JP2721222B2 - Source gas supply device for plasma CVD - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plasma CVD source gas supply apparatus for supplying a source gas to a plasma CVD reaction vessel.

[Prior art] Plasma CVD on a substrate in a conventional plasma CVD reactor
As shown in FIG. 2, a plasma CVD apparatus for forming a thin film by a method comprises a room temperature solid phase or a liquid phase raw material 3 in a crucible 2 in a vacuum (0.05 to 5 Torr) plasma CVD reaction vessel 1. And heating it to obtain a gaseous source gas,
A high voltage is applied from the high voltage power supply 4 between the parallel plate electrodes 3A and 3B provided below to generate plasma, and the upper plate electrode
A film was formed on the work 5 above 3A by a gas phase chemical reaction.

In such a plasma CVD apparatus, since the source gas is formed in the reaction vessel 1, if the source 3 in the crucible 2 runs out, the source gas cannot be formed, and thus the continuous supply of the source gas cannot be performed. There was a problem.

In order to improve this, a solid-phase raw material is put into a bubbler at room temperature outside the reaction vessel, melted into a liquid phase by heating, and a gaseous raw material gas is obtained by bubbling a carrier gas with respect to the liquid-phase raw material. A source gas supply apparatus for plasma CVD having a structure in which a source gas is supplied to a reaction vessel via a pipe and a valve has been studied.

In a plasma CVD apparatus, when the raw material is a metal, the plasma is disturbed and it is difficult to form a uniform thin film. Therefore, use of a polymer material as a raw material has been studied so as not to disturb the plasma. In this case, if the temperature of the pipe is low during the supply of the raw material gas through the pipe, the raw material gas made of the polymer material is likely to precipitate on the inner surface of the pipe, which causes impurities.

In order to avoid this, it is necessary to heat by wrapping a heater around the pipe and the outer periphery of the valve.

[Problems to be Solved by the Invention] However, it is difficult to uniformly heat pipes and valves by heating with a heater wound therearound. There is a problem that occurs.

An object of the present invention is to provide a source gas supply device for plasma CVD that can uniformly heat pipes and valves.

Another object of the present invention is to provide a source gas supply apparatus for plasma CVD that can easily supply a required flow rate of a source gas that does not disturb the plasma.

[Means for Solving the Problems] The constitution of the present invention for achieving the above object will be described. The present invention melts a raw material comprising a solid phase polymer material at room temperature into a liquid phase in a bubbler, In a plasma CVD source gas supply device, a gas phase source gas is obtained by bubbling a carrier gas with respect to the phase source material, and the source gas is supplied into a plasma CVD reaction vessel through a pipe and a valve. The pipe and the valve are housed in a thermostat.

[Operation] When the bubbler, the pipe, and the valve are housed in the thermostat, the pipe and the valve can be easily and uniformly heated, so that the deposition of the raw material gas on the pipe and the valve can be prevented.

In addition, when a polymer material is used as a raw material, it is melted into a liquid phase in a bubbler, and a gaseous raw material gas is obtained by bubbling a carrier gas with respect to the liquid phase raw material and supplied into a plasma CVD reaction vessel. The required flow rate of the gas can be easily supplied. Therefore, it is possible to easily form a high-quality thin film having a uniform thickness in the plasma CVD reaction vessel.

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG.

For example, a reactor 1 for plasma CVD reduced to 0.1 Torr
Inside, a pair of shower-like electrodes 6 and 7 are arranged in parallel and opposed to each other. The shower-like electrodes 6, 7 are provided with perforated electrode plates 6B, 7B having a number of small holes on the front surface of the equalizing vessels 6A, 7A, and feed the raw material gas in the equalizing vessels 6A, 7A to the perforated electrode plates 6B. , 7B, through which it flows out uniformly. These shower-like electrodes 6, 7 are grounded. The work 5 is arranged between the perforated electrode plates 6B and 7B while being supported by a work holder (not shown). The work 5 is connected to the work holder by 13.5
It is connected to a high-frequency power supply (not shown) that applies a high-frequency voltage of 6 MHz. As a result, plasma is generated between the work 5 and the perforated electrode plates 6B, 7B on both sides thereof, and a raw material gas is supplied from each shower-like electrode 6, 7 into each plasma, and simultaneously formed on both surfaces of the work 5. A membrane can be formed. A source gas is supplied into the pressure equalizing vessels 6A, 7A of the shower-shaped electrodes 6, 7 via an internal source gas pipe 8. A heater 9 is wound around and attached to the outer periphery of the internal raw material gas pipe 8 in the reaction vessel 1.

A bubbler for forming a source gas is provided outside the reaction vessel 1.
The source gas formed by the bubbler 10 is supplied to the internal source gas pipe 8 via the external source gas pipe 11. The external source gas pipe 11 has a valve V1,
The throttle valve N1 and the valve V2 are connected.

The bubbler 10 contains a raw material 12 made of a polymer material that is in a solid phase at normal temperature, and is melted into a liquid phase by heating in a constant temperature bath described later. A carrier gas pipe 13 for bubbling and a temperature sensor 14 are inserted into the raw material 12 in the liquid phase in the bubbler 10. Carrier gas pipe 13 for bubbling
Is connected to a valve V3.

First to third carrier gas pipes 15, 16, 17 for supplying a carrier gas such as Ar are connected to the external source gas pipe 11. The first carrier gas pipe 15 has a valve V1 and a throttle valve.
An external source gas pipe 11 is connected to N1 via a valve V4. Similarly, the second carrier gas pipe 16 is also connected to the external source gas pipe 11 between the valve V1 and the throttle valve N1. The third carrier gas pipe 17 is connected to the external source gas pipe 11 after the valve V2 via a valve V5.

The first to third carrier gas pipes 15 to 17 are provided with valves.
First to third mass flow controllers (hereinafter, referred to as first and second MFCs) 18 to 20 are connected via V6, V7 and a throttle valve N2. The carrier gas supplied from each of the first to third MFCs 18 to 20 is (the flow rate from the first MFC 18) + (the flow rate from the second MFC 19) = (the flow rate from the third MFC 20). (I) is satisfied. Valve V6
A carrier gas piping 13 for bubbling is connected to the first carrier gas piping 15 between the first carrier gas piping 15 and the valve V4.

A vent line 21 is connected to the external source gas pipe 11 between the throttle valve N1 and the valve V2 via a valve V8. Further, between the throttle valve N2 and the valve V5, the third carrier gas pipe 17 is connected to the valve V9.
And is connected to the vent line 21 via the.

The first to third carrier gas pipes 15 to 17 after the valves V6, V7 and the throttle valve N2, the external raw material gas pipe 11, the carrier gas pipe 13 for bubbling, some vent lines 21, the bubbler 10,
The valves V1 to V5, V8 and the throttle valve N1 are housed in a thermostat 22, and are uniformly heated to a temperature at which the raw material gas does not precipitate. A heater 23 is also attached to a short external raw material gas pipe 11 between the constant temperature bath 22 and the reaction vessel 1. This portion corresponds to a connection portion between the external source gas pipe 11 and the internal source gas pipe 8.

 An exhaust pipe 24 is connected to the bottom of the reaction vessel 1.

Next, the operation of the plasma CVD reaction vessel 1 and the plasma CVD source gas supply device provided on the left side thereof will be described. The pressure inside the reaction vessel 1 is reduced to 0.1 Torr, and a high frequency voltage of 13.56 MHz is applied to the work 5.

At first, open valve V6, close valve V3, open valve V4, close valve V1,
The valve V2 is closed, the valve V8 is opened, and the valve V9 is closed, and a carrier gas composed of Ar gas flows from the first MFC 18 to the vent line 21 via the first carrier gas pipe 15.

Further, the valve V7 is opened, and the carrier gas composed of Ar gas flows from the second MFC 19 to the vent line 21 via the second carrier gas pipe 16.

Further, the valve V5 is opened, and the carrier gas composed of Ar gas is supplied from the third MFC 20 through the third carrier gas pipe 17 and the internal raw material gas pipe 8, and the shower-like electrodes 6,
Pour into 7. This allows the work 5 to be moved from both shower electrodes 6 and 7
Carrier gas is flowing toward. In this case, the first to first
The flow rate of the carrier gas from the third MFCs 18 to 20 satisfies the above-described formula (I). In this state, plasma is generated on both sides of the work 5.

In this state, the valve V4 is closed, the valve V3 is opened, and the valve V1 is switched to open to flow the source gas to the vent line 21 via the first carrier gas pipe 15.

Next, the valve V2 is opened, the valve V8 is closed, the valve V5 is closed, and the valve 9 is simultaneously switched to the open state, and the raw material gas is supplied to the shower electrodes 6,7. At this time, the raw material 12 in the normal temperature solid phase is heated to, for example, 150 ° C. in the bubbler 10 to be in the liquid phase by the constant temperature bath 22, and the raw material gas is formed by blowing the carrier gas as described above.

When such a source gas is supplied into the plasma on both sides of the work 5, a film is formed on both surfaces of the work 5 by a gas phase chemical reaction.

The film formation needs to be stopped after a certain time. At this time, the valve V2 is closed, the valve V8 is opened, the valve V5 is opened, and the valve V9 is simultaneously switched to the closed state. Next, the plasma is stopped, and the valve
Close V3, close valve V1, and open valve V4.

During such work, the bubbler 10, the valve V6, the valve V7 and the first to third carrier gas pipes 15 to 17 after the throttle valve N2, the carrier gas pipe 13 for bubbling, the external raw material gas pipe 11,
The first half of the vent line 21, the valves V1 to V5, the valve V10, and the throttle valve N1 are uniformly heated in the constant temperature bath 22.

Therefore, no deposition of the raw material gas occurs in these parts. Further, the portion of the short external source gas pipe 11 between the constant temperature bath 22 and the reaction vessel 1 and the internal source gas pipe 8 in the reaction container 1 are also heated by the heaters 23 and 9 to the same temperature as in the constant temperature bath 22. ing. The portion of the external raw material gas pipe 11 between the constant temperature bath 22 and the reaction vessel 1 is very short, but the temperature is adjusted. Since the inside of the reaction vessel 1 is vacuum, the differential pressure is maintained at 0.1 Torr on the right side and 760 Torr (atmospheric pressure) on the left side by the throttle valves N1 and N2. Therefore, the first to third MFCs 18 to 20 can be used at normal pressure. Also, the inside of the bubbler 10 is kept at a constant pressure without the influence of the reaction vessel 1 due to the pressure shielding action of the throttle valve N1. When the inside of the reaction vessel 1 is vacuum when the valves V2 and V5 are closed, the same vacuum is applied to the valves V2 and V5. Since the vapor pressure of the raw material 12 in a vacuum is high, the raw material 12 is originally unlikely to solidify in the piping up to the valves V2 and V5.

Specific Example First MFC 18: 40 cc / min, Ar Second MFC 19: 40 cc / min, Ar Third MFC 20: 80 cc / min, Ar Bubbler 10 has a solid phase at room temperature and a liquid phase at 150 ° C. Add the molecular material as a raw material and raise the temperature in the
° C. Valves V1 to V9 are all pneumatically operated valves, and
Each valve in 22 was made of a constant temperature and heat resistance. The throttle valves N1 and N2 were manually operated.

The vent line 21 was connected to a rotary pump (not shown) so that the internal pressure in the vent line 21 was 0.1 Torr. Although not shown, a mechanical booster pump (hereinafter, referred to as MBP) is connected to the exhaust pipe 24 from the reaction vessel 1, and an automatic exhaust valve is connected to the exhaust pipe 24 in front of the MBP, and the inside of the reaction vessel 1 is connected. The pressure was controlled to be constant. The reaction vessel 1 and all pipes were made of stainless steel.

A temperature sensor 14 composed of a thermocouple was placed in the bubbler 10, and the temperature of the thermostat 22 was kept constant by a signal from the temperature sensor 14. Since the vapor pressure of the source gas varies depending on the temperature, it is important for the stability of the supply of the source gas.

By providing the second MFC 19, the carrier gas (Ar) passing through the bubbler 10 can be separately controlled.

[Effects of the Invention] As described above, in the plasma CVD source gas supply apparatus according to the present invention, the bubbler, the pipe, and the valve are housed in the thermostat, so that the pipe and the valve can be easily and uniformly heated. . For this reason, it is suitable for plasma CVD, but it is possible to prevent a raw material gas made of a polymer material that is easily deposited from being deposited on a pipe or a valve.

In addition, when a polymer material is used as a raw material, it is melted into a liquid phase in a bubbler, and a gaseous raw material gas is obtained by bubbling a carrier gas with respect to the liquid phase raw material and supplied into a plasma CVD reaction vessel. The required flow rate of the gas can be easily supplied. Therefore, it is possible to easily form a high-quality thin film having a uniform thickness in the plasma CVD reaction vessel.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a piping diagram of one embodiment of a source gas supply apparatus for plasma CVD according to the present invention, and FIG. 2 is a conventional plasma CVD.
FIG. 2 is a schematic longitudinal sectional view of the device. 1 ... reaction vessel for plasma CVD, 3 ... raw material, 5 ... work, 6,7 ... shower electrode, 6A, 7A ... equalizing vessel, 6
B, 7B ... perforated electrode plate, 8 ... internal raw material gas piping, 9 ...
Heater, 10: Bubbler, 11: External source gas pipe, V1
~ V9 ... Valve, N1, N2 ... Throttle valve, 12 ... Raw material, 13 ... Carrier gas piping for bubbling, 14 ... Temperature sensor, 15 ~
17 ... first to third carrier gas pipes, 18 to 20 ... first
-Third mass flow controller (MFC), 21 ... vent line, 22 ... constant temperature bath, 23 ... heater, 24 ... exhaust pipe.

Claims (1)

(57) [Claims] 1. A raw material comprising a polymer material in a solid phase at ordinary temperature is melted into a liquid phase in a bubbler, and a gaseous raw material gas is obtained by bubbling a carrier gas with respect to the liquid phase raw material. And a source gas supply apparatus for plasma CVD supplied to a reaction vessel for plasma CVD through a valve, wherein the bubbler, the pipe, and the valve are housed in a thermostat. Feeding device.