JP3891682B2 - Valve device and on-off valve cleaning method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an on-off valve cleaning method and apparatus, and more particularly to an open / close used in a thin film vapor deposition apparatus for vapor-depositing a high dielectric or ferroelectric thin film such as barium titanate / strontium on a substrate. The present invention relates to an optimum on-off valve cleaning method and apparatus used for cleaning the inside of a valve.
[0002]
[Prior art]
In recent years, the degree of integration of integrated circuits in the semiconductor industry has been remarkably improved, and research and development of DRAMs with a gigabit order in the future from the current megabit order has been conducted. In order to manufacture such a DRAM, a capacitor element capable of obtaining a large capacity in a small area is required. As a dielectric thin film used for manufacturing such a large capacity element, tantalum pentoxide (Ta ₂ O ₅ ) having a dielectric constant of about 20 is used instead of a silicon oxide film or a silicon nitride film having a dielectric constant of 10 or less. A thin film or a metal oxide thin film material such as barium titanate (BaTiO ₃ ), strontium titanate (SrTiO ₃ ) or a mixture thereof having a dielectric constant of about 300 is promising. In addition, ferroelectric thin film materials such as PZT, PLZT, and Y1, which have a higher dielectric constant, are also promising.
[0003]
By the way, chemical vapor deposition (CVD) is considered promising as a method for forming such a material, and in this case, the source gas is finally stably supplied to the deposition target substrate in the deposition chamber. There is a need to. The raw material gas is a solid Ba (DPM) ₂ , Sr (DPM) _2, etc. that is liquefied at room temperature and then mixed with an organic solvent (such as THF) in order to stabilize the vaporization characteristics. It is generated by vaporizing. In this type of vaporizer, when a liquid (liquid raw material) is vaporized by the vaporizer, a compound with a metal, an intermediate product, or the like is generated.
[0004]
In such a thin film vapor phase growth apparatus, a bypass channel having a trap device is provided to be switchable by an on-off valve in the middle of a source gas supply channel for supplying a source gas vaporized by a vaporizer to a film forming chamber. ing. This is because when the film formation process is completed or until the vaporization state of the vaporizer is stabilized, the raw material gas is caused to flow through this bypass flow path, and the components of the raw material gas are trapped and collected by the trap device and then discharged. It is.
[0005]
[Problems to be solved by the invention]
By the way, since this kind of source gas is generally difficult to vaporize and has high reactivity, unvaporized substances and reaction products often flow out to the secondary side of the vaporizer. Therefore, as shown in FIG. 5, there is a problem that this unvaporized product or reaction product adheres to the valve seat 12 or the valve body 14, damages the mating surface, and deteriorates the function of the on-off valve 10 . This is not limited to the illustrated bellows type, and the same applies to other on-off valves such as a diaphragm type.
[0006]
In addition, it is conceivable to keep the on-off valve warm to prevent adhesion, but if the heating is incomplete and the temperature drops, recondensation of the raw material gas will occur in the on- off valve , and if it is heated too much, There is a problem that the gas deteriorates and adheres.
[0007]
In view of the above, the present invention is intended to prevent the function from being deteriorated by easily and surely washing the inside of the on-off valve even if a fluid accompanied by unvaporized substances or reaction products flows. An object of the present invention is to provide a valve device.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is a valve device for opening and closing a flow path of a source gas that easily deposits solids, a gas discharge port that supplies a purge gas toward a gap between a valve body and a valve seat; The valve device is characterized in that a cleaning liquid port is provided for supplying a cleaning liquid from the vicinity of the valve body toward the flow path upstream of the valve device.
[0009]
Thus, the solid adhering to the valve seat and the valve body is vaporized accelerated by gas, or blowing, so closing the valve after removing the valves sealing surface, the valve is closed in a state in which sandwich the solid This prevents the occurrence of poor sealing and damage to the valve seat. In addition, the solid material deposited in the vicinity of the valve body is washed by flowing a cleaning liquid from the vicinity of the valve body, and when the valve device is opened next, the occurrence of a sealing failure or damage to the valve seat due to the solid material is prevented. .
[0010]
According to the second aspect of the present invention, when the on-off valve for opening and closing the flow path of the source gas that is liable to deposit solid matter is operated, the gap between the valve body and the valve seat is immediately before closing the on-off valve. A cleaning gas is supplied to the flow path upstream of the on- off valve from the vicinity of the valve body after supplying the purge gas toward the end and closing the on-off valve.
[0011]
This ensures, by washing the solid deposited in the vicinity of the valve body, then the valve device the occurrence of sealing failure and valve seat scratches by solids Ru is prevented when opened.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, for example, a liquid raw material in which liquid Ba (DPM) ₂ , Sr (DPM) ₂ or the like is dissolved in an organic solvent (for example, THF) is vaporized by a vaporizer 20 to generate a raw material gas. A film forming system in which a raw material and an oxygen-containing gas are mixed and sprayed onto a substrate heated to a certain temperature in a film forming chamber (reaction chamber) 22 to vapor-phase grow a metal oxide thin film on the substrate. It is shown.
[0014]
The vaporizer 20 is provided with a liquid source channel 26 connected to the upstream liquid source source, and a heater 24 that heats the liquid source to the vaporization temperature or higher. Further, on the downstream side, a raw material gas flow path 28 for discharging the vaporized raw material gas is provided, and this is a film forming flow path 29 connected to the on-off valve 32a, the film forming chamber 22 and the trap device 36a downstream of the vaporizer 20. If, on-off valve 32b, and branched into the bypass passage 30 having a trap device 36b, and joins again downstream of the opening and closing valve 32 c provided in the downstream of the trap apparatus 36a is connected to pump 38. These raw gas channel 28, around the film formation passage 29及beauty bypass flow path 30, a heater 40 for thermal insulation the temperature of the raw material gas flowing through these constant are arranged.
[0015]
In this example, the trap devices 36a and 36b cause a component of the source gas to adhere to the trap portion by circulating a cooling heat medium such as liquid nitrogen or cooled air, and remove this from the exhaust gas. Each trap is provided with a cooling medium supply passage and a discharge passage connected to a heat medium supply source (not shown). The structure of the trap device is not limited to this.
[0016]
A cleaning liquid supply channel 42 extending from the cleaning liquid tank 44 via the pump 58 is connected to the on-off valve 32 a installed in the film forming channel 29 and the on-off valve 32 b installed in the bypass channel 30. Yes. The cleaning liquid supply channel 42 is branched into two branch channels 46a and 46b downstream of the pump 58. The branch channels 46a and 46b are connected to the on-off valves 32a and 32b via the on-off valves 32d and 32e, respectively. They are connected to cleaning liquid ports 49a and 49b provided on the primary side, respectively. The open / close valves 32a and 32b are provided with gas injection ports 48a and 48b in close proximity to the cleaning liquid ports 49a and 49b, to which gas flow paths 50a and 50b connected to a purge gas source such as Ar are connected, respectively. Has been.
[0017]
A cleaning liquid 52 made of, for example, tetrahydrofuran (THF) is stored in the cleaning liquid tank 44, and a heater 54 for heating the cleaning liquid 52 and pressurization for pressurizing the liquid surface of the cleaning liquid 52 with a gas such as He gas. A device 56 is provided. The cleaning liquid supply flow path 42 is provided with a pump 58 that sequentially feeds the cleaning liquid 52 while pressurizing it.
[0018]
The pressurizing device 56 is provided to pressurize the cleaning liquid 52 to a pressure equal to or higher than its vapor pressure and to constantly supply the cleaning liquid 52 to the inside of the on-off valves 32a and 32b in a liquid state. It is not always necessary when possible. However, by providing the pressurizing device 56, it is possible to prevent the cleaning liquid 52 from partially vaporizing on the suction side of the pump 58 due to a low pressure on the suction side of the pump 58. Of course, a check valve having a cracking pressure equal to or higher than the vapor pressure may be provided at the outlet end of the cleaning region so as to apply pressure to the cleaning region.
[0019]
Further, a cleaning liquid vent channel 60 branched from the liquid raw material channel 26 immediately upstream of the vaporizer 20 and communicating with the cleaning liquid tank 44 is provided. The vent channel 60 is provided with an opening / closing valve 32 f, and an opening / closing valve 32 g is provided upstream of the branch point of the liquid source channel 26.
[0020]
Hereinafter, the operation of the cleaning system of this embodiment will be described. When film formation is performed, the on- off valve 32 a in the film-formation channel 29 is opened, the on- off valve 32 b in the bypass channel 30 is closed, and the source gas is guided into the film-formation chamber 22. While the film is not formed or until the vaporization state is stabilized, the on- off valve 32a in the film-forming channel 29 is closed, and the on- off valve 32b in the bypass channel 30 is opened to supply the source gas to the bypass channel 30. Lead in. The processing gas from the film forming chamber 22 via the exhaust passage 34 and the trap device 36a and the raw material gas flowing through the bypass passage 30 via the trap device 36b are merged and exhausted from the exhaust pump 38 to the outside. Is done.
[0021]
In these processes, the raw material gas flows inside the on-off valves 32 a and 32 b, and unvaporized components and reaction products in the raw material gas adhere to the valve seat 62 and the valve body 64. Therefore, as will be described below, an adhesion prevention and cleaning process for these substances on the on-off valves 32a and 32b is performed.
[0022]
First, immediately before closing the on-off valves 32a and 32b, with the on-off valves 32d and 32e in the branch flow paths 46a and 46b closed, as shown in FIG. 2, the gas injection ports 48a and 48b are opened and heated. It was injected Pajiga scan such as Ar gas, to remove the deposits adhered to between the opening and closing valve 32a, the valve seat 62 and the valve element 64 of 32b. Thereafter, the on-off valves 32a and 32b are closed, but since the deposits attached to the valve seat 62 and the valve body 64 are removed, damage to the valve seal surface can be prevented and the sealing performance can be maintained.
[0023]
Next, the gas injection ports 48a and 48b are closed and the pump 58 is driven, and at the same time, the on-off valves 32d and 32e and the cleaning liquid ports 49a and 49b in the branch flow paths 46a and 46b are opened. Thereby, as shown in FIG. 3, the cleaning liquid 52 pressurized through the pump 58 and the pressurizing device 56 is caused to flow into the primary side of the on-off valves 32a and 32b. Then, the on-off valve 32 f in the cleaning liquid vent channel 60 is opened, and the cleaning liquid 52 is circulated from the vaporizer 20 into the cleaning liquid vent channel 60. At this time, since the cleaning liquid 52 is pressurized so as not to be vaporized, it flows from the on-off valves 32a and 32b to the vaporizer 20 while being in a liquid state, and the adhering substances inside these are dissolved and washed efficiently. By heating the cleaning liquid 52 with the heater 54 of the cleaning liquid tank 44, the dissolution rate and saturation solubility of the deposit can be increased, and the cleaning effect can be increased.
[0024]
Then, the pump 58 together with the stop, the branch flow path 46a, 46b of the on-off valve 32d, closed 32e, thereafter, introducing a purge gas injection ports 48a, gas passages 50a open 48b, from 50b, which Thus, the cleaning liquid 52 in the vaporizer 20 is all collected in the cleaning liquid tank 44 from the on-off valves 32a and 32b, and the cleaning is completed. Thereby, the flow path including the vaporizer 20, the liquid raw material flow path 26 and the bypass flow path 30, and the valve seats 62 and the valve bodies 64 of the on-off valves 32a and 32b are cleaned.
[0025]
When a predetermined amount of the source gas is dissolved by repeating the cleaning several times, the deposition of the cleaning liquid also increases and the cleaning performance decreases, so the cleaning liquid is replaced. The timing of liquid change can be detected by changes in various parameters such as the volume, mass, specific gravity, light transmission amount, dielectric constant, viscosity, etc. of the cleaning liquid.
[0027]
【The invention's effect】
As described above, according to the present invention, the solid matter adhering to the valve seat or the valve body is blown off with gas and removed from the valve seal surface, and then the valve is closed. Therefore, the valve is closed with the solid matter sandwiched therebetween. This prevents the occurrence of poor seals and damage to the valve seat, and the cleaning liquid is poured from the vicinity of the valve body to wash the solid matter that has accumulated near the valve body. Occurrence of poor sealing due to solid matter and damage to the valve seat are prevented. Accordingly, a valve device is provided that prevents the function from deteriorating by easily and reliably cleaning the inside of the on-off valve even if a fluid with unvaporized substances or reaction products flows. can do.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a main part showing one process of cleaning.
FIG. 3 is an enlarged cross-sectional view of a main part showing one cleaning step in the same manner.
FIG. 4 is a cross-sectional view of a conventional on-off valve.
[Explanation of symbols]
20 Vaporizer 22 Deposition chamber 28 Raw material gas supply flow path 30 Bypass flow paths 32a to 32g On-off valves 36a and 36b Trap device 42 Cleaning liquid supply flow paths 46a and 46b Branch flow paths 48a and 48b Ports 50a and 50b Gas injection flow path 58 Pump 60 Cleaning liquid vent flow path

Claims (2)

In the valve device for opening and closing the flow path of the raw material gas that easily deposits solid matter,
And a gas discharge port for supplying a purge gas toward the gap between the valve body and the valve seat, that the cleaning liquid port is provided for supplying cleaning liquid toward the upstream side of the flow path of the valve device from the vicinity of the valve body Characteristic valve device. When operating the on-off valve for opening and closing the flow path of the source gas that tends to precipitate solids,
Supplying purge gas toward the gap between the valve body and the valve seat immediately before closing the on-off valve,
A cleaning method for an on-off valve, characterized in that after the on-off valve is closed, a cleaning liquid is supplied from the vicinity of the valve body toward a flow path upstream of the on- off valve.

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