JPH01175225A - Method and apparatus for vapor growth - Google Patents

Abstract

PURPOSE:To stabilize a growth speed of a CVD by gasifying, at a constant speed, a raw material such as TMG, TEI, TEG or the like which is a liquid at room temperature by a method wherein a flow rate is measured in a liquid- phase state of the raw material and the raw material is gasified and supplied to a growth apparatus. CONSTITUTION:Ten % soulitons of triethylindium (TEI) 11 and triethylgallium (TEG) 12 are filled into containers 13, separately; a pressure is applied through pressurization pipes 4; the solutions are pushed up into delivery pipes 15 and are jetted into a gasification chamber 18 through a nozzle 17. AsH3 is contained in a carrier gas; a mixed gas is fed to a reaction tube 35; an epitaxial growth operation is executed. A liquid flow meter 16 measures a flow rate; its measured result is fed back to a pressurization apparatus; the delivery amount can be kept constant.

Description

[Detailed Description of the Invention] CI! [Summary] The present invention relates to controlling the amount of raw material supplied in vapor phase Evita kinetic growth or cVD treatment, and aims to supply a constant amount of raw material regardless of the shape of the raw material container or the height of the liquid level. It is configured to measure the flow rate in a liquid phase state, vaporize it, and supply it to the growth apparatus.

[Industrial application field]

The present invention relates to controlling the amount of raw material supplied in vapor phase epitaxial growth or chemical vapor deposition (CVD). As is clear from the following description, the subject of the present invention does not matter whether epitaxial growth or non-epitaxial growth is performed, so when CVD is simply referred to in this specification, epitaxial growth is also included.

It goes without saying that CVD is an indispensable technology for forming semiconductor devices, but in recent years, MOCVD using organic metals as raw materials has become increasingly popular.
D is heavily used. For example, this can be done by mixing trimedelgallium (TMG) fumes with a carrier gas and arsine (
GaA
It is used to grow s epitaxially.

Organic metals such as TMO are liquid at room temperature, and bubbling is performed to mix them with the carrier gas. This process is performed, for example, on a 7MG33, as shown in FIG.
is stored in a bubbler 32, and a carrier gas such as H2 is bubbled therein to saturate it with TMG, which is then sent into the reaction tube.

In that case, the amount of TMG transported is determined by the flow rate of the carrier gas, and the flow rate of the carrier gas is determined by the flow rate of the carrier gas, such as a mass flow meter. The measurement is controlled by a ttWk meter 31.

Also, other raw materials such as AsHs+Ht are delivered from the vessel and introduced into the reaction tube 35 along with the TMG-containing carrier gas. , 22 is a valve, 34 is a constant temperature bath, 36 is a substrate, 37 is a susceptor that generates heat by absorbing high frequency power, 38
is a high frequency coil.

[Prior art and problems to be solved by the invention] A constant temperature bath 34 is used to keep the TMG content in the carrier gas constant, but the carrier gas becomes saturated due to bubbling when the gas flow rate is small. , as the flow rate increases, TMG will be delivered in an unsaturated state, so TMG
The amount of transportation is not accurately controlled.

The purpose of the present invention is to provide a method and apparatus for transporting a liquid raw material such as TMG by a predetermined amount, and thereby to provide a CVD technique that can control the growth rate with higher precision. be.

[Means for solving problems]

In order to achieve the above object, the vapor phase growth method of the present invention involves sending raw materials for performing vapor phase growth in a liquid phase while controlling the flow rate, evaporating the delivered raw materials, The vaporized raw material is transported in the gas phase to the reactor.

Furthermore, the vapor phase growth apparatus of the present invention includes a means for delivering raw material for performing vapor phase growth while controlling the flow rate in a liquid phase, a means for evaporating the delivered raw material, and a means for evaporating the raw material to be vaporized. A means for transporting the raw materials in the gas phase to the reactor is provided.

[For production]

When handling liquid materials as in the present invention, if the method measures the volume or volumetric flow rate of the liquid mass, instability due to saturation/unsaturation will not occur, and accurate measurement will be performed. Furthermore, in the case of a liquid, there is almost no change in volume due to pressure, so highly accurate measurement is also possible from this point of view.

[Embodiment] FIG. 1 is a schematic diagram showing the configuration of a first embodiment of the present invention. CVD according to this example is performed as follows.

Triethyl indium (TRI) 11 and triethyl gallium (TEG) are placed in two stainless steel containers 13, respectively.
12 are accommodated. In this example, these organic metals are diluted with hexane to a concentration of 10%.

When pressure is applied to the internal space of these containers with It or N2 gas through the pressurizing pipe 14, the above-mentioned organometallic solution is forced into the delivery pipe 15 and is ejected into the vaporization chamber 18 through the nozzle 17. Hexane is a solvent that evaporates easily,
Since the content of TEI and TEG is small, the sprayed solution is instantaneously vaporized and mixed with a carrier gas such as H2.

The carrier gas contains a compound of group V elements such as AsHt, and a mixture of these gases is sent to the anti-polishing tube 35 to epitaxially grow a material having a predetermined composition. As in FIG. 3, 36 is a substrate, 37 is a carbon susceptor,
38 is a high frequency coil.

container! The flow rate of the raw material solution extruded from 3 is measured by a liquid flow meter 16, and the measurement results are fed back to a pressurizing device (not shown). Delivery of raw material solution? is determined by the pressure difference, so this control system keeps the feed rate of the raw material solution constant.

In this example, the feed rate of the raw material is controlled by the extrusion pressure as described above, but the dilution rate of the organometallic is increased or decreased.
By adjusting the flow rate to the one that is easiest to control, it is possible to further improve the raw material supply accuracy.

FIG. 2 is a schematic diagram showing a second embodiment of the present invention. The structure of the growth apparatus is the same as that of the first embodiment, so it is omitted in the drawing.

In this embodiment, the raw material TMG is dropped into the vaporization chamber 23. Since the carrier gas rising in the vaporization chamber is heated by the heater 24 to a temperature above the boiling point of TMC and below the decomposition temperature, the 7M0 droplets are vaporized and mixed into the carrier gas without being decomposed.

22 is a finely adjustable valve such as a needle valve. The feed rate of the raw material gas corresponds to the dropping rate of TMG, and this is adjusted by the way the valve 22 is opened. As in the first embodiment, TMG transport type adjustment can be made more precise by appropriately diluting TMG, but the dropping rate control technology used in automatic titrators can also be applied to this embodiment. It is.

In this embodiment, liquid TMG is supplied at a constant rate and vaporized in one shot at a temperature above the boiling point, so that saturation/unsaturation is irrelevant and the supply rate becomes stable.

In both the first and second embodiments, it is desirable that the piping from the vaporization chamber to the reaction tube be heated to prevent the organometallic from condensing again. This is also done in normal vapor phase growth equipment.

〔Effect of the invention〕

In the present invention, TMG, TUT, which is liquid at room temperature,
Since raw materials such as TIEG are vaporized at a constant rate, CVD
The growth rate of will be stable.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of the first embodiment, FIG. 2 is a schematic diagram showing the configuration of the second embodiment, and FIG. 3 is a conventional CVD
11 is a diagram showing the configuration of the device, and in the diagram, 11 is a TUT, 12 is a TEG, 13 is a container, 14 is a pressurizing pipe, 15 is a delivery pipe, 16 is a flow meter, 17 is a nozzle, 18 is a vaporization chamber, 21 is TMG. 22 is a valve, 23 is a vaporization chamber, 2o is a heater, 31 is a gas flow meter, 32 is a bubbler, and 33 is a TM. 34 is a constant temperature bath, 35 is a reaction tube, 3G is a base, 37 is a susceptor, and 38 is a high frequency coil. Schematic diagram showing the configuration of the first embodiment. Figure 2 is a schematic diagram showing the configuration of a conventional CVD device. Figure 3 is a diagram showing the configuration of a conventional CVD device.

Claims (4)

[Claims] (1) The raw material for performing vapor phase growth is delivered in a liquid phase while controlling the flow rate, the delivered raw material is evaporated, and the vaporized raw material is transferred to a reaction device in a gas phase. A vapor phase growth method characterized by transporting to. (2) A means for delivering the raw material for performing vapor phase growth while controlling the flow rate in a liquid phase, a means for evaporating the delivered raw material, and a means for converting the vaporized raw material into a gas phase. 1. A vapor phase growth apparatus comprising means for transporting the state to a reaction apparatus. (3) The vapor phase growth apparatus according to claim 2, wherein the means for vaporizing the liquid raw material is configured to pressurize the liquid raw material and eject it into a vaporization chamber. (4) The vaporizer according to claim 2, wherein the means for vaporizing the liquid raw material is configured to drop the liquid raw material into a carrier gas heated to a temperature higher than the boiling point of the raw material. Phase growth device.