JPS63204713A - Substrate holder for molecular beam crystal growth - Google Patents

Abstract

PURPOSE:To prevent the local temperature rise on the part of a substrate in contact with a substrate holder and to make it possible to obtain uniform temperature on the whole surface of the substrate by a method wherein the substrate is provided by inserting it into the recessed part provided on the tabular member which transmits infrared rays. CONSTITUTION:A recessed part 23, into which a substrate 22 will be inserted, is provided on the tabular member 21 which is a substrate holder and transmits infrared rays. As the substrate holder is made of the material which transmits infrared rays, the substrate is directly heated up by the infrared rays emitted from a heater. On the other hand, as the holder itself does not absorb the infrared rays, it is not heated up, heat is not transmitted to the substrate from the holder, and the circumferential part of the substrate is prevented from heating up to the temperature higher than that of the center part of the substrate. As a result, the temperature distribution on the surface of the substrate becomes uniform, and the molecular beam epitaxial crystal having uniform thickness and composition can be obtained.

Description

[Detailed Description of the Invention] [Summary] A substrate holder for a molecular beam crystal growth apparatus, in which a recess is provided in a plate-like member that transmits infrared rays, and a substrate is inserted and installed in the recess. Molecular beams that do not absorb infrared rays prevent local temperature increases at the parts of the substrate that are in contact with the substrate holder, and ensure that the temperature of the substrate installed in the substrate holder is uniform over the entire surface of the substrate. Substrate holder for crystal growth.

[Industrial application field]

The present invention relates to a molecular beam epitaxial growth apparatus, and particularly to a substrate holder for this growth apparatus.

In recent years, the molecular beam epitaxial growth method has been developed using its characteristic excellent film thickness controllability, for example, gallium arsenide (
A method of forming a heterostructure crystal of aluminum, gallium, arsenic (AIIGaAs) into a superlattice structure on a compound semiconductor substrate such as a G plate, and a growth method of realizing new devices using a selective doping structure, etc. has been in the spotlight as a

In particular, devices such as high electron mobility transistors (HEMT) developed using this method have entered the stage of practical use.

In such a molecular beam crystallization device, there is a need for a substrate holder that can heat the substrate at a uniform temperature in order to maintain a uniform composition and thickness of the epitaxial crystal formed on the substrate.

[Conventional technology]

FIG. 3 shows the main parts of such a molecular beam crystal growth apparatus.

As shown in the figure, a crystal growth chamber 1 evacuated to a vacuum level of 10'' torr is equipped with a substrate holder 2 at its tip.
A metal plate made of tantalum (Ta) that heats the substrate holder 2.
A substrate manipulator 3 that has a built-in holder and is rotatably driven is provided, and at a position facing the substrate holder 2 there is an Al molecular beam source cell 4 that serves as a source for epitaxial crystals to be formed on the substrate, and a Ga molecule source cell 4. A radiation source cell 5 is installed.

As shown in FIG. 4, the structure of a conventional substrate holder is formed using a cylindrical metal material such as molybdenum (MO).
A through hole 1 in which a protrusion 11 is formed at the top and bottom in the center.
2 is provided, and a heat equalizing plate 14 is provided on the inner wall 13 of this through hole 12.
A substrate 16 made of GaAs or the like for epitaxial growth is placed thereon with a spacer 15 made of tantalum (Ta) interposed therebetween.

The substrate holder 17 is connected to the substrate manipulator 3 described above.
A substrate holder 17 made of Mo is attached to the substrate using an installation jig (not shown), and a heater 18 made of Ta is built into the substrate manipulator 3 to heat the substrate to a temperature of about 650°C. By heating the heater 18, the substrate 16 is heated together with the substrate holder 17 from the heat equalizing plate 14 side.

[Problem that the invention seeks to solve]

However, in the substrate holder 17 having such a conventional structure, the temperature of the substrate 16 installed in the substrate holder 17 is low due to the transfer of heat from the substrate holder 17 to the substrate 16. The temperature of the substrate 16 becomes lower at the periphery of the substrate 16 that is in contact with the substrate holder 17, and becomes lower at the center of the substrate 16, resulting in the disadvantage that the temperature of the substrate 16 is not uniform over the entire surface.

If the temperature of the substrate is not uniform in all regions, the thickness of the epitaxial layer formed on it,
The composition also has the disadvantage of not being uniform.

The present invention aims to solve the above-mentioned problems and provide a substrate holder in which the surface temperature of the substrate is made uniform.

[Means for solving problems]

As shown in the principle diagram of FIG. 1, the substrate holder for a molecular beam crystallization apparatus of the present invention is provided with a recess 23 into which a substrate 22 is inserted in a plate member 21 that transmits infrared rays.

[Effect]

In the substrate holder for molecular beam crystal growth of the present invention, since the substrate holder is made of a material that transmits infrared rays, the substrate is directly heated by the infrared rays from the heater, while the holder itself is heated because it does not absorb infrared rays. Unlike conventional holders, heat is not transferred from the holder to the substrate, and it is possible to prevent the periphery of the substrate from becoming hotter than the center of the substrate.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a cross-sectional view of a substrate holder for a molecular beam crystal growth apparatus according to the present invention. As shown in the figure, the substrate holder 31 for molecular beam crystal growth according to the present invention is made of two circular sheets such as sapphire that transmit infrared rays. It is composed of plate-like members 32 and 33. Each of these disc-shaped members 32 and 33 is provided with a recess 35 for inserting the board 34 and a recess 36 for reducing the contact of the board 34 with the board holder 31. 32 and 33 are attached to the substrate manipulator 37,
The substrate manipulator 3 described above is equipped with a rear mounting jig 39 having a thread groove 38 and made of Mo, and a front mounting jig 40 having a screw that fits into the thread groove 38.
It is fixed at 7.

A heater 41 made of Ta is embedded in the substrate manipulator 37.

A compound semiconductor substrate 34 such as GaAs is placed on the substrate holder 31 of the present invention, and the substrate is heated to a temperature of about 650° C. with the heater 41 embedded in the substrate manipulator 37. As shown in the direction of arrow A from the front side, molecular beams are irradiated onto the substrate 34 from a molecular beam source cell such as AI 5Gax As, and /l It is applied onto the substrate.
Form a GaAs crystal.

Then, since the substrate holder 31 is made of sapphire that transmits infrared rays, the substrate holder itself is not heated, and the substrate is heated only by the heat from the heater 41, so that the substrate 34 is heated uniformly over the entire surface. For,
An epitaxial layer having a uniform composition and thickness is formed thereon.

In this embodiment, sapphire was used as the material for forming the substrate holder 31, but PBN, which transmits infrared rays, may also be used.
(pyrolytic boron nitride) may also be used.

(Effects of the Invention) As described above, according to the substrate holder of the present invention, the temperature distribution on the surface of the substrate becomes uniform, so that the thickness and composition of the molecular beam epitaxial crystal formed thereon are reduced. Also has the effect of obtaining epitaxial crystals with uniform thickness.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram of the substrate holder of the present invention, Fig. 2 is a sectional view showing an embodiment of the substrate holder of the present invention, Fig. 3 is an explanatory diagram of the main parts of the molecular beam crystal growth apparatus, and Fig. 4 is a sectional view of a conventional substrate holder. In the figure, 21 is a plate member, 22.34 is a substrate, 23.35.36
31 is a substrate holder, 32.33 is a disc-shaped member,
37 is the board manipulator, 38 is the screw, and 39 is the rear mounting jig.

Claims (1)

[Claims] A substrate holder for molecular beam crystal growth, characterized in that a plate-like member (21) that transmits infrared rays is provided with a recess (23), and a peripheral part of a substrate (22) is fitted and fixed into the recess (23). .