JPH116067A - Vaporization equipment for liquid raw material, and its operation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide vaporization equipment capable of effectively removing a residue sticking to the inside of a vaporization vessel in a short time. SOLUTION: This vaporization equipment 8a is equipped with a vaporization vessel 10 where a liquid raw material 4 is to be introduced and plural holes 11 are formed in the wall surface, plural bar-shaped bodies 38 fitted in respective holes 11, and a driving device 40 for taking out and putting in the bar-shaped bodies 38 as shown by an arrow A. A heater 12, for heating the vaporization vessel 10 and the bar-shaped bodies 38 up to a temp. not lower than the vaporization temp. of the liquid raw material 4, is provided to the periphery of the vaporization vessel 10. This vaporization equipment is further equipped with a cleaning solution feeding means 30 for allowing a cleaning solution 34 for dissolving a residue formed in the vaporization vessel 10 to flow. The cleaning solution feeding means 30 is constituted so that a cleaning solution source is connected via a valve to a liquid raw material pipe 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a vaporizer for vaporizing a liquid raw material by heating and a method of operating the same, which is used in a (chemical vapor deposition) apparatus, a MOCVD (CVD using an organometallic compound) apparatus, and the like.

[0002]

2. Description of the Related Art Conventionally, as a method of sending a liquid material which is liquid at normal temperature in a vaporized state, a method called a bubbler or a bubbling device as described in Japanese Patent Application Laid-Open No. 60-2111072 is generally used. It is also adopted in many film forming apparatuses such as a TEOS (tetraethoxyorthosilane) film forming and a superconducting thin film forming in a semiconductor manufacturing process and the like.

On the other hand, in recent years, as an important technology for producing a next-generation DRAM (dynamic random access memory) device, for example, a high-quality film such as a BST (BaSrTiO ₃ , that is, barium strontium titanate) film and an SrTiO ₃ (strontium titanate) film have been developed. Dielectric thin films are starting to attract attention.

When such a high dielectric thin film is formed by a CVD apparatus, generally, Ba (DPM) ₂ , Sr
Organic metal raw materials such as (DPM) ₂ and Pb (DPM) ₂ are used (DPM is dipivaloyl methane), and these are all solids at normal temperature. It is necessary to maintain the liquid state by maintaining the temperature at a high temperature of about ° C or higher, but it is known that the raw material is immediately decomposed and deteriorated in this high temperature state.

In order to make the liquid state at a relatively low temperature, a method has been developed in which the organometallic raw material (solid raw material) is dissolved in an adduct (a type of solvent) such as THF (tetrahydrafuran). If this is also vaporized and sent out by a bubbling device, it is necessary to maintain a high temperature because if the piping from the bubbling device to the processing chamber is not maintained at about 200 ° C. or more, the vaporized material will condense and liquefy, In this case, it is decomposed due to high temperature in the piping, and THF
However, there is a problem in that only the adduct such as Sr (DPM) ₂ vaporizes and the desired raw material such as Sr (DPM) ₂ is condensed and fixed inside the pipes or the like.

In order to solve this problem, a liquid material obtained by dissolving a desired solid material in a solvent as described above is delivered as a liquid, and this is vaporized by heating in a vaporizer immediately before a processing chamber and delivered. In recent years, a method of immediately supplying this to a processing chamber has been studied.

A CVD apparatus provided with such a vaporizer is described in Japanese Patent Application Laid-Open No. 7-268634. FIG.
1 shows a simplified example of the CVD apparatus described therein.

A liquid raw material 4 obtained by dissolving a desired solid raw material such as Sr (DPM) _{2 in} a solvent such as THF is supplied from a liquid raw material supply device 2 to a vaporizer 8 via a liquid raw material pipe 6 in specified amounts. Supplied.

In the vaporizer 8, a dilution gas supply pipe 16 is connected to the vaporization vessel 10, a nozzle 14 is inserted into the vaporization vessel 10 coaxially with the dilution gas supply pipe 16, and the vaporization vessel 1
It has a structure in which a heater 12 is provided around zero. The nozzle 14 is connected to the liquid source pipe 6. A dilution gas 18 such as a nitrogen gas is supplied to the dilution gas supply pipe 16.

The liquid raw material 4 supplied to the vaporizer 8 is supplied to the nozzle 14 at a tip thereof by a high-speed dilution gas 18 flowing around the nozzle 14.
Thus, the particles are roughly atomized and dispersed and collide with a wide range of the inner wall of the vaporization vessel 10 heated to about 250 ° C. or more, and are instantaneously vaporized. Due to the pressure difference, the vaporized raw material 20
The gas is supplied to the processing chamber 26 through the vaporized raw material pipe 22 and the valve 24.

In the processing chamber 26, in addition to the vaporized raw material 20, for example, in the case of forming an SrTiO ₃ thin film, TTIP @ Ti vaporized by a bubbling device (not shown) or the like.
(OiC ₃ H ₇ ) ₄ } and oxygen are supplied, mixed, and brought into contact with the surface of a heated substrate (not shown) to form a thin film such as SrTiO ₃ by a CVD reaction. . The mixed gas not used for forming the thin film is discharged to the outside.

[0012]

The above-mentioned Sr (D
Raw materials such as PM) ₂ and Ba (DPM) ₂ are easily bonded and precipitated with trace amounts of impurities such as H ₂ O, CO, CO _{2 and the} like, and gradually decompose and precipitate with time at high temperatures. Therefore, these residues accumulate in the vaporization container 10 and cause various problems. For example, the residue adheres to the inner wall of the vaporization container 10 and the vaporization efficiency of the liquid raw material 4 decreases,
The fixing method becomes uneven and the vaporization becomes unstable. Further, if the adhered residue is peeled off, there is a possibility that the downstream valves and pipes may be clogged. Further, there is a possibility that particles (dust) may adhere to the substrate surface during film formation.

In order to prevent this, conventionally, the vaporizing vessel 1 is periodically cleaned with a cleaning liquid (for example, nitric acid) for dissolving the residue.
Although the inside of the cleaning chamber was cleaned, the adhered residue cannot be easily removed by flowing the cleaning liquid, so that it takes a long time for cleaning, and the removal is insufficient, so There is a problem of causing the above problem.

SUMMARY OF THE INVENTION Accordingly, it is a main object of the present invention to provide a vaporizer and a method of operating the vaporizer capable of effectively removing the residue stuck in the vaporization vessel in a short time.

[0015]

The vaporizer according to the present invention comprises:
A vaporization container into which the liquid raw material is introduced, which has a plurality of holes in its wall surface, a plurality of rods respectively fitted in a plurality of holes of the vaporization container, and the plurality of rods A drive device for pulling in and out the inside, a heater for heating the vaporization container and the plurality of rods, and cleaning liquid supply means for flowing a cleaning liquid for dissolving a residue generated in the container into the vaporization container. Features.

According to the above configuration, the plurality of rods can be inserted into the vaporization container when the liquid raw material is vaporized, and can be extracted when cleaning the inside of the vaporization container by the driving device. At the time of vaporization, the rod is heated by a heater together with the vaporization container.

If the rods are inserted into the vaporization vessel during vaporization, the liquid raw material comes into contact with the heated surfaces of the plurality of rods, and is mainly vaporized on the surfaces of the plurality of rods. Therefore, the residue will mainly adhere to the surfaces of the plurality of rods.

When this rod is removed from the vaporization container during cleaning, the residue fixed on the surface of the rod is
It is scraped off by the peripheral wall surface of the hole in which each rod is inserted. By flowing the cleaning liquid into the vaporizing container in this state, the scraped-off residue can be dissolved and removed by the cleaning liquid. Therefore, the residue fixed in the vaporization container can be effectively removed in a short time by the cooperation of the residue scraping action and the dissolving action.

[0019]

FIG. 1 is a view showing an example of a CVD apparatus provided with a vaporizer according to the present invention. Parts that are the same as or correspond to those in the conventional example of FIG.

In this embodiment, a vaporizer which replaces the conventional vaporizer 8 is provided between the liquid source supply device 2 and the processing chamber 26 as described above, and more specifically, immediately before the processing chamber 26. 8a is provided.

Referring to FIGS. 2 and 3, the vaporizing device 8a includes a vaporizing vessel 1 into which the liquid raw material 4 as described above is introduced.
0 is provided. The liquid raw material 4 is introduced into the vaporization container 10 via the liquid raw material pipe 6 and the nozzle 14 described above. The aforementioned diluent gas supply pipe 16 is provided around the nozzle 14. The diluent gas 18 described above is supplied to the diluent gas supply pipe 16 via the flow rate controller 17. The vaporized raw material 20 is supplied to the processing chamber 26 via the vaporized raw material pipe 22 described above. In this example, the vaporization container 10 has a plurality of holes 11 on two opposing wall surfaces (side surfaces).

Each of the holes 11 of the vaporization container 10 is fitted with, for example, a round bar-shaped rod 38 having a thickness that fits almost exactly into the hole 11. In this example, between each rod-shaped body 38 and the wall surface of the vaporizing container surrounding the rod-like body 38, a sealing gasket (a sealing packing) for preventing the liquid material 4 introduced into the vaporizing container 10 and the cleaning liquid 34 described later from leaking out. (Not shown)
Are provided respectively. This packing is, for example, O
It is a ring.

The plurality of rods 38 fitted into the holes 11 on one wall side are fixed to one connecting plate 44, and the plurality of rods 38 fitted into the holes 11 on the other wall side are The rods 38 of both groups are fixed to the other connecting plate 44.
Are inserted into the vaporization container 10 so as to be alternated in this example.

In this example, the rods 38 of the two groups are simultaneously inserted into and removed from the vaporization container 10 by two driving devices 40 as shown by arrows A (see FIG. 2).
That is, it is inserted into the vaporization container 10 or extracted from the vaporization container 10. The shafts 42 of the respective driving devices 40 are respectively connected to the respective connection plates 44. However, the above-mentioned insertion and removal of the rod-shaped bodies 38 of both groups may be performed simultaneously by one driving device 40.

Around the vaporizing vessel 10, the vaporizing vessel 1
A heater 12 is provided for heating the rod 0 and the rod 38 above the vaporization temperature of the liquid raw material 4. For example, what is contained in the liquid raw material 4 is Sr (DPM) ₂ , Ba (D
In the case of (PM) ₂ , heat to about 250 ° C. or more. The heater 12 is, for example, an electric heater.

Referring to FIG. 1, the vaporizer 8a further includes a cleaning liquid supply means 30. The cleaning liquid supply means 30 is for flowing a cleaning liquid 34 for dissolving a residue generated in the container 10 into the vaporization container 10. In this example, the cleaning liquid source 32 is connected to the liquid source pipe via a valve 36. 6 is connected. Therefore, in this example, the cleaning liquid 34 is supplied into the vaporization container 10 by using (and also serving as) the liquid source pipe 6. The cleaning liquid 34 includes, for example, HNO ₃ (nitric acid), HNO ₂ (nitrite), H ₂ O ₂ (hydrogen peroxide),
HCl (hydrogen chloride), HF (hydrogen fluoride) and the like.

In this example, as shown in FIG. 1, a waste liquid reservoir 64 is connected to the vaporized raw material pipe 22 via a valve 62. Further, a vacuum exhaust device 68 is connected to the vaporized raw material pipe 22 via a valve 66.

In the present embodiment, the liquid material supply device 2 includes a liquid material container 52 for storing the liquid material 4 described above, valves 54 to 57, a liquid flow meter 58, and a pipe connecting them. Have. The liquid source container 52 is supplied with a pumping gas 60 such as a nitrogen gas or an inert gas for pumping the liquid source 4 via a valve 54.

In the processing chamber 26, a susceptor 74 for holding a substrate 76 on which a film is to be formed and a gas diffusion plate 78 having a large number of small holes for diffusing gas to be introduced are provided. . The susceptor 74 and the substrate 76 thereon
Heated by heating means (not shown). A vacuum evacuation device 82 for evacuating the inside of the processing chamber 26 is connected via a valve 80. In addition to the vaporized raw material 20, a gas 70 that reacts with the vaporized raw material 20 is introduced into the processing chamber 26 through a flow controller 72. The gas 70 is, for example, a mixed gas of TTIP and an oxidizing gas (such as O ₂ ) when forming a SrTiO ₃ thin film, as described above.

The operation of the CVD apparatus shown in FIG. 1 including the vaporizer 8a will be described.
When the film is vaporized to form a film in the processing chamber 26, the rods 38 are inserted into the vaporization container 10 by the driving device 40 (the state of FIG. 2). And valves 54, 55, 57
And 24 are opened, the valves 56, 36, 62 and 66 are closed, and the liquid raw material 4 is pumped by the pumping gas 60 in the liquid raw material supply device 2, and the liquid flow rate is measured and controlled by the liquid flow meter 58. 4 is supplied to the vaporizer 8a, more specifically to the nozzle 14 thereof.

At the same time, the dilution gas 18 is supplied to the dilution gas supply pipe 16. The vaporizer 10 and the rods 38 are heated by the heater 12 to a temperature equal to or higher than the vaporization temperature of the liquid raw material 4.

As a result, the liquid raw material 4 is
, Are roughly atomized and ejected, and come into contact with the heated surfaces of the plurality of rods 38 and are instantaneously vaporized mainly on the surfaces of the plurality of rods 38. Although a part of the liquid raw material 4 spouted from the nozzle 14 comes into contact with the inner wall of the heated vaporization container 10 and is vaporized there, the rod 3
The liquid material 4 is mainly vaporized on the surface of the plurality of rods 38 because the liquid material 8 is located more on the flow path of the liquid material 4 ejected from the nozzle 14, and therefore the residue is also removed. Mainly, it is fixed to the surface of the plurality of rods 38.

The vaporized raw material 20 is introduced into a processing chamber 26 via a vaporized raw material pipe 22 and a valve 24 by a pressure difference. After that, it is the same as in the case of the conventional example shown in FIG. 4. The vaporized raw material 20 and the gas 70 are mixed in the processing chamber 26, and this mixed gas is dispersed by the gas diffusion plate 78 at a uniform flow rate. The thin film of SrTiO ₃ or the like is formed on the substrate 76 by diffusing into the processing chamber 26 evacuated by the vacuum exhaust device 82 and contacting the heated surface of the substrate 76 by the CVD reaction. The mixed gas that has not been used for film formation is exhausted to the outside via the vacuum exhaust device 82.

When residues accumulate in the vaporizing vessel 10 of the vaporizing device 8a and need to be cleaned, first, the valve 5
7, 36, 62 and 24 are closed, the valve 66 is opened, and the inside of the vaporization vessel 10 is evacuated by the vacuum exhaust device 68.
6 is closed, the valves 36 and 62 are opened, and the cleaning liquid 34 flows from the cleaning liquid supply means 30 into the vaporization container 10. In addition, at this time, extracting the rod-shaped body 38 by the driving device 40 is also used. Specifically, the cleaning liquid 34 is flown after the rod-shaped body 38 is partially or completely extracted by the driving device 40, the cleaning liquid 34 is flowed while the rod-shaped body 38 is extracted by the driving device 40, or the rod-shaped body 38 is drawn by the driving device 40. One of the operations of flowing the cleaning liquid 34 while reciprocating the body 38 back and forth (in the insertion / removal direction) is performed. The waste liquid after cleaning is accumulated in the waste liquid reservoir 64 through the valve 62.

At the time of cleaning, the rod-shaped body 38 is
0, the residue fixed on the surface of the rod-like body 38 is removed from each of the rod-like bodies 38 in the vaporization container 10.
Is shaved off by the peripheral wall surface of the hole 11 into which is inserted. That is, as described above, each rod 38 is formed in each hole 11.
Therefore, the residue fixed on the surface of each rod 38 cannot pass through each hole 11 and is scraped off on the wall around the hole 11. By flowing the cleaning liquid 34 into the vaporization container 10 in this state, the shaved residue can be dissolved and removed with the cleaning liquid 34. Therefore, the residue fixed in the vaporization container 10 can be effectively removed in a short time by the cooperation of the residue scraping action and the dissolving action.
As a result, a long-time stable operation of the vaporizer 8a can be performed.

As shown by a two-dot chain line in FIG. 2, the vaporizing container 10 and the plurality of rods 38 are connected to one closed container 4.
6 and the shaft 42 of the driving device 40 is
6 may be penetrated. In the penetrating portion of the shaft 42, a packing (not shown) such as a sealing O-ring is provided. This makes it possible to more completely prevent the liquid material 4 and the cleaning liquid 34 from leaking to the outside.

Further, it is preferable that a nozzle 14 and a dilution gas supply pipe 16 are provided in the introduction portion of the liquid raw material 4 into the vaporization container 10 to roughly atomize the liquid raw material 4 as described above. However, it is not always necessary to do so, and the liquid raw material 4 may be appropriately dispersed and introduced into the vaporization container 10.

[0038]

Since the present invention is configured as described above, it has the following effects.

According to the first and third aspects of the present invention, the function of scraping off the residue fixed to the rod by driving the rod-shaped body and the action of dissolving the scraped-off residue with the cleaning liquid can be used together. Residues fixed in the vaporization container can be effectively removed in a short time.

According to the second aspect of the present invention, the leakage of the liquid material and the cleaning liquid to the outside can be more completely prevented by the closed container.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a CVD apparatus provided with a vaporizer according to the present invention.

FIG. 2 is a cross-sectional view showing a detailed example of the vaporizer in FIG.

FIG. 3 is a longitudinal sectional view around a vaporization container of the vaporization device of FIG. 2;

FIG. 4 is a schematic view showing an example of a conventional CVD apparatus provided with a vaporizer.

[Explanation of symbols]

 Reference Signs List 4 liquid raw material 8a vaporizer 10 vaporizer 11 hole 12 heater 20 vaporized raw material 30 cleaning liquid supply means 34 cleaning liquid 38 rod 40 driving device 46 closed container

Claims (3)

[Claims] 1. A vaporizer for vaporizing a liquid raw material by heating, wherein the liquid raw material is introduced into a vaporization container having a plurality of holes in a wall thereof, and a plurality of holes respectively fitted into the plurality of holes of the vaporization container. A plurality of rods, a driving device for inserting and removing the plurality of rods into and from the vaporization container, a heater for heating the vaporization container and the plurality of rods, and An apparatus for vaporizing a liquid raw material, comprising: cleaning liquid supply means for flowing a cleaning liquid for dissolving a residue. 2. A method according to claim 1, wherein the vaporizing container and the plurality of rods are housed in a single closed container, and a shaft of the driving device is connected to the plurality of rods through the closed container. An apparatus for vaporizing a liquid raw material as described above. 3. The vaporizing device for a liquid raw material according to claim 1, wherein the plurality of rods are inserted into the vaporizing container by the driving device when the liquid raw material is vaporized. At the time of cleaning of the liquid raw material vaporizing device, the driving device pulls out the plurality of rod-shaped bodies and the cleaning liquid supply means flows the cleaning liquid into the vaporizing container. how to drive.