JPH10256242A - Method for cleaning passage and vaporizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To clean the inside of a vaporizer in a short time without fail by partitioning off a part of a passage, thereby constituting a cleaning liquid region which has specified pressure resistance, and letting cleaning liquid flow into it while pressurizing it to such a cleaning pressure that it exists in liquid form at the cleaning temperature of this region. SOLUTION: In the case of cleaning a vaporizer 10, two opening and closing valves 24a and 24c within a liquid material passage 16a and a gas passage are closed, and two opening and closing valves 24b and 24d within a cleaning passage 22 are opened, whereby the cleaning passage is made a sealed line. Then, the operation temperature of a vaporizer 10 is heated to, for example, at about 250 deg.C with a heater 30, and a circulation pump 32 is operated while pressurizing the cleaning passage to, for example, 41kg/cm<2> or over which is the steam pressure of cleaning liquid at the operating temperature of the vaporizer 10 with an accumulator 34. The cleaning liquid 26 flows into the vaporizer 10, maintaining its liquid condition at high pressure of 41kg/cm<2> or over even at a temperature of about 250 deg.C, after the removal of solid components with a filter 36, and cleans the inside of the vaporizer 10, dissolving or being accompanied with the extraneous matters within the vaporizer 10. The cleaning liquid returns to a tank from the cleaning passage 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for cleaning a vaporizer, and more particularly, to a vapor deposition apparatus for forming a high-dielectric or ferroelectric thin film such as barium / strontium titanate. TECHNICAL FIELD The present invention relates to a vaporizer cleaning method and a vaporizer suitable for cleaning the inside of a vaporizer used for supplying a gas.

[0002]

2. Description of the Related 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 from the current megabit order to the future gigabit order have been conducted. To manufacture such a DRAM,
A capacitor element that can obtain a large capacity with a small area is required. A tantalum pentoxide (Ta ₂ O ₅ ) thin film having a dielectric constant of about 20, instead of a silicon oxide film or a silicon nitride film having a dielectric constant of 10 or less, as a dielectric thin film used for manufacturing such a large capacity element. Metal oxide thin film materials such as barium titanate (BaTiO ₃ ) having a dielectric constant of about 300, strontium titanate (SrTiO ₃ ), or a mixture thereof, such as barium strontium titanate, are promising. In addition, PZT, P
Ferroelectric thin film materials such as LZT and Y1 are also promising.

As a method for forming such a material, chemical vapor deposition (CVD) is considered to be promising. In this case, a source gas is finally deposited on a substrate to be formed in a reaction tank. Stable supply is required. The raw material gas liquefies solid Ba (DPM) ₂ , Sr (DPM) _{2 and the} like at room temperature, and further stabilizes the vaporization characteristics.
It is produced by heating a mixture of organic solvents such as tetrahydrofuran (THF) with a vaporizer and vaporizing the mixture.

In this type of vaporizer, when a liquid (liquid raw material) is vaporized by the vaporizer, a compound with the metal, for example, SrCO ₃ or an intermediate product obtained by decomposing the raw material organic metal is generated. It may be solidified and deposited inside the vaporizer, or unvaporized components may remain inside the vaporizer as a solid or liquid fluid. If such deposits or residues are generated, the passage inside the vaporizer may be blocked, or the quality may be deteriorated due to a change in concentration.

For this reason, it is necessary to clean the interior of the vaporizer as needed or periodically. Conventionally, this type of cleaning is generally performed by flowing a solvent (cleaning liquid) into the interior of the vaporizer. It was done.

[0006]

However, since the inside of the vaporizer is usually at high temperature and low pressure, the solvent is vaporized inside the vaporizer, and the solvent dissolves and accompanies the deposits (dirt). Since the power is reduced, there is a problem that the cleaning ability is lost. Further, if the degree of vacuum of the entire system including the film forming chamber is reduced in order to increase the pressure of the vaporizer, there is a problem that it takes time to start up after cleaning.

[0007] The present invention has been made in view of the above problems, without reducing the degree of vacuum of the entire vacuum processing apparatus,
An object of the present invention is to provide a vaporizer cleaning method and a vaporizer capable of reliably cleaning the inside of a vaporizer in a short time.

[0008]

According to a first aspect of the present invention, there is provided a method for cleaning a flow path for flowing a gas having a component which tends to precipitate a solid, wherein at least a part of the flow path is partitioned. Forming a cleaning liquid region having a predetermined pressure resistance by flowing the cleaning liquid into the cleaning region while applying a pressure to the cleaning pressure such that the cleaning liquid exists in a liquid state at the cleaning temperature in the cleaning region. This is a method for cleaning roads.

[0009] Thus, the cleaning liquid is allowed to flow into the cleaning liquid region in a liquid state, and the cleaning ability of dissolving or washing away the deposits by the cleaning liquid can be sufficiently exhibited, and the cleaning can be efficiently performed.

According to a second aspect of the present invention, there is provided a method for cleaning a flow path for flowing a gas having a component which tends to precipitate a solid, wherein at least a part of the flow path is partitioned to have a predetermined pressure resistance. A method of forming a cleaning liquid flow path, and a step of flowing the cleaning liquid while pressurizing the cleaning liquid to a cleaning pressure at which the cleaning liquid partially boils at the cleaning temperature of the cleaning area. It is.

[0011] With this, the cleaning ability is such that after the cleaning liquid flows into the cleaning liquid region in a liquid state, the cleaning liquid is partially boiled, particularly at the high-temperature inner wall portion, and the attached substance is dissolved or washed away by utilizing the stirring of the cleaning liquid. And the washing can be efficiently performed.

[0012] The cleaning liquid region may have a vaporizing region for vaporizing the liquid raw material into a gaseous raw material under a vaporizing temperature and a vaporizing pressure, and the cleaning temperature may be substantially equal to the vaporizing temperature. This prevents the temperature of the vaporization region from lowering even when the cleaning step is performed, and the vaporization step after cleaning can be started quickly.

[0013] The cleaning temperature may be lower than the vaporization temperature. The higher the temperature, the higher the pressure required to maintain the cleaning liquid in a liquid state, and the vaporizer itself must be a high-pressure container. Therefore, when the vaporization temperature is high, the necessary pressurization can be minimized by lowering the temperature to some extent and then performing cleaning.

The cleaning solution may be heated beforehand and then flowed. Accordingly, for example, if the cleaning liquid is heated to the cleaning temperature, the cleaning area is prevented from being deprived of heat by the cleaning liquid and the temperature is prevented from lowering, so that the vaporization step after cleaning can be started quickly.

The cleaning area may be set to a negative pressure to promote the flow of the cleaning liquid. After the step of applying a negative pressure to the cleaning area to fill the cleaning area with the cleaning liquid, a step of flowing the cleaning liquid may be performed. By completely filling the cleaning area with liquid, all the cleaning areas can be brought into contact with the cleaning liquid, thereby increasing the cleaning effect and eliminating the leakage.

According to a third aspect of the present invention, there is provided a vaporizer for vaporizing a liquid raw material supplied from a liquid raw material flow path at a predetermined vaporization pressure and a predetermined vaporization temperature and sending the liquid raw material to the vaporized raw material flow path, and at least one of the vaporizers. A cleaning liquid supply means for flowing the cleaning liquid into the cleaning area including the section, and a pressurizing means for pressurizing the cleaning liquid flowing into the cleaning area.

According to a fourth aspect of the present invention, there is provided the vaporizer according to the third aspect, wherein the pressurizing means can pressurize the cleaning liquid to a pressure higher than its vapor pressure at the cleaning temperature. The invention according to claim 5 is characterized in that the cleaning liquid supply means has a cleaning flow path that joins the liquid raw material flow path and branches off from the vaporized raw material flow path. It is.

The main flow direction of the cleaning liquid may flow from top to bottom with respect to gravity. Accordingly, it is possible to prevent the insoluble matter in the cleaning liquid from remaining in the cleaning area and becoming particles or the like during the process. A heating unit for heating the cleaning liquid may be provided in the cleaning channel, and a cooling unit for cooling the cleaning region may be provided.

According to a sixth aspect of the present invention, the heat evaporator is provided with a heat medium flow path through which a heat medium for heating and a heat medium for cooling are switchably circulated.
4. The vaporizer according to claim 1. Thereby, the vaporizer is heated or cooled with a simple structure to control the temperature, and the vaporization or cleaning operation is performed efficiently. By using a common heat medium for heating and cooling, there is no need to perform cleaning even when the operation is switched.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a vaporizer according to a first embodiment of the present invention, in which a liquid material supplied from a liquid material flow path 16a is heated to a vaporization temperature by a heater 14 and vaporized, and a gas flow path 16b is formed. A vaporizer 10 for supplying the film to the film forming chamber 12 is provided. In the film forming chamber 12, the vaporized raw material and an oxygen-containing gas from a pipe (not shown) are jetted onto a substrate heated to a predetermined reaction temperature, and a metal oxide thin film is vapor-phase grown on the substrate. After passing through the trap 18, the processing gas after the processing is exhausted to the outside from the exhaust pump 20.

In this vaporizer, the liquid material flow path 16a is joined upstream of the vaporizer 10 and branched off from the gas flow path 16b downstream of the vaporizer 10, and the cleaning liquid tank 28, the circulation pump 3
2. The washing channel 22 circulating through the filter 36 is provided. An opening / closing valve 2 having an opening / closing position 2 is provided in each of the flow paths on the upstream side of the junction of the liquid material flow path 16a and the washing flow path 22.
4a and 24b are provided with similar on-off valves 24c and 24d in respective flow paths on the downstream side of the branch point between the gas flow path 16b and the cleaning flow path 22.
Are provided respectively. The cleaning area surrounded by these on-off valves and configured by a part of the liquid flow path and the gas flow path and the flow path inside the vaporizer is formed to have a pressure resistance that can withstand a cleaning pressure described later. .

The washing channel 22 is provided with an accumulator 34 for containing a pressurized gas for pressurizing the entire channel. The cleaning liquid 26 is filled with the cleaning liquid 26 in the vaporizer 1.
A heater 30 for heating to an operating temperature of 0, for example 250 ° C.
Is provided. As the cleaning liquid 26, for example, THF
By using the same component as the solvent used for preparing the liquid raw material as described above, even if the cleaning liquid remains inside the vaporizer 10, the vapor phase growth of the metal oxide thin film is not hindered.

Next, the operation of the vaporizer of this embodiment will be described. The film forming process is performed by closing the two on-off valves 24b and 24d in the cleaning channel 22 and opening the two on-off valves 24a and 24c in the liquid source channel 16a and the gas channel.

When the vaporizer 10 is to be cleaned, two on-off valves 24a, 24a in the liquid material passage 16a and the gas passage are used.
c is closed and the two on-off valves 24b and 24 in the washing flow path 22 are closed.
Open d to make the washing channel a closed system. And heater 3
0 means that the operating temperature of the vaporizer 10 is about 250 in advance.
C., and the circulation pump 32 is operated by the accumulator 34 while pressurizing the cleaning flow path to, for example, 41 kg / cm ² or more, which is the vapor pressure of the cleaning liquid at the operating temperature of the vaporizer.

After the solid components have been removed by the filter 36, the cleaning liquid 26 has a temperature of about 250.degree.
The gas flows into the vaporizer 10 while maintaining the liquid state by the high pressure of kg / cm ² or more, and dissolves or accompanies the deposits (dirt) in the vaporizer 10 and cleans the inside of the vaporizer 10. The cleaning liquid that has cleaned the vaporizer returns from the cleaning channel 22 to the tank. As described above, the cleaning liquid is supplied to the vaporizer while maintaining the liquid state, thereby efficiently cleaning the inside of the vaporizer.

When the cleaning step is completed, the two on-off valves 24b and 24d in the cleaning flow path 22 are closed, and the liquid material flow path 16
a and the two on-off valves 24a and 24c in the gas flow path are opened to restart the film forming process. In this embodiment, since the cleaning liquid 26 is heated to the operating temperature of the vaporizer 10, the temperature of the vaporizer 10 does not decrease in the cleaning process, and therefore, the startup time of the vaporizer 10 is minimized. Can be.

The cleaning liquid may be introduced at a lower temperature than the operating temperature, for example, at normal temperature. Although the temperature of the vaporizer decreases to a certain extent, if the temperature decreases only slightly, the reheating time is also short and the time loss is small.

In the above-described process, the accumulator 34 controls the pressure in the washing channel to 41 kg / cm ^2.
Although set as described above, the pressure may be set lower than this, and the cleaning may be performed under conditions that allow partial vaporization. In this case, especially when the temperature of the cleaning liquid is set lower than the temperature of the vaporizer, the cleaning liquid boils on the inner wall portion inside the vaporizer, thereby generating a turbulent flow and stirring to scrape off the adhered substances, Efficient removal by dissolution or entrainment. Further, instead of the pressure holding means by the accumulator 34, an on-off valve is provided at the end of the cleaning area, that is, at the return portion of the cleaning liquid, and the primary pressure of the on-off valve can be maintained at a pressure higher than the cracking pressure of the on-off valve. Of course.

FIG. 2 shows a second embodiment of the present invention. This embodiment is different from the first embodiment in that the heating means of the carburetor 10 is not an electric heater, but a carburetor. The point is that it is configured as a jacket 40 provided on the outside, through which a heat medium flows. The jacket 40 is provided with both a high-temperature heat medium source 42 for heating and a low-temperature heat medium source 44 for cooling, with a switching valve 46 and a pump 4.
8 is selectively supplied by a heat medium pipe 50 having the same.

An example of the cleaning step of this embodiment will be described. In the film forming process, a heating medium having a temperature higher than the vaporization temperature of the liquid raw material is supplied to the jacket of the vaporizer to vaporize. When the cleaning process is performed after the vaporization process, the on-off valve is switched to supply a low-temperature heat medium to the jacket, and the temperature of the vaporizer is reduced to an appropriate temperature between the vaporization temperature and the normal temperature to reduce the cleaning pressure. Let it.

If this temperature is lowered too much, it takes time to start up again, so an appropriate value is selected. For example,
When the vaporization temperature is 250 ° C., the vapor pressure of the cleaning liquid is 41
When kg / cm ^2, the vapor pressure lowering the temperature to 200 ° C. can reduce the pressure becomes 20 kg / cm ^2, to be a structure such as that amount carburetor and an accumulator 34 as a simple it can. When the temperature is lowered to 150 ° C., the vapor pressure becomes 8 kg / cm ² and the pressure can be further reduced.

[0032]

As described above, according to the present invention,
The inside of the vaporizer can be cleaned with a liquid cleaning liquid having a sufficient cleaning ability, thereby increasing the cleaning efficiency,
The inside of the vaporizer can be reliably cleaned in a short time.
Therefore, it is possible to improve the operation rate of a processing apparatus such as a vapor phase growth apparatus and to greatly reduce the operation cost.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a first embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Vaporizer 12 Film-forming chamber 16a Liquid flow path 16b Gas flow path 22 Cleaning flow path 26 Cleaning liquid 30 Heater (heating means) 34 Accumulator (pressure means) 40 Jacket

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeshi Murakami 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation

Claims (6)

[Claims] 1. A method for cleaning a flow path for flowing a gas having a component that easily precipitates solids, comprising: forming a cleaning liquid region having a predetermined pressure resistance by partitioning at least a part of the flow path. Flowing the cleaning liquid while applying a cleaning pressure such that the cleaning liquid is present in a liquid state at the cleaning temperature in the cleaning area. 2. A method for cleaning a flow path for flowing a gas having a component which tends to precipitate a solid, wherein at least a part of the flow path is partitioned to form a cleaning liquid flow path having a predetermined pressure resistance. And a step of flowing the cleaning liquid while pressurizing the cleaning liquid to a cleaning pressure at which the cleaning liquid partially boils at the cleaning temperature of the cleaning area. 3. A vaporizer for vaporizing a liquid material supplied from the liquid material flow path at a predetermined vaporization pressure and temperature and sending the liquid material to the vaporized material flow path, and a cleaning liquid in a cleaning area including at least a part of the vaporizer. And a pressurizing means for pressurizing the cleaning liquid flowing into the cleaning area. 4. The vaporizer according to claim 3, wherein the pressurizing means can pressurize the cleaning liquid to a pressure higher than its vapor pressure at the cleaning temperature. 5. The vaporization apparatus according to claim 3, wherein the cleaning liquid supply unit has a cleaning flow path that joins the liquid raw material flow path and branches off from the vaporized raw material flow path. 6. The vaporizer according to claim 3, wherein the vaporizer is provided with a heat medium flow path that allows a heat medium for heating and a heat medium for cooling to flow in a switchable manner.