JPS6026080B2 - Liquid phase epitaxial growth method - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for liquid phase epitaxial growth of a semiconductor layer for a Ga-As light emitting diode. Recently, research has been actively conducted on light emitting diodes for optical communications to be coupled with optical fibers. This type of light emitting diode that has already been developed includes:
As shown in FIG. 1a, weir layers a, .
After the semiconductor layer is grown, the substrate that serves as a base for creating semiconductor growth layers such as the light emitting layer a2 and the window layer 3 is etched away to form a relatively thin semiconductor layer la (la = 60 to 70〃m) as a light emitting element. As shown in Fig. 1b, instead of leaving the substrate b for growing the semiconductor layer after the growth, a part of the substrate in the light emitting part is removed to prevent light absorption (lb~ 2001m) and a method in which the light emitting element is constructed by leaving the entire substrate CO as shown in Figure 1c (
lc = 100 to 200 mm), etc. In the figure, A is an electrode for supplying an operating current, and B is a heat sink to which an element is attached. Among these methods, the method shown in FIG. 1a is considered to be the most superior in terms of manufacturing method and characteristics. However, in the method shown in Figure 1a, usually 60
Since the first layer with a layer thickness of ~70〃m is manufactured by a liquid phase epitaxial growth process using a slow cooling method, the following '11~

[3''There were drawbacks as described below. ○'
With a layer thickness of 60 to 70 Am, the device is easily broken and is extremely difficult to handle. If you try to increase the layer thickness, the growth period becomes longer and the slow cooling method is used, so the initial growth temperature must be 900°C or higher. contamination becomes a problem, and the crystallinity of the deposited growth layer also deteriorates. [21
If the second layer and subsequent layers are to be grown continuously following the first layer, it is necessary to allow a considerable amount of precipitation to reach the growth temperature of the second layer. This precipitates and has an adverse effect on the growth layer. '31 In the first layer grown by slow cooling for a relatively long time, there is a considerable difference in AI concentration between the initial stage and the end of growth.
If you try to obtain a growth layer with a predetermined peak concentration at the end of growth, a layer with a fairly large peak concentration will grow at the beginning of growth, and it is extremely difficult to form an ohmic electrode in a layer with such a high AI concentration. . Due to the above-mentioned drawbacks, the first layer of conventional light emitting diodes has been limited to 60 to 70 meters. It is also conceivable to grow only the first layer GaAI whistle by the temperature difference method, and then grow the second layer and other layers by the liquid phase epitaxial growth method using the usual sliding method in a separate furnace. However, there is a drawback that an oxide film is easily formed on the surface of the first CanAs layer, and the second and subsequent layers cannot be grown smoothly, and the manufacturing process is also complicated. The present invention eliminates the drawbacks of the conventional method and provides an easy manufacturing method without impairing the advantages of the light emitting diode shown in FIG. . Figure 2 shows an apparatus for manufacturing CamAs light emitting diodes, in which a boat 3 is slidably placed on a slider 2 that has a recess carved into it for installing a Ga melon substrate 1, similar to this type of conventional apparatus. It is provided. Four melt storage tanks 4, 5, 6, and 7 are formed in the boat 3 and reach the slider 2 surface, and four types of melt are held in the tanks. The first tank 4 that holds the first melt among the four melt tanks is provided with a heater 8 for creating a temperature difference in the rattan liquid, and as described later, a temperature difference of 5°C/min is provided. can be added. Reference numeral 9 denotes a lid provided on each of the melt tanks 4 to 7. In the above manufacturing apparatus, the first melt tank 4 has a first melt 10
For Ga5 evening, AI5 female○aAs source 300 of 9
and Teo. The second melt tank 5 is filled with Ga500, AIM9, Ga false source 500, and Zn2.
The third melt tank 6 contains Ga5, AI5, Ga ship source 300 and Zn20, and the fourth melt tank 7 contains ○a5 and AI2. No. 3, GaAS
9 of source 500 and Teo. 1 of 9 formulations are filled for melts 1 1, 12 and 13, respectively. As shown in the temperature control diagram of FIG. 3, the compounded semiconductor material was brought to a melt state by being brought to a melt state by rising to a temperature of 80,000 in a specific gas atmosphere, and after being maintained at the temperature of 800,000 for 2 hours.
The slider 2 and the boat 3 are moved relatively to bring the GaAs semiconductor substrate 1 into contact with the first melt 10 at a certain time. After contacting the substrate 1, the electric wire is put into the heater 8 and the first melt 1
The heater is controlled to create a temperature difference of 5° C./arc so that the slider side is at a lower temperature. Due to the concentration difference based on the temperature gradient, the As and N components in the first melt 10 become supersaturated on the low temperature side in contact with the semiconductor substrate 1, and the first Ga. -yA]yAs layer 10' is grown. The amount of growth is proportional to the contact time between the substrate 1 and the first melt 10, and in this example, a growth layer of 50 mm was formed per hour. Therefore, by isothermal incubation for 2 hours, 100 m of N-type Ga with a uniform AI concentration on the substrate 1,
A 1yA1yAs layer 10' was obtained. After the growth of the first layer, the substrate is cooled at a cooling rate of 1° C./min during the isothermal holding process, and after 2 minutes, the substrate 1 is transferred to the second melt tank 5.
After holding the contact for 1 minute, the third molten liquid 12 and the substrate 1 are held in contact for 2 minutes to form the second layer P-type Ga. -XAIXAs(x<y)
11′, the third layer P-type Ga, yA1yAs1 2
' is grown, and then the substrate 1 is moved under the fourth melt 13 at a certain time to allow contact growth for 1 minute. The 1 minute contact causes the fourth layer N-type (or p-type) Ga, -zA1zAs(x
<z<y) grows, and after 1 minute, the fourth bag liquid is transferred to substrate 1.
The plant is removed from the plant and the furnace is turned off to finish growing. As shown in the cross-sectional view of FIG. 4, the semiconductor device manufactured by the above process is a loovm N-type GaO.
Mochi 10. Necessary layer 1 0', 1〃m P-type Gao. 9 Secretion 1
0.0 ship s layer 1 1', 1mm P type Gao. ship 1
0. Public layer 1 2', 1 m N type Gao
．． 8 pine 10.1 Is layers 13' are formed in sequence. AI203 and S which serve as a mask are placed on the surface of the stacked semiconductors.
A double film consisting of i02 is formed, and a current is supplied to the film.
Window processing was done for the picture, and then Zn was changed to P-type Ga.
o. 6AIO. It is diffused until it reaches the 4As layer. The Z
After the n-diffusion treatment, the double film is etched, and then the substrate 1 is etched.
is removed with an etching solution of NH40H:day202=1:5 to produce a semiconductor layer for a light emitting diode. Although the etching solution for the substrate 1 etches the GaAs substrate, the grown layer is hardly attacked. Au is applied to the surface of the N-type GaAIAs of the semiconductor layer from which the above substrate has been removed.
After sequentially depositing O-Nj-Au and removing the light extraction port by photo-etching, A side r
-Au is deposited, alloyed by heat treatment at 500° C. for 3 minutes, and finally divided into chips by dazing. Here, since the GaAI* is formed to a thickness of 00 mm by isothermal growth, there is almost no manipulation that would cause damage such as cracking even after the substrate 1 is removed. As described above, according to the present invention, since the first CaAI layer is produced by isothermal growth, a relatively thick layer can be grown without any inconvenience in handling the AI concentration or doping material, and during the device manufacturing process. It is possible to obtain devices with excellent light emitting characteristics at a high yield without causing chip cracking.

[Brief explanation of the drawing]

1A to 1C are cross-sectional views of a conventional device, FIG. 2 is a cross-sectional view of a semiconductor layer manufacturing apparatus according to the present invention, FIG. 3 is a temperature control diagram for explaining the growth method according to the present invention, and FIG. 4 is a cross-sectional view of a conventional device. 1 is a cross-sectional view of a semiconductor growth layer according to the present invention. 1: GaAs substrate, 2: slider, 3: boat, 4 to 7
: melt, 8: heater, 10': IGaAIAs growth layer, 11', 12', 13': second, third and fourth GaN
As growth layer. Figure 2 Figure 3 Figure 4 Younger brother's figure

Claims (1)

[Claims] 1. In a liquid phase epitaxial growth method in which an epitaxial layer is precipitated and grown by successively contacting a crystal growth melt on a GaAs substrate, the temperature of the melt gradually increases as it moves away from the contact surface with the GaAs substrate. After growing a thick GaAlAs epitaxial layer based on the concentration distribution of components in the melt formed in response to the temperature gradient, the epitaxial layer is continuously deposited. A liquid phase epitaxial growth method characterized by: