JPH0339476A - Gas introducing device for cvd device - Google Patents

Abstract

PURPOSE:To uniformly heat the gas introducing device even if there is some difference in heat capacity between respective parts by housing the gas introducing device provided with a bubbler for generating a film forming gas, a control valve, etc., in an oven kept at a fixed temp. CONSTITUTION:The gas introducing device 2 is connected to a film forming reaction tube 1 of the CVD device for growing the thin film of a compd. semiconductor or a ceramic high temp. superconductor. The device 2 is provided with the bubbler 3 for gasifying the solid or liq. having a low vapor pressure at ordinary temp. and an introduced gas pipe 5 for introducing the gas generated by the bubbler 3 into the reaction tube 1 through the control valve 4. The device 2 is housed in the temp.-controlled oven 6.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a gas introduction device for a CVD apparatus for growing thin films of compound semiconductors and ceramic high temperature superconductors.

(Prior art) Conventionally, CVD equipment for growing thin films of compound semiconductors and ceramic high-temperature superconductors sometimes uses a condensable film-forming gas, and in this case, it is necessary to use a condensable film-forming gas in the film-forming reaction tube of the CVD equipment. The gas introduction pipe that sends the film-forming gas, the control valve, and the gas introduction device of the bubbler that generates the film-forming gas are heated with a wire heater, etc., and the film-forming gas condenses in the gas introduction pipe, or condenses 1; Prevents the introduction tube from clogging.

(Problem 8 to be solved by the invention) As mentioned above, a wire heater or the like that is configured to heat the gas inlet pipe or valve cannot be heated uniformly, and the temperature may partially rise. There were disadvantages in that high temperatures and low temperatures occurred, and the film-forming gas condensed in the low temperature areas, causing clogging of the gas introduction pipe. Furthermore, depending on the type of film-forming gas, some gases may decompose if the temperature is raised too high, and in this case, if decomposition occurs, the desired film quality cannot be obtained. Furthermore, it has been found that if the low temperature section is set to a temperature at which the film forming gas does not condense, a decomposition reaction of the film forming gas occurs in the high temperature section.

To explain this more specifically, CVD for growing thin films of compound semiconductors and ceramic high-temperature superconductors includes:
Substances that are liquid or solid at room temperature, have low vapor pressure, and are highly condensable are used as film-forming gases, such as 81 s (hexaf l
uroacety l acetonato)co
pper (seal): Cu(DPM)z
and Trls(dtptva+oy!Iethanato
)yttrtu@: Substances such as Y(DPM)3 are
Most are solid at room temperature and have a melting point or sublimation point of 100°C to 20°C.
Many of these substances have a temperature of 0℃, and these substances also have a temperature of 300℃~
Many of them undergo decomposition reactions at 400°C. Therefore, it is necessary to introduce the vapors of these substances into the film-forming reaction tube while controlling the temperature within a very narrow range. If the film-forming gas decomposes, it may be deposited as powder inside the introducing gas pipe, or a thin film with the desired chemical composition cannot be grown.

Bubblers for vaporizing solids and liquids are usually made of stainless steel to ensure airtightness and have a very large heat capacity. Furthermore, pneumatically actuated valves also have a relatively large heat capacity, which is significantly different from the heat capacity of the inlet gas pipe. When these components of a gas introduction device with different heat capacities are heated simultaneously by a wire heater, a temperature difference occurs between each component due to the difference in heat capacity, and measurements show that the gas introduction tube and bubbler Depending on the substance, the vapor may condense or decompose within the gas introduction device, which is not preferable.

The present invention solves these shortcomings and inconveniences by using a CVD method that can maintain a constant temperature without causing condensation or decomposition of the film-forming gas.
The object of the present invention is to provide a gas introduction device for the device.

(Means for Solving the Problems) In the present invention, a bubbler for gasifying solids and liquids with low vapor pressure at room temperature is installed in a film-forming reaction tube of a CVD apparatus for growing thin films of compound semiconductors and ceramic high-temperature superconductors. and an introduction gas pipe for guiding the gas generated in the bubbler to the film-forming reaction tube via a control valve. The above objective was achieved by housing the device in a temperature-controlled open space. A plurality of bubblers can be connected to the film-forming reaction tube, and each bubbler can be housed in an open space whose temperature can be controlled independently, and the inlet of the film-forming reaction tube, the bubbler, and the It is also possible to separately control the temperature of the control valve and part of the gas introduction pipe by placing them in separate openings.

(Function) For example, when growing a thin film of a ceramic high-temperature superconductor by CVD using Cu(DPM)z, a heated substrate is prepared in a film-forming reaction tube, and Cu(DPM) is injected into it from a gas introduction device. ) 2 steam is introduced, but C
The bubbler that generates the steam of u(DPM) 2, the inlet gas pipe, and the control valve are housed in an open space, so even if there are differences in the heat capacity of each part, the temperature is almost uniform so that there is no large difference in temperature between each part. It can be heated to In actual measurements, a maximum temperature difference of less than 30@ was observed, and the temperature difference became smaller over time.

(Example) An example of the present invention will be described based on the attached drawings.
1 shows a gas introduction device for introducing a film-forming gas into the film-forming reaction tube (1). The gas introduction device (2) is made of Cu (DPM)
2 Bubbler that generates gas from other raw materials <3>
The gas (steam) generated by the bubbler (3) is controlled by a pneumatically operated valve (4a) or a manual valve (4).
It consists of an inlet gas pipe (5) with a valve (4>) intervening, such as b), and these components are housed in an open space (6>) and heated to a constant temperature state.

When there is only one type of raw material, the gas introduction device (2)
bubblers (3) are provided, in which case the valve (
4) and one open (6) along with the inlet gas pipe (5)
The temperature of the open (6) and the substance in the bubbler (3) are controlled to a temperature suitable for generating gas.This prevents the gas from condensing or decomposing the entire gas introduction device (2). It is maintained at constant temperature and can perform good CVD processing.

The example shown is four bubblers (3a) (3b) (3c
) (3d), one bubbler and one part valve (
4> and the inlet gas pipe <5> with one electric open (
6) and the remaining valves (4) and inlet gas pipes (5)
is placed in another open (8e), and the bubbler (3a) has, for example, Y (DPM)! , CU (DPM) 2 for bubbler (3b), bubbler (ac)
(3d) contains Ba (DPM) 2, Ca (DPM) 2
, B1 (CsHs) 3 (7), open (8a) (6b) is controlled in the temperature range of 130℃ to 180℃, open (Be) (6d) is controlled in the temperature range of 260℃ to
Controlled within a temperature range of 300°C. In specific embodiments, Y
(DPM) s bubbler (3a) open (8a) at 125℃, Cu (DPM) 2 bubbler (3b) open (ab) at 126℃, Ba (DPM) 2 bubbler (3c) open ( 6c) at 226"C, YB
-x crystal growth was performed to form a ceramic high temperature superconducting thin film exhibiting Tc-88K.

The high-temperature piping section is housed in the open (6e), and the temperature is controlled at 250°C to 300°C to prevent condensation and decomposition of the organometallic compound film-forming gas transported from the bubbler.

The film-forming reaction tube (1) was provided with a long inlet (la), but the inlet (la) was also kept open (6r) and controlled at the same temperature as the open (6e).

(D is a gas source of carrier gas such as Ar gas, (8) is a gas source of stable film forming gas such as 02 gas, and (9) is an exhaust pump such as a rotary pump.

Although the above embodiments have been described for the deposition of ceramic high temperature superconductors, they are also applicable to other CVD techniques using condensable gases, such as 140 cVD for compound anticonductors.

(Effects of the Invention) As described above, according to the present invention, 1. Since the gas introduction device that supplies film-forming gas to the film-forming reaction tube of the CvD apparatus is housed in the open space, condensable gas is used. CV
In the D process, the temperature of the film-forming gas can be controlled within a very narrow temperature range, preventing clogging of the gas introduction pipe or decomposition reaction of the film-forming gas, and efficiently producing a thin film with the desired quality. There are effects such as being able to do it.

[Brief explanation of drawings]

The drawings are diagrams of embodiments of the invention. (1)... Reaction tube for film formation (2)... Gas introduction device (3) (3a) (3b) (3c) (3d) - Bubbler (4) (4a) (4b)... Valve (5)
...Introduction gas pipe (6) (6a) (8b) (Be) (ad) (
Be) (60-Open patent applicant Oki Electric Industry Co., Ltd. and 3 others)

Claims (3)

[Claims] 1. A bubbler that gasifies solids and liquids with low vapor pressure at room temperature and a valve that controls the gas generated by the bubbler are installed in the film-forming reaction tube of a CVD device that grows thin films of compound semiconductors and ceramic high-temperature superconductors. The gas introduction device is connected to an introduction gas pipe that leads to the film-forming reaction tube via the gas introduction device, and is characterized in that the gas introduction device is housed in a temperature-controlled opening. Gas introduction device for CVD equipment. 2. 2. The gas introduction device for a CVD apparatus according to claim 1, wherein a plurality of bubblers are connected to the film-forming reaction tube, and each bubbler is housed in an open structure whose temperature can be controlled independently. 3. 2. The method according to claim 1, wherein the inlet portion of the film-forming reaction tube, the bubbler, the control valve, and a part of the introduction gas pipe are each placed in independent openings to control the temperature of each. A gas introduction device for the CVD apparatus described above.