JPH1192938A - Liquid material vaporizing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the facts that a liq. material wetted the sliding part of a pump for feeding liq. is brought to contact with the air to produce solid products caused by hydrolysis and volatilization, by which the wear of the sliding part is promoted. SOLUTION: Liq. sealing mechanisms 2 and 3 of a pump for feeding liq. are doubly arranged as the one for feeding liq. and the one for cleaning on the back direction thereof along a plungerl, and the space therebetween is provided with a small chamber (cleaning chamber). A liq. for cleaning is caused to flow into the cleaning chamber 10 by the pump, or the liq. for cleaning is sealed therein and is periodically replaced to flow away the liq. material wetted the surface of the plunger, or, even in the case products are generated, they are swiftly dissolved away, by which the progression of the wear of the sliding part can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for vaporizing a liquid material capable of suitably supplying a liquid material for film formation in a semiconductor manufacturing apparatus, and more particularly to a liquid feeding pump in the apparatus.

[0002]

2. Description of the Related Art In the production of semiconductor devices, a process of forming a metal thin film on a substrate is indispensable.
(Physical vapor deposition) has been used.
VD (Chemical Vapor Deposition or Chemical Vapor Deposition), among which MOCVD (Metal Organic Chemical Vapor Deposition) has become popular. In this method, a volatile organic compound of a metal to be formed into a thin film, or a liquid obtained by dissolving it in a solvent (hereinafter, these are simply referred to as a liquid material) are vaporized and sent to the substrate surface in a vapor state, A thin film of a product is deposited by a reaction such as thermal decomposition. It is said to be superior to the previous method in terms of film quality, film forming speed, step coverage at the step, and the like.

In a liquid material vaporizing apparatus for performing MOCVD, a plunger pump is often used as a pump for accurately sending a liquid material to a vaporizer at a small flow rate.

[0004]

The liquid material used here is likely to be hydrolyzed by moisture in the air when it comes into contact with air, and to precipitate a solid product due to volatilization of the solvent. In such a device, it is difficult to handle such a case that the piping line must be evacuated and then replaced with a dry inert gas before flowing the liquid. Also in the plunger pump that sends the liquid, the liquid material that wets the surface of the plunger comes into contact with the atmosphere and generates a solid product by hydrolysis or volatilization.
Another problem is that abrasion of the plunger seal sliding with this is accelerated.

According to the present invention, a solid product is prevented from being generated in a sliding portion of a pump for feeding a liquid material, and if a solid product is generated, the solid product is promptly removed and the sliding is performed. It is an object of the present invention to provide a liquid material vaporizer that has a longer service life than conventional ones and can save the trouble of maintenance by minimizing wear of parts.

[0006]

In order to achieve the above object,
According to the present invention, in a liquid feed pump of a liquid material vaporizer, a liquid sealing mechanism of a plunger is arranged along a plunger, two times for liquid feeding and for washing behind the plunger, and between them, the liquid for washing is filled. A small room (washing room) is provided. The cleaning liquid is circulated in the cleaning chamber by the pump, or is sealed and periodically replaced to maintain the cleaning action. The liquid material that wets the surface of the plunger is washed away, and solid products are prevented from being generated on the plunger surface. Even if a product is generated, the product is quickly dissolved and removed. Can be prevented from progressing.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid material vaporizer includes a material container containing a liquid material, a plunger pump for feeding a liquid, a pipe connecting the liquid container and the pipe, a vacuum pump, a purge pipe, and the like.
In addition, pipes, valves, vaporizers, and the like for providing an external supply line that enables liquid supply from the outside are laid out. Here, an embodiment of the plunger pump as a part directly related to the present invention is shown in FIG. Show.

In FIG. 1, a plunger 1 is provided with a piston motion by a driving source (not shown) disposed on the left side thereof, and reciprocates in the left-right direction in the figure while sliding with two plunger seals 2 and 3. I do. The tip of the plunger 1 is in the pump chamber 4. The pump chamber 4 is a hole formed in the pump head 5 and the internal volume thereof is
Of the liquid material, the liquid flows in one direction (from the bottom to the top in this figure) by the check valves 8 and 9 provided at the inlet 6 and the outlet 7 of the liquid material. . That is, a pump action occurs.

The liquid is discharged when the plunger 1 moves rightward in the figure, and is sucked when the plunger 1 moves leftward. There is also a double plunger type in which two plunger pumps having the same structure are arranged in parallel and driven by shifting the phase of the plungers by 180 degrees in order to prevent interruption of liquid supply during the suction stroke. However, for simplicity, the case of a single plunger type will be described below.

Here, the plunger seal 2 plays a role of sealing the liquid material in the pump chamber 4 while allowing the axial movement of the plunger 1, but also for the purpose of lubricating the sealing material and the plunger. Rather than stopping the liquid completely with the seal, the liquid material emerges behind the seal (left in FIG. 1) in a manner that somewhat wets the plunger surface. When this part comes into contact with air, a solid product is formed, which is caught between the plunger 1 and the plunger seal 2 as the plunger moves, which promotes the wear of the sliding part. In the example, the second plunger seal 3 is disposed further behind and at a distance equal to or longer than the reciprocating range of the plunger.
A small chamber (cleaning chamber 10) is formed by being covered with a housing 13 having a housing 2 and hermetically closed. The cleaning chamber 10 is filled with the cleaning liquid, and the liquid material on the sliding surface of the plunger and the products generated therefrom are washed away.

The cleaning liquid is always kept flowing by another pump (not shown) provided outside. In consideration of economy, the cleaning liquid may be circulated from an externally provided container, and the cleaning liquid may be periodically replaced. Alternatively, a method is also conceivable in which a valve is provided at the end of the inlet / outlet without using a pump, and the cleaning liquid is always sealed in the cleaning chamber, and is periodically replaced manually using a syringe or the like. As the cleaning liquid, it is desirable to use the same or the same type of organic solvent used for the liquid material.

FIG. 2 shows another embodiment of the present invention.

In FIG. 2, the parts denoted by the same reference numerals as in FIG. 1 are the same as the corresponding parts in FIG.

The main difference between the embodiment of FIG. 2 and the embodiment of FIG. 1 is the plunger. That is, the plunger 1 in the embodiment of FIG. 2 has a larger outer diameter at the rear (drive source side) than at the tip. There is a step 11 near the center of the range of movement of the plunger in the cleaning chamber, and the portion thereafter becomes thicker, and accordingly, the inner diameter of the rear plunger seal 3 is larger than that of the front. Therefore, according to the reciprocating motion of the plunger, not only the pump chamber 4 but also the internal volume of the cleaning chamber 10 changes. Therefore, if an appropriate check valve (not shown) is arranged in the middle of each of the flow path pipes on the inlet side and the outlet side of the cleaning liquid, the cleaning chamber 10 also functions as a single pump. There is no need to provide a separate pump, and the configuration of the entire system is simplified. Since the pressure and flow rate accuracy do not need to be considered when sending the cleaning liquid, a check valve with a very simple structure is sufficient, and the check valve does not need to be used as described later. There are ways. Of course, it is also possible to provide the check valve fixedly on the housing at the entrance and exit of the washing chamber.

FIG. 3 shows a third embodiment in which the embodiment of FIG. 2 is further modified. The main difference of the embodiment of FIG. 3 from that of FIG. 2 is that a bellows 33 is used as a liquid sealing mechanism instead of the second plunger seal 3 in FIG. Bellows 33 has plunger 1 at one end
In addition, since the other end is sealed to the cleaning chamber housing 13, the liquid does not leak backward. In this case, bellows 3
3, a space surrounded by the housing 13 and the seal 2 forms the cleaning chamber 10. With this structure, when the plunger 1 reciprocates in the left-right direction in the figure, the bellows 33 expands and contracts, and the internal volume of the cleaning chamber 10 changes. Therefore, the cleaning liquid is pushed out from the cleaning chamber or sucked into the cleaning liquid container 14 and Between the container 14 and the cleaning chamber 10 because the liquid is mixed with the cleaning liquid in the container 14 and exchanged little by little while moving back and forth.
It will circulate between. If the inlets and outlets 12 are separately provided, the container 14 and the cleaning chamber 10 are connected by two pipes, and a check valve is provided for each, so that the liquid can be circulated more efficiently. Depending on the degree, the purpose of cleaning can be achieved even with a simple configuration in which no check valve is provided as described above.

FIG. 4 shows another embodiment in which the present invention is applied to a syringe pump.

The syringe pump is almost the same in principle as the plunger pump described above. In the plunger pump, the plunger slides and moves between a sealing member fixed to the pump chamber. On the other hand, in the syringe pump, the only difference is that the sealing material moves with the plunger and slides between the inner wall of the pump chamber. Accordingly, FIG. 4 illustrates that the present invention can be easily applied to a syringe pump. In other words, the present invention is not limited to a plunger pump.

In FIG. 4, the plunger 1 reciprocates in a cylinder 15 together with a seal 2 fixed to the tip thereof, and the right side of the seal 2 is coupled with the action of the check valves 8 and 9 to displace the liquid material with an arrow. Inhale and discharge in the direction. On the other hand, also on the left side of the seal 2, the rear of the cylinder 15 is sealed with the seal 3 to form a sealed washing chamber 10 leaving the entrance 12, and the inner volume thereof is increased according to the movement of the plunger 1. Since the cleaning liquid changes, the cleaning liquid flows in and out of the external container 14 to clean the inner wall of the cylinder 15 and the like. It is needless to say that the cleaning liquid can flow in one direction by providing a separate inlet and outlet for the cleaning liquid and using a check valve.

[0019]

As described in detail above, the present invention provides
In a liquid material vaporizer, a liquid sealing mechanism of a plunger sliding portion of a pump for sending a liquid of an organometallic compound or the like that generates a reaction product when exposed to the air is provided in a double arrangement along the plunger. A small chamber having a liquid inlet / outlet is formed between the two liquid sealing mechanisms, and the small chamber is filled with the cleaning liquid, so that no product is generated on the sliding surface of the plunger. The generated product is promptly removed to reduce wear of the plunger and the liquid sealing mechanism that slides on the plunger, thereby improving the durability.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Plunger 2 ... 1st plunger seal 3 ... 2nd plunger seal 4 ... Pump chamber 5 ... Pump head 6 ... Liquid material inlet 7 ... Liquid material outlet 8, 9 ... Check valve 10 cleaning chamber 11 plunger step 12 cleaning liquid inlet / outlet 13 cleaning chamber housing 14 cleaning liquid container 15 cylinder 33 bellows

Claims (1)

[Claims] The liquid sealing mechanism of the plunger sliding portion is arranged in two layers along the plunger to form a small chamber having a liquid outflow / inlet between the two liquid sealing mechanisms. A liquid material vaporizer that supplies a liquid material to a vaporizer by a liquid pump that fills a small chamber with a cleaning liquid.