JPS61117195A - Vapor phase growth method - Google Patents

Abstract

PURPOSE:To form a crystal growth film having uniform and good quality on a substrate fixed to a susceptor in tight contact therewith by disposing the substrate in such a manner that the fluid layer of the reactive gas flows on the bottom surface of the substrate and executing the thermal decomposition and vapor phase growth of an org. metal. CONSTITUTION:A spacer 33 is subjected to vacuum evacuation through a discharge hole 35 of a vacuum chuck from the susceptor 32 and the substrate 8 is held to the susceptor 32 by a vacuum chuck. The susceptor 32 is heated by a high-frequency heater 36 from the outside and on the other hand the wall of a reaction tube 31 is cooled by cooling air. The reactive gaseous flow passes through a reactive gas supply hole 3 as shown by an arrow and grows the crystal by bringing the surface of the substrate 8 into reaction from the lower side. Since the passage of the reactive gas is formed to approximately a specified cross section, there is no disturbance of the reactive gas and the growth on the substrate is executed by the reactive gas having the relatively constant concn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a metal organic pyrolysis vapor phase growth method (MO-CVD).
) is a method of growing crystals on a substrate by using a vacuum chuck system installed on a susceptor, and in particular, it allows the substrate placed in an organometallic pyrolysis vapor phase growth apparatus to be tightly fixed in place using a vacuum chuck system installed on a susceptor, and also to prevent temperature drop. Considering the tendency of the reactant gas to form an upward airflow, the substrate was placed above the fluid surface of the reactant gas flow, and the substrate was placed at an angle of 60 degrees from the horizontal. The present invention provides a method for performing stable organometallic pyrolysis vapor phase growth by attaching it to a susceptor.

In the organometallic pyrolysis vapor phase growth method, a predetermined reaction gas is flowed into the reaction tube while heating the substrate placed in the reaction tube using an electric resistance heating method, a high frequency heating method, a light irradiation method, etc. This method grows crystals on a substrate, and has many advantages such as a steep distribution of impurities between the resulting crystal layers and excellent electrical mobility.For example, it has good light-emitting properties. This is an extremely popular method for forming multilayer compound semiconductors, for example, gallium arsenide (
It is often used when forming compound semiconductors mainly composed of (GaAs).

Conventionally, the method of placing a substrate on a susceptor in this MO-CVD apparatus is simply mounting the substrate on the susceptor, so a gap is created between the two, and the temperature of the substrate becomes lower than that of the susceptor. There are many things.

In particular, when the substrate is a GaAs compound semiconductor, the temperature of the substrate rises primarily due to heat conduction from the susceptor rather than due to radiant heat from the outside, so the adhesion between the susceptor and the substrate is poor. Although important, conventional devices do not take this point into consideration.

In addition, since the substrate is normally placed on top of the susceptor, the reaction gas is supplied from the top surface of the substrate, and the MO-
Because the CVD method uses a cold-walled reaction tube,
An updraft is generated near the susceptor, and this competition with the flow of the reactant gas causes the flow of the reactant gas to become turbulent and the density of the reactant gas to be uneven, resulting in poor quality and uniformity of the crystal growth layer. There was a problem and it needed to be improved.

[Conventional technology]

FIG. 4 is a schematic side view for explaining the conventional metal-organic pyrolysis vapor phase growth method, in which 1 is a reaction tube, 2 is a susceptor, 3 is a high-frequency heating device, and 4 is a temperature control device for the susceptor. Thermocouple to detect, 5 is a substrate.

The reactant gas flows as shown by the arrow, but there is a smooth airflow as shown by arrow a, and a turbulent flow of the reactant gas around the susceptor 2 as shown by the arrow a, allowing for smooth introduction and discharge of the reactant gas. However, this makes it impossible for the crystals grown on the substrate to grow uniformly.

FIG. 5 is a schematic side view for explaining another conventional organometallic pyrolysis vapor phase growth method, in which 1 is a reaction tube;
2 is a susceptor, 3 is a high-frequency heating device, 4 is a thermocouple that detects the temperature of the susceptor, and 5 is a substrate.The fact that the substrate placement part of susceptor 2 is tilted causes the reaction gas to flow upward. Although the substrate is tilted correspondingly, it is inevitable that the airflow of the reaction gas becomes turbulent as shown by the arrows, as in FIG.

[Problem that the invention seeks to solve]

In the organometallic pyrolysis vapor phase growth method with the above configuration, the substrate does not have good adhesion to the susceptor, so the temperature control of the substrate is insufficient, and the reaction gas is heated while flowing in the reaction tube. The problem is that the susceptor becomes an updraft and increases the density on the upper side of the reaction tube, and this problem can be solved by considering the structure of the susceptor and the relative position between the susceptor and the substrate.

[Means for solving problems]

The present invention provides a metal-organic pyrolytic vapor phase growth method that solves the above-mentioned problems. This can be achieved by a vapor phase growth method characterized in that the substrate is closely fixed and arranged so that a fluid layer of a reactive gas flows through the lower surface of the substrate to perform organometallic pyrolysis vapor phase growth.

[Effect]

The present invention provides a vacuum chuck in the region of the susceptor in which the substrate of the metal-organic pyrolysis vapor phase growth apparatus is placed, so that the substrate and the susceptor are closely fixed, so that the temperature of the susceptor is almost the same as that of the substrate. Having the same temperature makes it easier to control the temperature of the substrate, and even if the substrate is attached to the bottom of the susceptor using a vacuum chuck, it will not fall due to gravity, so it can cope with the rising airflow of the reaction gas in the reaction tube. The substrate is arranged horizontally or inclined above the reaction tube, so that crystal growth is performed on the substrate from the bottom by the reaction gas.

〔Example〕

FIG. 1 (al is a schematic perspective view of a susceptor for explaining the present invention in detail.

Reference numeral 11 denotes a susceptor having a carbon body covered with a quartz wall surface, and 12 is a substrate placement portion, in which a large number of pores 13 are provided to adsorb the substrate; It is evacuated by a vacuum exhaust hole 14 provided in the carbon body so as to have a vacuum chuck function,
There is also a thermocouple 15 to detect the temperature of the susceptor.

FIG. 1(b) is a schematic cross-sectional view of a susceptor for explaining the present invention in detail.

The carbon body 16 is covered with a quartz cover 17, and the piping 18 of the small hole 13 provided as a vacuum chuck is connected to the vacuum exhaust hole 14 in the center, and attracts the substrate 8.

FIG. 2 is a schematic cross-sectional view for explaining one embodiment of the reaction tube of the organometallic pyrolysis vapor phase growth apparatus of the present invention.

A reaction tube 21 includes a susceptor 22, which is supported by a spacer 23 and a spacer 24.

The spacer 24 is evacuated from the susceptor 22 through the exhaust hole 26 of the hole 25 of the vacuum chuck, and the substrate 8 is held on the susceptor by the vacuum chuck.

The susceptor is heated from the outside by a high-frequency heating device 27, while the tube wall of the reaction tube is cooled by cooling air from the direction of arrow p.

The reactive gas airflow flows as indicated by arrow q, and the surface of the substrate 8 is attached facing downward, reacting with the reactive gas to cause crystal growth.

FIG. 3 is a schematic cross-sectional view for explaining another embodiment of the reaction tube of the organometallic pyrolysis vapor phase growth apparatus of the present invention.

Reference numeral 31 denotes a reaction tube, and there is a susceptor 32, which is supported by a spacer 33. In this case, the susceptor is arranged at an angle, and similarly, the spacer 34 facing the susceptor is also supported by a spacer 33. Because the structure is inclined parallel to the , the reactant gas passes smoothly through a certain gap without turbulence, as shown by the arrow.

The spacer 33 is evacuated from the susceptor through an exhaust hole 35 of a vacuum chuck, and the substrate 8 is held on the susceptor by the vacuum chuck.

The susceptor is externally heated by a high frequency heating device 36, while the tube wall of the reaction tube is cooled by cooling air.

The reactive gas airflow flows from the reactive gas supply hole 37 in the direction of the arrow, reacts with the surface of the substrate 8 from below to grow crystals, and reacts with the rising airflow of the reactive gas. However, since the reactant gas passage has a substantially constant cross-sectional area, there is no turbulence of the reactant gas, and crystals are grown on the substrate by the reactant gas having a relatively constant concentration.

As the results obtained in the example, the length is 3cn+ and the width is 4.5cm.
, 10III on a GaAs substrate with a height of 500 p m
Comparing the thickness uniformity of crystal growth of GaAs II with conventional results, it is found that the growth thickness t' of the substrate on the upstream side with respect to the flow of reaction gas and the growth thickness of the substrate on the downstream side with respect to the flow of reaction gas. If you take the ratio by dividing the difference from t'' by t'', the conventional result is about 10%, but in the case of the present invention, (t''-t'')/l'' is only 3%. Moreover, the crystal could be grown only by using the conventional flow rate of the reactant gas of about 273 ml.

〔Effect of the invention〕

As explained in detail above, by employing the metal-organic pyrolysis vapor phase growth method of the present invention, it is possible to form a uniform, high-quality crystal growth film on a substrate, which is highly effective. .

[Brief explanation of the drawing]

FIG. 1(a) is a schematic perspective view of a susceptor for explaining an embodiment of the reaction tube of the metal-organic pyrolysis vapor phase growth apparatus of the present invention. FIG. 2 is a schematic cross-sectional view of a susceptor for explaining an embodiment of a reaction tube of a phase growth apparatus; FIG. , FIG. 3 is a schematic diagram for explaining another embodiment of the reaction tube of the metal-organic pyrolytic vapor phase growth apparatus of the present invention. FIG. 4 is a schematic diagram for explaining a conventional metal-organic pyrolytic vapor-phase growth method. FIG. 5 is a schematic side view for explaining another conventional organometallic pyrolysis vapor phase growth method. In the figure, 11 is a susceptor, 12 is a substrate placement part, 1
3 is a pore, 14 is a vacuum exhaust hole, 15 is a thermocouple, 16 is a carbon body, 17 is a quartz cover, 18 is a piping tube, 21 is a reaction tube, 22 is a susceptor, 23.24 is a spacer, 25
26 is the hole of the vacuum chuck, 26 is the exhaust hole, 27 is the high frequency heating device, 31 is the reaction tube, 32 is the susceptor, 33, 34 is the spacer, 35 is the exhaust hole, 36 is the high frequency heating device, 37 is the reaction gas supply hole Each is shown below. Applicant: Director of the Agency of Industrial Science and Technology Tatsu Todoroki Figure 4 Figure 5

Claims (1)

[Claims] A plurality of intake holes are provided in the substrate attachment part of the susceptor of the metal-organic pyrolysis vapor phase growth apparatus, and the substrate is tightly fixed. A vapor phase growth method characterized by phase growth.