JPS63317674A - Gas supplying device - Google Patents

Abstract

PURPOSE:To precisely regulate the amt. and pressure of a gaseous organometal to be introduced into a vacuum vessel by providing a mechanism for regulating the pressure or flow rate of the gas on the secondary side of a needle valve. CONSTITUTION:In the device for supplying a gaseous organometal into a vacuum device, the pressure, etc., are roughly regulated by the needle valve 8, and the pressure and flow rate are finely adjusted by the mechanism 10 for finely adjusting the pressure and flow rate connected to the secondary side of the valve 8. A pressure gage 14 connected to the main line A of the fine adjustment mechanism 10, a pressure controller 13 is operated by the signal from the pressure gage 14, and hence the flow regulating valve 11 of a bypass line B is operated. A vacuum pump 12 is connected to the flow regulating valve 11. The pressure of the main line is regulated by opening and closing the flow regulating valve 11 to fix the signal outputted from the pressure gage 14 and to regulated the amt. of the gas to be discharged into a vacuum pump 9.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a gas supply device for supplying organometallic gas to a vacuum container.

(Prior art and problems to be solved by the invention) GaA
Compound semiconductors represented by s are widely used as constituent materials not only for optical devices such as lasers but also for high-speed devices such as field effect transistors.

These elements are manufactured using a thin film forming apparatus.

With the aim of further improving device performance, thin film forming equipment that allows more precise control has been developed year by year. At present, molecular beam epitaxy (hereinafter referred to as MBE) and metal organic thermal decomposition method (hereinafter referred to as MOCVD) are two excellent technologies. The former is based on ultra-high vacuum technology and has the advantage of allowing precise control in the direction of film thickness, but has the disadvantage of productivity.

The latter is suitable for mass production because it is based on plant technology, but film thickness control is inferior to MBH. The organometallic molecular beam epitaxy method (hereinafter referred to as MOMBE) consists of MBE and M
This technology aims to integrate OCVD.

(Reference, Nikkei Electronics, December 1985,
p.

89) However, as the research is still in the early stages, the equipment used for this is not yet commercially available.

The MOMBIlu device is expected to have features of both MBE and MOCVD, but since the technology bases of the two are completely different, there are many problems in device development.

One of them is a raw material gas supply device. The MOMBE apparatus forms a film in an ultra-high vacuum chamber, but the raw material gas for the film is supplied from outside the vacuum. The supply method depends on the method used in the MOCVD method, as schematically shown in FIG. That is, a hydrogen purifier 1 that is a hydrogen supply source has a mass flow controller 2 that adjusts the hydrogen gas flow rate, a pressure gauge 3 that measures the gas pressure, and a bubbler 4 that contains an organic metal.
It consists of a temperature controller 5 for adjusting the temperature of the bubbler, and a needle valve 6 for adjusting the pressure inside the vacuum container, and these are connected by a stainless steel pipe 7. The other end of the needle valve is connected to a vacuum vessel 8 via a stainless steel pipe, and the vacuum equipment He is constantly pumped to 5 by a high vacuum pump 9.
It is maintained at a high vacuum of more than X 10-' Torr.

Hydrogen gas, meteor-controlled by the mass flow controller 2, is flowed into the bubbler 4, hydrogen gas containing organic gas is taken out from the outlet, and the pressure is controlled using the needle valve 6, and the hydrogen gas is sent into the vacuum container 8. is called a carrier gas because it carries organometallic gases. The amount of organometallic introduced into the vacuum vessel is determined by the carrier gas flow M if the temperature of the bubbler is kept constant. The pressure P inside the vacuum container is expressed by P=Q/S using vL5kQ and the exhaust capacity S of the vacuum pump. The maximum value of S of commercially available pumps is 20001! , /sec.

For this reason, the pressure P changes greatly due to a small change in the flow IQ value.For example, ΔQ=1cc/min is ΔF −
Corresponds to 10-'Torr.

The needle valve is 1 to 10 used in MOCVD method.
It was developed for pressure control in the range of 0.00 Torr, and using this, 5X 10-
It was almost impossible to control pressures below 'Torr. Therefore, MO using a conventional gas supply device
The MBE apparatus has the disadvantage that the controllability and reproducibility of the composition and growth rate of mixed crystal semiconductors such as AlGaAs are extremely low.

(Object of the Invention) The present invention was proposed to solve the above-mentioned drawbacks, and its purpose is to provide a gas supply device that can precisely adjust the amount and pressure of organometallic gas introduced into the vacuum container in a MOMBB device. It is about providing.

(Means for Solving the Problems) In order to achieve the above object, the present invention uses a mass flow controller and a needle valve to provide a gas supply device that supplies an organometallic gas together with a carrier gas into a vacuum device. Pressure 1 on the secondary side of the valve! Adjustment mechanism or flow Ill! The gist of the invention is a gas supply device characterized by being provided with either one of the II adjustment mechanisms.

Next, examples of the present invention will be described. Note that the embodiments are merely illustrative, and it goes without saying that various changes and improvements can be made without departing from the spirit of the present invention.

FIG. 1 shows the gas supply device of the present invention. In the figure, 1 is a hydrogen purifier, 2 is a mass flow controller, and 3 is a hydrogen purifier.
is a pressure gauge, 4 is a bubbler, 5 is a temperature controller, 6 is a needle valve, 7 is a stainless steel pipe, 8 is a vacuum container, 9 is a high vacuum pump, 10 is a pressure/flow ff1ml! Showing the adjustment mechanism,
However, in the present invention, pressure is applied to the secondary side of the needle valve 6.
The main feature is that it is equipped with a flow ff1v & adjustment mechanism lO.

As with conventional devices, the pressure inside the piping from the mass flow controller 2 to the needle valve 6 is approximately atmospheric pressure.
The vacuum container from the needle valve is 5 x 10'''' Torr.
The vacuum is as follows, and the needle valve plays the role of maintaining this differential pressure. In the present invention, after rough pressure adjustment is performed by the needle valve 6, the pressure and flow rate fine adjustment mechanism 10 is used to adjust the pressure inside the vacuum container 8. Pressure of the organometallic gas introduced ・′/! Make fine adjustments to Lffi.

Figure 2 is a pressure/flow machine! I! 1 shows an example of the adjustment mechanism.

In the figure, l is a hydrogen purifier, 2 is a mass flow controller, 3 is a pressure gauge, 4 is a bubbler, and 5 is a temperature 1! 6 is a needle valve, 7 is a stainless steel vibrator, 8 is a vacuum container, 9 is a high vacuum pump, 10 is a pressure/flow ff1m! The secondary side of the needle valve 6 shows the main line A leading to the vacuum vessel 8, and the flow it! PI valve adjustment 11
It is branched into a bypass line B that leads to .

A pressure gauge 14 is connected to the main line A, and this pressure gauge 14
A pressure controller 13 operated by a signal from the
This pressure controller 13 is the flow rate regulating valve 1 of the bypass line B.
1. Also, this flow rate adjustment valve has a vacuum pump 12.
is connected.

The pressure in the main line is adjusted by opening and closing the flow ffl regulating valve 11 so that the output signal from the pressure gauge 14 remains constant, and adjusting the amount of gas discharged to the vacuum pump 9.

FIG. 3 shows an overall view of the MOMBE device, and FIG. 4 shows details of the gas supply device of the present invention.

An example in which the Al composition in the AlGaAs film is precisely controlled will be described below.

As shown in FIG. 3, the gas supplied from the gas supply bag 215 passes through the gas sources 16a and 16b and is deposited on the substrate 18 placed in the vacuum container 8. 10 inside the vacuum container 8 using the vacuum pump 9
- Exhaust to ''' Torr. GaAs substrate is 40
From the 0-order gas supply bag Tl1s heated to 0°C, arsine was added as a group Ⅰ element source, and triethyl gallium (hereinafter referred to as TEG) and trimethylaluminum (hereinafter referred to as TEG) were added as a group Ⅰ element source.
(hereinafter referred to as TMA) was supplied using a carrier gas.

FIG. 4 schematically shows a piping system diagram inside the gas supply device. In FIG. 0, 1 is a hydrogen purifier;
19 is an arsin cylinder, 2a12b+2c is a mass flow controller, 3a, 3b is a pressure IL 4a.

4b is a bubbler, 5a, 5b is a temperature controller, 6a, 6b
is a needle valve, lla, llb are pressure regulating valves, 1
2 is a vacuum pump, 13a and 13b are pressure controllers, 14
a, 14b, 14c, 14d are pressure gauges, 16a,
Reference numerals 16b indicate gas supply sources. Arsine is connected to the gas source 16a, and hydrogen gas containing TEG and TMA is integrated into one line and connected to the gas source 16b. Arsin.

TEG, TMA supply f! ki7) The control is as follows'
I did it.

Open the main valve of the 100% concentration arsine cylinder 19 and check its tl, M@10C using the mass flow controller 2C.
It was controlled at C/min. The temperature of the gas source 16a is 990
Since the temperature is maintained at 0.degree. C., arsine is thermally decomposed into Ash and reaches the GaAs substrate. Arsine has a GaAs substrate 4
When the substrate is heated to 00° C. or higher, the substrate is always irradiated.

On the other hand, a part of the hydrogen supplied from the hydrogen purifier 1 is transferred to a bubbler containing TEG by setting the flow rate to 2 cc/min using the mass flow controller 2a while monitoring the pressure gauge 38 so that the pressure is always higher than atmospheric pressure. 48 will be introduced. The temperature of the bubbler was maintained at 48° C. by a temperature regulator 5a, and the needle valve 6a was opened to introduce hydrogen gas containing TEG into the vacuum line. At that time, the flow rate to the vacuum container 8 was adjusted as follows. First, the reading of the pressure gauge CMKS Baratron Gauge Type 390) 14a is approximately I.
Adjust the needle valve 6a so that it becomes Xl0-'Torr.
“'Torr.Almost all of the hydrogen gas including TEG is pumped to the vacuum pump 1 through the pressure regulating valve 11m.
The set value of the zero-order pressure gauge 14b discharged by 2 is set to 6.
A portion of the gas was introduced into the gas source 16a, set at Xl0-'Torr. The procedure for controlling the amount of TMA introduced was the same as that for TEG. However, bubbler 4b
The temperature is 35°C, and the set value of the pressure gauge 14d is 3 x 1
It was set to 0-'Torr. The gas source 16b was kept at a temperature of 150°C. This is because the gas source is housed in a container cooled with liquid nitrogen, so TEG and T
This is to prevent MA from adhering to the inside of the gas source. When the GaAsjJ plate 18 is heated to 650°C,
Shutter? (See Figure 3), open the TEG and TMA
A GaAs substrate is irradiated with hydrogen gas containing AlGaAs.
Films were grown for 1 hour. nIi thickness is 1.51tm, 5
．． The film thickness variation within an 8 cm (2 inch) GaAs substrate was within 1%. Further, the ^l&[l composition of the AlGaAs film determined from the two-crystal X-cotton diffraction method was 0.33, and the in-plane compositional variation was about 0.33±0.01.

By appropriately combining the set values of the pressure gauges 14b and 14d, the AIl[formation
Control was possible with an accuracy of 0.01 (0.05<x<0.95).

Although AlGaAs has been described above, it goes without saying that this method can be applied to precise composition control of all IV compound and n-vr compound semiconductor films.

(Effects of the Invention) According to the present invention, in a gas supply device that supplies an organometallic gas together with a carrier gas into a vacuum device using a mass flow controller and a needle valve, the secondary side of the needle valve By providing either a pressure adjustment mechanism or a flow ItA adjustment mechanism, a needle valve can be used to maintain the pressure difference from atmospheric pressure to 10-'Torr, and a vacuum gauge can be placed in the vacuum line to make minute pressure adjustments. Since a control mechanism is provided that allows for control, there is an advantage that the amount of organic metal supplied to the vacuum container can be precisely controlled.

In the embodiment, a gauge with a full scale of 1 Torr was used for the pressure needle, but it goes without saying that if a gauge with a full scale of 1000 τ orr is used, it can be applied to an MOCVD gas supply device.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the present invention, Fig. 2 shows a pressure/flow rate fine adjustment mechanism, Fig. 3 shows an overall view of the organometallic molecular beam epitaxy apparatus, and Fig. 4 shows a specific example of the pressure/flow rate Fft fine adjustment mechanism. FIG. 5 shows a conventional example. l...Hydrogen purifier 2+2a, 2b+2c...Mass flow controller 3.3a, 3b...Pressure gauge 4.4a, 4b...Bubbler 5.5a, 5b...・Temperature controller 6.6a, 6b...Needle valve 7...
・Stainless steel pipe 8...Vacuum container 9...High vacuum pump 10...Pressure/2it amount fine adjustment mechanism 11a,
llb...Pressure regulating valve 12...Vacuum pump 13a, 13b...Pressure side'1n2314.1
4a, 14b, 14c, 14d...pressure gauge 15...
...Gas supply devices 16a, 16b...Gas source source 17...
...Shafter I8 ..... Board 19 ..... Alsin cylinder Fig. 1 Fig. 2 71°

Claims (2)

[Claims] (1) In a gas supply device that supplies organometallic gas together with a carrier gas into a vacuum device using a mass flow controller and a needle valve, two of the needle valves are used.
A gas supply device characterized in that either a pressure adjustment mechanism or a flow rate adjustment mechanism is provided on the next side. (2) The gas supply device includes a main line that connects the secondary side of the needle valve to the vacuum container and a bypass line that connects to the vacuum pump, and the pressure of the main line is measured by a pressure gauge installed in the main line. A patent claim characterized in that the pressure on the secondary side of the needle valve is controlled by measuring the value and adjusting a flow rate regulating valve via a pressure control device to change the amount of gas flowing into the bypass line. The gas supply device according to item 1.