JPH03208883A - Method and device for liquid phase epitaxial growth - Google Patents

Abstract

PURPOSE:To prevent liquid drops from remaining on a substrate and to obtain a uniformly grown layer by supporting this substrate on the side wall of a vertically or diagonally slit growth chamber and epitaxially growing a single crystal on the substrate by a raw material melt introduced from above and then discharging the melt stepwise little by little. CONSTITUTION:The substrate 3 is supported in the recess on the side wall of the above-mentioned growth chamber 2 formed on a horizontal substrate holding member 1. The bottom aperture of a raw material melt tank 4 constituted slidable atop the member 1 is mated by the chamber 2 and the raw material melt 5 is introduced from the tank 4 into the chamber 2 to epitaxially grow the single crystal. The opening 8 of a jig 7 for discharging the melt is then mated with the chamber 2 and the melt 5 is housed into the opening 8. This jig 7 is slid to mate the opening 8 with a melt recovering tank 6 and to transfer the melt 5 into this tank 6. The jig 7 is slid to mate the opening 8 and the chamber 2 again and to transfer the melt 5 in the chamber 2 into the opening 8, from which the melt is discharged to the tank 6.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for growing a semiconductor single crystal by liquid phase epitaxial growth.

(Prior art) As a method for liquid-phase epitaxial growth of single crystals such as gallium arsenide and aluminum gallium arsenide, a substrate is supported on the side wall of a diagonal slit-shaped growth chamber, and a raw material melt is introduced into the growth chamber and deposited on the substrate. A method of discharging the melt downward after epitaxially growing a single crystal is proposed, for example, in Japanese Patent Laid-Open No. 7615/1983.

FIG. 2 is a cross-sectional view of the apparatus used in this method. This device supports a substrate 3 on the side wall of an oblique slit-shaped growth chamber 2 formed in a horizontal substrate holding member 1, and has a plurality of raw material melt tanks 4 that are slidable on the upper surface of the holding member 1. An opening for supplying the raw material melt 5 to the growth chamber 2 was provided at the bottom of the raw material melt tank 4, and a plurality of melt collection WJs 6 that were slidable on the lower surface of the holding member 1 were arranged. In the liquid phase epitaxial growth apparatus, the opening of the raw material melt tank 4 is connected to the growth chamber 2.
By adapting to the raw materials? &5 into the growth chamber 2, and after epitaxially growing a predetermined single crystal on the substrate 3 by keeping the raw material melt at the growth temperature, aligning the opening of the melt recovery tank 6 with the growth chamber 2. Accordingly, raw material melt 5
is discharged all at once to terminate crystal growth. This method is based on the previous method, in which the substrate is held horizontally in a recess on the surface of a holding member, and a raw material melt tank having an opening at the bottom is slid onto the upper surface of the holding member to bring the raw material melt into contact with the substrate. Compared to , there is no member that slides directly on the substrate, so there is no risk of damaging the substrate surface. This method has excellent mass productivity.

(Problem to be solved by the invention) However, in this method, after the growth is completed, the raw material melt in the growth chamber is discharged all at once into the melt collection tank by gravity, so the raw material melt is not completely discharged. , raw material melt may remain on the substrate.

In particular, when reducing the thickness of the slit-like growth chamber, that is, the thickness of the liquid, in order to obtain a thin growth layer, droplets tend to remain, and when the liquid thickness is less than III, it is difficult to drain the raw material melt. I can't.

In this way, if droplets remain on the substrate after growth, the growth layer may become thicker in that area, or they may mix with the raw material melt introduced for the next growth, changing the composition of the raw material melt. Therefore, the desired crystal cannot be obtained.

The present invention aims to solve the above-mentioned problems and to provide a liquid phase epitaxial growth method and an apparatus therefor, which ensure discharge of the melt after the growth is completed and prevent droplets from remaining on the substrate.

(Means for Solving the Problems) The present invention provides (1) a method in which a substrate is supported on the side wall of a vertical or diagonal slit-shaped growth chamber, and a raw material melt is introduced from above to epitaxially grow a single crystal on the substrate; (2) a substrate holding member having a vertical or diagonal slit-like growth chamber;
A support means for the substrate provided on the side wall of the growth chamber, a raw material melt tank having a sliding upper surface on the holding member and an opening at the bottom, and a melt recovery tank disposed below the holding member. In the liquid phase epitaxial growth apparatus, a melt discharge jig is slidably disposed between the lower surface of the holding member and the upper surface of the melt recovery tank, and the jig is provided with an opening having a smaller volume than the growth chamber. By using a liquid reservoir for discharging the melt and moving the opening of the jig between the lower part of the growth chamber and the upper part of the melt collection tank,
This is a liquid phase epitaxial growth apparatus characterized in that the melt in the growth chamber can be discharged.

(Function) The present inventors investigated the degree of droplets remaining on the substrate by changing the size of the opening of the melt collection tank for the raw material melt flowing down the diagonal slit-shaped growth chamber. Small (
It has been found that by suppressing the flow rate of the raw material melt, there are fewer remaining droplets, that is, the amount of droplets remaining depends on the flow rate. However, if this opening is made too small, the melt will not flow and the entire amount will remain, so instead of allowing the melt to fall naturally in one step, the present invention has devised a method of gradually discharging small amounts. FIG. 1 is a sectional view of a liquid phase epitaxial growth apparatus which is a specific example of the present invention. In this apparatus, a vertical or diagonal slit-shaped growth chamber 2 is formed in a horizontal substrate holding member 1, a recessed portion for supporting a substrate 3 is provided on the side wall of the growth chamber 2, and a raw material melt is provided on the upper surface of the holding member 1. By making the tank 4 slidable and aligning its bottom opening with the growth chamber 2, the raw material melt 5 is transferred from the raw material melt tank 4 to the growth chamber 2.
In addition, a melt discharge jig 7 is provided on the lower surface of the holding member 1, and a melt recovery tank 6 is provided on the lower surface of the holding member 1.
By aligning the opening 8 of the jig 7 with the growth chamber 2, the raw material melt 5 is placed in a slidable manner.
Then, after sliding the jig 7 to align the opening 8 with the melt recovery tank 6 and transferring the raw material melt into the melt recovery tank 6, the jig 7 is slid. The opening 8 is aligned with the growth chamber 2 again, and the raw material melt 5 in the growth chamber 2 is transferred to the opening 8 and discharged into the melt recovery tank 6. In this way, by moving the jig 7 back and forth between the growth chamber 2 and the melt recovery liquid supply 6,
The raw material melt 5 can be transferred from the growth chamber 2 to the melt recovery tank 6 in stages. It is also possible to provide a plurality of openings 8 in the jig 7 and transfer raw material melt corresponding to the number of openings in one operation.

In this way, by controlling the volume and sliding speed of the opening 8 of the melt discharge jig 7, the discharge speed of the raw material melt 5, that is, the flow rate of the raw material melt flowing on the substrate 3 can be easily controlled. It is possible to adjust the amount of liquid and prevent droplets from remaining on the substrate 3.

(Example) A gallium arsenide crystal was grown using the liquid phase epitaxial growth apparatus shown in FIG. A circular GaAs substrate with a diameter of 50 mm was set in a growth chamber with a slit interval of 2 ms.

The melt discharging jig used had an opening with a width of 4 mm, a height of 4 mm, and a depth of 50 m. 30 g of high-purity gallium and 3 g of GaAs polycrystals were put in the raw material melt tank, and heated to 850°C in a hydrogen atmosphere to melt the raw materials.
After slowly cooling to 848℃ at a cooling rate of ``C/■in,
The raw material melt tank was slid to introduce the raw material melt into the growth chamber.

Then, it was slowly cooled to 840°C at the above cooling rate, and while maintaining this temperature, the above melt discharge jig was heated at 1 l/s.
After reciprocating 10 times at a speed of ee and discharging the melt into a melt recovery tank, it was cooled to room temperature. When the substrate was taken out and observed, there were no gallium droplets on the surface and it was a mirror surface.

When the substrate was cleaved, a cross section thereof was subjected to hydrofluoric acid etching, and observed under a microscope, an epitaxially grown layer with a thickness of flu- was observed. In the above example, when the raw material melt in the growth chamber was allowed to fall directly into the melt recovery tank at once without using a melt discharge jig, droplets remained on the substrate at a rate of 20%. The epitaxially grown layer in this portion had a thickness of 40 to 70 μm.

(Effects of the Invention) By adopting the above configuration, the present invention can slow down the flow rate of the raw material melt flowing on the substrate, and as a result, it is possible to prevent droplets from remaining on the substrate. is possible,
A uniform growth layer can be obtained. Furthermore, since the mixing of raw material melt is prevented even in multilayer growth, designed characteristics can be obtained for each growth layer.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a liquid phase epitaxial growth apparatus which is a specific example of the present invention, and FIG. 2 is a sectional view of a conventional apparatus. Figure 1 Figure 2

Claims (2)

[Claims] (1) A method in which a substrate is supported on the side wall of a vertical or diagonal slit-shaped growth chamber, and a raw material melt is introduced from above to epitaxially grow a single crystal on the substrate. A liquid phase epitaxial growth method characterized by discharging water. (2) a substrate holding member having a vertical or diagonal slit-shaped growth chamber, and a substrate support means provided on the side wall of the growth chamber;
In a liquid phase epitaxial growth apparatus having a raw material melt tank whose upper surface is slidable and which has an opening at the bottom of the holding member, and a melt recovery tank disposed below the holding member,
A melt discharge jig is slidably arranged between the lower surface of the holding member and the upper surface of the melt recovery tank, and an opening with a smaller volume than the growth chamber is provided in the jig to serve as a melt discharge reservoir. A liquid phase epitaxial growth apparatus characterized in that the melt in the growth chamber can be discharged by moving the jig k opening between the lower part of the growth chamber and the upper part of the melt recovery tank.