JPH0196090A - Liquid phase epitaxial growth process of semiconductor crystal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for epitaxial growth of semiconductor crystals,
In particular, it relates to a method for epitaxially growing semiconductor crystals using a temperature difference method.

[Conventional technology and problems]

Conventionally, in the liquid phase epitaxial growth method of ■-V group compound semiconductors such as GaAlAs, as shown in FIG. GaAs,
- After dissolving the doping pure substance, these melt tanks 2
By applying a temperature difference between the top and bottom, the GaAs substrate crystal 4 set on the top surface of the wafer slider 3 that moves linearly in one direction is brought into contact with the low temperature side of these melts 1 and held for a certain period of time. A temperature difference method is widely known in which a supersaturated component in the melt 1 is precipitated on the substrate crystal 4, thereby epitaxially growing a semiconductor crystal on the substrate crystal 4.

In the above-mentioned temperature difference method, when producing a so-called shrimp wafer with, for example, a double heterostructure, each melt tank 2a,
Melt 1a+ 1b+1c received in 2b, 2c
A plurality of substrate crystals 4 are set on the upper surface of the wafer slider 3, and these substrate crystals 4 are sequentially placed in each melt tank 2a, 2b.
, 2c received melt la, lb.

1c, as shown in FIG.
0. Layer 5 of sAs, P Gao, hsAI
o, *sAs second layer 6, and n Ga6. zA
A third layer 7 of lo and aAs is crystal-grown to complete the shrimp wafer.

However, at this time, the odd numbered, ie, the first, substrate crystal 4a
The crystal growth is performed so as to obtain crystal growth of desired thickness, that is, the crystal growth is performed so that the first layer 5 and the third layer 7 are relatively thick and the second layer 6 is relatively thin. Select a time, for example 60 minutes for the first melt 1a,
If you select a crystal growth time of 1 minute for the second melt 1-1b and 60 minutes for the third melt IC, the even-numbered
That is, as shown in FIG. 7(B), on the second substrate crystal 4b, the first melt la was heated for 1 minute, the second melt 1b was heated for 60 minutes, and the third melt IC was heated for 1 minute. On the other hand, the crystal growth time is 1 minute, so that the -th layer 5 and the third layer 7 are formed relatively thin, and the second layer 6 is formed relatively thick.

Thus, as shrimp wafers with a double heterostructure, for example, shrimp wafers that can be used for manufacturing LED chips are limited to odd-numbered shrimp wafers, and therefore, even if the yield of odd-numbered shrimp wafers is 100%, the overall yield of shrimp wafers is As a result, a maximum yield of only 50% can be achieved, which poses a problem in terms of productivity.

In addition, an intermittent drive device is required as a feeding device for the wafer slider 3 on which the substrate crystal 4 is placed, and furthermore, the spacing between the devices is not constant, resulting in problems with the structure. ! It became complicated and the cost was high.

[Purpose of the invention]

In view of the above points, it is an object of the present invention to provide a method for liquid phase epitaxial growth of semiconductor crystals that has a simple structure and a high yield.

[Means and actions for solving the problem] The above purpose is:
According to the present invention, a substrate crystal placed on a wafer slider that is linearly moved in one direction is sequentially brought into contact with a plurality of melts containing melted growth materials respectively received in a plurality of melt baths. In a liquid phase epitaxial growth method for semiconductor crystals in which a plurality of semiconductor crystals are epitaxially grown on a substrate crystal, each melt bath has a structure in which the thickness of each of the plurality of semiconductor crystals is determined based on the thickness of each of the plurality of semiconductor crystals with respect to the movement direction of the substrate crystal. It has a length of
This is achieved by moving the substrate crystal in one direction at a constant speed and, if necessary, holding the substrate crystal in contact with each melt for a certain period of time to grow the crystal to a predetermined thickness. be done.

According to this invention, the length of the substrate crystal in each melt tank in the moving direction is selected in proportion to the crystal growth time for the melt in each melt tank, so that the substrate crystal moves in one direction at a constant speed. By doing this, the melt in each melt tank is sequentially deposited on the substrate crystal, and the crystal is grown to a predetermined thickness.In this way, the shrimp wafer made of all the substrate crystals has the desired structure, and the yield is increased. Furthermore, since the substrate crystal, that is, the wafer slider on which the substrate crystal is placed, only needs to be moved in one direction at a constant speed, automatic feeding of the substrate crystal is possible with a feeding device of simple structure. Costs will be reduced.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on one embodiment shown in the drawings.

The liquid phase epitaxial growth apparatus for carrying out the present invention basically has almost the same structure as the conventional apparatus, and differs only in the longitudinal dimension of each melt tank.

In the first episode showing an embodiment of an epitaxial growth apparatus for carrying out the present invention, the melt tanks 1° are sequentially arranged from the right side of the drawing as 10 melt tanks 11. No. 20 melt tank 12. A third melt tank 13 is provided. Each of these first, second and third melt tanks 11, 12, 13 has its substrate crystal 4
The length in the direction of movement of each melt tank 11.12.13
The predetermined crystal growth times for the melts 1a+lb, tc are selected to be, for example, lengths proportional to the crystal growth times of 60 minutes, 1 minute, and 60 minutes, respectively, in the conventional example described above.

The embodiment of the melt tank 10 according to the present invention is configured as described above, and when producing a shrimp wafer with a double heterostructure by growing crystals on a substrate crystal, each melt tank of the melt tank 10 according to the present invention is 11. The melts la, lb, and lc in the melts 12 and 13 are doped with P type, n type, and n type, respectively, and a plurality of substrate crystals 4 are set on the upper surface of the wafer slider 3, and these substrate crystals 4 are doped. By moving the tl in the direction not shown by arrow A at a constant speed, the melt tl received in each melt tank 11, 12, 13 is
a, Ib+ lc, pGas, , A+, 5 . A first layer 5 of As, a second layer 6 of P Gao, *sA]o, 5sAs, and a third layer 7 of n-Gao, 281o, sAs are grown as shown in FIG. The shrimp wafer shown is fabricated. During this crystal growth, a certain point on each substrate crystal 4 moves at a constant speed in the direction of arrow A, so that the melts la, lb, l in each melt tank 11.12.13 are
Crystals grow by contacting c for a time proportional to the length of each melt tank 11, 12, 13 in the direction of substrate crystal movement (
(See FIG. 3) Therefore, for all the substrate crystals 4, as shown in FIG. A shrimp wafer with a double heterostructure is fabricated.

Further, according to this method, the substrate crystal 4 is
．． Since it is always sliding at a constant speed with respect to 12.13, crystal growth is performed using part of the supersaturation accumulated at the bottom of each melt la, ib, and lc.
As shown by the solid line in FIG. 4, the crystal growth rate with respect to the growth time is very slow compared to the crystal growth by the conventional method (shown by the dotted line). Since the supersaturated portion does not precipitate all at once, the crystal growth rate becomes constant and thin film growth with high precision can be obtained.

The crystal growth rate can be adjusted as shown in FIG. 5 by appropriately selecting the length of each melt tank 11, 12, 13 in the substrate crystal movement direction. Therefore, instead of sliding the substrate crystal in one direction at a constant speed as described above, the desired double heterostructure shrimp wafer can be obtained by bringing the substrate crystal into contact with each melt tank and holding it for a certain period of time. It will be done. In this case, since the time for holding the substrate crystals in each melt bath is constant, shrimp wafers with the desired double heterostructure can be obtained for all the substrate crystals.

〔Effect of the invention〕

As described above, according to the present invention, the substrate crystal placed on the wafer slider is linearly moved in one direction with respect to the melt obtained by melting the growth materials respectively received in a plurality of melt tanks. In a liquid phase epitaxial growth method for semiconductor crystals in which a plurality of semiconductor crystals are epitaxially grown on a substrate crystal by sequential contact with a melt, each melt bath is used to grow each of the plurality of semiconductor crystals with respect to the movement direction of the substrate crystal. By setting the length based on the thickness, the substrate crystal is moved in one direction at a constant speed, and preferably the substrate crystal is kept in contact with each melt for a certain period of time, so that a crystal of a predetermined thickness can be obtained. Since the structure is configured to allow growth to occur, the length in the direction of movement of the substrate crystal in each melt tank is selected in proportion to the crystal growth time for the melt in each melt tank, so that the substrate crystal remains constant in one direction. By moving at a high speed, the melt in each melt tank is sequentially deposited on the substrate crystal, and the crystal is grown to a predetermined thickness.

Therefore, since the shrimp wafer made of all the substrate crystals has the desired structure, the yield is improved,
Moreover, the substrate crystal, that is, the substrate crystal! Since the wafer slider to be placed only needs to be moved in one direction at a constant speed, costs are reduced while automatic feeding of the substrate crystal is possible using a feeding device with a simple structure.

Thus, according to the present invention, it is possible to provide a method for liquid phase epitaxial growth of semiconductor crystals with a simple structure and a good yield, in which a double heterostructure shrimp wafer suitable for all substrate crystals can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an embodiment of a liquid phase epitaxial growth apparatus for carrying out the present invention, FIG. 2 is a schematic cross-sectional view of a shrimp wafer produced by the apparatus shown in FIG. 1, and FIG. 3 is a slide for melting. FIG. 4 is a graph showing the relationship between time and crystal growth thickness. FIG. 4 is a graph showing the crystal growth rate in the example of FIG. 1. FIG. 5 is a graph showing the relationship between the length of the melt tank and the crystal growth rate. be. FIG. 6 is a schematic cross-sectional view showing an example of a conventional liquid phase epitaxial growth apparatus, and FIG. 7 is a schematic cross-sectional view of shrimp wafers produced using the apparatus shown in FIG. The second shrimp wafer is shown. 1, la, Ib, 1c--melt; 2
, 2a, 2b, 2cm melt tank; 3- wafer slider; 4, 4a, 4b- substrate crystal; 5-
・-first layer; 6--second layer; 7--third layer; 10,
11. 12. 13.--melt tank. Patent applicant: Stanley Electric Co., Ltd. Representative: Patent attorney Hirayama - Muroma: Patent attorney Tamotsu Kaizu Figure 1 Figure 3 Figure 4

Claims (2)

[Claims] (1) By sequentially bringing a substrate crystal placed on a wafer slider that is linearly interlocked in one direction into contact with the melt containing melted growth materials received in a plurality of melt tanks, In a liquid phase epitaxial growth method for semiconductor crystals in which a plurality of semiconductor crystals are epitaxially grown on a substrate crystal, each of the melt baths is configured to perform a process based on the thickness of each of the plurality of semiconductor crystals with respect to the movement direction of the substrate crystal. 1. A method for liquid phase epitaxial growth of a semiconductor crystal, characterized in that the substrate crystal has a certain length and a predetermined crystal growth is performed by moving the substrate crystal in one direction at a constant speed. (2) The liquid phase epitaxial growth method of a semiconductor crystal according to claim 1, which includes an operation of bringing the substrate crystal into contact with each melt and holding the substrate crystal for a certain period of time.