JPS6258641A - Vapor-phase epitaxial growth equipment - Google Patents

Abstract

PURPOSE:To enable a high-accuracy epitaxial growth by a method wherein the temperature and flow rate of gas passing through capillaries for a gas flow path in the interior of a reservoir filled with a highly evaporative element are controlled and the evaporation quantity of highly evaporative material is controlled. CONSTITUTION:There is a susceptor 12 made of carbon in the interior of a growth ampul 11, a CdTe substrate 13 is placed on the susceptor 12, and moreover there is a reservoir 14 made of quartz and filled with mercury Hg. Capillaries 14 for gas flow path connected with a gas pipe 15 for temperature control and branched into plural fine tubes are formed in the interior of the reservoir 14 and these branched capillaries 16 are again integrally formed by a gas pipe 17 for temperature control at the outlet of the reservoir 14. The method to control the temperature of the Hg filled in the reservoir 14 comprises a high- pressure bomb 18 which feeds gases of nitrogen gas and the like as the kinds of gases. These gases are controlled in a flow rate of a proper amount by a flow rate control unit 19, but are fed back by the control and thermocouples 20 which detect the temperature of the Hg.

Description

Detailed Description of the Invention [Summary] The present invention is a vapor phase epitaxial growth apparatus in which a reservoir filled with an easily evaporable element is heated at a temperature of By forming a plurality of capillary tubes through which controlled gas flows, and passing gas at a predetermined temperature through the capillary tubes, the temperature and flow rate of the easily evaporable element connected to the capillary tubes in the reservoir are controlled. By adjusting the temperature appropriately, the temperature of the easily evaporable element in the reservoir is controlled to ensure proper evaporation.

[Industrial Field of Application] The present invention relates to vapor phase epitaxial growth, and particularly to a method for controlling the temperature of easily evaporable elements.

The vapor phase epitaxial growth method involves vaporizing a material containing ingredients that cause crystal growth, and heating the growth substrate in that atmosphere to form a film on the surface of the growth substrate. It is widely used for film growth.

For example, when performing vapor phase growth of mercury cadmium, tellurium (HgCdTe), etc., which are used in materials such as infrared lasers, mercury is an extremely volatile element, so conventionally, easily vaporizable elements were stored in the reservoir. This is inserted into a growth ampoule, and the mercury is evaporated by resistive heating of the reservoir.

However, this reservoir has the disadvantage that the temperature of the reservoir is affected by reflection from the susceptor, which is located close to the reservoir and has a high temperature, and there is a demand for an improvement in this problem.

[Prior Art] FIG. 4 is a sectional view of a main part of a conventional vapor phase epitaxial growth apparatus.

As an example of vapor phase epitaxial growth, a case will be described in which a Hg Cd Te layer is grown on a cadmium telluride (CdTe) substrate.

A susceptor 2 made of carbon is placed inside a growth ampoule 1 made of quartz, and a substrate 3 of CdTe is placed on the susceptor 2.

Inside the growth ampoule, there is a quartz reservoir 5 filled with mercury (Hg), and a heater 6 is provided to raise the temperature of Hg.The heater power supply 7 controls the temperature using a signal from a thermocouple 10. is being done.

Outside the growth ampoule is a high frequency induction heating device 8 for heating the substrate, which heats the substrate to a predetermined temperature.

To grow Hg Cd Te crystals, dimethyl cadmium ((CH3) 2 Cd) is used as a reaction gas at about 20 Torr and diethyl tylide ((C2H5) 2
Te) is supplied at a pressure of about 10 Torr, and hydrogen gas is supplied as a carrier gas at a pressure of approximately atmospheric pressure.

The Hg vapor is heated by the heater 7, and by raising the temperature to about 300°C, the Hg vapor is heated to about 70 Torr.
becomes the pressure.

In this way, the temperature of the substrate 3 is controlled by the high frequency induction heating device 8.
By heating the substrate temperature to 500℃,
The film is deposited at a growth rate of a/hr.

In such conventional methods, it is necessary to control the vapor pressure of mercury in particular, but the reservoir is affected by the temperature of the susceptor and it is difficult to maintain it at a constant temperature.
The vapor pressure of g fluctuates during the growth, resulting in a uniform Hg Cd T
The disadvantage is that it is impossible to grow e.

[Problems to be Solved by the Invention] A problem with the conventional vapor phase epitaxial growth method described above is that the temperature of the reservoir filled with mercury in the growth ampoule fluctuates.

[Means for Solving the Problems] The present invention provides a vapor phase epitaxial growth apparatus that solves the above problems. A vapor phase epitaxial growth apparatus comprising a substrate, a quartz reservoir filled with an easily evaporable material such as mercury, and a reactant gas supply hole, and in which an easily evaporable element is used as a constituent element of a compound semiconductor to be grown. A plurality of gas flow capillary tubes are arranged in a reservoir filled with an easily evaporable element, and gas whose temperature is completely controlled is passed through the plurality of gas flow capillary tubes.
By controlling the flow rate, the surface temperature of the gas channel capillary tube is maintained constant, and the temperature of the easily evaporable material in contact with the surface of the gas channel capillary tube is controlled, thereby controlling the amount of evaporation. This is what I did.

[Function] The present invention is a vapor phase epitaxial growth method in which an easily evaporable element is used as a constituent element of a compound semiconductor to be grown. Since the temperature cannot be maintained accurately because the element is heated by both radiant heat and radiant heat, multiple capillary tubes for the gas flow path are arranged in the reservoir that stores the easily evaporable element to serve as a direct heating or cooling body. By passing a gas whose temperature is completely controlled through the plurality of gas flow capillary tubes and controlling the if, the contact area of the easily evaporable material with the gas flow capillary tubes is increased. for,
Enables highly sensitive temperature control of easily evaporable materials,
It controls the vapor pressure of easily evaporable materials.

[Example] FIG. 1 is a sectional view of a vapor phase epitaxial growth apparatus of the present invention.

A carbon susceptor 12 is placed inside the growth ampoule 11.
There is a CdTe substrate 13 placed on a susceptor 12, and a quartz glue reservoir 14 filled with mercury Hg.

Inside the reservoir 14, a capillary tube 1 for a gas flow path is connected to a gas pipe 15 for temperature adjustment and branched into a plurality of thin tubes.
6 is formed, and at the outlet of the reservoir 14, these branched capillary tubes I6 for the gas flow path are again unified by the gas pipe 17 for temperature adjustment.

A method for controlling the temperature of Hg filled in the reservoir is a high-pressure cylinder 18 that sends gas such as nitrogen, and the flow rate of these gases is controlled to an appropriate amount by a flow rate control device 19. Thermocouple 2 that detected the temperature of and Hg
0 is fed back.

That is, by optimally adjusting the gas flow rate, the temperature of the Hg filled in the reservoir can be controlled extremely accurately through heat exchange between the mercury and the gas.

FIG. 2 is a side sectional view of the reservoir, and FIG. 3 is a front sectional view thereof.

It is shown that the capillary tube 16 for the gas flow path is formed by penetrating the mercury 21.

[Effects of the Invention] As described above in detail, by employing the vapor phase epitaxial growth apparatus of the present invention, it is possible to accurately control the vapor pressure of easily evaporable elements, and high-precision epitaxial growth is possible. There is a great effect of becoming.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the vapor phase epitaxial growth apparatus of the present invention, FIG. 2 is a side cross-sectional view of the reservoir of the present invention, FIG. 3 is a front cross-sectional view of the reservoir of the present invention, and FIG. The figure is a sectional view of main parts of a conventional vapor phase epitaxial growth apparatus. In the figure, 11 is a growth ampoule, 12 is a susceptor, 13 is a substrate, 14 is a reservoir, 15 and 17 are gas pipes for temperature adjustment, and 16 is for a gas flow path. Capillary tube, 18 is high pressure cylinder, 19 is flow control device, 20 is thermocouple, 21 is mercury, rihe 1 syl precept + k) f-interruption 1 ka review sl @ child departure E s qr +) 7” bar n LrHJ mtliI
PA Figure 3

Claims (1)

[Claims] A growth ampoule (11) is provided with a growth substrate (13), a reservoir (14) filled with an easily evaporable material (21), and a supply hole for a reaction gas. In a vapor phase epitaxial growth apparatus using an element as a constituent element of a compound semiconductor, a plurality of capillary tubes for gas flow paths (16) are arranged in the reservoir (14) filled with the easily evaporable element, and the plurality of gas A vapor phase epitaxial growth apparatus characterized in that the amount of evaporation of the easily evaporable material is controlled by controlling the temperature and flow rate of gas passing through the channel capillary (16).