JPH02302391A - Liquid-phase epitaxial growth and apparatus therefor - Google Patents

Abstract

PURPOSE:To accurately control the thickness of an epitaxial layer and easily obtain a multi-layered epitaxial layer having high quality by placing semiconductor substrates on horizontal supporting plates in a reaction tube and controlling the distance between the supporting plates according to the thickness of the epitaxial layer to be grown. CONSTITUTION:A horizontal supporting plate 1 is maintained in a suspended state and a 1st molten raw material liquid is introduced 8 from the 1st liquid reservoir 6 to a growth vessel 9. The crystal growth is carried out while keeping the height of the molten raw material liquid layer at a high level to form a thick epitaxial layer. A connection hole 8 is closed, the discharging port 12 of the vessel 9 is connected to the recovery port 13 of a recovery vessel 10, the 1st molten raw material liquid is completely discharged to the vessel 10, the suspension shaft 4 is lowered and the supporting plates 1 are stacked on the bottom of the vessel 9. The 2nd molten raw material liquid is introduced 8 from the 2nd liquid reservoir 7 into the vessel 9 and the crystal growth is carried out while keeping the height of the 2nd molten raw material liquid at a low level to form a thin epitaxial layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a liquid phase epitaxial growth method for laminating two or more epitaxial layers on a 21' conductor substrate and an apparatus therefor.

<Prior Art> A vertical liquid phase epitaxial growth apparatus can simultaneously perform epitaxial growth on a large number of semiconductor substrates using a relatively small growth chamber.

This equipment places a semiconductor substrate on a horizontal support plate, fixes the support plate at regular intervals, places it in a reaction tube, and then introduces a raw material melt and slowly cools it to form an epitaxial layer on the semiconductor substrate. It is formed by a predetermined epitaxial formation &
After performing this, a multilayer epitaxial layer can be formed by discharging the raw material melt from the reaction tube, introducing the next raw material melt, and performing epitaxial 1-lengthening in the same manner. Japanese Unexamined Patent Publication No. 61-261291 describes a liquid phase epitaxial growth apparatus equipped with melt switching means for sequentially introducing and discharging different raw material melts into a reaction tube.

(Problem to be solved by the invention) In conventional devices, the spacing of the horizontal support plates is identified.

If this interval is narrowed to perform epitaxial growth with a thin layer of raw material melt on the semiconductor substrate, the variation in the thickness of the epitaxial layer can be kept low, but this is disadvantageous in forming a thick epitaxial layer. be.

Furthermore, if this interval is widened to increase the height of the raw material melt layer and epitaxial growth is performed, there will be large variations in the thickness of the epitaxial layer, poor controllability of the thickness, and an increase in the amount of raw material melt used. This increases costs.

As described above, the conventional apparatus in which the spacing between the supporting plates is identified cannot adequately cope with the lamination of epitaxial layers of different thicknesses on the conductor Jλ plate.

The present invention aims to eliminate the above-mentioned drawbacks and provide a liquid phase epitaxial growth method and an apparatus therefor, which enable epitaxial growth under the height of the raw material melt layer corresponding to each epitaxial layer.

(Means for Solving the Problems) The present invention provides: (1) After placing conductor substrates on a large number of horizontal support plates stacked under -L at regular intervals and housing them in a reaction tube, In the liquid phase epitaxial growth method, in which multiple epitaxial layers are formed by sequentially introducing different raw material melts, when it is difficult to form a thin epitaxial layer, the spacing between the support plates is narrowed, and a thick epitaxial layer is formed. A liquid phase epitaxial growth method is characterized in that when forming a semiconductor substrate, the spacing between the support plates is widened and the space between the support plates is filled with a raw material melt for epitaxial growth.(2) A horizontal support plate on which a semiconductor substrate is placed, In a liquid phase epitaxial growth apparatus having a connecting member held at a constant interval between the supporting plates, a reaction tube accommodating these, and means for sequentially supplying different raw material melts to the reaction tube, means for changing the spacing between the support plates in multiple stages. (3) one end of the connecting member is fixed to one side wall of an adjacent support plate, a stopper protruding inward is provided at the other end, and the stopper is slidable. The height of the recess is defined so as to maintain a predetermined spacing between the support plates by engaging a stopper at the upper and lower ends of the recess. This is the liquid phase epitaxial growth apparatus '4if' described in (2).

(Function) FIG. 1 is a sectional view of a liquid phase epitaxial growth apparatus which is an example of an IFL body of the present invention. FIG. 2 is a conceptual diagram of the support device for the conductive board in FIG. 1, and (a) is an IE side view;
(b) is a side view, and (c) is a plan view. FIG. 3 is a conceptual diagram of the growth container shown in FIG. 1, where (a) is a front view and (b)
, ) is ・1/ the diagram.

The support plate 1 that holds the conductor board 2 has a structure in which the support plate 1 below is connected to the lower support plate by a connecting member 3 fixed to its side wall. It can be lifted with. Further, a liquid reservoir 6.7 for storing two types of raw material melts is mounted on one side of the first supporting plate through a lid plate 5. On the other hand, the growth container 8 containing the stacked support plates 1 is slidably covered at the bottom of the liquid reservoir L.

By rotating only the liquid reservoir on the lid plate and aligning the liquid reservoir with the communication port 8 of the lid plate 5, the raw material melt in the liquid reservoir is introduced into the growth container 9. Below the growth container 9,
A recovery container 10 for recovering the raw material melt is arranged, and the bottom of the growth container 9 is slidably fitted into the upper side wall of the recovery container 10 to rotate a rotating shaft 11 fixed to the growth container 9. By doing so, the positions of the discharge port 12 of the growth container 9 and the collection 1] 13 of the collection container 10 can be aligned, and the raw material melt can be discharged from the growth container to the collection container. These devices are placed in a quartz tube 14 and heated by a heater 15.

As shown in FIG. 2, the connection of the support plate 1 is such that the upper end of the connecting member 3 is located below the side wall of the support plate 1, a recess 16 is provided on both sides, and the lower end of the connecting member of the support plate directly above is provided with a recess 16. The provided protrusion 17 is movable in the L downward direction within the recess 16, and
The structure is such that one end and the lower end of the recess 16 engage with the protrusion 17. The growth container 9 is provided with a layer 19 on its inner wall for receiving the connecting member 3 of the support plate 1 so as to be movable in -1-F.

” - Note @ When lifting the support plate 1 from the city axis 1,
As shown in FIG. 4(a), the protrusion 17 of the connecting member 3 engages with the upper end of the recess 16 of the support plate directly below, forming a high raw material melt layer above the support plate, and When stacking the Φ on the bottom of the growth container, the protrusion 17 of the connecting member 3 engages with the lower end of the recess 16 of the support plate, as shown in FIG. A low raw material melt layer can be formed. A groove 17 for passing the raw material melt is provided in the side wall of the support plate l.

In addition, the connection means of the support plate of this invention is not limited to the connection structure of ``-''. For example, adjacent support plates may be connected using a wire rod having flexibility in one direction. To explain the procedure for one-liquid phase eviaxial growth, the semiconductor substrate 2 is attached to the support plate L, and then the growth container Place it within 9,
The discharge port 12 of the growth container 9 is shifted from the recovery port 13 of the recovery container IO and closed, and the raw material melt reservoir 6.7 is mounted on the lid plate 5 of the support plate 1 so as to close the communication port 8. Two types of raw material melts are stored in each reservoir.

First, while maintaining the support plate l in a lifted state, the communication port 8 of the first liquid reservoir 6 is opened, and the first raw material melt is introduced into the growth container 9 to form a high first raw material melt layer. Crystal growth is performed while maintaining a high temperature to form a thick epitaxial layer.

Next, the communication port 8 is closed, and the growth container 9 is discharged [112
and the recovery port 13 of the recovery container 10, and after discharging all of the first raw material melt into the recovery container 10, the suspension shaft 4 is lowered and the support plates 1 are stacked and placed on the bottom of the growth container 9. ,
The discharge port 12 and the recovery port 13 are shifted and closed, the communication port 8 of the second liquid reservoir 7 is opened, and the second raw material melt is introduced into the growth container 9 to form a low second raw material melt layer. Crystal growth is performed while maintaining the height to form a thin epitaxial layer.

As described above, when using the liquid phase epitaxial growth apparatus of the present invention, when forming a thin epitaxial layer, by stacking support plates at the bottom of the growth container, the layer height of the raw material melt can be kept low and the film thickness can be increased. Control is facilitated, and when a thick epitaxial layer is formed, by suspending the support plate and using an I-groove, a high raw material melt layer height can be maintained and a high growth rate can be ensured.

(Example) Using the apparatus shown in Figs. 1 to 3, a p-shaped film (!
A p-type^1xGa+-xAs mixed crystal epitaxial layer and an n! P! Alx(ia+-x^S
A pn junction as shown in FIG. 6 was obtained by sequentially growing mixed crystal epitaxial layers. In the first step, the spacing between the support plates is 5
−, Ga is 3QQg, GaAs is 24g1A
A first raw material melt containing 1200 mg of Zn and 150 mg of Zn was introduced into a growth container, and epitaxial growth was performed for 500 minutes under temperature control as shown in FIG. 5, and then the first raw material melt was discharged. In the second step, after narrowing the spacing between the support plates to 2.5 mm, 175g of GaAs
108. A second raw material melt containing 97'n-g of AI was introduced into the growth vessel and heated to 150 nm under the temperature control shown in FIG.
Epitaxial growth was performed for minutes.

The obtained n-type epitaxial layer film JT7 has a thickness of 220 μ-
The film thickness distribution was ±30 μm, the film thickness of the n-type epitaxial layer was 24 μm, and the film thickness distribution was 12 μm.

(Effects of the Invention) The present invention makes it possible to select the layer height of the raw material melt according to the thickness of the epitaxial layer to be grown by adopting the configuration described in 2. This method ensures precise film thickness control, enables high growth rates for thick epitaxial layers, and makes it possible to easily create high-quality multilayer epitaxial layers.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the liquid phase epitaxial growth apparatus of the present invention, and FIG. 2 is an explanatory view of the support plate in FIG. 1, where (a) is a front view, (b) is a side view, and (c) is The plan view and FIG. 3 are explanatory diagrams of the growth container shown in FIG.
) is a plan view, and FIG. 4 is a small explanatory diagram of the state when changing the spacing between the support plates. A diagram showing the state when the support plates are piled up to form a narrow interval, FIG. 5 is a diagram showing the spacing of the support plates and temperature control conditions during epitaxial growth in the example, and FIG. FIG. 2 is a cross-sectional view of a heterojunction obtained in an example. Figure 1 Nishiki 5

Claims (3)

[Claims] (1) Semiconductor substrates are placed on a large number of horizontal support plates stacked vertically at regular intervals, and after being placed in a reaction tube, different raw material melts are sequentially introduced to form multiple epitaxial layers. In the phase epitaxial growth method, when forming a thin epitaxial layer, the spacing between the supporting plates is narrowed, and when forming a thick epitaxial layer, the spacing between the supporting plates is widened, and the space between the supporting plates is filled with a raw material melt to perform epitaxial growth. A liquid phase epitaxial growth method characterized by (2) A horizontal support plate on which a semiconductor substrate is placed, a connecting member that holds the support plate vertically at a constant interval, a reaction tube that accommodates these, and a means for sequentially supplying different raw material melts to the reaction tube. What is claimed is: 1. A liquid phase epitaxial growth apparatus comprising: a liquid phase epitaxial growth apparatus, characterized in that the liquid phase epitaxial growth apparatus is provided with means for changing the spacing between support plates in multiple stages. (3) One end of the connecting member is fixed to one side wall of an adjacent support plate, a stopper that protrudes inward is provided at the other end, a recess that slidably receives the stopper is provided in the side wall of the adjacent support plate, and the recess 3. The liquid phase epitaxial growth apparatus according to claim 2, wherein the height of the recess is defined so as to maintain a predetermined spacing between the support plates by engaging stoppers at the upper and lower ends of the recess.