JP4019133B2 - Liquid phase epitaxial growth method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid phase epitaxial growth method and apparatus used in manufacturing a semiconductor element such as a light emitting diode (LED), a light emitting diode wafer, and a light emitting diode.
[0002]
[Prior art]
10 is a longitudinal sectional view of a conventional liquid phase epitaxial growth apparatus, and FIG. 11 is a sectional view taken along line XI-XI in FIG. In these drawings, a growth chamber 2 is formed in the growth container 1, and a large number of substrate holding plates 101 and substrates 110 are held and stored by two substrate holding bars 21a and 21b. In addition, a raw material container 3 is provided on the top of the growth container 1 so as to be able to slide closely on the upper surface. A raw material introduction port 2a for introducing a liquid raw material is formed in the ceiling portion of the growth chamber 2, and a raw material discharge port 2b is formed at the bottom thereof. The material discharge port 2b is configured to be opened and closed by a shutter 4.
[0003]
Furthermore, the raw material container 3 has three independent raw material storage chambers 31, 32, and 33. The bottoms of the raw material containers 3 are opened to form raw material supply ports 31 a, 32 a, and 33 a, and are always upper parts of the growth container 1. When the raw material container 3 is moved and the raw material supply ports 31a, 32a, 33a coincide with the raw material introduction port 2a of the growth chamber, the respective raw material storage chambers are closed. The liquid raw material is supplied into the growth chamber 2.
[0004]
Moreover, the upper part of each raw material storage chamber is opened, and raw material supply ports 31b, 32b, 33b are formed, and lid bodies 31c, 32c, 33c that can be freely opened and closed are respectively attached thereto. The growth vessel 1 and the raw material vessel 3 are installed in a furnace core tube made of quartz or the like (not shown), and the furnace core tube is accommodated in a heat treatment furnace. Furthermore, the growth vessel 1 and the raw material vessel 3 are provided with a temperature control device (not shown) for setting them to a predetermined temperature as necessary.
[0005]
For example, when an AlGaAs double heterostructure light emitting diode is manufactured using a GaAs wafer as the substrate 110 and Ga, GaAs, Al, and impurities (Zn, Mg, Te, etc.) as raw materials by the above-described apparatus, Follow the procedure. First, Ga (liquid at 30 ° C. or higher), GaAs (solid), Al (solid), and impurities (Zn, Mg, Te, etc. → solid) are charged into the raw material storage chambers 31, 32, 33. In this case, a raw material for the P-type cladding layer (added with Zn or Mg as an impurity) is stored in the raw material storage chamber 31, a raw material for the P-type active layer is stored in the raw material storage chamber 32, and an N The raw material for the mold cladding layer (added with Te or the like as an impurity) is introduced.
[0006]
Next, the inside of the furnace core tube is set to a predetermined temperature and atmosphere. When the temperature of the raw material container 3 reaches a predetermined temperature, the liquid material is introduced into the growth chamber by moving the raw material supply port 31a and the raw material introduction port 2a of the growth chamber to coincide. Next, the temperature of the growth vessel 1 is lowered, and a P-type cladding layer is epitaxially grown on the GaAs wafer. When the growth is completed, the shutter 4 is opened to discharge the unnecessary liquid raw material, and then the shutter 4 is closed. Similarly, liquid raw materials in the raw material storage chambers 32 and 33 are sequentially introduced into the growth chamber 2 and epitaxially grown to obtain an AlGaAs double heterostructure light emitting diode.
[0007]
[Problems to be solved by the invention]
However, it has been found that the conventional apparatus described above has the following drawbacks.
(1) In the raw material storage chamber, solid GaAs, Al, and impurities (solute) are dissolved in a Ga solution (solvent) at a predetermined ratio to form a liquid raw material having a predetermined composition. In some cases, the composition ratio differs between the lower portion and the lower portion. That is, the solute concentration may be low at the bottom of the liquid raw material. In that case, a liquid raw material having a low solute concentration is first introduced into the growth chamber, and a part of the substrate is instantaneously dissolved, which may hinder good epitaxial growth.
[0008]
(2) When introducing a liquid raw material from the raw material storage chamber into the growth chamber, the liquid raw material may scatter and adhere to the substrate surface before the liquid raw material fills the entire growth chamber. Thus, abnormal growth is likely to occur at the previously attached portion, which may hinder high-quality epitaxial growth.
(3) When a P-type cladding layer, a P-type active layer and an N-type cladding layer are sequentially grown on the surface of the substrate, a liquid material in which liquid materials for forming each layer are mixed at the boundary between the layers. As a result, a grown layer may be formed, and a desired grown layer may not be obtained. In particular, if such a layer is formed at the interface between the P-type active layer and the N-type clad layer that become the light emitting part, the characteristics of the light emitting diode may be greatly affected. There is also a risk of causing abnormalities.
[0009]
According to the studies by the present inventors, the cause of the above (1) is that the specific gravity of solid GaAs, Al and impurities (solute) is smaller than the specific gravity of Ga solution (solvent). For this reason, as shown in FIG. 12, it turned out that the solute floated on the upper part of the liquid raw material, and this resulted in a portion having a low solute concentration at the lower part of the liquid raw material.
[0010]
As for the above item (2), the material introduction port 2a formed in the ceiling of the growth chamber 2 is larger than necessary, and the substrate is also disposed at the site where the liquid material falls. It turned out to be the cause.
[0011]
Furthermore, it was found that the above point (3) was caused by the fact that the liquid raw material forming the previous layer was not sufficiently discharged. That is, it was found that the size of the material discharge port 2b is insufficient and the shape thereof has a problem.
[0012]
The present invention has been made based on the above-mentioned elucidation results, and a liquid phase epitaxial growth method and apparatus capable of growing a good quality epitaxial layer with good reproducibility, and a light emitting diode manufactured using the method and apparatus. It is an object to provide a wafer and a light emitting diode.
[0013]
[Means for Solving the Problems]
As means for solving the above problems, the first invention provides:
Liquid phase epitaxial growth in which a liquid material is supplied from a raw material container containing a liquid raw material to a growth container containing a substrate in a processing region set to a predetermined processing condition, and crystals of the raw material material are epitaxially grown on the surface of the substrate. In the method
In the liquid phase epitaxial growth method, the solid raw material floating in the liquid raw material in the raw material container is buried in the liquid raw material by the solid raw material burying means.
[0014]
The second invention is
In the liquid phase epitaxial growth method according to the first invention,
The liquid phase epitaxial growth method, wherein the raw material contains Ga, As, and Al, and the substrate is a GaAs wafer.
[0015]
The third invention is
A growth container in which a substrate is stored; and a raw material container disposed above the growth container, and the liquid raw material stored in the raw material container is controlled in the growth container while controlling the temperature of the raw material container and the growth container. In a liquid phase epitaxial growth apparatus for epitaxially growing raw material crystals on the substrate surface by supplying to
A liquid phase epitaxial growth apparatus comprising a solid material burying apparatus for burying a solid material floating in a liquid material in the material container in the liquid material.
[0016]
The fourth invention is:
In the liquid phase epitaxial growth apparatus according to the third invention,
The solid material burying apparatus includes a network that allows only a liquid material to pass through without passing through the solid material, and the solid material is liquidized by the network by burying the network in the liquid material. A liquid phase epitaxial growth apparatus characterized by being buried in the inside.
[0017]
The fifth invention is:
In the liquid phase epitaxial growth apparatus according to the third or fourth invention,
The growth vessel has a growth chamber in which a large number of substrates are set up substantially vertically and stored in parallel with a predetermined distance from each other, and a liquid material is introduced into the ceiling of the growth chamber. The raw material introduction port is formed with a raw material discharge port for discharging the liquid raw material at the bottom,
The raw material container is installed on the upper part of the growth container so that the bottom part thereof can be slid closely on the upper surface, and has a plurality of independent raw material storage chambers. The bottom of the chamber is opened and used as a raw material supply port, which is normally blocked by being in contact with the upper surface of the growth vessel. The raw material supply port and the raw material in the growth chamber are moved by moving the raw material vessel. The liquid phase epitaxial growth apparatus is characterized in that the liquid source in the source chamber is supplied to the growth chamber when the inlet coincides.
[0018]
The sixth invention is:
A growth container in which a substrate is stored; and a raw material container disposed above the growth container, and the liquid raw material stored in the raw material container is controlled in the growth container while controlling the temperature of the raw material container and the growth container. A liquid phase epitaxial growth apparatus for epitaxially growing a raw material crystal on the substrate surface,
The growth vessel has a growth chamber in which a large number of substrates are set up substantially vertically and stored in parallel with a predetermined distance from each other, and a liquid material is introduced into the ceiling of the growth chamber. The raw material introduction port is formed with a raw material discharge port for discharging the liquid raw material at the bottom,
The raw material container is installed on the upper part of the growth container so that the bottom part thereof can be slid closely on the upper surface, and has a plurality of independent raw material storage chambers. The bottom of the chamber is opened and used as a raw material supply port, which is normally blocked by being in contact with the upper surface of the growth vessel. The raw material supply port and the raw material in the growth chamber are moved by moving the raw material vessel. In the liquid phase epitaxial growth apparatus that supplies liquid raw material in the raw material storage chamber to the growth chamber when the inlet coincides with the inlet,
The growth chamber is a liquid phase epitaxial growth characterized in that a substrate is not disposed immediately below the introduction port so that the material introduced from the material introduction port does not directly contact the substrate during the introduction. Device.
[0019]
The seventh invention
In the liquid phase epitaxial growth apparatus according to the fifth or sixth invention,
In the liquid phase epitaxial growth apparatus, the raw material inlet of the growth chamber is formed in an elongated slit shape along a direction parallel to the main surface of the substrate disposed in the growth chamber.
[0020]
The eighth invention
In the liquid phase epitaxial growth apparatus according to any one of the fifth to seventh inventions,
In the liquid phase epitaxial growth apparatus, the material discharge port of the growth chamber has a structure in which 1/3 or more of the bottom of the growth chamber is opened.
[0021]
The ninth invention
A light emitting diode wafer comprising a plurality of semiconductor layers containing Ga and As as constituent elements formed on a GaAs wafer by sequential epitaxial growth,
The plurality of semiconductor layers are formed using the liquid phase epitaxial manufacturing method according to the first or second invention and / or the liquid phase epitaxial manufacturing apparatus according to any of the third to eighth inventions. This is a light emitting diode wafer.
[0022]
The tenth invention is
A light emitting diode characterized in that the light emitting diode wafer according to the ninth invention is cut and formed into a chip shape.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
1 is a longitudinal sectional view of a liquid phase epitaxial growth apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is a sectional view taken along line III-III in FIG. FIG. 5 is a cross-sectional view taken along line V-V in FIG. 1, FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 1, and FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. A liquid phase epitaxial growth method and apparatus according to embodiments of the present invention will be described below with reference to these drawings. Since the liquid phase epitaxial growth apparatus according to the present embodiment has many parts in common with the conventional apparatus shown in FIG. 10, the same reference numerals are given to the common parts, and a part of the detailed description is provided. The description is omitted.
[0024]
In the drawing, a growth chamber 2 is formed in the growth vessel 1, and a plurality of substrate holding plates 101 and two substrate holding plates 102 are held in the growth chamber 2 together with a number of substrates 110. It is held and stored by the bars 201a and 201b.
[0025]
The substrate holding plate 102 is configured so that the surfaces on which the wafer 110 is not held are opposed to each other, and the gap between each other is made larger than the gap between the other holding plates. It is held by the substrate holding rods 201a and 201b so as to be positioned directly below. Thereby, when the liquid material is introduced, the scattered material of the liquid material is prevented from directly adhering to the wafer.
[0026]
A raw material introduction port 2a for introducing a liquid raw material is formed in the ceiling portion of the growth chamber 2, and a raw material discharge port 2b is formed at the bottom thereof. The raw material introduction port 2 a has a slit-like opening (cross-sectional shape of the introduction port) whose major axis is substantially parallel to the surface of the substrate holding plate 101. In this embodiment, the size of the opening is 8 mm wide and 25 mm long. The shape of the opening may be elliptical. By making the slit shape, the introduction of the raw material is performed relatively slowly, and the introduced raw material is prevented from coming into direct contact with the wafer and the scattered raw material is not attached to the wafer.
[0027]
The material discharge port 2b is formed large at the bottom of the growth chamber 2 so as to be released over almost half of the growth chamber. In addition, it is desirable that the size of the material discharge port 2b is 1/3 or more of the bottom of the growth chamber so that the used material can be quickly and completely discharged. The material discharge port 2b is configured to be freely opened and closed by a shutter 4. When the epitaxial growth is performed, the shutter 4 seals the growth chamber 2 as shown in FIGS. 1 and 2.
[0028]
Further, when the raw material after the epitaxial growth is discharged, it is moved in the direction indicated by the arrow in FIG. 1, and the lower portion of the growth chamber 2 is released over almost half of the growth chamber. 7 is a cross-sectional view taken along line VII-VII in FIG. 2 with the shutter 4 closed, FIG. 8 is a cross-sectional view taken along line II in FIG. 2 with the shutter 4 opened, and FIG. It is the VII-VII sectional view taken on the line in FIG.
[0029]
The shutter 4 moves from the position shown in FIGS. 1 and 7 along the guide columns 11 and 12 fixed in the growth vessel 1, and is set to the position shown in FIGS. As shown in FIG. 7 and FIG. 9, the shutter 4 releases the entire opening of the raw material discharge port 2 b (the lower half of the growth chamber 2) at the raw material discharge position, and can discharge the raw material very quickly and completely. It is like that.
[0030]
A raw material container 3 is provided on the upper part of the growth container 1 so as to be able to slide closely on the upper surface. The raw material container 3 has three independent raw material storage chambers 31, 32, 33, and the bottoms thereof are opened to form raw material supply ports 31 a, 32 a, 33 a, which are always on the upper surface of the growth container 1. When the raw material container 3 is moved and the raw material supply ports 31a, 32a, 33a coincide with the raw material introduction port 2a of the growth chamber, the liquid in each raw material storage chamber is closed. The raw material is supplied into the growth chamber 2.
[0031]
Moreover, the upper part of each raw material storage chamber is opened, and raw material supply ports 31b, 32b, 33b are formed, and lid bodies 31c, 32c, 33c that can be freely opened and closed are respectively attached thereto. Two support rods 31d, 32d, and 33d are attached to the inner surfaces of the lids 31c, 32c, and 33c at substantially right angles, respectively. A mesh 31e is fixed to the tip of the support bar 31d. The net 31e sinks a solid raw material 51 floating in the liquid raw material 5 below the liquid raw material. Therefore, the fineness of the mesh may be a size that does not allow most of the solid raw material 51 to pass through. Instead of the net 31e, another member having the same function, for example, a carbon plate formed with a large number of through holes may be used.
[0032]
The growth vessel 1 and the raw material vessel 3 are installed in a furnace core tube made of quartz or the like (not shown), and the furnace core tube is accommodated in a heat treatment furnace. Furthermore, the growth vessel 1 and the raw material vessel 3 are provided with a temperature control device (not shown) for setting them to a predetermined temperature as necessary. The material constituting the growth vessel 1 and the raw material vessel 3 can be a material to which the liquid raw material 5 does not adhere and does not react, for example, carbon or p-BN (spotted boron nitride). .
[0033]
For example, when an AlGaAs double heterostructure light emitting diode is manufactured by using the above-described apparatus using a GaAs wafer as the wafer 110 and using Ga, GaAs, Al, and impurities (Zn, Mg, Te, etc.) as raw materials, Follow the procedure. First, Ga (liquid at 30 ° C. or higher), GaAs (solid), Al (solid), and impurities (Zn, Mg, Te, etc. → solid) are charged into the raw material storage chambers 31, 32, 33. In this case, a raw material for the P-type cladding layer (added with Zn or Mg as an impurity) is stored in the raw material storage chamber 31, a raw material for the P-type active layer is stored in the raw material storage chamber 32, and an N The raw material for the mold cladding layer (added with Te or the like as an impurity) is introduced. Next, the lids 31 c, 32 c and 33 c are used so that the solid raw material 51 is held below the liquid raw material 5.
[0034]
Next, the furnace core tube is held at 920 ° C. for 1 hour. Next, the raw material container 3 is moved so that the raw material supply port 31a is aligned with the raw material introduction port 2a of the growth chamber, and the liquid raw material is introduced into the growth chamber in about 20 seconds. Next, the temperature of the growth vessel 1 is lowered at a rate of 0.1 to 2.0 ° C./min, and a P-type cladding layer is epitaxially grown on the GaAs wafer. When the growth is completed, the shutter 4 is opened to discharge the unnecessary liquid raw material, and then the shutter 4 is closed. Similarly, liquid raw materials in the raw material storage chambers 32 and 33 are sequentially introduced into the growth chamber 2 and epitaxially grown to obtain an AlGaAs double heterostructure light emitting diode wafer.
[0035]
Next, the AlGaAs double heterostructure light emitting diode wafer thus obtained is cut into chips having a size of 0.3 to 0.5 mm square to obtain an AlGaAs double heterostructure light emitting diode. In practice, this chip-like light emitting diode is mounted on a predetermined mounting base or the like to be finished into a light emitting diode product.
[0036]
According to the apparatus and method according to the above-described embodiment, the concentration of the liquid raw material in the raw material storage chamber can be kept extremely uniform, and a part of the wafer is dissolved when the liquid raw material is introduced into the growth chamber. In addition, it has been confirmed that the scattered material does not adhere to the wafer, and that the material is discharged almost completely after the epitaxial growth is completed. This makes it possible to grow a good quality epitaxial layer with good reproducibility.
[0037]
In the above-described embodiment, the raw material introduction port is located at the intermediate portion of the two substrate holding plates 102 so that the scattered material of the liquid raw material does not directly adhere to the wafer when the liquid raw material is introduced. However, the raw material introduction port may be located at any end of the growth chamber so that the scattered material of the liquid raw material does not directly adhere to the wafer.
[0038]
【The invention's effect】
As described above, in the present invention, the solid raw material floating in the liquid raw material in the raw material container is buried in the liquid raw material by the solid raw material burying means, and the raw material introduced into the growth chamber is in the middle of introduction. Do not place the substrate directly under the inlet so that it does not directly contact the substrate. Furthermore, the raw material discharge port of the growth chamber is made more than 1/3 of the bottom of the growth chamber so that the used raw material is quickly As a result, it is possible to grow a high-quality epitaxial layer with high reproducibility.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a liquid phase epitaxial growth apparatus according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line II-II in FIG.
3 is a cross-sectional view taken along line III-III in FIG.
4 is a cross-sectional view taken along line IV-IV in FIG.
FIG. 5 is a cross-sectional view taken along line VV in FIG.
6 is a cross-sectional view taken along line VI-VI in FIG.
7 is a cross-sectional view taken along line VII-VII in FIG. 2 in a state where the shutter 4 is closed.
8 is a cross-sectional view taken along the line II in FIG. 2 with the shutter 4 open.
9 is a cross-sectional view taken along the line VII-VII in FIG. 2 in a state where the shutter 4 is open.
FIG. 10 is a longitudinal sectional view of a conventional liquid phase epitaxial growth apparatus.
11 is a cross-sectional view taken along line XI-XI in FIG.
FIG. 12 is an explanatory diagram of a conventional liquid phase epitaxial growth apparatus.

Claims (3)

A growth container in which a substrate is stored; and a raw material container disposed above the growth container, and the liquid raw material stored in the raw material container is controlled in the growth container while controlling the temperature of the raw material container and the growth container. A liquid phase epitaxial growth apparatus for epitaxially growing a raw material crystal on the substrate surface,
A solid material burying device for burying the solid material floating in the liquid material in the material container in the liquid material;
The growth vessel has a growth chamber in which a large number of substrates are erected substantially vertically and stored in parallel with a predetermined distance from each other, and a liquid raw material is introduced into the ceiling of the growth chamber. The raw material introduction port to be formed is formed,
The raw material inlet of the growth chamber has an elongated slit shape along a direction parallel to the main surface of the substrate disposed in the growth chamber,
The substrates arranged in the growth chamber are held by a large number of substrate holding plates arranged at a distance from each other, and on the opposing surfaces of two of the large number of substrate holding plates. The substrate is not held, and the center of the gap between the two substrate holding plates is located directly below the raw material introduction port, so that the substrate is disposed immediately below the raw material introduction port. A liquid phase epitaxial growth apparatus characterized by not being formed. A liquid phase epitaxial growth method using the liquid phase epitaxial growth apparatus according to claim 1,
In the raw material container, after burying the solid raw material floating in the liquid raw material in the liquid raw material,
When introducing the liquid material from the material container into the growth chamber, the liquid material is not directly brought into contact with the substrate during the introduction,
A liquid phase epitaxial growth method characterized in that when the raw material is discharged, the shutter is moved and released over the lower half of the growth chamber for discharge.   3. The liquid phase epitaxial growth method according to claim 2, wherein the raw material contains Ga, As, and Al, and the substrate is a GaAs wafer.

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