JP2003282450A - Boron phosphide based semiconductor layer and method of manufacturing the same, and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vapor phase growth method for obtaining a boron phosphide based semiconductor layer having superior continuity on a crystalline substrate having a large degree of lattice mismatching. <P>SOLUTION: In a method of manufacturing the boron phosphide based semiconductor layer wherein a boron phosphide based semiconductor layer containing boron (B) and phosphorus (P) as constituent elements is formed by vapor growth on the surface of the crystalline substrate, particles containing either boron or phosphorous are formed in advance on the surface the crystalline substrate, and then the boron phosphide based semiconductor layer is formed by vapor phase growth. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boron phosphide-based semiconductor layer and a semiconductor element using the same, and particularly to a boron phosphide-based semiconductor layer having excellent surface flatness and continuity on the surface of a crystal substrate. The present invention relates to a technique for vapor-phase growing a semiconductor layer.

[0002]

2. Description of the Related Art Conventionally, a boron phosphide-based semiconductor layer containing boron (B) and phosphorus (P) as constituent elements has been used to form various semiconductor elements. For example, boron phosphide (B) which is a typical monomer as a boron phosphide-based semiconductor is used.
The semiconductor layer made of P) is used to form an n-type base layer of an npn-type hetero bipolar transistor (HBT) (J. Electroche).
m. Soc. , 125 (4) (1978), 633-6.
(See page 37). Also, a blue laser diode (LD)
However, it is used as a contact layer for forming an ohmic electrode having a low contact resistance (see Japanese Patent Laid-Open No. 10-242567). It is also used as a buffer layer for forming a light emitting diode (LED) that emits light of a short wavelength such as near ultraviolet or blue (US Pat. No. 6,069,021).
No.).

The boron phosphide-based semiconductor layer for forming the semiconductor element as described above has been conventionally formed by vapor phase growth means. Conventional vapor phase growth means include, for example:
Halogen vapor phase growth method using boron trichloride (BCl ₃ ) or phosphorus trichloride (PCl ₃ ) as a starting material (“Journal of Japanese Society for Crystal Growth”, Vol. 24, No. 2).
(1997, p. 150), borohydride (BH ₃ ) or diborane (B ₂ H ₆ ) and phosphine (PH ₃ ) as raw materials, and hydride vapor phase growth method (J. Crystal Growth, 25/25). (1
974), pp. 193-196), molecular beam epitaxy (J. Solid State Chem., 1).
33 (1997), 269-272), and metalorganic chemical vapor deposition (MOCVD) (Inst. Ph.
ys. Conf. Ser. , No. 129 (IOP P
publishing Ltd. (UK, 1993), 1
57 to 162)).

When vapor-depositing a boron phosphide-based semiconductor layer, a single crystal of a semiconductor material is mainly used for a substrate. Conventionally, silicon (S
i) Single crystal (silicon) (above J. Electro
chem. Soc. , 125 (1978), and US Pat. No. 6,069,021), silicon carbide (SiC).
(See JP-A-10-242569), gallium phosphide (GaP) (see JP-A-10-242568) and gallium nitride (GaN) (JP-A-10-2477).
For example, a single crystal such as Japanese Patent No. 45) is used.

[0005]

However, the single crystal material forming the above substrate and, for example, boron phosphide (BP) are used.
The lattice constants of and are significantly different. The lattice constant of silicon single crystal is 5.431 Å, while cubic zinc blende type BP
It is 4.538Å (see Iwao Teramoto, "Introduction to Semiconductor Devices" (March 30, 1995, first edition published by Baifukan Co., Ltd.), p. 28). Therefore, the degree of lattice mismatch is as large as about 16.5% (Katsufusa Shono, “Semiconductor Technology (1)” (June 25, 1992, 9th edition, published by The University of Tokyo Press), 97-). (See page 98).

As described above, on a crystal substrate having a large degree of lattice mismatch, the boron phosphide-based semiconductor layer is formed by the Volmer-
Initiate island-like growth with Weber-like growth (edited by Japan Society of Applied Physics, Thin Film and Surface Physics Subcommittee, "Handbook for Thin Film Fabrication" (March 25, 1991, Kyoritsu Shuppan Co., Ltd., first edition, first edition) ), P. 59). Therefore, it is difficult to obtain a continuous boron phosphide-based semiconductor layer.

If there is a means for vapor phase growing a boron phosphide-based semiconductor layer having excellent continuity without cracks, for example, a forward voltage (so-called Vf ) Low LED and LD low threshold voltage (so-called V _th ) can be easily provided.
The present invention provides a vapor phase growth method for obtaining a boron phosphide-based semiconductor layer having excellent continuity even on a crystal substrate having a large degree of lattice mismatch. Further, a semiconductor element constituted by using the boron phosphide-based semiconductor layer is provided.

[0008]

Means for Solving the Problems That is, according to the present invention, (1) a boron phosphide-based semiconductor layer containing boron (B) and phosphorus (P) as constituent elements is vapor-phase grown on the surface of a crystal substrate. In the method for producing a boron phosphide-based semiconductor layer, particles containing either boron or phosphorus are formed in advance on the surface of a crystal substrate, and then a boron phosphide-based semiconductor layer is vapor-phased on the surface of the crystal substrate. A method for manufacturing a boron phosphide-based semiconductor layer, which comprises growing the semiconductor layer. (2) The diameter of the particles containing either boron or phosphorus is 1
nm or more and 30 nm or less, The manufacturing method of the boron phosphide system semiconductor layer as described in said (1) characterized by the above-mentioned. (3) The method for producing a boron phosphide-based semiconductor layer according to (1) or (2) above, wherein the crystal substrate is made of an n-type or p-type conductive single crystal. (4) The production of a boron phosphide-based semiconductor layer according to any one of (1) to (3) above, wherein the particles containing either boron or phosphorus are formed of polycrystal. Method. (5) The particles containing either boron or phosphorus are formed from a polycrystalline body containing an amorphous body in the region of the bonding interface with the surface of the crystal substrate, which is characterized in (1) to (). 4. The method for producing a boron phosphide-based semiconductor layer according to any one of 4). (6) A boron phosphide-based semiconductor layer is vapor-grown on the surface of a crystal substrate at a temperature higher than the temperature at which particles containing boron or phosphorus are formed and at 1200 ° C. or lower. The method for producing a boron phosphide-based semiconductor layer according to any one of (1) to (5) above. (7) The same vapor phase growth as that for forming particles containing either boron or phosphorus by using the same raw material as the boron raw material or phosphorus raw material used for forming particles containing either boron or phosphorus. (1) to (6), wherein the boron phosphide-based semiconductor layer is vapor-phase-grown by means.
10. The method for producing a boron phosphide-based semiconductor layer according to any one of 1. (8) Metal vapor chemical vapor deposition (MOC)
VD) method, The method for producing a boron phosphide-based semiconductor layer according to (7) above. (9) A boron phosphide-based semiconductor layer produced by using the method for producing a boron phosphide-based semiconductor layer according to any one of (1) to (8) above. (10) A semiconductor device using the boron phosphide-based semiconductor layer according to (9) above. Is.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a boron phosphide-based semiconductor means, for example, B containing phosphorus and phosphorus as constituent elements.
_{α Al β Ga γ In 1- α} - β - γ P 1- δ As δ (0 <α ≦
1,0 ≦ β <1, 0 ≦ γ <1, 0 <α + β + γ ≦ 1,0
≦ δ <1), for example, B _α Al _β Ga _γ In _{1- α −
β - γ} P _{1- δ} N _δ (0 <α ≦ 1, 0 ≦ β <1, 0 ≦ γ <
1, 0 <α + β + γ ≦ 1, 0 ≦ δ <1). To describe an example of the first embodiment of the present invention, first, for example, triethylboron ((C ₂ H ₅ ) ₃ B) is uniformly adsorbed on the surface of the crystal substrate. In particular, a boron-containing compound that is liquid at room temperature,
For example, boron oxide (B (OCH ₃ ) ₃ ; melting point = -2
9 ° C., boiling point = + 68 to + 69 ° C.) or the like, this is uniformly sprayed on the surface of the crystal substrate. After that, the temperature of the crystal substrate is raised to increase the addition group (additional gr).
uop) is desorbed and solidified as particles containing boron. The temperature of the crystal substrate is set to a temperature suitable for solidifying the particles containing boron. In this way, before the vapor phase growth of the continuous film of the boron phosphide-based semiconductor layer, particles containing boron or phosphorus can be deposited on the surface of the substrate in advance.

Particles containing phosphorus can be similarly formed.
For example, phosphine (PH ₃ ) is supplied and adsorbed on the surface of the crystal substrate placed inside the MOCVD growth furnace. After that, if the temperature of the crystal substrate is raised to a temperature not higher than the practical heat resistance temperature of the crystal substrate at 400 ° C. or higher, PH ₃ molecules adsorbed on the surface of the crystal substrate are thermally decomposed to remove particles containing phosphorus. Can be formed. Also, for example, (C ₂ H ₅ ) ₃ B and P
There is also a means of causing particles containing both boron and phosphorus formed by causing H ₃ to flow at the same time to cause a gas phase reaction to fly toward the surface of the crystal substrate and deposit the particles on the surface.

The size of particles containing boron or phosphorus provided on the crystal substrate is preferably 1 nm or more and 30 nm or less in terms of particle diameter (particle diameter). Particles having an extremely large particle diameter exceeding 30 nm generally have a high altitude from the surface of the crystal substrate. In the boron phosphide-based semiconductor layer grown on the grains as "nuclei", the presence of large grains results in the disadvantage that the surface flatness of the boron phosphide-based semiconductor layer is impaired. Further, in the case of fine particles having a particle diameter of less than 1 nm, the boron phosphide-based semiconductor layer is limitedly grown only around the fine particles, which causes a problem in obtaining a continuous film.

Further, if the density of particles existing on the surface of the crystal substrate is low, it is not possible to stably obtain a continuous boron phosphide-based semiconductor layer. In order to stably obtain a continuous boron phosphide-based semiconductor layer, for example, in the case of particles having an average particle size of 10 nm, the particles should be present on the surface of the crystal substrate at a density of about 1 × 10 ⁸ / cm ² or more. desirable. More desirable is the situation in which the particles are present at a high density so as to cover the surface of the crystal substrate almost completely. More preferred is
This is a situation in which the surface of the crystal substrate is almost completely covered with particles that make the top plate flat. The particles, which are substantially parallel to the surface of the crystal substrate and have a flat top plate, particularly contribute to obtaining a boron phosphide-based semiconductor layer having a flat surface. As the total concentration of the boron raw material, the phosphorus raw material, or the like supplied to the surface of the crystal substrate is increased, particles having a large particle diameter can be generated at high density. The composition of particles existing on the surface of the crystal substrate can be investigated by a composition analysis method such as Auger electron analysis method or electron microscope analysis method. Further, the particle diameter and the particle density can be measured using, for example, an atomic force microscope (AFM).

By forming particles containing either boron or phosphorus according to the present invention on the surface of a crystal substrate, a boron phosphide-based semiconductor layer having continuity even on a single crystal substrate having a large degree of lattice mismatch. Can be formed. For example, a group III-V compound semiconductor single crystal such as gallium arsenide (GaAs), a group III nitride semiconductor single crystal such as aluminum nitride (AlN), or silicon (Si) single crystal can be used as the substrate. Further, an insulating α-alumina (α-Al ₂ O ₃ ) single crystal or a perovskite crystal type oxide single crystal can be used as a substrate. When an n-type or p-type conductive single crystal is used as a substrate, an ohmic electrode of positive or negative polarity of either polarity can be laid on the back surface of the substrate as a back surface electrode, and an LED can be easily used.
Can contribute to the construction of a light emitting device such as. A single crystal substrate with a low resistivity of 1 mΩ · cm or less is an LED with a low forward voltage.
Contribute to bring.

The particles containing either boron or phosphorus according to the present invention may be composed of polycrystalline particles. Polycrystalline particles refer to, for example, crystal grains formed by coalescing single crystals having different orientations via grain boundaries. Further, the polycrystalline particles may be composed of a set of single crystals having different crystal types. For example, there are also polycrystalline particles that are composed of a single crystal of the same crystal type as the crystal forming the substrate and a single crystal of a different crystal type. The polycrystalline particles can be formed by making the substrate temperature lower than the substrate temperature at which the single crystal particles are formed. As an example of the second embodiment of the present invention, (C ₂ H ₅ ) ₃ B is used as a boron raw material,
Boiling point of (C ₂ H ₅ ) ₃ B (= + 95 in MOCVD growth furnace)
On the surface of the silicon single crystal substrate kept at a low temperature of
Hydrogen (H ₂ ) accompanied with (C ₂ H ₅ ) ₃ B is supplied. After waiting for a while, the temperature of the silicon single crystal substrate is desirably raised to about 450 ° C to about 650 ° C. Then, after waiting for a while again, polycrystalline particles containing boron are formed on the surface of the crystal substrate. In this case, the longer the standby time at high temperature,
It is possible to obtain polycrystalline grains having a large grain size. In the case of particles made of polycrystal, a lattice mismatch between the crystal substrate and the boron phosphide-based semiconductor layer is absorbed due to the crystal grain boundaries included therein, stacking faults, etc., and a high-quality boron phosphide-based semiconductor layer with few crystal defects is obtained. It is effective to obtain. The constituent elements of the crystal grains can be analyzed by, for example, an electron diffraction technique using a transmission electron microscope (TEM).

In the third embodiment of the present invention, in particular, after the particles of boron or phosphorus are deposited on the surface of the crystal substrate, the temperature of the crystal substrate is rapidly raised so that the bonding boundary with the crystal substrate is increased. Crystal grains that make the region amorphous are formed. For example, using (C ₂ H ₅ ) ₃ B as a boron raw material, particles containing boron are formed at 350 ° C. in a MOCVD growth furnace, and then 1
The temperature is rapidly raised to 650 ° C. at a rate of 00 ° C. to form crystal grains that make the junction boundary region with the crystal substrate amorphous. The amorphous layer existing in the region near the bonding interface with the crystal substrate is
It is possible to provide a boron phosphide-based semiconductor layer with less crystallinity and less lattice distortion and excellent crystallinity. According to an electron diffraction technique using a transmission electron microscope (TEM), it is possible to identify the presence or absence of an amorphous material in a region near a bonding interface with a crystal substrate.

The particles containing boron or phosphorus which are formed in advance on the surface of the crystal substrate act as growth nuclei, and are effective in providing a continuous boron phosphide-based semiconductor layer. In order to grow the boron phosphide-based semiconductor layer with these particles as nuclei, the temperature of the crystal substrate at the time of growing the boron phosphide-based semiconductor layer exceeds the temperature at which particles containing either boron or phosphorus are formed, It is suitable that the temperature is 1200 ° C or lower. Growing the boron phosphide-based semiconductor layer at the same temperature as that used for forming the particles is disadvantageous in that a polycrystalline boron phosphide-based semiconductor layer having a non-uniform orientation is often obtained. A preferable temperature is a temperature of 750 ° C. or higher and 1200 ° C. or lower. 12
A high temperature of more than 00 ° C. produces a multimer of boron phosphide such as B ₆ P or B _{1 3} P _2, which is inconvenient for obtaining a compositionally homogeneous boron phosphide-based semiconductor layer. As an example of the fourth embodiment of the present invention, 450 ° C. is formed on the surface of a p-type silicon single crystal.
After forming particles containing boron and phosphorus in advance, the temperature is raised to 1050 ° C. at a rate of 75 ° C./min to form a continuous film of monomeric boron phosphide (BP) by the MOCVD method. How to do.

As a means for forming a boron phosphide-based semiconductor layer using particles containing boron or phosphorus as growth nuclei, a pre-brown halogen (halogen) vapor phase epitaxy method, hydride (h) is used.
vapor deposition method, molecular beam epitaxy method,
And vapor phase growth means such as metalorganic chemical vapor deposition (MOCVD). If the particles provided on the surface of the crystal substrate and the boron phosphide-based semiconductor layer on the particles are formed by the same vapor phase growth means using the same boron raw material or the same phosphorus raw material, it is easy to configure. Becomes Especially, MOCV
The D means is a halogen vapor phase growth means (J. Appl. Phys., 42 (1), which uses chloride or bromide as a raw material.
(1971), pp. 420-424), there is an advantage that grain etching (etching) due to halogen species can be avoided. Therefore, this is a convenient method for forming the boron phosphide-based semiconductor layer without reducing the density of particles formed on the surface of the crystal substrate. As an example of the fifth embodiment of the present invention, the particles containing boron or phosphorus and the boron phosphide-based semiconductor layer are MOCV using (C ₂ H ₅ ) ₃ B as the same boron raw material.
Means for forming by the D method can be mentioned. Further, using PH ₃ as the same phosphorus material, atmospheric pressure (approximately atmospheric pressure) or reduced pressure M
Means for forming the particles and the boron phosphide-based semiconductor layer by the OCVD method can be given.

Various semiconductor devices can be formed by forming one layer of a boron phosphide-based semiconductor layer provided with particles containing boron or phosphorus as growth nuclei. For example, n-type silicon carbide (Si
C) The n-type boron phosphide-based semiconductor layer formed through the particles containing boron and phosphorus formed on the single crystal substrate can be used as a barrier (clad) layer in an LED. Further, an oxygen-doped high-resistance boron phosphide-based semiconductor layer formed through particles containing boron and phosphorus formed on the surface of an insulating sapphire (α-Al ₂ O ₃ single crystal) substrate is a field effect transistor. It can be used as a high resistance buffer layer for (FET) applications. Specifications such as the layer thickness and the resistance of the boron phosphide-based semiconductor layer provided through the particles containing boron or phosphorus are determined in consideration of the function to be performed by the layer. For example, from a boron phosphide layer of a monomer having a bandgap of about 3 eV at room temperature, if the layer thickness is adjusted, a clad layer also serving as a light emitting reflection layer capable of reflecting light emission of a specific wavelength with high reflectance. Can be configured (Japanese Patent Application 20
02-18188).

[0019]

When the boron phosphide-based semiconductor layer is vapor-deposited on the surface of the crystal substrate, particles formed beforehand on the surface of the crystal substrate and containing either boron or phosphorus are not formed in the subsequent boron phosphide-based semiconductor layer. Acts as a growth nucleus that promotes the growth of.

In particular, the particles containing boron or phosphorus, which are made of polycrystal, are excellent in crystallinity with few crystal defects regardless of the lattice mismatch between the crystal substrate and the boron phosphide-based semiconductor layer. Has the effect of

In particular, when the particles containing boron or phosphorus are formed of a polycrystal containing amorphous in the region of the bonding interface with the surface of the crystal substrate, the amorphous forms the crystal substrate and boron phosphide. The effect of alleviating the lattice mismatch with the system-based semiconductor layer and providing a boron phosphide-based semiconductor layer having excellent crystallinity.

[0022]

EXAMPLES (First Example) The present invention will be described in detail by taking as an example the case where a boron phosphide semiconductor layer is vapor-deposited after particles containing either boron or phosphorus are previously formed on a crystal substrate. Explained.

In the first embodiment, a general halogen vapor phase growth apparatus (for example, "Semiconductor / Transistor Research Group Material / Material No. SSD74-89 (19) of the Institute of Electronics and Communication Engineers")
75-03) (March 25, 1975)) was used to form particles containing boron and phosphorus on the surface of a Si single crystal substrate having a p-type {111} plane. To form the particles 102 containing boron and phosphorus, boron trichloride (BCl ₃ ) is used as a boron raw material, and phosphorus trichloride (P) is used as a phosphorus raw material.
Cl ₃ ) was used. BCl ₃ was bubbled with hydrogen gas and then supplied to the reaction furnace of the vapor phase growth apparatus. The temperature of BCl ₃ was maintained at 0 ° C., and the flow rate of the hydrogen gas for foaming accompanied with the vapor was adjusted to 15 ml (ml) per minute. PCl
The flow rate of hydrogen gas for foaming ₃ was set to 30 ml / min. These raw materials were circulated in the reaction furnace of the vapor phase growth apparatus together with the hydrogen (H ₂ ) carrier gas. The flow rate of the hydrogen carrier gas was 2 liters (l) per minute. BCl ₃ , P
Hydrogen gas accompanied by Cl ₃ vapor and carrier gas were continuously circulated for 1 minute to form particles 102 containing boron and phosphorus on the surface of the substrate 101.

Particles 1 formed under the above conditions on the surface of a substrate 101 made of Si single crystal held at 450 ° C.
A copy of the atomic force microscope image of No. 02 is shown in FIG. The particles 102 formed on the surface of the substrate 101 were analyzed to be composed of boron-enriched non-stoichiometric boron phosphide based on observation by a general cross-sectional TEM technique and an atomic force microscope. The height was about 25 nm on average. The maximum height is about 28 nm, and the minimum height is about 20 nm.
Met. Further, the horizontal cross-sectional shape of the particles 102 was substantially circular, and the diameter (particle diameter) was about 20 nm.
The existence density of the particles 102 on the surface of the substrate 101 having a diameter of 2 inches is about 10 from the surface observation by an atomic force microscope.
It was determined to be ⁷ pieces / cm ² .

After forming the particles 102, the Si single crystal substrate 101 was taken out from the halogen vapor phase growth furnace. Next, a boron phosphide layer was vapor-grown using the particles 102 as growth nuclei by MOCVD means different from the halogen vapor deposition method. FIG. 2 schematically shows the outline of the MOCVD apparatus used in the first embodiment. An introduction hole 12 for supplying a boron raw material or a phosphorus raw material for forming particles is provided at one end of the MOCVD reactor 11 of the MOCVD apparatus. A discharge hole 13 for discharging the boron raw material or the phosphorus raw material to the outside of the furnace is provided at the other end of the MOCVD reaction furnace 11 which faces the MOCVD reaction furnace 11. Further, inside the MOCVD reaction furnace 11, a substrate support 14 that can be carried in and out of the furnace is installed.

First, the substrate support 14 is provided with particles 10 on the surface.
After placing the Si single crystal substrate 101 on which No. 2 was formed, the substrate support 14 was inserted into the MOCVD reaction furnace 11. next,
The temperature of the substrate support 14 was raised from room temperature to 1050 ° C. at a slow temperature rising rate of 20 ° C. per minute by a high frequency induction heating method using a high frequency induction coil 15 arranged on the outer periphery of the MOCVD reactor 11. Then, triethylboron ((C ₂ H ₅ ) ₃ B) as a boron raw material and phosphine (PH ₃ ) as a phosphorus raw material are introduced through the introduction hole 12 together with the hydrogen (H ₂ ) carrier gas, and the MOCVD reactor 11 Distributed inside.
(C ₂ H ₅ ) ₃ B was supplied after foaming with hydrogen gas.
The temperature of (C ₂ H ₅ ) ₃ B was maintained at 25 ° C., and the flow rate of the hydrogen gas for foaming accompanied with the vapor was adjusted to 45 ml (ml) per minute. The flow rate of PH ₃ (concentration 100%) was set to 400 ml / min. The flow rate of the hydrogen carrier gas was 8 liters (l) per minute. While maintaining the internal pressure of the MOCVD reactor 11 at substantially atmospheric pressure, hydrogen gas accompanied by (C ₂ H ₅ ) ₃ B vapor, PH ₃ , and hydrogen carrier gas were continuously circulated for 8 minutes. Using the particles 102 as a growth nucleus, an undoped p-type monomer boron phosphide layer was vapor-phase grown on the Si single crystal substrate 101. The thickness of the boron phosphide layer was about 240 nm. The boron phosphide layer was a continuous film having no projection and excellent surface flatness. In addition, the carrier (hole) concentration was about 2 × 10 ¹⁹ cm ⁻³ , resulting in a low-resistance p-type boron phosphide semiconductor layer.

(Second Embodiment) In the second embodiment, polycrystalline particles are previously formed on a crystal substrate by a halogen vapor deposition method, and then a boron phosphide semiconductor layer is vapor-deposited by a MOCVD method. The content of the present invention will be described in detail by taking the case of performing it as an example.

Particles containing boron or phosphorus were formed on a Si single crystal substrate by a halogen vapor phase growth method under the condition that the temperature was different from that of the first embodiment. In the second embodiment, BCl ₃ and PCl ₃ are circulated together with the hydrogen carrier gas under the same conditions as in the first embodiment toward the surface of the Si single crystal substrate kept at room temperature of about 23 ° C. Droplets of boron raw material and phosphorus raw material were deposited on the surface. Then, the supply of the raw material into the halogen vapor phase growth apparatus was stopped, and the temperature of the substrate was raised to 650 ° C. at a temperature rising rate of 20 ° C./min to solidify the droplets. Particles solidified under these conditions have a diameter of approximately 5 as determined by common cross-sectional TEM techniques.
It was found to be a polycrystal containing boron or phosphorus having a flat and substantially spherical shape with a thickness of nm, or both. Moreover, in the measurement using an atomic force microscope, the particles were distributed approximately uniformly on the surface of the substrate having a diameter of 2 inches, with the average distance between them being about 10 nm.

However, in Auger electron analysis, the
Fine precipitates with a diameter of tens of nanometers
confirmed. The in-plane density of this precipitate is about 100
/ Cm ²It was about. In vapor phase growth according to the second embodiment
Contains boron or phosphorus as in the first embodiment.
Forming particles and boron phosphide layer by different vapor deposition methods
Particles were formed by means of halogen vapor phase growth means.
After that, take out the silicon single crystal substrate once from the outside of the device and modify it.
MOCVD reactor for vapor phase growth of boron phosphide layer
I had to put it. Therefore, the silicon single crystals that formed the particles
The crystalline substrate will be exposed to the atmosphere, at which time boron or
The precipitate is formed by the oxidation of particles containing phosphorus or phosphorus.
It was thought to be done.

Then, according to the same means as in the first embodiment, atmospheric pressure MOCVD is performed using the polycrystalline particles as growth nuclei.
A boron phosphide semiconductor layer was formed by the method. The obtained boron phosphide semiconductor layer was a continuous film with no visible cracks.

(Third Embodiment) In the third embodiment, particles containing amorphous are preliminarily formed on the crystal substrate in the region of the bonding interface with the crystal substrate, and then the boron phosphide semiconductor layer is vapor-phased. The content of the present invention will be described in detail by taking the case of growing it as an example.

By the same means as in the first embodiment, 450 ° C.
Then, a boron raw material and a phosphorus raw material were deposited on the surface of the silicon single crystal substrate. After that, the substrate temperature was rapidly raised to 1050 ° C. at a heating rate of 150 ° C. per minute. By this temperature raising operation, particles containing boron or phosphorus were formed, which made the region of the bonding interface with the silicon single crystal substrate amorphous. Then, the monomer boron phosphide semiconductor layer was vapor-grown by the same means as in the first embodiment.

FIG. 6 shows the dependence of the reflectance of the boron phosphide semiconductor layer vapor-deposited on the silicon single crystal substrate of the third embodiment on the wavelength of light. The reflectance of blue band light having a wavelength of about 450 nm is about 30% and about 33% for the boron phosphide semiconductor layers produced in the first and second embodiments, respectively.
On the other hand, in the third embodiment, the highest value reaches about 43%. From this, it was shown that the particles containing an amorphous material are effective in providing a boron phosphide layer having excellent surface flatness.

(Fourth Embodiment) In the fourth embodiment of the present invention, the case where the boron phosphide semiconductor layer is vapor-phase-grown after the particles containing amorphous are previously formed on the crystal substrate will be described. The contents of will be described more specifically.

FIG. 3 schematically shows a sectional structure of an epitaxial multilayer structure 1A according to the fourth embodiment. The same components as those shown in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted.

In the fourth embodiment, a p-type phosphorus having a layer thickness of about 240 nm and a carrier (hole) concentration of about 2 × 10 ¹⁹ cm ⁻³ , which is manufactured by the same method as the above-mentioned third embodiment. N-type Ga _0.90 In was formed on the boron bromide layer 103 at 800 ° C. using atmospheric pressure MOCVD of trimethylgallium ((CH ₃ ) ₃ Ga) / ammonia (NH ₃ ) / hydrogen (H ₂ ).
_{A 0.10} N layer was laminated as the light emitting layer 104. Light emitting layer 104
The layer thickness was set to about 65 nm, and the carrier (electron) concentration was set to about 4 × 10 ¹⁸ cm ⁻³ . The w-zurtzite crystal type Ga _0.90 In _0.10 N layer forming the light-emitting layer 104 has an a-axis lattice constant of about 3.216Å, and the underlayer zinc blende crystal type monomer boron phosphide (lattice constant). It was decided to match the lattice plane spacing (≈3.209Å) of the {110} crystal plane of ≈4.538Å).

On the light emitting layer 104, (C ₂ H ₅ ) ₃ B / P
An undoped n-type monomer boron phosphide (BP) layer 105 was laminated at 850 ° C. using H ₃ / H ₂ system atmospheric pressure MOCVD. The layer thickness of the n-type BP layer 105 is the layer thickness 1 of the p-type BP layer.
The thickness is about 240 nm, which is almost the same as 03. Carrier (electronic)
The concentration was about 8 × 10 ¹⁸ cm ^-3 .

In the fourth embodiment, in particular, the p-type boron phosphide layer 103 is vapor-grown by using particles containing amorphous as a growth nucleus, so that it becomes a continuous film and has excellent surface flatness. It was Therefore, both the light emitting layer 104 and the n-type boron phosphide layer 105, which were vapor-deposited using the same layer 103 as a base layer, were continuous films having flat mirror surfaces.

(Fifth Embodiment) In the fifth embodiment, the same boron source material and phosphorus source material are used to form both the particles on the surface of the crystal substrate and the boron phosphide semiconductor layer by MOCVD. The contents of the present invention will be specifically described by way of example.

In the fifth embodiment, the MOCV shown in FIG. 2 is used.
Using a D apparatus, particles containing boron or phosphorus containing amorphous were formed on a silicon single crystal substrate having a p-type and a (111) plane. (C ₂ H ₅ ) ₃ B was used as the boron raw material. The phosphorus raw material was PH ₃ . (C ₂ H ₅ ) ₃ B is 25 ° C
Foam the boron raw material kept at a constant temperature (Bubbling)
Through the introduction hole 12 along with the hydrogen gas for
It was supplied into the D reactor 11. The flow rate of hydrogen gas for foaming was 5 ml / min. The flow rate of PH ₃ (concentration 100%) was 400 ml / min. In addition, these raw materials are MO
The flow rate of hydrogen gas for transporting into the CVD reaction furnace 11 was 16 liters (l) per minute. Si single crystal substrate 101
At a temperature of 450 ° C., the boron raw material and the phosphorus raw material were circulated toward the surface of the substrate 101 together with the hydrogen carrier gas at the above flow rates for 1.5 minutes. From this, particles 102 containing boron and phosphorus were formed. In the surface observation by a general atomic force microscope, the average particle size of the particles 102 was measured to be about 10 nm. The surface density of the particles 102 existing on the surface of the substrate 101 was determined to be about 10 ⁸ / cm ² .

After the supply of the boron raw material into the MOCVD reaction furnace 11 is stopped, PH ₃ and the hydrogen carrier gas are circulated in the MOCVD reaction furnace 11 at the above flow rates while the substrate 1 is being supplied.
The temperature of 01 was rapidly increased from 450 ° C. to 1050 ° C. at a heating rate of 150 ° C./min. Next, in accordance with the same procedure as in the fourth embodiment, each of the p-type boron phosphide layer, the light emitting layer, and the n-type boron phosphide layer, which are the same as those in the fourth embodiment, is treated with the particles 102 as growth nuclei. Using the same MOCVD apparatus used for forming, the layers were laminated by the MOCVD method.

The surfaces of the p-type boron phosphide layer, the light emitting layer and the n-type boron phosphide layer which were vapor-phase grown through the particles 102 were all flat. If the particles and the boron phosphide-based semiconductor layer are formed by the same vapor phase growth means using the same raw material, the particles and the boron phosphide-based semiconductor layer provided therethrough are provided by different vapor phase growth means. The results teach that the boron phosphide layer having excellent surface flatness and continuity can be simply formed while avoiding complexity. In addition, in the above-mentioned first to fourth examples, the presence of the precipitates mainly composed of phosphorus oxide scattered on the surface can be almost confirmed by Auger analysis and scanning electron microscope observation of the fifth example. There wasn't.

(Sixth Embodiment) In the sixth embodiment, an LED is constructed by using a boron phosphide-based semiconductor layer vapor-phase-grown on a crystal substrate with grains containing amorphous as growth nuclei. The content of the present invention will be specifically described by taking as an example.

FIG. 4 shows a schematic plan view of an LED 1B according to the sixth embodiment. Further, FIG. 5 schematically shows the structure of the cross section of the LED 1B taken along the broken line XX ′ in FIG. In FIGS. 4 and 5, the same components as those shown in FIGS. 1 to 3 are designated by the same reference numerals and the description thereof will be omitted.

The LED 1B described in the sixth embodiment is constructed by providing an ohmic electrode on the laminated structure 1A described in the fifth embodiment. In the central portion of the surface of the n-type boron phosphide layer 105, Au.Ge/nickel (Ni) / Au in which an ohmic electrode made of a gold-germanium (Au.Ge) alloy is arranged on the side in contact with the same layer 105. The surface electrode 106 having a three-layered structure is provided. Connection pedestal (pa
d) The surface electrode 106 that also serves as an electrode has a diameter of about 120 μm.
It was a circular electrode with m. Further, an ohmic electrode made of aluminum (Al) was arranged as the back surface electrode 107 on substantially the entire back surface of the p-type Si single crystal substrate 101.
The film thickness of the Al vapor deposition film was about 2 μm. As a result, the n-type light emitting layer 104 is replaced with the p-type and n-type boron phosphide layers 103, 105.
An LED 1B having a pn junction type DH structure sandwiched between was constructed. Both p-type and n-type boron phosphide layers 103, 104
Since each of them has a bandgap of about 3 eV at room temperature, they can be effectively used as a clad layer for the light emitting layer 104.

When an operating current of 20 milliamperes (mA) was passed in the forward direction between the front surface electrode 106 and the rear surface electrode 107, the LED 1B emitted blue-violet band light having a wavelength of about 440 nm. The brightness in a chip state measured using a general integrating sphere was 9 millicandelas (mcd), and the LED 1B having high emission intensity was provided. In addition, the n-type light emitting layer 104 and the p-type boron phosphide layer 103
In both cases, since the pn junction is composed of a continuous film having excellent surface flatness, good rectification characteristics are revealed, and the forward voltage (Vf, but forward current = 20 mA) is about 3V.
The reverse voltage (VR, reverse current = 10 μA) was 5 V or more.

[0047]

According to the present invention, a method for producing a boron phosphide-based semiconductor layer in which a boron phosphide-based semiconductor layer containing boron and phosphorus as constituent elements is vapor-phase grown on a surface of a crystal substrate. For example, after previously forming particles containing either boron or phosphorus on the surface of the crystal substrate, it was decided to vapor-deposit the boron phosphide-based semiconductor layer next. This effect is effective in vapor-depositing a boron phosphide-based semiconductor layer having excellent surface flatness and continuity.

Further, according to the present invention, since the particles containing either boron or phosphorus are made of particularly polycrystal, a continuous film of a boron phosphide-based semiconductor layer excellent in surface flatness is formed. It is effective in growing the phase.

Further, according to the present invention, the particles containing either boron or phosphorus are made of a polycrystalline material containing an amorphous material in the region of the bonding interface with the surface of the crystal substrate.
Due to the action of the amorphous material which relaxes the lattice mismatch with the crystal forming the substrate, it is particularly effective in vapor-phase growing a boron phosphide-based semiconductor layer having excellent surface flatness and continuity.

Further, according to the present invention, since the boron phosphide-based semiconductor layer is formed at a substrate temperature of 1200 ° C. or lower, which is higher than the temperature at which particles containing either boron or phosphorus are formed, It is effective in vapor-phase growing a boron phosphide-based semiconductor layer having excellent crystallinity.

Further, according to the present invention, the boron phosphide-based semiconductor layer is vapor-phase grown by the same means as the same boron source material or phosphorus source material used for forming particles containing either boron or phosphorus. Therefore, it is effective in easily forming a boron phosphide-based semiconductor layer having a flat surface and excellent continuity.

Further, according to the present invention, a semiconductor element is constituted by using a boron phosphide-based semiconductor layer having excellent surface flatness and continuity brought about by the action of the particles of the present invention. , For example, p that exhibits good rectification
An n-junction can be formed, and an LED with high emission intensity that is excellent in forward and reverse voltage characteristics can be provided.

[Brief description of drawings]

FIG. 1 is a reproduction of an atomic force microscope image showing particles containing boron or phosphorus formed on the surface of a substrate according to the first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a MOCVD apparatus.

FIG. 3 is a schematic sectional view of a laminated structure according to a fourth example of the present invention.

FIG. 4 is a schematic plan view of an LED according to a sixth embodiment of the present invention.

5 is a schematic cross-sectional view taken along the broken line XX ′ of the LED shown in FIG.

FIG. 6 is a diagram showing the dependence of the reflectance of the boron phosphide layer according to the third embodiment of the present invention on the wavelength of light.

[Explanation of symbols]

1A laminated structure 1B LED 11 MOCVD reactor 12 Introduction hole 13 Discharge hole 14 Substrate support 15 High frequency induction coil 16 Boron raw material container 17 Phosphorus raw material container 101 crystal substrate 102 Particles containing boron or phosphorus 103 p-type boron phosphide layer 104 light emitting layer 105 n-type boron phosphide layer 106 surface electrode 107 Back electrode

Continued front page    F-term (reference) 4K030 AA03 AA11 AA17 BA49 BA51                       CA04 DA01 FA10 JA01 JA10                       LA14                 5F045 AA04 AB15 AC05 AC08 AC09                       AD08 AD14 AF03 BB12 CA10                       CB02 DA53 DP04 EK02                 5F052 JA07 KA01

Claims (10)

[Claims] 1. A method for producing a boron phosphide-based semiconductor layer, which comprises vapor-depositing a boron phosphide-based semiconductor layer containing boron (B) and phosphorus (P) as constituent elements on a surface of a crystal substrate. A boron phosphide-based semiconductor characterized in that particles containing either boron or phosphorus are previously formed on the surface of the crystal substrate, and then a boron phosphide-based semiconductor layer is vapor-deposited on the surface of the crystal substrate. Layer manufacturing method. 2. The method for producing a boron phosphide-based semiconductor layer according to claim 1, wherein the particles containing either boron or phosphorus have a diameter of 1 nm or more and 30 nm or less. 3. The method for producing a boron phosphide-based semiconductor layer according to claim 1, wherein the crystal substrate is made of an n-type or p-type conductive single crystal. 4. The method for producing a boron phosphide-based semiconductor layer according to claim 1, wherein the particles containing either boron or phosphorus are formed of polycrystal. . 5. A particle containing either boron or phosphorus is formed from a polycrystalline body containing an amorphous body in a region of a bonding interface with the surface of a crystal substrate. 4. The method for producing a boron phosphide-based semiconductor layer according to any one of 4 above. 6. A boron phosphide-based semiconductor layer is vapor-deposited on the surface of a crystal substrate at a temperature of 1200 ° C. or lower and above a temperature at which particles containing either boron or phosphorus are formed. The method for producing a boron phosphide-based semiconductor layer according to claim 1, wherein 7. The same vapor as used to form particles containing either boron or phosphorus using the same raw material as the boron raw material or phosphorus raw material used to form particles containing either boron or phosphorus. 7. The method for producing a boron phosphide-based semiconductor layer according to claim 1, wherein the boron phosphide-based semiconductor layer is vapor-phase grown by a phase growth means. 8. The method for producing a boron phosphide-based semiconductor layer according to claim 7, wherein the vapor phase growth means is a metal organic chemical vapor deposition (MOCVD) method. 9. A boron phosphide-based semiconductor layer produced by the method for producing a boron phosphide-based semiconductor layer according to claim 1. 10. A semiconductor device using the boron phosphide-based semiconductor layer according to claim 9.