JPH0354820A - Feeder of organic and metallic gas - Google Patents

Abstract

PURPOSE:To enable multiple organometallic gasses to simultaneously reach a vapor deposition device when gas flow is changed over by a method wherein systems to feed the gasses through a vent/run valves are provided. CONSTITUTION:Organic metals are contained in respective cylinders 14, 15. A carrier gas flow rate-controlled respectively by mass flow controllers 11, 12 is led into the cylinders 14, 15 to gasify the liquid organic metals in the cylinders 14, 15 by bubbling process. The gasified organic metals respectively flow together on the inflow side of a flow rate adjusting valve 19 so as to be led into a vent/run valve 20 through the valve 19. The flow rate of the gas externally fed through the valves 19, 20 can be changed by changing over the flow rate of the carrier gas fed into the cylinders 14, 15. In order to compensate the change in flow rate, a flow rate compensation line 18 feeding the carrier gas through the intermediary of the other mass flow controller 13 comprising only one line is connected to the valves 19, 20. Through these procedures, the flow rate of the gas fed into a reaction chamber through the valve 20 can be specified.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to the structure of a gas supply device that supplies a plurality of organometallic gases to a vapor phase growth apparatus (hereinafter also referred to as a reaction chamber) such as an MOCVD apparatus. In detail, the change in gas flow rate of the organometallic gas system due to the change in tLN of the carrier gas for changing the amount of generation of the organometallic gas is expressed as the flow rate. This article relates to the structure of a supply device for organometallic gas, which is supplied to a vapor phase growth apparatus such as an MOCVD apparatus through a vent/run valve while being supplemented by a carrier gas through a compensation line. [Prior Art] Usually, this type of gas supply device is 81 shown in Fig. 2.
A device for supplying one organometallic gas is used as a unit, and a plurality of these uninotes are arranged in parallel. This unit introduces a carrier gas, typically H8 gas, through a mass flow controller 1 to a cylinder 3 containing an organic metal that is liquid at around room temperature and has a relatively high vapor pressure, and bubbles the liquid organic metal. The organometallic gas generated as saturated vapor in the carrier gas is passed through the organometallic gas system 4 to the flow rate adjustment valve 7 and the vent/run valve (the outlet of the inflowing gas is directed to the reaction chamber side and bypasses the reaction chamber to the outside). The molar fraction of the organometallic gas to be sent to the vapor phase or lengthening device, that is, the amount of the organometallic gas sent to the gaseous phase or lengthening device, is When the proportion of the organometallic gas in the total gas flow rate, including other process gases, is changed in proportion to the flow rate of the carrier gas, the total gas flow rate out of the vent/run valve is kept constant and the proportion of the other process gases is In order to allow the reaction to proceed without changing the conditions or the operating conditions of the gas phase lengthening device, a flow rate compensation line is provided to guide the carrier gas whose flow rate is controlled by the mass flow controller 2 to the inlet side of the flow rate adjustment valve 7. 6 is provided to bypass the cylinder 3, and normally a flow rate adjustment valve 7 is used to maintain the internal pressure of the cylinder, which is normally adjusted to atmospheric pressure, at a constant level.

A mass flow controller usually has the function of passing a flow rate proportional to the control signal voltage applied. If the full scale flow rate of the mass flow controller is equal to 1.2, the control signal voltage that provides this full scale flow rate is set to 5 volts. If the control signal voltage given to 1 is V, then the control signal voltage given to 2 is given as follows. 5. When V+ is applied, the gas flow rate flowing out through the vent/run valve 8 is kept constant, and the pressure inside the cylinder adjusted by the flow rate adjustment valve 7 is kept constant. Further, the inverted signal (2) for v1 can be easily generated using a known converter.

[AI problem that the invention aims to solve]

Problems when using gas supply device units configured as described above in parallel as a plurality of organometallic gas supply devices are as follows.

When the reactive substrate produced in the vapor phase growth apparatus is a ternary or quaternary mixed crystal, there may be cases where two or more organometallic gases are simultaneously transferred into the vapor growth apparatus. At this time, if one vent/run valve corresponds to one organometallic gas, when switching the gas from the vent side to the reaction chamber side by inputting a signal to each vent/run valve at the same time, each vent/run valve corresponds to one organometallic gas. Because the length of the piping from the run valve to the reaction chamber is slightly different, there is a difference in the time it takes for each organometallic gas to reach the reaction chamber, and the reaction material produced is a film on the substrate. In this case, a deviation from the design value of the composite ratio occurs in the boundary layer between the film and the underlying layer. This results in deterioration of the crystallinity and electrical properties of the fabricated film. In addition, this configuration requires twice as many mass flow controllers as the types of organometallics, and
Requires the same number of flow control valves and vent/run valves as organometallic Als.

An object of the present invention is to supply a plurality of organometallic gases to a reaction chamber so that a reaction product produced using a plurality of organometallic gases does not contain a product having a composition different from a designed value. The objective is to provide a gas supply device that can be used in a variety of ways. (Means for Solving Ll!a) In order to solve the above problems, in the present invention, a plurality of organic metals each gasified by bubbling of a carrier gas are The change in the amount of gas 2iIL in the organometallic gas system due to the change in the flow rate of the carrier gas is compensated for by the carrier gas through the flow rate compensation line, and the M O is added through the vent/run valve.
The plurality of organometallic gas systems are connected to one organometallic gas supply device for supplying an organometallic gas to a vapor phase lengthening device such as a C V D device.
The vent/run valves are connected to the inlet sides of the l vent/run valves, and a plurality of organometallic gases are sent out through the l vent/run valves. In this configuration, it is more preferable to configure one flow rate compensation line through which the carrier gas passes to compensate for the change in the gas flow rate of the organometallic gas system due to the change in the flow W1 of the carrier gas that bubbles the organometallic material.

[Effect]

When the gas supply device is configured in this way, multiple organometallic gas systems are commonly connected to the inlet side of one vent/run valve, so when the vent/run valve is switched to the reaction chamber side, multiple organometallic gas systems are The organometallic gases simultaneously reach the reaction chamber through one conduit from this one vent/ram bulb.

In addition, by configuring the flow rate compensation line as one line, only one mass flow controller is required to control the 2i 1 fill of the <'a view compensation line, which is related to the number of types of organometallic gases, and the gas supply device The configuration is simple and inexpensive. [Embodiment] Figure 1 shows an embodiment of the organometallic gas supply system purchase structure according to the present invention. This example shows the structure of the gas supply system when there are two types of organic metals, and each organic metal has one cylinder.
It is stored within 4.15. A flow rate of 1 is supplied to each of these cylinders 14l5 by a mass flow controller 11.12.
A carrier gas of 111 fl is introduced and bubbles the liquid organic metal in the cylinder to gasify it. The gasified organometallic gas is transferred to the organometallic gas system 16. 17 and merges at the inlet side of the flow rate adjustment valve l9, and the flow fi
! It is led to the vent/run valve 20 via the IN regulating valve 19. In order to change the molar fraction of one or both of the organometallic gases supplied to the reaction chamber, by changing the set flow rate of the mass flow controllers 11 and/or 12 and changing the tit of the carrier gas fed into the cylinders 14 and/or 15, the flow rate! Adjustment valve 198 Changes the flow rate of gas sent to the outside via the vent/run valve 20. In order to compensate for this flow rate change, a flow rate compensation line l8, which is composed of only the l line and sends the carrier gas through the mass flow controller 13, bypasses the cylinder 14.15 and is connected to the inlet side of the carrier gas source and the flow rate adjustment valve 19. is connected to. A control signal for setting the flow rate of the mass flow controller 13 is given as follows. Now, if the full scale flow rates of the mass flow controllers 11 and 12 are respectively A and B, then the mass flow controller 13
The full-scale flow rate of is required to be A+B.

Also, the flow of mass flow controller IL12! The setting signal voltage is set to V,,V. Then, mass flow controller 1
When the signal voltage applied to 3 is set to A+B, the flow rate of gas sent to the reaction chamber via the vent/run valve 20 is kept constant. Here, 5 in the formula is a signal voltage that gives the full scale flow rate of each mass flow controller. Note that although the signal voltage given by the above equation can be realized using a known converter, it is desirable that A=B in terms of the accuracy of the mass flow controller. [Effects of the Invention] As described above, the present invention provides a gas supply device that has a plurality of organometallic gas systems and supplies a plurality of organometallic gases to a vapor phase growth device via a vent/lumbar pump. The plurality of organometallic gas systems are connected to the inlet side of one vent/lumbar pump, and the plurality of organometallic gases are connected to the inlet side of one vent/lumbar pump.
Since the configuration is such that the gas flow flowing out from the vent/run valve is switched from the vent side to the reaction chamber side, multiple organometallic gases are sent out at the same time without any lag in arrival time. It is possible to reach the vapor phase growth apparatus and realize the designed formation in the boundary layer of the reaction biobottom, such as a membrane, within the vapor phase growth apparatus. In addition, in this equipment configuration, venting/
By constructing a single flow rate compensation line to compensate for changes in the gas flow rate from the run valve and keep the gas flow constant, only one expensive mass flow controller is required to control the flow rate of the flow rate compensation line. In addition to requiring only one flow rate adjustment valve and one vent/run valve on the device body side, the gas supply device has the advantage of being simple and inexpensive.

[Brief explanation of drawings]

Fig. 1 is a structural diagram of an organometallic gas supply device according to an embodiment of the present invention, and Fig. 2 shows a plurality of organometallic gases arranged in parallel to supply a plurality of organometallic gases. FIG. 1 is a device configuration diagram showing an example of a conventional gas supply device that supplies one organometallic gas. L2, 11, 12.13: mass flow controller,
4.1617: Organometallic gas system, 6.18 = flow rate compensation line, 8" to the anti-crow chamber Figure 1

Claims (1)

[Scope of Claims] 1) A plurality of organic metals each gasified by bubbling of a carrier gas are changed to a gas flow rate of the organic metal gas system in accordance with a change in the flow rate of the carrier gas to change the amount of generation of the organic metal gas. MOC through the vent/run valve while compensating for changes with carrier gas through the flow compensation line.
In an apparatus for supplying organometallic gas to a vapor phase growth apparatus such as a VD apparatus, the plurality of organometallic gas systems are connected to the inlet side of one vent/run valve, and the plurality of organometallic gases are connected to the inlet side of one vent/run valve. An organometallic gas supply device characterized in that the organometallic gas is delivered through a vent/run valve. 2) In the organometallic gas supply device according to claim 1, there is one flow rate compensation line through which the carrier gas compensates for changes in the gas flow rate of the organometallic gas system due to changes in the flow rate of the carrier gas that bubbles the organometallic. An organometallic gas supply device comprising: