JP2975740B2 - Liquid phase epitaxial growth method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to GaAlAs or Ga
The present invention relates to a liquid phase epitaxial growth method for an As semiconductor.

[0002]

2. Description of the Related Art Conventionally, compound semiconductors, in particular, GaAs
The liquid phase epitaxial growth of lAs is described in JP-A-63-516.
As shown in Japanese Patent Publication No. 24, 2411 or the like, a slide method is used. A semiconductor substrate 32 is arranged on a lower holder 31 as shown in FIG. The semiconductor substrate 32 is brought into contact with the melt 33 from above, and is gradually cooled to epitaxially grow. However, according to an experiment, when the epitaxial growth is performed from 950 ° C. to 600 ° C., the thickness becomes only 100 μm at most as shown in FIG. 5C. Using this first apparatus, a plurality of GaAlAs growth layers are grown on a semiconductor substrate 32 to produce a double hetero type light emitting diode.
No. 618, the growth layer has a thickness of 15 to 40 μm.
Thin, the wafer is easily broken, and the workability is poor.

On the other hand, as shown in Japanese Patent Application Laid-Open No. 2-79422, when the exposed semiconductor substrate is brought into contact with the melt below and grown, the thickness of the grown layer can be increased as shown in FIG. When a double hetero type light emitting diode is manufactured using this second device, the first growth layer on the semiconductor substrate can be formed as thick as 120 μm. But 0.5 ~ 2μ
The active layer required to have a thickness of m, that is, the second growth layer formed on the first growth layer also grows thickly to a thickness of 0.5 to 2
It is very difficult to control the thickness in μm. As described above, if the thickness of the first and second growth layers is strictly controlled in this conventional apparatus, it is necessary to switch the first and second apparatuses during the manufacturing process to perform epitaxial growth.
Poor workability. Furthermore, it is difficult to strictly control the film thickness of each of the first and second growth layers even by the conventional rotational epitaxial growth method in which the semiconductor substrate is horizontally or vertically arranged and rotated.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned drawbacks, and has a structure in which a plurality of layers having different thicknesses are epitaxially grown so that the film thickness can be easily controlled. Further, the present invention provides an epitaxial growth method which can be performed in a series of steps, has good workability, and reduces wafer cracking.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is directed to GaAlAs or GaAs.
The exposed semiconductor substrate made of s is contacted with the melt in the growth chamber upward or downward to grow a first growth layer, and the growth chamber is rotated to reversely expose the exposed semiconductor substrate downward or upward. The second growth layer is grown by contacting another melt in the chamber.

[0006]

According to the above-described method, the exposed semiconductor substrate is grown by contacting it with the melt above or below, so that thin and thick growth layers can be obtained under easy control, respectively, and the overall thickness can be increased. Is obtained, the cracking of the wafer is reduced. In addition, since this epitaxial growth can be performed by a series of continuous operations, workability is improved and crystallinity is improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal epitaxial growth apparatus used in an embodiment of the present invention will be described below with reference to FIGS. In addition,
FIG. 2 is an AA sectional view of FIG. In these figures, a container 1 is made of carbon, quartz or the like, has a substantially cylindrical outer shape in the vicinity of a center, has a rotating shaft 2 and is rotatable by a handle 3 engaged with the rotating shaft. I have. The inside of the container 1 is formed with a growth chamber 4 which is a substantially rectangular parallelepiped cavity.
In the growth chamber 4, a plurality of substrate holders 6 for holding a large number of semiconductor substrates 5 substantially vertically in the illustrated state are fixed. The substrate holder 6 is made of carbon, quartz, or the like, and holds the semiconductor substrate 5 by attaching the semiconductor substrate 5 with an adhesive or a material having an equivalent function, or by providing nails or bent pieces to lock the semiconductor substrate 5. doing. The container 1 has an oval-shaped through-hole 7 of a growth chamber at a portion which is almost directly above in the set state shown in the figure.
Are formed.

The container holder 8 is formed so as to hold the container 1 having a substantially cylindrical shape in the vicinity of the center, and has a discharge hole formed in the lower part. As shown in FIG. 2, when the through hole 7 of the growth chamber is located at a position directly above, the upper through hole is formed so that the through hole of the container holder 8 is located at the same position as the through hole 7. Have been. A melt holder guide 9 made of carbon or the like is provided on the container holder 8, and a through hole is formed at a position matching the through hole on the upper side of the container holder 8, and is preferably fixed to the container holder 8. Have been. The melt holder guide 9 supports a melt holder 10 having a melt reservoir. The melt holder 10 is made of carbon or the like, and a plurality of melt reservoirs 11, 12, 13 are formed by partition walls, and a through hole 14 of the melt reservoir is formed below each of the melt reservoirs. The guide 15 is located on the long side of the melt holder guide 10, and the container holder 8, the melt holder guide 9,
Melt holder 10 located on melt holder guide 9
Support. Hook 1 locked on melt holder 10
By virtue of 6, the melt holder 10 can be slid in the horizontal direction such that the through holes 14 of the melt reservoir coincide with the through holes on the upper side of the container holder 8, respectively. The liquid phase epitaxial growth apparatus 17 is constituted by these.

The liquid phase epitaxial growth method of the present invention using such a growth apparatus is applied to a semiconductor substrate 5 made of GaAs in order to manufacture a double hetero light emitting diode.
A case where an aAlAs layer is grown will be described as an example. First, 6 g of GaAs is added to 100 g of Ga,
Is prepared by mixing 600 mg of Zn and 100 mg of Zn. 6 g of GaAs in 100 g of Ga
g, another melt 19 containing 300 mg of Al and 600 mg of Zn are prepared. Then, Ga10 is introduced into the melt reservoir 13.
0 g, 6 g of GaAs, 500 mg of Al, and 2 m of Te
The next melt 20 mixed with g is prepared.

When the preparation of the melt is completed, the melt holder 10 is placed so that the through holes 14 of all the melt reservoirs do not overlap with the through holes of the melt holder guide 9 and the through holes 7 of the growth chamber face upward. And the container 1 are set, and the melts 18, 19 and 20 are held at about 940 ° C. for about 1 hour. Thereafter, the hook 16 is operated to slide the melt holder 10, and the first melt reservoir 1 is moved.
The first through hole 14 and the through hole of the melt holder guide 9 are aligned. As a result, the melt 18 falls through the through hole, and the growth chamber 4 is filled with the melt 18.

Next, when the handle 3 is rotated clockwise by 90 degrees, as shown in FIG. 3, the position of the through hole 7 of the growth chamber and the position of the through hole of the container holder 8 are separated, and the growth chamber 4 becomes a closed chamber. At this time, since the exposed semiconductor substrate 5 is in contact with the melt 18 below, epitaxial growth is performed by gradually cooling at a temperature gradient of about 0.5 to 1 ° C./min. The thickness (B) of the melt 18 in contact with each semiconductor substrate 5 is about 5 mm. Melt 18
Is lowered to about 835 ° C., the handle 3 is further rotated clockwise by 90 degrees, and the melt 18 is discharged from the discharge hole of the container holder 8 with the through hole 7 of the growth chamber facing downward.
Due to the growth at this time, about 120 μm
A first growth layer made of a P-type GaAlAs layer having a thickness of 3 nm is formed.

Further, the handle 3 is turned clockwise or counterclockwise by 18 degrees.
After rotating it 0 degrees and returning it to its original position,
Slide. The position of the through hole 14 of the melt reservoir 12 and the position of the through hole of the melt holder guide 9 are matched, another melt 19 is dropped, and the growth chamber 4 is filled with the melt 19. Thereafter, the handle 3 is rotated counterclockwise by 90 degrees, and the exposed semiconductor substrate 5 is brought into contact with another melt 19 above as shown in FIG. Cool down to 833 ° C. Then, the handle 3 is further rotated counterclockwise by 90 degrees, the through hole 7 of the growth chamber is turned downward, and another melt 19 is discharged from the discharge hole of the container holder 8. By this growth, a second growth layer having a thickness of about 1.5 μm, that is, an active layer is formed on the surface of the first growth layer.

Further, the handle 3 is turned to return to the original position, and at the same time, the melt 20 is slid so that the next melt 20 is dropped to fill the growth chamber 4. Then, the handle 3 is rotated counterclockwise by 90 degrees, the exposed semiconductor substrate 5 is again brought into contact with the next melt 20 as shown in FIG. 4 and gradually cooled at a temperature gradient of 1 to 3 ° C./min. Temperature of the melt 20 is about 690 ° C
, And then turn the handle 3 to discharge the next melt 20. By this growth, an N-type GaAlAs layer having a thickness of about 30 μm is formed on the surface of the second growth layer.

After the completion of the epitaxial growth, the wafer is taken out, the semiconductor substrate 5 is removed by etching as necessary, electrodes are formed, mesa etching is performed as necessary, and dicing is performed to complete a light emitting diode.

The thickness of the growth layer by such an epitaxial method will be described again with reference to FIG. As mentioned earlier, the characteristic D in FIG. 5 represents the characteristic of the growth layer when the exposed semiconductor substrate 5 is brought into contact with the melt below as shown in FIG. 3, and the characteristic C as shown in FIG. The characteristics of the growth layer when the exposed semiconductor substrate 5 is brought into contact with the melt above are shown. In the characteristic D, as the thickness (B) of the melt increases,
Although a thick growth layer can be obtained, the number of semiconductor substrates 5 that can be stored in the growth chamber 4 having a fixed size is reduced.
As in the present embodiment, the thickness of the melt of about 5 mm is appropriate.
In this embodiment, the growth temperature of the first growth layer made of the P-type GaAlAs layer is 940 to 835 ° C., so that the thickness of the growth layer is slightly smaller than the characteristic D.

[0016]

As described above, in the method of the present invention, formation of growth layers having different thicknesses can be easily controlled. In addition, in this method, different film thicknesses can be formed in a series of steps without switching the apparatus as in the related art, so that workability is good and crystallinity is good. In addition, a plurality of GaAl
Since a thick semiconductor layer made of an As layer can be manufactured and the wafer does not need to be handled during the manufacture of the epitaxial growth layer, cracking of the wafer during handling including the post-process is drastically reduced. In the method of the present invention, contrary to the embodiment, if the first exposed semiconductor substrate is contacted with the melt above and then the exposed semiconductor substrate is contacted with another melt below, the first growth The layer can be formed under easy control so that the layer is thin and the second growth layer is thick. Thereby, for example, the position of the active layer can be changed.

Further, in the conventional sliding method, since the semiconductor substrate and the melt are slid, stress is applied to the interface between the semiconductor substrate and the growth layer thereon. On the other hand, in the present invention, since the melt is allowed to fall freely, stress is not applied to the semiconductor substrate and the growth layer thereon, so that the strain in the crystal is further reduced, and a uniform growth layer having a long life is obtained. Can be

[Brief description of the drawings]

FIG. 1 is a sectional view of a liquid phase epitaxial growth apparatus used in an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is an explanatory diagram of one state of the process of the present invention (when the growth chamber is rotated clockwise by 90 degrees).

FIG. 4 is an explanatory diagram of one state of the process of the present invention (when the growth chamber is rotated counterclockwise by 90 degrees).

FIG. 5 is a characteristic diagram of a thickness of an epitaxial growth layer.

FIG. 6 is a sectional view of a conventional epitaxial growth apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Growth chamber 5 Semiconductor substrate 6 Substrate holder 18, 19, 20 Melt

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-218139 (JP, A) JP-A-4-367587 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C30B 1/00-35/00

Claims (1)

(57) [Claims] 1. An exposure made of GaAlAs or GaAs.
The semiconductor substrate above or below with the melt in the growth chamber
Growing a first growth layer, rotating the growth chamber,
Growing the exposed semiconductor substrate downward or upward
Growing the second growth layer by contact with another melt in the chamber
A liquid phase epitaxial growth method characterized by the following.