KR940010147B1 - Cracker cell for hybride gas - Google Patents

Abstract

The cracker cell for compound semiconductor epitaxy thin films includes a gas injection tube (9) and a thermal insulation reflector (10). The cell can dissociate the hydride gas with a high efficiency and with a low gas leakage and outgassings, by use of a gas injection tube made of stainless steel, a ceramic tube made of alumina, and a baffle and a thermal insulation reflector made of tantalum (Ta). It consists of a gas injection flange section (3) with a ceramic (7) and a stainless steel tube (14), a gas dissociation section (4) with baffle (17), and an electrical feedthrough flange section (2) with Cu wire (5) connecting lead wires of thermocouple (8) and lead wires (16) of heating filament (6).

Description

Cracker cell for hydride gas

1 is a cross-sectional view of a cracker cell assembly of the present invention.

Sections 2a, b or in cross section and plan view of the gas injection flange.

Section 3a, b or a cross-sectional view and plan view of the gas cracker.

* Explanation of symbols for main parts of the drawings

1: Deposition chamber flange 2: Flange part for electric feed throw

3: gas injection flange portion 4: gas decomposition device portion

5: copper wire 6: filament

7: ceramic tube 8: thermocouple

9 injection tube 10 reflector

11: alumina ceramic tube 14: stainless steel tube

16: lead wire 17: baffle

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a device used to fabricate a compound semiconductor epitaxy thin film, which efficiently thermally dissociates a hydride raw material gas such as asin (AsH ₃ ) and phosphine (PH ₃ ). It relates to a cracker cell which is a device.

In electronic and photonic device fabrication, high-quality compound semiconductor epitaxy thin films are required. To achieve this, chemical beam epitaxy (CBE) and gas source molecular beam epitaxy (GSMBE) are operated under ultra high vacuum. Deposition systems are being developed, and various major devices such as cracker cells are being actively developed to maximize the performance and efficiency of the deposition system.

Thin film action of compound semiconductor epitaxy CBE and GSMBE systems use metalorganic gas and hydride gas as raw material gas. To produce high quality epitaxy thin film suitable for device fabrication, hydride raw material gas is used. It must be pyrolyzed at high temperature and injected into the ultra high vacuum deposition chamber. Therefore, the present invention must be injected into the deposition chamber of the ultra-high vacuum state device. Therefore, the cracker cell of the present invention receives a hydride raw material gas such as acine or phosphine from a gas handling system, so that these raw material gases are in a hot zone or a crackin zone at 800 to 1000 ° C. ) Is a device for stably supplying a dimer gas beam such as As 2 and P2 to the deposition chamber while having high efficiency of pyrolysis through several layers.

The cracker cell used in the previously developed moecular beam epitaxy (MBE) system is a two-stage device, in which monoatomic solid masses such as Asic and phosphorus (P) are loaded by sources such as Kundsen cells. Evaporate the raw material gas in one step and pass the evaporated raw material gas through a cracking zone to pyrolyze it in two steps.

In addition, the cracker cell, which is a conventional gas source used in CBE and GSMBE systems, can be mounted on a 4.5 "size flange, which requires a lot of installation space.

In the existing device, since the gas injection pipe made of metal is installed vertically with the flange, the number and installation space of the injection pipe are limited. Due to the structure of the metal injection pipe, a heat transfer prevention measure from the high temperature portion to the flange is a lower structure. There are many problems in manufacturing, installing, and repairing the device due to the incomplete structure and the complicated structure of the device.

In order to solve the problems of the existing apparatus and to perform efficient pyrolysis function, the required apparatus must satisfy various conditions.

First, the material used must be extremely low in outgassing because the device must be operated under ultra-high vacuum.

Secondly, due to the high operating temperature of around 1000 ° C, all materials must be high melting point materials.

Third, the device uses good raw material gas, so stability without gas leakage should be ensured.

Fourth, the ratio of the dimer to the tetramer should have a thermal decomposition property of 90% or more, and the stability of the generated force should be good to ensure reproducibility during the deposition of a large number of times.

Fifth, the gas pressure difference between the gas inlet line and the high vacuum deposition chamber is maintained, so that the low gas beam must be precisely controlled and have fast response characteristics.

Sixth, the device should be effectively compacted to be installed on a 2,75 "(70mm) size flange, and the device should be easy to manufacture, install, maintain, and repair.

The present invention has been made for the purpose of satisfying the above conditions.

In order to achieve the above object, in the present invention, the gas injection pipe and the flange part are made of stainless steel, and the ceramic tube is made of materials such as alumina, baffle, and heat shield reflector such as tantalum (Ta), so that gas generation is extremely low in ultra high vacuum. It was.

In particular, alumina, filament, baffle, and tantalum (Ta) metal body used in the heat shield reflector, which are used in the high temperature heater of about 1000 ° C, is a high melting point material that can operate at a high temperature of about 1000 ° C. It may be used.

The stainless steel tube, which is a gas inlet used in this device, is welded to the flange part, preventing gas leakage, and the connection to the gas line outside the gas injection tube is made of VCR fitting so that there is no gas leakage. The alumina ceramic tube and the baffle collide a number of times.

Due to such collisions, high efficiency pyrolysis characteristics are secured. Especially, the efficiency of gas decomposition is increased due to the micropores of 0.25 mm or less, which are manufactured by laser or ultrasonic processing in the baffles, and the gas emission of the inner wall of the deposition chamber is increased due to the effective thermal barrier device. In addition to preventing contamination and maintaining high temperature in the decomposition chamber, high efficiency pyrolysis characteristics and reproducibility are ensured at the same time.

In addition, the pressure difference between the deposition chamber and the gas injection pipe is maintained due to the reduction of the gas conductance to the minute holes having a diameter of 0.25 mm or less installed in the baffle, and thus a small amount of precise gas control and fast response characteristics are secured.

And the flange used in the present invention is a stainless steel flange of 2.75 inches (70mm) size, the gas injection pipe which is a main component is installed on the flange side, as a dense device in which a support, an electric signal line, an alumina ceramic tube is installed perpendicular to the flange It is characterized by making the device easy to manufacture, install, maintain and repair. Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 is a cross-sectional view of the cracker cell (A) assembly installed in the deposition chamber flange (1), the cracker cell (A) is a flange portion for electrical feedthrough (2), a gas injection flange portion ( 3) It consists of three main parts which are gas cracking apparatus parts (4).

The flange portion 2 for the electrical feedthrough is composed of four copper wires 5 having a diameter of 1/4 ". Each copper wire 5 is attached to the flange body by a ceramic and electrically insulated from the main body. have.

The gas injection flange portion 3 can mount the copper gaskets 1a and 2a on both upper and lower sides, so that the flanges 1 of the deposition chamber are provided by the two copper gaskets 1a and 2a. ) And the electrical throw flange portion (2).

The long ceramic tube 7 for gas supply was self-supported and arranged with a stainless steel tube 14, and a hole 9a was drilled in the side and center of the gas injection flange portion 3 so that the gas injection tube 9 and It was to be connected to the long ceramic tube (7).

(A) and (b) of FIG. 2 show cross-sectional views and plan views of the gas injection flange portion 3, respectively, and as shown in (b), between the bolt holes 13 for assembling the gas injection flange. Position and drill the gas through hole 9a in the flange side.

In the center of the flange, make a staircase as shown in the figure to install the ceramic tube (7), and install a stainless steel tube (14) that can drill a hole and support the gas tube (7) for welding, and weld the tube around the tube. Array and support.

The gas leakage prevention function between the ceramic tube 7 and the stainless steel tube 14 is solved by the small manufacturing error of the tubes and the large gas conductance of the ceramic tube 7. Connection to the external gas line with the gas injection pipe 9 is made of VCR fitting terminal, so it is easy to remove and assemble.

Four through-holes 15 are drilled in the flange larger than 1/4 "in diameter to provide insulator Makro spacers 18 for insulation between the various lead wires 16 and the flange to ensure good insulation. .

In order to electrically insulate the four copper wires 5 of the electrical feed throw flange portion 2 and the gas injection flange 3 main body, a Makro spacer 28 as an insulator was used.

The gas cracker unit 4 includes a tungsten or tantalum filament 6 for generating heat, a heat shield reflector 10 for preventing the generated heat from being radiated to the outside, a thermocouple 8 for measuring temperature, and various lead wires ( 16) and the ceramic tube 11 for lead wire insulation, and three baffles 17 for increasing the number of collisions of gases and the pressure difference between the pressure of the injection tube 9 and the ultra-high vacuum of the deposition chamber. It is.

Since the operating temperature of this part is a high temperature of 800-1000 degreeC, the ceramic tube 11 is made of alumina (A1 ₂ O ₃ ), and the metal body is made of tantalum (Ta) material.

(A) and (b) of FIG. 3 show the cross section and plane of the gas cracker part 4, respectively.

The filament 6 has a spiral spring shape in which the tantalum wire is made slightly smaller in diameter than the outer diameter of the ceramic tube 11.

Both ends of the filament 6 are connected to the power lead wire 16 by spot welding or mechanical coupling, and to keep the lead wire insulated from other components in the alumina ceramic tube 11. Let it pass

In order to prevent heat emission to the outside, that is, radiant heat, a thin tantalum thin film is made into two or three layers in a cylindrical shape, and a heat-dissipating reflector 10 is manufactured, and the inner diameter of the ceramic tube 7 is formed at the upper end of the reflector 10. The same cylindrical shape (10a) was attached to facilitate the arrangement and self-support in the ceramic tube (7).

The lower heat shield reflector 10b has a hole 10c through which three power supply and thermocouple lead lumina ceramic tubes 11 can pass. And the reflector 10 does not come into contact with the filament 6 or the inner wall of the deposition chamber.

Three baffles 7 are installed in the ceramic tube 7 heated by the filament 6, and each of the baffles 17 is a microhole 17a having a diameter of 0.25 mm or less through laser or ultrasonic processing on a thin tantalum plate. ) Is perforated like the 3a diagram, and the edge of the baffle 17 is manufactured in the form of a bracket for uniform contact with the inner wall of the ceramic tube 7 and the baffle 17.

In addition, in order to connect the four lead wires 16 of the gas cracker unit 4 and the four copper wires 5 of 1/4 "in diameter, a fastening hole 12a is drilled in the upper end of the copper wire 5, and the copper wire (5) Holes were made perpendicular to the longitudinal direction to allow the use of bolts (12c) by screwing in one part and the other part to be used to remove residual gas generated during bonding.

The manufacturing method as described above facilitates the connection and detachment of various lead wires and removes gas trapping that is hindered by ultra-high vacuum. The gas cracker unit 4 has a function of thermally decomposing the supplied raw gas, and the heat generated in the filament 6 when the power is applied is directly in contact with the ceramic tube 7 through which the gas passes. It forms a high temperature part, the radiant heat emitted to the outside is blocked by the heat shield reflector 10, the heat of the upper end of the high temperature of the ceramic tube 11 by using a long ceramic tube (7) is the lower portion of the ceramic tube (11) By preventing the transfer to the temperature increase of the flange portion (2, 3), which is the lower part of the present invention.

Referring to the operation and effects of the present invention configured as described above, the electrical feed throw flange portion 2 includes a lead wire 16 and a ceramic tube for supplying power to the filament 6 which is a part of the gas cracking device portion 4. It functions to provide an output lead wire of the thermocouple 8 for measuring the temperature of (7).

The function of the gas injection flange portion 3 serves to receive the raw material gas from the outside of the deposition chamber to the injection pipe (9), and to send the raw material gas to the gas decomposition device (7) through the long ceramic tube (7). .

The gas injection flange portion 3 according to the present invention has the advantage that the long ceramic tube 7 is accurately arranged and supported on the flange itself, and a smooth gas supply from the outside to the deposition chamber is provided in an extremely limited space without gas leakage. Is done.

The gas injection pipe 9 welds the stainless steel pipe 14 to prevent leakage of toxic gases, and easily mixes and separates the two gases by using a T-shaped pipe.

In addition, the flange (1) and the electrical feed-through flange (2) of the deposition chamber and the self-aligning and easy to separate characteristics.

The filament 6 has a strong contactability when mounted on the ceramic tube 7 due to its elasticity and diameter difference in the form of a spring, and the spacing between the threads of the filament 6 is kept constant so that the ceramic tube can be efficiently without short circuit. The upper end of (7) can be heated.

Due to the fine holes 17a of the baffle 17, the number of collisions increases when the source gas passes through the high temperature portion, thereby improving thermal decomposition efficiency, and reducing the gas conductance of the fine holes 17a and the ultra-high vacuum deposition chamber and the gas. A pressure difference with the injection pipe 9 is generated, so that a small amount of precision gas is easily adjusted.

It is easy to replace parts that occur during malfunctions that can be easily separated and assembled, and can be installed on a 2.75 "size flange because of its self-support and arrangement in a narrow space. Insulation is good.

In the gas cracker 4 of the present invention, the gas injected by the three baffles provided in the high-efficiency alumina ceramic tube collides a large number of times with the baffle of the ceramic tube which is the high temperature portion.

Due to such collisions, high efficiency pyrolysis characteristics are secured. Especially, the efficiency of gas decomposition is increased due to the micropores of 0.25 mm or less, which are manufactured by laser or ultrasonic processing in the baffles, and the gas emission of the inner wall of the deposition chamber is increased due to the effective thermal barrier device. To prevent contamination, maintain ultra-high vacuum, and maintain high-temperature pyrolysis characteristics and reproducibility by maintaining high temperature in the decomposition chamber.

In addition, due to the self-arrangement and support of the thermal barrier reflector, the reliability required for long-term operation such as short circuit protection is high, and it is easy to replace various parts in case of malfunction.

In the present invention, the material of the flange portion is made of stainless steel, the ceramic tube is made of alumina, and the baffle and the thermal barrier refiller are made of tantalum (Ta) and the like to minimize the generation of gas in ultra high vacuum. .

In addition, as described above, the ceramic tube uses a tantalum (Ta) metal body for alumina, filament, baffle, and thermal barrier reflector, and thus has a high melting point capable of operating such a material at a high temperature heater of about 1000 ° C.

The stainless steel tube, which is the gas inlet, is welded to the flange part to prevent gas leakage, and the connection to the external gas line of the gas inlet tube is made of VCR fitting so that there is no gas leakage at all.

In addition, the pressure difference between the deposition chamber and the gas injection tube is maintained due to the reduction of the gas conductance to the micropores having a diameter of 0.25 mm or less installed in the baffle, and the small amount of precision gas control and fast response characteristics are secured due to the pressure difference.

And the flange used in the present invention is a stainless steel flange of 2.75 inches (70 mm) size, the gas injection pipe which is the main part is installed on the side of the flange, the vertical device on the flange, the electric signal line, the alumina ceramic tube dense apparatus installed It is very easy to manufacture, install, maintain and repair the device.

Claims (5)

In the hydrolysis device used in the CBE and GSMBE systems for producing a compound semiconductor epitaxy thin film, a gas inlet pipe 9 for supplying raw material gas from the outside is provided by arranging gas through holes 9a in the flange side. A gas injection flange portion (3) provided with a stainless steel tube (14) for supporting the gas through cylindrical tube (7) and the gas through cylindrical tube (7) with the center of the flange as a step; On the outer side of the ceramic tube 7 for transferring the raw material gas from the gas injection flange portion 3 to the upper portion, a spring-type combustible filament 6 and a heat-transfer reflector 10 are installed. The gas cracking device unit is formed by multiplying a baffle 17 in which the micro holes 17a are installed in order to increase the number of collisions and to have a pressure difference between the pressure of the injection tube 9 and the ultra-high vacuum of the deposition chamber and a quick response characteristic. 4) and; A plurality of copper wires 5 to which lead wires 16 for supplying power to the filament 6 of the gas cracker unit 4 and output leads of thermocouples 8 for temperature measurement of the ceramic tube 7 are connected. The cracker cell for hydride gas containing the flange part (2) for electrical feed throwing insulated and fixed to the flange part main body by the ceramic. The lower end of the heat shield reflector 1 (0) of the gas cracker 4 has a hole 10c through which three luminescent ceramic tubes 11 for power supply thermocouple lead wires can pass. The cracker cell for the hydride gas characterized in that it is in the form of a bent to be coupled to the upper reflector 10, the reflector 10 does not touch the filament (6) or the inner wall of the deposition chamber. 2. The baffle (17) according to claim 1, wherein the baffles (17) used to improve the thermal decomposition characteristics and the stability of the gas beam are arranged in a circular shape (17a) with micropores having a diameter of 0.25 mm or less, and the shape of the edges of the baffles (17). A cracker cell for hydride gas, which is stably provided on the inner wall of the ceramic tube (7) and has a small amount of gas leakage. According to claim 1, wherein the filament (6) has a high efficiency pyrolysis characteristics by the thermal barrier reflector 10 to block the radiant heat emitted to the outside from the high temperature portion formed in the ceramic tube (11), the long length of the ceramic tube ( 7) a hydride having a structure to prevent the heat of the high temperature portion of the alumina ceramic tube 11, which is high temperature, from being transferred to other portions, such as the gas injection flange portion 4 and the electrical feed-through flange portion 2, etc. Gas cracker cell. The heat shield reflector 10, the baffle 17, and the filament 6 used in the gas cracker unit 4 are tantalum (Ta) having a high melting point. The ceramide tube 11 is formed of an alumina material, and the gas injection tube 9 and the flange portion are made of stainless steel so that no gas is generated under ultra-high vacuum conditions.