JPH0846238A - Manufacture of semiconductor multilayered film and light-emitting diode - Google Patents

Abstract

PURPOSE:To enable using a dip method of high productivity when a second epitaxial layer is grown, by introducing a step for forming a thin film on the uppermost layer surface of a first epitaxial layer, between a step for growing a first epitaxial layer containing a P-N junction and a step for forming a second epitaxial layer. CONSTITUTION:An N type AlGaAs clad layer 12 doped with Te, an P-type AlGaAs active layer 13 doped with Zn, and a P-type AlGaAs clad layer 14 doped with Zn are formed in this order on an N-type GaAs substrate 11 by a horizontal slide board method. A wafer is taken out from a slide board, and the surface is cleaned with sulfuric acid based etching solution. The wafer is dipped in 50% hydrofluoric acid at 25 deg.C for 20 minutes. A thick film layer 15 of AlGaAs is grown in a crucible of a vertical type dip furnace. The GaAs substrate 11 is eliminated, and an Au-Ge electrode 16 is formed on the clad layer 12. A plurality of Au-Zn electrodes 17 are formed on the surface of the thick film layer 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a semiconductor multilayer film made of AlGaAs or GaAs and a method for producing a light emitting diode having an ohmic electrode formed on the semiconductor multilayer film.

[0002]

2. Description of the Related Art A GaAs / AlGaAs light emitting diode (hereinafter referred to as an LED) is used as a high power light emitting source in a space transmission system because it is excellent in temperature stability, reliability and economy. There is.

The semiconductor multilayer film used in this GaAs / AlGaAs LED generally has a structure including a first epitaxial layer including a pn junction and a relatively thick second epitaxial layer (thick film layer). . The first epitaxial layer is required to have high crystal quality and thickness uniformity because it is related to light emission characteristics. On the other hand, the thick film layer is an element for maintaining the mechanical strength of the multilayer film, only a certain thickness is required, and nonuniformity of the thickness is allowed to some extent.

As a method for producing such a semiconductor multilayer film, for example, liquid phase epitaxy (LPE) by the horizontal slide boat method (slide boat method) is useful.
The reason is that the slide boat method a) can continuously grow a plurality of epitaxial layers, b) can maintain a relatively high growth rate, and c) can grow a layer having a relatively uniform thickness. Etc. As a specific process using the slide boat method for manufacturing a semiconductor multilayer film for a high-brightness LED, there is a method disclosed in JP-A-3-234069.

[0005]

However, although a method of manufacturing a semiconductor multilayer film using only the slide boat method can provide a high quality product, it is not compatible with high productivity.
As described above, when the first epitaxial layer is grown by the slide boat method, the thickness is uniform and the first epitaxial layer having high quality can be obtained. However, since the number of wafers that can be processed in one step is limited when the slide boat method is used for the second epitaxial growth that requires a large amount of time due to the thick film, the productivity of the entire multilayer film manufacturing process is increased. Aggravate.

Further, when the second epitaxial layer is grown in a plurality of continuous epitaxial layer growth steps of the slide boat method, the growth temperature region is often restricted because it is continuous, which is sufficient. Often it is difficult to grow to different thicknesses.

Therefore, the present invention is based on p using AlGaAs.
In a method of manufacturing a semiconductor multilayer film for a high-brightness LED including a first epitaxial layer including an n-junction and a second epitaxial layer formed of AlGaAs, a method of manufacturing a semiconductor multilayer film that simultaneously satisfies high quality and high productivity is provided. Offer to,
It is an object of the present invention to provide a method for manufacturing a high-quality high-brightness LED.

[0008]

In order to realize a method for producing a semiconductor multi-layer film which can achieve the above-mentioned object, the present inventor first consists of two kinds of different semiconductor multi-layer films. I focused on being there. That is, the semiconductor multilayer film to be realized is composed of a relatively thin first epitaxial layer including a pn junction composed of a double heterojunction or a single heterojunction, and a single material serving as a supporting member for the first epitaxial layer ( Paying attention to the fact that the epitaxial layer is composed of a relatively thick second epitaxial layer (which does not have a heterostructure), it was thought that a growth method suitable for each epitaxial layer could be used.

For the growth of the first epitaxial layer, for example, the slide boat method disclosed in the above-mentioned Japanese Patent Laid-Open No. 3-234069 is suitable, and for the growth of the second epitaxial layer, for example, the dip method is used. It is believed to be more suitable to use.

Therefore, the present inventor follows this idea and
As a result of repeated experiments and trial production, it is not possible to obtain the desired result simply by continuously applying these two methods,
Good results were obtained by growing the first epitaxial layer, performing surface treatment under certain conditions, and then growing the second epitaxial layer. Here, "surface treatment under certain conditions" means to immerse the first epitaxial layer in an aqueous solution of hydrogen fluoride or an aqueous solution of sulfide. According to this method, the first epitaxial layer is A so-called passivation film was formed on the surface of, and it became possible to transfer it from a slide boat device or the like to a dip furnace or the like. The sulfide here is sodium sulfide (Na
₂ S), ammonium sulfide ((NH ₄ ) ₂ S), phosphorus sulfide (P ₂ S ₅ ) and the like. The term "passivity" as used herein means that the surface of a solid is chemically changed by the gas or liquid with which it comes into contact, so that the interface of the solid is kept chemically stable with respect to the outside.

Therefore, the method for producing a semiconductor multilayer film according to the present invention is based on AlGaAs or AlGaAs and GaAs.
A first step of growing on a GaAs substrate a first epitaxial layer including a pn junction having a single heterojunction structure or a double heterojunction structure using
Second step of forming a thin film on the uppermost layer surface by immersing the uppermost layer surface of the epitaxial layer in a hydrogen fluoride aqueous solution or a sulfide aqueous solution, and conducting the same kind of conductivity as the uppermost layer on the uppermost layer of the first epitaxial layer. It is characterized by comprising a third step of growing a second epitaxial layer made of AlGaAs having the properties of the GaAs substrate by liquid phase epitaxy and a fourth step of removing the GaAs substrate.

By the way, an aqueous sodium sulfide solution (Na ₂
S) or ammonium sulfide ((NH ₄ ) ₂ S) to form a sulfide thin film on the surface of AlGaAs, and the passivation in the atmosphere is described in V. L. Berkovit
S. et al. (“Liquid phase epitaxi
al regrowth on sulfide-passivated Ga (1-x) Al (x) A
s ", Appl. Phys. Lett. 63, 970 (1993)). Also, by immersing in an aqueous solution of hydrogen fluoride, As
An oxide film is formed, which also acts as a passivation film.
That is, these passivation films can be formed on the surface of the AlGaAs epitaxial layer to prevent oxidative erosion of AlGaAs by the atmosphere. Therefore, the AlGaAs epitaxial layer on which the passivation film is formed can be taken out of the LPE device, stored, or transferred to another LPE device. Also, the sulfide film and As oxide film are
It scatters in the atmosphere while being heated around the epitaxial growth temperature of AlGaAs. Therefore, a good-quality AlGaAs epitaxial layer can be grown on the surface of the AlGaAs epitaxial layer on which the passivation film is formed. Furthermore,
The order of steps is to grow a first epitaxial layer including a pn junction, to form a passive film on the first epitaxial layer,
The second epitaxial growth is performed in this order. According to this order, the first epitaxial layer, which requires thickness accuracy, grows first, and nothing is formed on the second epitaxial layer. Therefore, the thickness accuracy of the second epitaxial layer does not have to be high. .

Therefore, a method capable of realizing a uniform thickness, such as a slide boat method, is used for the growth of the first epitaxial layer, and the second epitaxial growth lacks uniform growth thickness. In addition, a two-step process using a method capable of processing a large number of wafers, such as a dipping method, is possible. Further, as a result, it becomes possible to set the conditions for the growth step of the first epitaxial layer and the growth conditions for the second epitaxial layer.

Further, in the method for producing a semiconductor multilayer film according to the present invention, the uppermost layer of the first epitaxial layer is made of AlGaAs having an Al composition ratio of less than 0.25, and the uppermost layer has a concentration of 5 to 5 in the second step. It may be characterized in that a thin film is formed on the uppermost layer by immersing in a 50% aqueous solution of hydrogen fluoride at a temperature of 0 to 60 ° C.

When the AlGaAs epitaxial layer is dipped in an aqueous solution of hydrogen fluoride, the surface of AlGaAs having an Al composition ratio x of less than 0.25 is heated at a temperature of 0 to 60 ° C. and a concentration of 5
A high-quality As oxide thin film is formed on the surface of this AlGaAs layer under the condition of being immersed in an aqueous solution of ˜50% hydrogen fluoride.

In the method for producing a semiconductor multilayer film according to the present invention, the first epitaxial layer is grown by liquid phase epitaxy by the slide boat method in the first step, and the second epitaxial layer is dipped in the third step. It may be characterized by growing by liquid phase epitaxy by the method.

In this case, high crystal quality and thickness uniformity are realized by growing the first epitaxial layer relating to the light emission characteristics by using the slide boat method, and a dip is applied to the growth of the second epitaxial layer. By using the method, the second epitaxial layer can be easily grown to a sufficient thickness and the productivity is improved.

Further, in the method for producing a semiconductor multilayer film according to the present invention, in the first step, the first epitaxial layer is composed of a first cladding layer, an active layer and a second cladding layer in this order from the GaAs substrate side. The Al composition ratio x of the first cladding layer, the Al composition ratio y of the active layer, and the Al composition ratio z of the second cladding layer are x> y ≧ 0 and 0.25>z>.
It may be characterized by being y.

This manufacturing method also makes it possible to easily manufacture a high-quality semiconductor multilayer film having a pn junction having a double heterojunction structure or a single heterojunction structure.

A method of manufacturing a semiconductor light emitting diode according to the present invention is a p-type semiconductor device having a single heterojunction structure or a double heterojunction structure using AlGaAs and GaAs.
The first step of growing a first epitaxial layer including an n-junction on a GaAs substrate, and immersing the uppermost layer surface of the first epitaxial layer in a hydrogen fluoride aqueous solution or a sulfide aqueous solution to form a thin film on the uppermost layer surface. A second step of forming, and a third step of growing on the uppermost layer of the first epitaxial layer a second epitaxial layer of AlGaAs having the same conductivity type as the uppermost layer by means of liquid phase epitaxy. , Removing the GaAs substrate to expose the surface of the first epitaxial layer, and forming an ohmic electrode on the surface of the first epitaxial layer and the surface of the second epitaxial layer exposed in the fourth step. And a fifth step of

By this manufacturing method, it is possible to manufacture a light emitting diode having high quality with high productivity.

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, the same reference numerals are given to elements that partially overlap.

(Example 1) Fabrication of an infrared LED having a double hetero structure including an active layer of AlGaAs.

In this embodiment, an LED having a double hetero structure composed of an n-type AlGaAs clad layer, a p-type AlGaAs active layer and a p-type AlGaAs clad layer is manufactured by the following manufacturing method.

The manufacturing method of this embodiment is as follows: (1) n-type GaA
A first epitaxial layer having a double heterostructure is grown on an s substrate by a lateral slide boat method: (2)
The surface of the epitaxial layer is immersed in hydrofluoric acid: (3) The second epitaxial layer (thick film layer) is formed thereon by the dipping method.
And (4) removing the n-type GaAs substrate and forming an ohmic electrode: (4). Hereinafter, each step will be described with reference to FIG. Figure 1 shows AlG
It is sectional drawing of an aAs multilayer film, and represents each process of a present Example.

(1) Formation of first epitaxial layer including pn junction by slide boat method (see FIGS. 1A and 1B) Si-added n-type GaAs substrate 11 shown in FIG. 1 (a)
1E, epitaxial layers 11 to 14 including a pn junction were grown thereon. That is, the n-type GaAs substrate 1
1, a Te-doped n-type AlGaAs clad layer 12 and a Zn-doped p-type AlGaAs active layer 1
3, Zn-doped p-type AlGaAs cladding layer 14
The steps of forming in order of were performed by the horizontal slide boat method. Incidentally, this pn junction is related to the Al composition ratio of each layer.
The n-type cladding layer 12 is larger than the active layer 13, and p
The type clad layer 14 has a double hetero structure in which it is larger than the active layer 13. Further, due to the subsequent hydrofluoric acid treatment, the Al composition ratio of the outermost surface of the p-type cladding layer 14 was selected to be less than 0.25.

The process of forming the first epitaxial layer will be described with reference to FIG. FIG. 2 shows a cross-sectional view of the slide boat used in this embodiment. Figure 2 (a)
Represents the arrangement of the slide boat before the epitaxial layer growth, and (b) represents the arrangement during the growth of the n-type AlGaAs cladding layer. The slide boat 20 includes an upper slide portion 21 and a lower wafer holding portion 22. Slide part 21
Is composed of a slider 26 in which three melt baths 23 to 25 for containing a melt containing an element of an epitaxial layer including a growing pn junction are opened, and a pull rod 27, which are integrally formed. Includes a wafer holder 28.
It should be noted that a reaction tube for inserting a slide boat into a hydrogen atmosphere and a heater for heating are not shown here.

According to FIG. 2A, first, the wafer 211 is set on the wafer holder 28. The composition of the melt layers 231, 241, and 251 is determined according to the growing epitaxial layer. Still referring to FIG. 1, the melt 231 containing 50 mg of Te for growing the n-type AlGaAs cladding layer 12 is contained in the first melt tank 23 and the second melt tank 24.
Zn for growing the p-type AlGaAs active layer 13 is added to
A melt 241 containing 0 mg and a melt 251 containing 50 mg of Zn for growing the p-type AlGaAs cladding layer 14 were placed in the third melt tank 25, respectively.
Regarding the Al composition ratio of each layer, each melt was prepared such that the n-type cladding layer 12 is larger than the active layer 13 and the p-type cladding layer 14 is larger than the active layer 13 and smaller than 0.25. ing. The specific composition of each of these melts is summarized in Table 1.

[0029]

[Table 1]

The entire slide boat 20 arranged as shown in FIG. 2 (a) is heated to 900 ° C. by a heater, and when the temperature is stable, the pull rod 27 is pulled in the direction of arrow 29, as shown in FIG. 2 (b). The first melt bath 23 is attached to the wafer 21
1 until the slide part 21 is completely covered with the arrow 29.
Moved in the direction of. Since the melt baths 23 to 25 do not have bottom surfaces, by sliding them to above the wafer 211, the melts 231 and 24 stored therein can be stored.
1 and 251 contact the wafer 211. After the melt 231 of the first melt tank 23 comes into contact with the wafer 211 and the slide portion stops, the n-type Al is cooled at a cooling rate of 0.5 ° C./min.
The process of growing the GaAs cladding layer 12 has begun. 8
When the temperature reached 50 ° C., the pull rod 27 moved the slide portion 21 toward the arrow again to stop the growth. The slide portion 21 is continuously moved until the entire surface of the wafer 211 comes into contact with the melt 241 of the second melt bath 24, where the slide portion 21 stops and the p-type AlGaAs active layer 13 grows, and after about 10 seconds. Again, the slide portion 21 has the third melt 251.
It moved and stopped until the entire surface of the wafer contacted. The temperature of the slide boat at this time was 850 ° C. And
After cooling to 800 ° C., the p-type AlGaAs cladding layer 14 was grown. When the temperature reached 800 ° C., the slide portion was moved to separate the third melt bath 25 from the wafer 211, and the growth of the first epitaxial layer including the pn junction was completed.

When the thickness of the epitaxial layer including the pn junction grown by this process was measured, the n-type cladding layer 12 had a thickness of 20 μm, the p-type active layer 13 had a thickness of 1 μm, and the p-type cladding layer had a thickness of 25 μm. When a 1 mm square piece was cut out from the edge of this wafer and a current was passed through it, infrared emission having a wavelength centered at 830 nm was observed at room temperature. The Al composition ratio of the p-type cladding layer 14 on the uppermost surface of the epitaxial layer including the pn junction and on which the thick film layer was grown was 0.15.

(2) Immersion in hydrofluoric acid (see FIG. 1 (b)) Next, the wafer was taken out from the slide boat, the surface was washed by sulfuric acid etching, and then the wafer was immersed in hydrofluoric acid having a concentration of 50% at 25 ° C. It was immersed for 20 minutes. At this time, the entire surface of the wafer turned brown and exhibited water repellency. Then, the wafer was taken out from the hydrofluoric acid and left to dry.

C) Formation of thick film layer (see FIG. 1 (c)) The subsequent growth of the AlGaAs thick film layer 15 is shown in FIG.
It was performed in the crucible 30 of the vertical dip furnace shown in FIG.
FIG. 3 is a vertical cross-sectional view of the vertical dip furnace, and the reaction tube and the heater are not shown in FIG. Inside the crucible 30, metal Ga is 200 g and metal Al is 400 m.
A melt 301, which is a mixture of g, 20 g of GaAs and 100 mg of Zn, was placed. The wafer 311 treated with hydrofluoric acid is placed in one of the wafer cassettes 31 with its epitaxial layer facing up. Wafer cassette 31
Are stored in the wafer cassette holder 32. Since this wafer cassette 31 has a structure in which a plurality of wafer cassettes 31 are combined with a constant distance between the cassettes, a constant space of 3 mm is secured on each wafer 311. The elevating rod 3 of the wafer cassette holder 32 until the whole wafer cassette is immersed in the melt.
When 21 is pushed down, the melt enters into the space with a thickness of 3 mm on the wafer 311, and each wafer 311 can come into contact with the melt of the same volume.

After the wafer cassette holder 32 is completely pulled up from the melt, the crucible 30 is heated to 900 ° C. to stabilize the temperature, and then the cassette holder 32 is lowered to move the wafer 31.
All 1 were immersed in the melt. Then, the growth was started at a cooling rate of 0.1 ° C./minute, and when the temperature reached 800 ° C., the cassette holder was pulled up to complete the growth. After the wafer was cooled to room temperature, the thickness of the thick film layer 15 formed was measured to be 100 to 120 μm, that is, the in-plane thickness variation was 20 μm. When an epitaxial layer including a pn junction is grown on this by using the lateral slide boat method, this variation is too large and causes a problem. However, in the present invention, an epitaxial layer including a pn junction is grown on the thick film layer 15. do not do. On the other hand, the thick film layer itself having this variation is within the allowable range for forming an electrode on the thick film layer and utilizing it in an LED. Therefore, the thickness variation of 20 μm has no problem for the quality of the LED.

(4) Fabrication of LED by removing GaAs substrate and forming electrodes (see FIGS. 1 (d) and 1 (e)) The epitaxial surface of this wafer is protected and a mixed solution of ammonia water and hydrogen peroxide water is prepared. After removing the GaAs substrate 11 by means of, the Au-Ge electrode 16 having a diameter of 150 μm is formed on the surface of the n-type cladding layer 12, and Au-Zn having a diameter of 80 μm is formed.
Several 17 electrodes were formed on the surface of the thick film layer 15. Then, the wafer was cut into 400 μm squares centering on the Au—Ge electrode 16 and assembled on a stem (not shown) to fabricate an LED. Since attachment to the stem is performed with the electrode 17 facing down, FIG. 1 (e) shows the order of the epitaxial layers as shown in FIG. 1 (b).
(D) are shown upside down. The LED produced by this example emitted infrared light having a wavelength centered at 830 nm at room temperature.

In the step (2) of dipping in hydrofluoric acid,
After drying the wafer and leaving it in the air for several days,
A thick film layer was formed by performing the step (3) in the same manner, but the thickness of the thick film layer at that time was also 100 to 120 μm, and an LED similarly manufactured using the thick film layer had a thickness of 83 at room temperature.
Infrared light having a wavelength centered at 0 nm was emitted. Therefore, it was shown that the protection of the surface by the As oxide film against the atmosphere is effective for at least several days.

(Example 2) Infrared L having a double hetero structure including an AlGaAs cladding layer and a GaAs active layer
Preparation of ED).

An infrared LED having a double heterostructure including an active layer of GaAs was also manufactured by the same method as in Example 1. This LED has an n-type AlGaAs clad layer, p
A multi-layered film having a double hetero structure composed of a p-type GaAs active layer and a p-type AlGaAs clad layer was used. The process will be described below with reference to FIG. FIG. 4 is a cross-sectional view of the semiconductor multilayer film of this example, showing the steps of this example. In addition, in order to avoid duplication of description, the description of the steps overlapping with those of the first embodiment is omitted in the description of the present embodiment.

Using the slide boat shown in FIG. 2, under the same method and temperature conditions as in Example 1, the n-type AlGaAs cladding layer 12 with a thickness of 20 μm and the p-type with a thickness of 1 μm were formed on the n-type GaAs substrate 11. GaAs active layer 43, thickness 25
An epitaxial layer including a pn junction was grown in the order of the μm p-type AlGaAs cladding layer 14. Each melt tank and growth conditions are as shown in Table 2.

[0040]

[Table 2]

Next, the wafer was taken out from the slide boat, the surface thereof was washed by sulfuric acid etching, then immersed in hydrofluoric acid having a concentration of 50% for 20 minutes at room temperature, and then taken out from the hydrofluoric acid and dried.

Thereafter, as in Example 1, the wafer was transferred to the crucible of the vertical dip furnace shown in FIG. 3, the wafer was dipped in the melt having the composition shown in Table 2, and the thickness varied from 100 to 120 μm. An AlGaAs thick film layer 15 was grown. Then, after forming the electrodes 16 and 17, the electrodes were mounted on a stem (not shown) to form an LED. This LED is
Infrared light with a wavelength centered at 890 nm was emitted.

Example 3 Fabrication of LED Having Single Hetero Structure Including AlGaAs Active Layer).

In this embodiment, a method for manufacturing an LED having a single hetero structure according to the present invention will be illustrated.

Also in the manufacturing method of this embodiment, the slide boat shown in FIG. 2 and the vertical dip furnace shown in FIG. 3 are used to (1) laterally slide an epitaxial layer having a single hetero structure on an n-type GaAs substrate. Growth by boat method: (2) Immersion of epitaxial layer surface including pn junction in hydrofluoric acid: (3) Growth of thick film layer thereon by dipping method: (4) Removal of GaAs substrate and ohmic electrode Forming: consisted of 4 steps. The process of this embodiment will be described below with reference to FIG. Figure 5
[FIG. 6B] is a cross-sectional view of the semiconductor multilayer film of the present embodiment, which shows the process of the present embodiment.

(1) Formation of Epitaxial Layer Including pn Junction (See FIG. 5B) In this example, only two melt boats 23 and 24 were used for the slide boat shown in FIG. Melt 2 at this time
The compositions of 31 and 241 are summarized in Table 3.

[0047]

[Table 3]

After the slide boat was heated and stabilized at 900 ° C., the melt 231 was moved onto the wafer and the n-type AlGa was formed on the n-type GaAs substrate 11 at a cooling rate of 1.0 ° C./min.
The As layer 52 was grown. When the temperature reached 850 ° C., the slider was moved to separate the wafer from the melt 231 to separate the n-type A.
The growth of the 1GaAs layer 52 is stopped, the melt 241 is moved onto the wafer, and p is reached at the same cooling rate until 750 ° C. is reached.
Type AlGaAs53 was grown. Formed n-type AlG
The thickness of the aAs layer 52 is 20 μm, and the p-type AlGaAs 53 is
Had a thickness of 40 μm. The Al composition ratio of the p-type AlGaAs layer 53, which is the uppermost surface of the epitaxial layer including the pn junction and on which the thick film layer is grown, was 0.20.

(2) Immersion in hydrofluoric acid Next, this wafer was taken out from the slide boat, the surface was cleaned by sulfuric acid etching, and then immersed in hydrofluoric acid having a concentration of 50% for 20 minutes at room temperature. Then, the wafer was taken out from the hydrofluoric acid and dried.

(3) Formation of Thick Film Layer (Refer to FIG. 5C) The growth of the p-type AlGaAs thick film layer 55 performed subsequently is as follows.
It was carried out in the crucible 30 of the vertical dip furnace shown in FIG. The composition of the melt inside the crucible 30 is 10 Ga.
0g, metal Al 250mg, GaAs 15g and Z
n was 100 mg. With the wafer cassette holder 32 completely lifted from the melt, the crucible 30 is heated to 950 ° C.
After the temperature was stabilized by heating to 0.degree. C., the cassette holder 32 was lowered, the whole wafer was immersed in the melt, and when the temperature reached 920.degree. C., the cassette holder was pulled up to complete the growth. The p-type AlGaAs thick film layer 55 thus formed had a thickness of 40 μm.

(4) Fabrication of LED by removing GaAs substrate and forming electrodes (see FIGS. 5 (d) and 5 (e)) The epitaxial surface of this wafer is protected and a mixed solution of ammonia water and hydrogen peroxide solution is prepared. After removing the GaAs substrate 11 by, the Au—Ge electrode 16 was formed on the surface of the n-type AlGaAs layer 52, and several 17 Au—Zn electrodes were formed on the surface of the thick film layer 55. Then, the Au-Ge electrode 16 was cut into a square having a size of 400 μm and assembled on a stem (not shown) to manufacture an LED. LE manufactured by this example
D emitted infrared light having a wavelength centered at 720 nm at room temperature.

In the step (1) of forming an epitaxial layer including a pn junction, a p-type AlGaAs layer is grown at a temperature of 850 ° C. using a melt having the same composition.
When the epitaxial layer having a single hetero structure manufactured under the cooling condition of stopping at ℃ was immersed in the above-mentioned hydrofluoric acid, the wafer was etched in the hydrofluoric acid and was not chemically stable. At this time, p-type AlGa before immersion
The Al composition ratio on the surface of the As layer was 0.25.

The present invention is not limited to the three embodiments described above, and modifications thereof are possible. For example, instead of immersing the uppermost surface of the first epitaxial layer in hydrofluoric acid, sodium sulfide (Na ₂ S), ammonium sulfide ((NH ₄ ) ₂ S ₂ ), phosphorus sulfide (P 2
_{The same} passivation film may be formed by immersing the uppermost surface of the first epitaxial layer in an aqueous solution of sulfide such as ₂ S ₅ ). In addition to the LPE by the slide boat method, the MOCVD method or the like may be used for the growth of the first epitaxial layer.
A method having good thickness controllability and capable of growing a multilayer film can be applied.

[0054]

As described above, in the method of manufacturing a semiconductor multilayer film according to the present invention, in the growing step, a step of growing a first epitaxial layer including a pn junction and a step of growing a second epitaxial layer are included. A highly productive dipping method is used to grow the second epitaxial layer by adopting the order of performing sequentially and introducing a step of forming a thin film on the uppermost surface of the first epitaxial layer between the two steps. It became possible to do. Therefore, the semiconductor multilayer including the two-step growth process using the lateral slide boat method or the like for the growth of the first epitaxial layer relating to the light emission characteristics and the dip method with high processing capacity for the growth of the second epitaxial layer. A method of making a membrane is provided.
As a result, a high-quality semiconductor multilayer film is manufactured with high productivity, and an LED using the semiconductor multilayer film is manufactured.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a semiconductor multilayer film manufactured according to a first example.

FIG. 2 is a vertical sectional view of a slide boat used in the present invention.

FIG. 3 is a vertical cross-sectional view of a vertical dip furnace used in the present invention.

FIG. 4 is a vertical cross-sectional view of a semiconductor multilayer film manufactured according to Example 2.

5 is a vertical cross-sectional view of a semiconductor multilayer film manufactured according to Example 3. FIG.

[Explanation of symbols]

11 ... n-type GaAs substrate, 12 ... n-type AlGaAs cladding layer, 13 ... p-type AlGaAs active layer, 14 ... p-type A
1-GaAs clad layer, 15 ... p-type AlGaAs thick film layer, 16 ... Au-Ge electrode, 17 ... Au-Zn electrode, 2
0 ... Slide boat, 21 ... Slide part, 22 ... Wafer holding part, 23, 24, 25 ... Melt bath, 26 ... Slider,
27 ... Pull bar, 28 ... Wafer holder, 29 ... Arrow,
30 ... Crucible, 31 ... Wafer cassette, 32 ... Wafer cassette holder, 43 ... P-type GaAs active layer, 52 ... N-type AlGaAs layer, 53 ... P-type AlGaAs layer, 54 ... P
Type AlGaAs thick film layer, 211 ... Wafer, 231, ... First melt, 241 ... Second melt, 251 ... Third melt, 3
01 ... Melt liquid, 311 ... Wafer, 321 ... Elevating rod.

Claims (5)

[Claims] 1. AlGaAs or AlGaAs and G
a first step of growing on a GaAs substrate a first epitaxial layer including a pn junction having a single heterojunction structure or a double heterojunction structure using aAs; and fluorinating the uppermost surface of the first epitaxial layer. A second step of forming a thin film on the surface of the uppermost layer by immersing it in an aqueous solution of hydrogen or an aqueous solution of sulfide, and consisting of AlGaAs having the same conductivity type as the uppermost layer on the uppermost layer of the first epitaxial layer. Second
3. A method for producing a semiconductor multilayer film, comprising: a third step of growing the epitaxial layer by liquid phase epitaxy; and a fourth step of removing the GaAs substrate. 2. The uppermost layer of the first epitaxial layer is made of AlGaAs having an Al composition ratio of less than 0.25, and in the second step, the uppermost layer is an aqueous solution of hydrogen fluoride having a concentration of 5 to 50%. The method for producing a semiconductor multi-layer film according to claim 1, wherein the thin film is formed on the uppermost layer by immersing it in a temperature of 0 to 60 ° C. 3. The first epitaxial layer is grown by liquid phase epitaxy by a slide boat method in the first step, and the second epitaxial layer is grown by liquid phase epitaxy by a dip method in the third step. The method for producing a semiconductor multilayer film according to claim 1, wherein 4. The first step in the first step
The epitaxial layer is composed of a first clad layer, an active layer, and a second clad layer in this order from the GaAs substrate side. The Al composition ratio x of the first clad layer, the Al composition ratio y of the active layer, and the 2 Al composition ratio z of the clad layer
The method of manufacturing a semiconductor multilayer film according to claim 1, wherein x> y ≧ 0 and 0.25>z> y. 5. A first epitaxial layer including a pn junction having a single heterojunction structure or a double heterojunction structure using AlGaAs and GaAs is formed of GaAs.
A first step of growing on the substrate; a second step of immersing the uppermost layer surface of the first epitaxial layer in an aqueous solution of hydrogen fluoride or an aqueous sulfide solution to form a thin film on the uppermost layer surface; A second epitaxial layer on top of the top layer of AlGaAs having the same conductivity type as the top layer;
A third step of growing the epitaxial layer using liquid phase epitaxy, a fourth step of removing the GaAs substrate to expose the surface of the first epitaxial layer, and a step of exposing the fourth epitaxial layer A fifth step of forming ohmic electrodes on the surface of the first epitaxial layer and the surface of the second epitaxial layer, respectively.