JPH11269653A - Liquid material vaporization apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid material vaporization apparatus which is excellent in vaporization efficiency, reproducibility and stability, is low in cost and is simple in structure. SOLUTION: When a heater 3 formed by winding a capillary tube 4 inserted in tight contact with the bore of an inner heater block 1 on the outside diameter of an inner heater block 1 at varied pitch intervals on the inner side of an outer heater block 2 is heated, a prescribed temp. and temp. gradient may be created at every block of the capillary tube 4. When the liquid material for MOCVD is introduced from an arrow A, the vaporized liquid material may be taken out of an arrow B through the respective steps of generation of bubbles in the liquid, liquid drop spraying and complete spraying.

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 used in a process for forming a film of a semiconductor or a superconductor by an (organic metal CVD) method.

[0002]

2. Description of the Related Art In the process of forming a film of a semiconductor device, the MOCVD method has recently been widely used because it is superior to the sputtering method in terms of film quality, film forming speed and step coverage. Was. As a gas supply method for CVD, there are a method of bubbling a liquid material with hydrogen or the like, a sublimation method, and the like. However, a liquid organic metal (for example, trimethylaluminum (CH ₃ ) ₃ Al and other alkyl group organometallics),
Alternatively, a method in which a material obtained by dissolving an organic metal in a solvent is vaporized immediately before a reaction layer is often used.

Conventionally, as a liquid material vaporizer 31 used in this liquid vaporization method, a liquid material A stored in a liquid material storage 32 as shown in FIG. A semiconductor manufacturing apparatus connected to an outlet 31b together with a carrier gas C introduced from an inlet 31a of a liquid material vaporizer 31 by heating and vaporizing by infiltrating into a mesh-shaped heating element 33 having an evaporation matrix structure (FIG. (Not shown).

[0004]

A conventional liquid material vaporizer is constructed as described above. In such a liquid vaporizer, a liquid material is sent from a pump in order to vaporize a large amount of liquid material. When the amount is increased, the heating element 33 is cooled by the sent liquid material itself, so that there is a problem that thermal efficiency is reduced and the amount of vaporization cannot be increased. Therefore, a vaporizer using ultrasonic vibration atomization has been proposed, but this method requires an atomization chamber using an ultrasonic vibration plate and a mesh for vaporization,
There was a problem that the structure became complicated.

The present invention has been made in view of such circumstances, and has as its object to provide a low-cost, simple structure liquid material vaporizing apparatus having excellent vaporization efficiency, reproducibility, and stability. I do.

[0006]

In order to achieve the above object, a liquid material vaporizer according to the present invention is a liquid material vaporizer for vaporizing a liquid material, which comprises: a thin tube for introducing and vaporizing the liquid material; The liquid material is vaporized by a thermospray provided with a metal block for heating the metal block, and a heating means for providing a temperature gradient for each axial section of the metal block. And

The liquid material vaporizer of the present invention is configured as described above, and can provide a low-cost, simple structure liquid vaporizer having excellent vaporization efficiency, reproducibility and stability.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments. FIG. 1 is a schematic configuration diagram of a liquid material vaporizer according to the present invention. As shown in FIG. 1, the present liquid material vaporizer winds a heater 3 in a coil shape around a cylindrical inner heater block 1, covers the outer heater block 2 with a tubular outer heater block 2, and covers the inner heater block 1 with a liquid material. Through a capillary tube 4 through which the water flows. The inner heater block 1 and the capillary tube 4 are brought into close contact with each other by using a heat conductive fixing substance or a method such as brazing to improve heat conduction.
(Hereinafter, this structure is referred to as a thermospray.) In the above configuration, a certain amount of a single or mixed liquid material is introduced into the capillary tube 4 from the direction of arrow A using a mass flow controller MFC or a pump (not shown). The liquid material is introduced, heat-treated in the capillary tube 4 to be gasified by heat treatment, taken out from the arrow B, and sent to a MOCVD apparatus (not shown). FIG. 2 shows a state of the temperature distribution in the capillary tube 4. As shown in the figure, the capillary tube 4 is gradually heated from the entrance for a predetermined section to start atomization of the liquid material. In the next section, the temperature is gradually lowered, and bubbles are generated in the liquid, and at the same time, droplets are present during spraying.
These droplets are miniaturized as they proceed. Further, in the next section, the temperature is rapidly increased, and the liquid material is completely atomized into a gaseous state. In this case, if the heating temperature is low, sufficient vaporization cannot be performed, and the mist is discharged into a downstream vacuum atmosphere as fog, and a residue may be generated near the outlet. On the other hand, if the temperature is too high, vaporization proceeds excessively, and a material weak to heat collides with the heated wall surface and is decomposed in the capillary tube. In addition, when a solution in which an organic metal is dissolved in an organic solvent is used as a material, it is assumed that the nonvolatile metal may remain in the capillary tube 4 due to decomposition in the capillary tube 4 and clogging may occur. The bumping phenomenon on the wall surface of the tube 4 and the supersonic jet flow due to the thermal expansion of the liquid eject the liquid, which makes it difficult to generate and grow a solid crystal. Therefore, this possibility is practically avoided. .

In such a liquid material vaporizer using the thermospray 21, the heating temperature according to the liquid material to be used is optimized according to each section, so that the diameter of the gas particles coming out of the thermospray 21 can be reduced. It can be 1 μm or less.

The temperature condition shown in FIG. 2 can be accurately set by drawing out the heater 3 through the lead wire for each section and controlling the current flowing through each heater. In addition,
The heater 3 has a rod shape, and the outer heater block 2
Can be inserted into a plurality of through holes provided in the axial direction and heated.

FIG. 3 is a schematic configuration diagram of a modification of the thermospray used as the liquid material vaporizer of the present invention.
As shown in FIG. 3, the thickness of the inner heater block 1 and the outer heater block 2 is changed for each section. The temperature distribution can be changed by utilizing the change in the heat capacity in each section.

FIG. 4 shows another modification of the liquid material vaporizer of the present invention. This liquid material vaporizer
The thermospray 21 as shown in FIG. 1 or FIG. 3 is fixed to the joint 22, and the joint 22 and the peripheral end of the pipe 25 are connected to the packing 24 by the cap nut 23. The liquid material introduced from the arrow A is vaporized in the capillary tube and taken out from the arrow A of the pipe 25. The pipe 25 is connected to the CVD, and the pipe 25
Requires a heating means for keeping the temperature from the outside, and the heater 26 is used for this. Further, a valve (not shown) is provided in the middle of the pipe 22 so that it can be switched to the drain side separately from the CVD, so that it can be selectively used for preliminary vaporization (VENT) before film formation and film formation (RUN). .

FIG. 5 shows another modification of the liquid material vaporizer of the present invention. The outer spray block 21a of the thermospray 21 is provided with a through hole for introducing a carrier gas. The liquid material introduced from the arrow A is vaporized in the capillary tube 21b, mixed with the carrier gas introduced from the arrow B, and taken out from the pipe 25. Since the carrier gas comes at room temperature, it is heated and introduced using the heater of the thermospray 21 and is introduced and mixed with the vaporized material. Since the heater is shared, the structure is simple, and a low-cost liquid material vaporizer can be obtained.

FIG. 6 shows a modification of the liquid material vaporizer of the present invention shown in FIG. Components having the same reference numerals as those in FIG. 5 have the same functions. In the case of a material in which the generation of products in the capillary tube 21b is unavoidable even by optimizing the heater temperature, by installing a filter heated from the outside downstream, the material cannot be completely vaporized in the capillary tube 21b. Droplets in the fog
Heating in a vacuum atmosphere has the effect of vaporizing and also preventing the product from flowing to the MOCVD side. The degree of clogging of the filter can be monitored by a pressure gauge 28 disposed between the joints. Thereby, the range of optimizing the temperature in the thermospray 21 is widened, and the range of liquid materials that can be used is widened.

The liquid material vaporizer in the above embodiment is desirably installed in a direction in which the liquid material flows from the top to the bottom so as to prevent dripping at the tip of the thermospray.

[0016]

The liquid material vaporizer according to the present invention is configured as described above, and allows the liquid material to pass through the capillary tube inserted into the metal block heated by the heater, and causes the liquid material to flow near the tip of the capillary tube. By using a vaporizer structure that is a thermospray that is vaporized by the vaporizer, it has excellent effects of vaporization efficiency, stability, and reproducibility, and it is possible to simplify the vaporizer structure and maintain it at low cost. A liquid material vaporizer having excellent properties can be obtained.

[Brief description of the drawings]

FIG. 1 is a structural view of an embodiment of a thermospray of a liquid material vaporizer according to the present invention.

FIG. 2 is a state diagram of a liquid change in a capillary tube of the liquid material vaporizer of the present invention.

FIG. 3 is a structural view of a modified example of the thermospray of the liquid material vaporizer of the present invention.

FIG. 4 is a configuration diagram of a modified example of the liquid material vaporizer of the present invention.

FIG. 5 is a configuration diagram of a modification of the liquid material vaporizer of the present invention.

FIG. 6 is a configuration diagram of a modified example of the liquid material vaporizer of the present invention.

FIG. 7 is a schematic configuration diagram of a conventional liquid material vaporizer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inner heater block 2, 21a ... Outer heater block 3 ... Heater 4, 21b ... Capillary tube 21 ... Thermospray 22 ... Joint 23 ... Cap nut 24 ... Packing 25 ... Piping 26 ... Warming heater 27 ... Filter 28 ... Pressure gauge 31 ... Liquid material vaporizer 31a ... Inlet 31b ... Outlet 32 ... Liquid material storage 33 ... Heating body 34 ... Pump

Claims (4)

[Claims] 1. A liquid material vaporizer for vaporizing a liquid material, a thin tube for introducing and vaporizing the liquid material, a metal block penetrating through the thin tube, and heating the metal block, and a shaft of the metal block. A liquid material vaporizer, comprising a heating means for providing a temperature gradient for each section in a direction, and vaporizing a liquid material. 2. A liquid material vaporizer, wherein a joint to which the liquid material vaporizer according to claim 1 is fixed and a pipe for supplying the liquid material vaporizer to MOCVD are connected with a cap nut. 3. The liquid material vaporizer according to claim 2, wherein a carrier gas introduction hole is provided in the metal block. 4. The non-vaporized liquid material heating means according to claim 3, wherein a filter heated by external heating energy is provided downstream of the thin tube for introducing and vaporizing the liquid material; A liquid material vaporizer comprising a pressure gauge for detecting clogging of a filter at the joint portion.