JPH0732132B2 - Vapor phase growth equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In the vapor phase growth apparatus of the present invention, a blade is provided in a rotating portion of a susceptor, gas is injected into the blade to rotate the rotating portion, and thereby powder generation due to abrasion is generated. To achieve good epitaxial growth without contamination.

[Industrial application field]

The present invention relates to a vapor phase growth apparatus, and more particularly to improvement of a vapor phase growth apparatus suitable for a metalorganic pyrolysis vapor phase growth method (MO-CVD method) and the like.

For example, in a compound semiconductor device or the like, a semiconductor substrate in which a single crystal layer of various compositions and impurity doping is epitaxially grown on a single crystal substrate is often used, and the growth method thereof is large in a vapor phase growth method, particularly a MO-CVD method. Expectations are coming.

However, the conventional vapor phase growth apparatus has the following problems and needs to be improved.

[Problems to be solved by conventional technology and invention]

The MO-CVD method is a vapor phase epitaxial growth method in which an organic compound is used as a starting material for a group II or III element for which a stable hydrogen compound is not obtained at room temperature and a hydrogen compound is usually used as a starting material for a group IV, V or VI element. For example, in the growth of gallium arsenide (GaAs), compounds that are stable near room temperature and decompose at the crystal growth temperature to dissociate elements, such as trimethylgallium ((CH ₃ ) ₃ Ga) and arsine (AsH ₃ ) And as a raw material, a crystal growth reaction of (CH ₃ ) ₃ Ga + AsH ₃ → GaAs + 3CH ₄ is applied.

The growth mechanism of vapor-phase growth method-halide method and hydride method-which does not use organometallic compounds, which was developed prior to MO-CVD method, is controlled by phase, whereas the growth mechanism of MO-CVD method is controlled. Is controlled by the kinetics of the substance transported to the growth surface, so that the growth rate tends to vary greatly depending on the position in the vapor phase growth apparatus.

Therefore, in the vapor phase growth apparatus used for the MO-CVD method, the growth substrate is often rotated in order to make the thickness of the epitaxial growth layer uniform. That is, as shown in the schematic diagram illustrated in FIG. 2, the growth substrate 21 is placed on a susceptor 22 usually made of graphite, and the susceptor 22 is heated by a high-frequency coil 24 surrounding a reaction tube 23 made of quartz glass,
A rotary part 22 provided on a susceptor 22 is a vapor phase growth apparatus for performing epitaxial growth by introducing a source gas from an introduction port 23i.
R is driven by a rotary shaft 25 inserted from the outside of the reaction tube 23 and made of, for example, quartz or carbon.

However, if a vapor phase growth apparatus that drives the rotating portion of the susceptor as described above from the outside by a mechanism such as a worm gear is used, the lubricant or the like is limited, so that the transmission mechanism from the rotating shaft 25 to the rotating portion 22R of the susceptor is limited. Also, the susceptor material and the like are scraped by the friction between the rotating portion 22R of the susceptor and the pedestal portion 22B to generate fine powder, which is accompanied by the problem that it is scattered on the growth surface and deteriorates the epitaxial growth layer, That improvement is needed.

[Means for solving problems]

The problem is that it has a susceptor and a gas supply means, and the susceptor has a disk-shaped portion on which a substrate to be grown is placed, a blade provided below the disk-shaped portion, and a rotation center shaft. A rotary portion provided with a hollow, a hollow into which the rotary portion fits freely, and at least two gas guide holes that are provided at positions deviated to the left and right with respect to the central axis of rotation and open into the hollow. The susceptor has a pedestal part, and the gas supply means injects gas from each of the gas guide holes to the blade so that the gas flow rate can be controlled, and the susceptor has a rotating part for controlling the gas supply means. This is solved by a vapor phase growth apparatus configured such that the rotation direction and the rotation speed can be arbitrarily changed depending on the gas flow rate. Also, when the rotating portion rotates, the structure is such that it floats above the pedestal portion of the susceptor, the gas is injected from a plurality of injection ports, and torque is applied to the rotating portion in opposite directions to control the rotation speed. A structure that does

[Action]

In the vapor phase growth apparatus according to the present invention, a blade is provided in the rotating portion of the susceptor, for example, as will be described later, and gas is injected to the blade to rotate the rotating portion to perform epitaxial growth.

In this driving method, there is no mechanical transmission mechanism, and further, the rotating portion comes into contact with the rotating portion in a state of floating and rotating with respect to the pedestal portion of the susceptor, or in a state of canceling at least a part of gravity by buoyancy. It is easy to reduce the load applied to the area or contact surface, and the generation of powder due to wear is prevented.

It is most convenient to make the injected gas the same as the carrier gas, but separate this from the raw material gas and guide it to multiple injection ports, and apply torques in opposite directions applied to the rotating parts to the flow rate of the gas. It is possible to easily select the rotation speed by controlling with.

〔Example〕

 The present invention will be specifically described below with reference to examples.

FIG. 1 (a) is a schematic view showing an embodiment of the present invention, FIG. 1 (b) is a plan view of the susceptor, FIG. 1 (c) is a side view in which the pedestal portion is cut away, and 1 is the growth target. Substrate 2, reference numeral 2R is a susceptor consisting of a rotating portion 2R and pedestal portion 2B, 3 is a reaction tube,
Reference numeral 4 is a high frequency coil, 5 is two gas supply pipes, and 6 is a gas guide hole connected to the gas supply pipe 5.

The rotating portion 2R of the susceptor of this embodiment is provided with a blade 2Rb below a disk-shaped portion 2Ra on which the growth substrate 1 is placed, and further has a rotation center axis 2Rc. Also, the pedestal part 2 of the susceptor
B has a recess into which the rotating portion 2R described above fits, and further two gas guide holes 6 are provided at positions deviated to the left and right with respect to the rotation center axis 2Rc.

Place the rotating part 2R of the susceptor on the pedestal part 2B, and let the normal carrier gas flow from the gas supply pipe 5 and the gas guide hole 6,
For example, the rotating portion 2R is rotated at a rotation speed of about 20 rpm or less. The rotation direction and the rotation speed can be easily controlled by selecting the gas flow rates of the two gas introduction holes 6.

Furthermore, buoyancy acts on the rotating portion 2R of the susceptor by the inflowing gas, and in this embodiment, the rotating portion 2R slightly floats from the pedestal portion 2B and contact between the two is almost eliminated, and fine powder generation due to wear is prevented. To be done. For example, the average defect density of the epitaxial growth layer due to dust, powder, etc. is about 2000 pieces / cm ² , whereas it is reduced to about 500 pieces / cm ² in this embodiment.

〔The invention's effect〕

As described above, according to the present invention, even if the susceptor of the vapor phase growth apparatus is rotated, generation of powder due to abrasion is prevented, and good epitaxial growth with almost no contamination is realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of an embodiment of the present invention, and FIG. 2 is a schematic diagram of a conventional example. In the figure, 1 is a substrate to be grown, 2 is a susceptor, 2R is a rotating part of the susceptor, 2Ra is a disk-shaped part, 2Rb is a blade, 2Rc is a central axis of rotation, 2B is a pedestal part of the susceptor, 3 is a reaction tube, 4 is a high frequency coil, 5 is a gas supply pipe, and 6 is a gas guide hole.

Claims (2)

[Claims] 1. A susceptor and a gas supply means, wherein the susceptor has a disk-shaped portion on which a substrate to be grown is placed, a blade provided below the disk-shaped portion, and a rotation center shaft. A rotary portion provided with a hollow, a hollow into which the rotary portion fits freely, and at least two gas guide holes that are provided at positions deviated to the left and right with respect to the central axis of rotation and open into the hollow. The susceptor has a pedestal portion, and the gas supply means injects gas from each of the gas guide holes to the blade so that a gas flow rate can be controlled. The susceptor has a rotating portion for controlling the gas supply means. A vapor phase growth apparatus characterized in that the rotation direction and the number of rotations can be arbitrarily changed depending on the gas flow rate to be generated. 2. The gas according to claim 1, wherein the gas is the same gas as the carrier gas supplied to the substrate to be grown and is supplied to the gas introducing hole independently of the carrier gas. Phase growth equipment.