising a region covered by silicon nitride and a region where gallium nitride is attached to the substrate. Next, an undoped GaN layer is formed on the mask layer.

Using the same MOCVD apparatus as Example 13, the MOCVD method was used to prepare a specimen comprising the GaN layer as follows. The sapphire substrate is thermally cleaned in the same manner as in Example 13, during which bubbling starts. After completion of the thermal cleaning, ammonia flows over the substrate for 20 minutes before stopping. Next, the nitrogen carrier gas valve is operated to start supplying nitrogen gas to the reactor. At this time, the silaneTMG valve is opened to supply a carrier gas containing silane and TMG water vapor to the reactor for 30 seconds, after which the TMG and silane are shut off and a carrier gas valve is used to start the movement of nitrogen into the reactor. . After 1 minute, the flow of ammonia into the reactor starts and lasts for 10 minutes, after which it is shut off and the nitrogen supply starts. This process forms a mask layer on the sapphire substrate including silicon nitride region 5 and gallium nitride region 8.

After formation of the mask layer, the substrate temperature is reduced to 1180 ° C. After confirming that the temperature has stabilized to 1180 ° C., ammonia supply is started and ammonia is flowed into the reactor. After 1 minute, the TMG line valve is operated so that a TMG steam containing gas is provided to the reactor and a GaN layer is grown on the mask layer. After the growth of the GaN layer proceeds for about 2 hours, the TMG supply is cut off and the growth process ends. Next, the heater is switched off and the sample is removed from the reactor using the procedure used in Example 1. According to the above-described procedure, mask layers 5 and 8 are formed on the sapphire substrate 1 and a 2 μm thick GaN layer is formed on the mask layer to prepare the specimen. The substrate removed from the reactor is colorless and transparent and the epitaxial layer has a mirror surface.

XRC measurements of the undoped GaN layer grown in this manner are performed. The (0002) plane has a peak width at half height value of 290 seconds, while the peak width of the (10-12) plane is 420 seconds. Irradiation of the top surface of GaN with an atomic microscope has been found to have a good surface morphology, but no growth pits are observed at all. In order to measure the etch-pit density of the film, a specimen was prepared in the same manner as in Example 13, and the surface was irradiated with an atomic force microscope to measure an etch-pit density of about 6 × 10 ⁷ cm ⁻² .

Example 15

This example is used to describe a method for manufacturing a light emitting device using a gallium nitride-based compound semiconductor, comprising the step of manufacturing a gallium nitride-based compound semiconductor by the method described in Example 13. The cross-sectional structure of the light emitting device has the same structure as that of Example 12, as shown in FIG. The MOCVD method flows ammonia and disilane (Si ₂ H ₆ ), flows a mixture of TMG and TMA, and then flows ammonia to form a wafer having a multilayer structure of a semiconductor light emitting device, and on a sapphire substrate heated to a high temperature. Form a mask layer having a region covered by silane nitride and a region covered by GaAlN. The next layer is a GaN layer 12 doped with 2 μm Si having an electron concentration of 1 × 10 ¹⁷ cm ⁻³ ; A GaN layer 13 heavily doped with 1 μm Si having an electron concentration of 1 × 10 ¹⁹ cm ⁻³ ; Multiple quantum consisting of six 70-μs GaN barrier layers 15 and five 20 μs undoped In _0.2 Ga _0.8 N well layers 16, starting with GaN barrier layer 15 and ending with GaN barrier layer 15. Well structure; It is formed on the substrate in the order of 0.15 μm Mg-doped GaN layer 18 having a hole concentration of 8 × 10 ¹⁷ cm ⁻³ .

Using the same procedure as in the MOCVD method and Example 13, the first layer formed is a GaN layer 12 doped with Si having a 2 μm thick horizontal surface with an electron concentration of 1 × 10 ¹⁷ cm ⁻³ . Next, using the same procedure as described in Example 12, a GaN layer 12 doped with Si was formed, followed by a multi quantum well structure, Al _0.2 Ga _0.8 N diffusion barrier layer 17, And Mg-doped GaN layer 18 is formed.

On the wafer removed from the reactor, a known photolithography process is used, starting from the surface of the p-type InGaN layer and layered in the order of titanium, aluminum, and gold, and in the order of p-side transparent electrode and nickel oxide formed of gold A bond pad consisting of the disposed layers is produced. Next, a dry etching method is used to expose a portion of the n-type GaN layer for the n-side electrode, and the n-side electrode made of aluminum is fabricated on the exposed portion. Next, the opposite side of the sapphire substrate is abraded and polished to complete the mirror surface and the wafer is cut into chips of 350 mu m ² . A chip is mounted on the lead frame electrode side and connected to the lead frame with gold wiring to form a light emitting element. When a 20 mA forward current is applied between the electrodes, the forward voltage is 3.0V. The light wavelength emitted through the p-side transparent electrode is 465 nm and the emission output is 3 cd.

Industrial availability:

As described above, the Group III nitride semiconductor crystals according to the present invention can easily produce high quality Group III nitride semiconductor crystals without strict control of the manufacturing conditions required by the conventional method using a low temperature buffer layer. Thus, when the group III nitride semiconductor crystals formed by the present invention are used to fabricate a light emitting device, a substantially uniform high brightness device characteristic can be obtained in a device manufactured from substantially all parts of the wafer.

In addition, according to the method for producing a gallium nitride-based compound semiconductor of the present invention, the gallium nitride-based compound semiconductor is prepared by attaching a metal nucleus to a substrate and used as a growth nucleus. In addition, the gallium nitride-based compound semiconductor layer is also grown on the growth nucleus. The density of the metal nuclei on the substrate can be controlled by controlling the flow rate of the metal-organic gas, gas use time, process temperature, and other conditions.

By annealing and nitriding the metal nuclei, the metal nuclei can be provided for vertical and horizontal epitaxial growth, and also a growth nucleus of a desired shape such as, for example, a trapezoid can be obtained. More gallium nitride-based compound semiconductors can be grown on growth nuclei, filling the spaces between adjacent growth nuclei and growing horizontal layers thereon. Thus, a gallium nitride-based compound semiconductor layer having a desired thickness and good crystallinity can be formed. Since the gallium nitride-based compound semiconductor is disposed on the gallium nitride-based compound semiconductor layer, very good lattice matching properties can be maintained. Thus, a gallium nitride-based compound semiconductor layer can be formed on the substrate, each layer having good crystallinity. This improves the emission characteristics of semiconductor light emitting devices produced using gallium nitride-based compound semiconductors. The semiconductor light emitting element manufactured by the above method can also be used as an electronic equipment, a vehicle, and a traffic light as a light source having excellent brightness and other emission characteristics. Compared with the semiconductor light emitting device manufactured by the conventional method, the light emitting device manufactured by the method of the present invention is more efficient and deteriorated at low speed, so that the light emitting device uses low energy, reduces cost, and is frequently replaced. no need.

Claims (88)

As a method for producing a nitride semiconductor crystal of group 3, Depositing Group III metal particles on the substrate surface; A second step of nitriding the particles in an atmosphere containing a nitrogen source; And Group 3 represented by In _X Ga _Y Al _Z N (x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) on the substrate surface on which the particles are deposited And a third step of using a vapor phase growth method to grow the nitride semiconductor crystals. The method of claim 1, wherein the substrate is a sapphire (Al ₂ O ₃ ) substrate. The metal of claim 3, wherein the Group 3 metal is In _u Ga _v Al _w (u + v + w = 1, 0≤u≤1, 0≤v≤1, 0≤w≤1) Nitride semiconductor crystal manufacturing method of group. The method of claim 1, wherein the Group 3 metal particles are deposited by thermal decomposition of a metal-organic material. The method of claim 1, wherein the first step is performed in an atmosphere that does not contain a nitrogen source. A method according to claim 1 or 5, wherein the first step is performed at or above the boiling point of the Group 3 metal. The method of claim 1, wherein the second step is performed in an atmosphere not containing a metal material. 8. A method according to claim 1 or 7, wherein said second step is carried out at or above the temperature used in said first step. The method of claim 1, wherein the third step is performed at or above the temperature used in the second step. The method of claim 1, wherein the vapor phase growth method is a metal-organic chemical vapor deposition method. The method of claim 1, wherein the Group 3 metal particles nitrided in the second step are polycrystalline and / or amorphous Group III nitrides and comprise an unreacted metal. The method of claim 1, further comprising forming a mask layer on the substrate to grow the gallium nitride-based compound semiconductor crystals at a low growth rate, thereby selectively growing the gallium nitride-based compound semiconductor crystals. A nitride group crystal manufacturing method of group 3, further comprising. The semiconductor device of claim 12, wherein the mask layer formed on the substrate comprises a portion composed of a material having a low growth rate of a gallium nitride-based compound semiconductor and a portion composed of a material having a high growth rate of a gallium nitride-based compound semiconductor. A group 3 nitride semiconductor crystal production method characterized by the above-mentioned. 13. The method of claim 12, wherein the forming of the mask layer is performed in an epitaxial growth apparatus used to grow the gallium nitride-based compound semiconductor crystals. The method of claim 12, wherein the mask layer is formed by flowing an Si-containing material gas over the substrate. 13. The method of claim 12, wherein the mask layer is formed by simultaneously flowing Si-containing material gas and ammonia on the substrate. The method according to claim 12, wherein the mask layer formed includes a portion covering the substrate and a portion exposing the substrate. The method of claim 12, wherein the mask layer is formed by simultaneously flowing a group III element-containing material gas and a Si-containing material gas on the substrate. As a method for producing a nitride semiconductor crystal of group 3, The metal on the sapphire substrate at a temperature T1 above the boiling point of the metal represented by In _u Ga _v Al _w (u + v + w = 1, 0 ≦ u ≦ 1, 0 ≦ v ≦ 1, 0 ≦ w ≦ 1) A first step of utilizing thermal decomposition of a metal-organic material comprising at least one metal element selected from In, Ga, and Al in an atmosphere not containing a nitrogen source to deposit a; A second step of nitriding the deposited metal at a temperature T2 (T2? T1) in an atmosphere containing a nitrogen source but no metal-organic material; And In _x Ga _y Al _z N (x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ at a temperature T3 (T3 ≧ T2) on the sapphire substrate on which the metal is deposited And a third step of using a metal-organic chemical vapor deposition method for epitaxially growing a nitride semiconductor crystal of Group 3 represented by 1). 20. The method according to claim 19, wherein the sapphire substrate comprises a (0001) plane having a vertical axis inclined in a specific direction from <0001>. A method according to claim 20, wherein the specific direction is <1-100> and the inclination angle from <0001> is 0.2 ° to 15 °. 20. The method according to claim 19, wherein the temperature T1 is at least 900 占 폚 and the temperature T3 is at least 1000 占 폚. 20. The method of claim 19, wherein thermal decomposition of the metal-organic material in the first step occurs in a hydrogen atmosphere. 20. The method of claim 19, wherein the metal is deposited on the sapphire substrate as particles, not as layers. The method of claim 24, wherein the metal particles have a height of 50 GPa or more and 1000 GPa or less from the surface of the sapphire substrate to the axis of the metal particles. The method of claim 19, wherein the metal nitrided in the second step is In _u Ga _v Al _w N _k (u + v + w = 1, 0, the stoichiometric ratio between the nitrogen and the metal is not 1: 1) A group 3 nitride semiconductor crystal production method comprising polycrystals present in the regions ≦ u, v, w ≦ 1 and 0 <k <1). 20. The method of claim 19, further comprising forming a mask layer on the substrate to grow gallium nitride-based compound semiconductor crystals at a low growth rate, thereby selectively growing the gallium nitride-based compound semiconductor crystals. A nitride group crystal manufacturing method of group 3, further comprising. 28. The method of claim 27, wherein the mask layer formed on the substrate comprises a portion composed of a material having a low growth rate of a gallium nitride-based compound semiconductor and a portion composed of a material having a high growth rate of a gallium nitride-based compound semiconductor. A group 3 nitride semiconductor crystal production method characterized by the above-mentioned. 28. The method of claim 27, wherein said mask layer forming step is performed in an epitaxial growth apparatus used to grow said gallium nitride-based compound semiconductor crystals. 28. The method of claim 27, wherein said mask layer is formed by flowing an Si-containing material gas over said substrate. 28. The method of claim 27, wherein the mask layer is formed by simultaneously flowing Si-containing material gas and ammonia onto the substrate. 28. The method of claim 27, wherein the formed mask layer includes a portion covering the substrate and a portion exposing the sapphire substrate. 28. The method of claim 27, wherein the mask layer is formed by simultaneously flowing a group III element-containing material gas and a Si-containing material gas over the substrate. A method for producing a nitride semiconductor crystal of Group 3 represented by In _X Ga _Y Al _Z N (x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1), Supplying said Group III metal material to said substrate for depositing Group III metal material and / or decomposition product on said substrate; A second step of heat treating the substrate in an atmosphere containing a nitrogen source; And And a third step of using the Group III metal material and the nitrogen source to grow the Group III nitride semiconductor crystals on the substrate by a vapor phase growth method. 35. The group III nitride semiconductor of claim 34, wherein the group III nitride semiconductor crystal grown on the substrate comprises a surface having a (0001) plane with a vertical axis inclined in a particular direction from <0001>. Crystal manufacturing method. 36. The method of claim 35, wherein the specific direction is <11-20> and the inclination angle from <0001> is 0.2 ° to 15 °. 35. The method of claim 34, further comprising forming a mask layer on the substrate to grow gallium nitride-based compound semiconductor crystals at a low growth rate, thereby selectively growing the gallium nitride-based compound semiconductor crystals. A nitride group crystal manufacturing method of group 3, further comprising. 38. The method of claim 37, wherein the mask layer formed on the substrate comprises a portion composed of a material having a low growth rate of a gallium nitride-based compound semiconductor and a portion composed of a material having a high growth rate of a gallium nitride-based compound semiconductor A group 3 nitride semiconductor crystal production method characterized by the above-mentioned. 38. The method of claim 37, wherein said mask layer forming step is performed in an epitaxial growth apparatus used to grow said gallium nitride-based compound semiconductor crystals. 38. The method of claim 37, wherein said mask layer is formed by flowing an Si-containing material gas over said substrate. 38. The method of claim 37, wherein the mask layer is formed by simultaneously flowing Si-containing material gas and ammonia onto the substrate. 38. The method of claim 37, wherein the formed mask layer includes a portion covering the substrate and a portion exposing the sapphire substrate. 38. The method of claim 37, wherein the mask layer is formed by simultaneously flowing a group III element-containing material gas and a Si-containing material gas over the substrate. As a method of manufacturing a gallium nitride-based compound semiconductor, Attaching a metal nucleus to the substrate; A second step of annealing the metal nucleus; A third step of nitriding the annealed metal nucleus to form a growth nucleus; And A gallium nitride-based compound semiconductor comprising a fourth step of growing a gallium nitride-based compound on the substrate having the growth nucleus to form and grow a gallium nitride-based compound semiconductor crystal layer Manufacturing method. 45. The method of claim 44, wherein said substrate is a sapphire substrate. 45. The gallium nitride-based substrate as claimed in claim 44, wherein in the first step, the metal nucleus is attached to the substrate by flowing a source gas containing water vapor of a metal-organic material but no nitrogen source. Compound semiconductor manufacturing method. 47. The gallium nitride-based compound of claim 46, wherein the metal-organic material comprises at least one member selected from gallium-containing metal-organic materials, aluminum-containing metal-organic materials, and indium-containing metal-organic materials. Semiconductor manufacturing method. 45. The method of claim 44, wherein in the second step, the metal nucleus is annealed by flowing only a carrier gas that contains neither a nitrogen source nor metal-organic material vapor. 45. The method of claim 44, wherein in the third step, the metal nucleus is nitrided by flowing a gas containing a nitrogen source but no metal-organic vapor. . 45. The method of claim 44, wherein in the fourth step, the gallium nitride-based compound semiconductor crystals are formed by flowing a gas containing both a nitrogen source and water vapor of the metal-organic material using a metal-organic chemical vapor deposition method. A method for producing a gallium nitride-based compound semiconductor, characterized in that it is grown. 49. The method of claim 44 or 48, wherein said second step is performed at or above the temperature at which said first step is performed. 50. The method of claim 44 or 49, wherein said third step is performed at or above the temperature at which said second step is performed. 51. The method of claim 44 or 50, wherein said fourth step is performed at or above the temperature at which said third step is performed. 45. The method of claim 44, wherein said third step is performed after alternately repeating said first and second steps two or more times. 45. The method of claim 44, wherein said fourth step is performed after repeating said first, second, and third steps two or more times. 45. The method of claim 44, wherein the first step comprises: a first state step of flowing a gas containing water vapor of at least one member selected from an aluminum containing metal-organic material, a gallium containing metal-organic material, and an indium containing metal-organic material, and And a second state step of flowing a gas containing water vapor of a metal-organic material different from the first state step. 59. The method of claim 56, wherein said second step is performed after alternately repeating the first and second state steps of said first step two or more times. 45. The method of claim 44, wherein said growth nucleus is a trapezoidal nitride semiconductor crystal having flat vertices and flat sides parallel to said substrate. 45. The method of claim 44, further comprising growing a separate gallium nitride-based compound semiconductor crystal layer on the gallium nitride-based compound semiconductor crystal layer formed in the fourth step. -Based compound semiconductor manufacturing method. 45. The method of claim 44, further comprising forming a mask layer on the substrate to grow gallium nitride-based compound semiconductor crystals at a low growth rate, thereby selectively growing the gallium nitride-based compound semiconductor crystals. Gallium nitride-based compound semiconductor manufacturing method characterized in that it further comprises. 61. The method of claim 60, wherein the mask layer formed on the substrate comprises a portion composed of a material having a low growth rate of a gallium nitride-based compound semiconductor and a portion composed of a material having a high growth rate of a gallium nitride-based compound semiconductor. Gallium nitride-based compound semiconductor manufacturing method characterized in that. 61. The method of claim 60, wherein said mask layer forming step is performed in an epitaxial growth apparatus used to grow said gallium nitride-based compound semiconductor crystals. 61. The method of claim 60, wherein the mask layer is formed by flowing an Si-containing material gas over the substrate. 61. The method of claim 60, wherein said mask layer is formed by simultaneously flowing Si-containing material gas and ammonia onto said substrate. 61. The method of claim 60, wherein the mask layer formed comprises a portion covering the substrate and a portion exposing the sapphire substrate. 61. The method of claim 60, wherein the mask layer is formed by simultaneously flowing a group III element-containing material gas and a Si-containing material gas over the substrate. As a method of manufacturing a gallium nitride-based compound semiconductor, A first state step of flowing a vapor-containing gas of at least one member selected from an aluminum-containing metal-organic material, a gallium-containing metal-organic material, and an indium-containing metal-organic material, and water vapor of a metal-organic material different from the first state step A first step of attaching a metal nucleus to the substrate, the second step comprising a second state step of flowing the containing gas; A second step of nitriding the metal nucleus to form a growth nucleus; And Gallium nitride-based compound semiconductor manufacturing comprising a third step of growing a gallium nitride-based compound on a substrate having the growth nucleus to form and grow a gallium nitride-based compound semiconductor crystal layer Way. 68. The method of claim 67, wherein said substrate is a sapphire substrate. 68. The method of claim 67, wherein the second step is performed after the first and second state steps of the first step are alternately repeated two or more times. Way. 68. The method of claim 67, wherein said third step is performed after alternately repeating said first and second steps two or more times. 68. The gallium nitride-based compound of claim 67, wherein in the first step, the metal nucleus is deposited on the substrate by flowing a gas containing metal-organic material water vapor but no nitrogen source. Semiconductor manufacturing method. 68. The method of claim 67, wherein in the second step, the metal nucleus is nitrided by flowing a gas containing a nitrogen source but no metal-organic vapor. . 68. The method of claim 67, wherein in the third step, the gallium nitride-based compound semiconductor crystal is grown by flowing a gas containing both a nitrogen source and a metal-organic material using a metal-organic chemical vapor deposition method. A method for producing a gallium nitride-based compound semiconductor, characterized in that. 73. The method of claim 67 or 72, wherein said second step is performed at or above the temperature at which said first step is performed. 80. The method of claim 67 or 73, wherein said third step is performed at or above the temperature at which said second step is performed. 68. The method of claim 67, wherein said growth nucleus is a trapezoidal group III nitride semiconductor crystal having flat vertices and flat sides parallel to said substrate. 68. The gallium of claim 67, further comprising a fourth step of growing a separate gallium nitride-based compound semiconductor crystal layer on the gallium nitride-based compound semiconductor crystal layer formed in the third step. Nitride-based compound semiconductor manufacturing method. 68. The fifth device of claim 67, wherein a mask layer is formed on the substrate to grow gallium nitride-based compound semiconductor crystals at a low growth rate, thereby selectively growing the gallium nitride-based compound semiconductor crystals. A method of manufacturing a gallium nitride-based compound semiconductor, further comprising the step. 79. The method of claim 78, wherein the mask layer formed on the substrate comprises a portion composed of a material having a low growth rate of a gallium nitride-based compound semiconductor and a portion composed of a material having a high growth rate of a gallium nitride-based compound semiconductor Gallium nitride-based compound semiconductor manufacturing method characterized in that. 80. The method of claim 78, wherein forming the mask layer is performed in an epitaxial growth apparatus used to grow the gallium nitride-based compound semiconductor crystals. 80. The method of claim 78, wherein the mask layer is formed by flowing an Si-containing material over the substrate. 80. The method of claim 78, wherein said mask layer is formed by simultaneously flowing Si-containing material gas and ammonia onto said substrate. 80. The method of claim 78, wherein the mask layer formed comprises a portion covering the substrate and a portion exposing the substrate. 80. The method of claim 78, wherein the mask layer is formed by simultaneously flowing a group III element-containing material gas and a Si-containing material gas over the substrate. A group III nitride semiconductor produced by the method for producing a group III gallium nitride-based compound semiconductor crystal according to any one of claims 1, 19 and 34. A gallium nitride-based compound semiconductor produced by the gallium nitride-based compound semiconductor manufacturing method according to claim 44 or 67. 86. A gallium nitride-based compound semiconductor light emitting device manufactured using the gallium nitride-based compound semiconductor of group 3 according to claim 85, or the gallium nitride-based compound semiconductor according to claim 86. 88. A light source manufactured using the gallium nitride-based compound semiconductor light emitting device according to claim 87.