JPH1085581A - Vaporizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transfer heat smoothly to a vaporizer with a porous body and vaporize efficiently and smoothly a liquid raw material of complicated characters by passing a heat transfer medium heated up to the vaporizing temperature or above of the liquid raw material through a heat transfer medium flow path being in contact with the porous body thermally. SOLUTION: A porous body 9 is disposed in a cylindrical casing 8 on a vaporizing section B with a raw material feed section A opened on the upper side, and a jacket 10 constituting an outer heat transfer flow path P1 for heating is provided on the outside of the casing 8, and an inlet 11 and an outlet 12 for a heat transfer medium L2 are formed thereon. An opening 16 constituting an inner heat transfer medium flow path P2 running through in the lateral direction is formed almost on a central section in the height direction of the porous body 9, and a pipe 17 is set on the position corresponding to the opening 16 in the casing 8. The heat supply to a site where vaporization heat is removed and the temperature is lowered inside the porous body 9 can be carried out smoothly by the arrangement to decrease the nonuniformity of temperature inside the porous body 9. Therefore, the vaporization of good efficiency utilizing the whole area of the porous body 9 can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vaporizer for use in, for example, a thin film vapor phase growth apparatus using a liquid as a raw material, and more particularly to a vaporizer for high permittivity thin film materials such as barium / strontium titanate. The present invention relates to a liquid material vaporizer.

[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. As a dielectric thin film used for manufacturing a large-capacity element required for manufacturing such a DRAM, a silicon oxide film or a silicon nitride film having a dielectric constant of 10 or less, and tantalum pentoxide (Ta ₂ O) having a dielectric constant of about 20 are used. ₅ ) Instead of the thin film, a metal oxide thin film material 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, is promising. Have been.

As a method for forming such a material, chemical vapor deposition (CVD) is promising. In this case, a source gas is finally supplied stably to a substrate on which the film is to be formed in a reaction tank. There is a need to. The raw material gas is Ba which is solid at room temperature.
In order to liquefy (DPM) ₂ , Sr (DPM) _{2 and the} like, and further stabilize the vaporization characteristics, an organic solvent (for example, TH
F) is vaporized by heating.

[0004] It is very difficult to stably vaporize such a high dielectric material gas as described above. This is because the vaporization temperature and decomposition temperature of these raw materials are close to each other, there is a difference between the vaporization temperature and the vaporization temperature of the organic solvent, and the vapor pressure is extremely low.

For example, Ba (DPM) ₂ , Sr (DP
The liquid material obtained by dissolving M) ₂ in a solvent such as THF,
The liquid phase range of the solvent is the region of FIG. 6A, and the liquid phase range of the raw material is a + c. Therefore, when passing the region c in order to vaporize the raw material in the region a, only the solvent is vaporized and the raw material precipitates, blocking the passages and causing quality deterioration due to a change in concentration.

[0006] Therefore, it is necessary to bring the liquid raw material to a high-temperature region at once at the time of vaporization. As such a vaporizer, there is known an apparatus in which a liquid material is supplied to a porous body and the porous material is heated in a state where the liquid material is dispersed inside the porous body.

[0007]

In the above-mentioned conventional vaporizer, since the heat of vaporization is taken from the vaporized portion of the porous body, it is necessary to supply a large amount of heat corresponding to the heat of vaporization to the porous body. is there. In the conventional apparatus, the supply of heat to the porous body is performed from the outside of the porous body, and the supply of heat to the center of the porous body mainly depends on the heat conduction of the porous body itself. Therefore, the heat supply to the inside of the porous body becomes insufficient and the temperature becomes low, and the inside of the porous body is clogged.

In a vaporizer in which only the lower limit temperature of evaporation is a problem, if the temperature of the outer peripheral portion is sufficiently higher than the vaporizing temperature, the temperature of the central portion does not drop below the vaporizing temperature. However, with a specific raw material liquid, if the temperature is too high, deterioration or decomposition may occur, and the upper limit and the lower limit are narrow, so that the above method cannot be taken.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for smoothly supplying heat to a vaporizer having a porous body to efficiently and smoothly vaporize a liquid material having complicated characteristics. It is intended for.

[0010]

According to a first aspect of the present invention, there is provided an evaporating section having a porous body having a liquid receiving surface and an exhaust surface opposed to each other, and a liquid raw material on a liquid receiving surface of the porous body. A raw material supply section having a raw material supply path to be supplied, a heat medium flow path that is in thermal contact with the porous body, and heat for flowing the heat medium heated to a temperature equal to or higher than the vaporization temperature of the liquid raw material through the heat medium flow path. A vaporizer characterized by having a medium supply system.

As a result, the porous body is heated with a sufficient heat capacity supplied by the heat medium flowing through the heat medium flow path, whereby efficient vaporization is effectively performed by effectively using the entire area of the porous body. . Such a heat medium flow path is made of a suitable material, diameter,
It is composed of casings having dimensions such as thickness, and heating is performed by heat conduction from these casings to the porous body.

A heat medium having a large heat capacity, such as oil, is usually used. As a result, stable control can be performed with small fluctuations in temperature. When a heat medium having a large heat capacity is used, it is not necessary to flow the heat medium at a high speed if the diameter of the heat medium flow path is set to a certain size. It goes without saying that heating other than the heat medium flow path may be used in combination for heating the porous body.

The invention according to a second aspect is the vaporizer according to the first aspect, wherein the heat medium flow path has an external heat medium flow path that covers a side surface of the porous body. The invention according to claim 3 is the vaporizer according to claim 1, wherein the heat medium flow path has an internal heat medium flow path penetrating the porous body. The invention according to claim 4 is the vaporizer according to claim 3, wherein the internal heat medium flow path has a transverse flow path extending in a direction intersecting the axis of the porous body.

According to a fifth aspect of the present invention, in the vaporizer according to the third aspect, the internal heat medium flow path has a vertical flow path extending in a direction parallel to an axis of the porous body. is there. The invention according to claim 6 is the vaporizer according to claim 3, wherein the internal heat medium flow path has a stagnant portion that expands at the center of the porous body. The invention according to claim 7 is characterized in that the heat medium flow path is provided so as to cover at least one edge of the liquid receiving surface and the exhaust surface of the porous body. The vaporizer according to the above.

The invention according to claim 8 is characterized in that the jacket forming the external heat medium passage has a divided structure sandwiching the edge of the porous body.
The vaporizer according to the above. Thereby, the porous body is stably held, and the work of attaching and detaching the porous body becomes easy.

According to a ninth aspect of the present invention, there is further provided a second external heat medium flow passage which covers a central portion of at least one of the liquid receiving surface and the exhaust surface. The vaporizer according to the above. The porous body may be formed in a column shape. The porous body may be formed in a flat disk shape.

[0017] The porous body may be formed so that its cross section becomes larger as it goes downstream. If the flow velocity is too high, the pressure on the liquid inlet side increases. However, by increasing the diameter on the downstream side, the flow velocity can be reduced and the pressure loss can be maintained at an appropriate value.

According to a tenth aspect of the present invention, there is provided the vaporizer according to the first aspect, wherein a carrier gas supply path for supplying a carrier gas toward the liquid receiving surface is formed. By supplying the carrier gas, the partial pressure of the source gas can be reduced to promote the vaporization.

According to an eleventh aspect of the present invention, the raw material supply section is formed separately from the vaporizing section, and a temperature maintaining mechanism for maintaining the raw material supply path at a temperature lower than the vaporization temperature of the liquid raw material is provided. The vaporizer according to claim 1, characterized in that: With the separate structure, heat conduction from the high temperature vaporizing section to the raw material supply path is prevented, and the temperature maintaining mechanism prevents the influence of heat due to radiation from the vaporizing section. This temperature is set to be slightly lower than the lowest temperature among the vaporization and decomposition temperatures of the individual components constituting the liquid raw material in order to surely prevent vaporization in this portion. Thus, the raw material is maintained in a stable composition until immediately before the liquid raw material reaches the vaporization region.

According to a twelfth aspect of the present invention, in the first aspect, the raw material supply path is provided with a pressure adjusting part for adjusting the pressure of the liquid raw material immediately before the vaporizing part. It is the vaporizer described. As the pressure adjusting section, a pressure adjusting valve, an orifice, a spring check valve, or the like, which can adjust the flow path pressure is used. As a result, the liquid raw material is maintained at the predetermined pressure immediately before the vaporizing section, so that only the easily vaporizable components in the raw material are prevented from being vaporized and separated.

According to a thirteenth aspect of the present invention, there is provided the vaporizer according to the twelfth aspect, further comprising a heat retaining mechanism for heating or cooling the pressure adjusting section. Since the pressure adjusting section is usually narrow, it is particularly easily clogged. By controlling the temperature of this section, clogging at this section can be suppressed.

The heat retaining mechanism may heat or cool the pressure adjusting section through a heat medium having fluidity. The temperature of the pressure adjusting section may be kept below the vaporization temperature of the liquid raw material.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show a vaporizer according to a first embodiment of the present invention. In order from the upper side, a supply section A for supplying a liquid raw material, a vaporizer which heats and vaporizes by contacting the liquid raw material to be vaporized. And a discharge pipe C for sending the raw material vaporized in the vaporization section B to the next step.

The supply section A is provided with a liquid source supply pipe 1 which is inserted vertically into the center thereof, and a source pipe is connected to an upper end thereof, and a lower end is opened above the vaporization section B. In the vicinity of the lower end, a pressure regulating valve 2 for flowing a fluid when the pressure on the upstream side is equal to or higher than a predetermined pressure is provided, and a raw material outlet (nozzle) 3 is provided below the pressure regulating valve 2. Then, the pressure regulating valve 2 insulation jacket 4 which surrounds the raw material supply pipe 1 including a is provided, the outflow pipe 6 is provided with inlet pipe 5 for circulating the cooling medium L ₁ such as cooling water thereto. The inflow pipe 5 extends near the bottom of the jacket 4,
The flow of the liquid in the jacket 4 is smooth. In this example, the heat insulation jacket 4 can be vertically divided via the flange 7, which is convenient for replacement work of the pressure regulating valve 2 and the like.

In the vaporizing section B, a porous body 9 is disposed in a cylindrical casing 8, and a jacket 10 forming an external heat medium flow path P ₁ for heating is provided outside the casing 8. provided, including an inlet 11 and an outlet 12 for circulating a heating medium L ₂ is formed. Heating medium L
_{As 2} , one having a large heat capacity is desirable, and usually a predetermined oil is used. In this example, the jacket 10
Are formed to extend around the heat retaining jacket 4 surrounding the upper raw material supply pipe, and a space 14 surrounding the nozzle 3 at the lower end of the raw material supply pipe in an airtight manner is formed by these and the top plate 13.

The top plate 13 is formed with a carrier gas inlet 15 for supplying a carrier gas such as Ar for promoting the replacement of the liquid material in the space 14. The tip of the nozzle 3 secures a predetermined narrow gap with the upper surface (liquid receiving surface) 9a of the porous body 9 so that even a small amount of liquid raw material can be smoothly supplied to the porous body 9. You can do it.

The porous body 9 is formed of a material having good heat conductivity so as to have a porosity having appropriate liquid permeability and air permeability. For example, powdery, granular, linear, needle-like, fibrous, or other irregularly shaped material filled into a gas permeable container, or molded into a porous or mesh shape by compression or heat. Several tens of μm
About 100 μm is desirable. Further, slits or pores may be formed in a non-porous material. As the material, a metal is usually used, but ceramics, plastics, and the like are appropriately used as long as they meet conditions of heat resistance and thermal conductivity.

Further, in a substantially central portion height direction of the porous body 9, the hole 16 of the inner heat medium passage P ₂ which penetrates in the lateral direction as shown in FIG. 2 (a) is formed, the casing 8
Also, a pipe 17 is provided at a position corresponding to this hole. The lower surface (exhaust surface) 9b of the porous body 9 is open in the discharge pipe C connected to the lower side of the vaporization section B. Incidentally, also the exhaust pipe C, the jacket 18 is provided that constitutes the external heat medium flow path P _3.

The raw material supply pipe 1 of the vaporizer is connected to a raw material supply source equipped with a flow controller and a pump.
A constant flow rate of the raw material is supplied at a predetermined pressure. Discharge piping C
Is connected, for example, to a vacuum chamber for performing a CVD process, and therefore has a considerably low pressure inside. The heat insulation jacket 4 of the raw material supply pipe 1 is maintained at a temperature lower than the vaporization temperature of the liquid raw material by water cooling, and the jackets 10 and 18 of the vaporization section B and the discharge pipe C are each maintained at a temperature higher than the vaporization temperature by oil circulation.

Here, when the pressure of the liquid raw material is raised to a value equal to or higher than the set value of the pressure regulating valve 2 by a pump or the like of the raw material supply source, the pressure regulating valve 2 is opened and the liquid raw material is supplied to the upper surface of the vaporizing section B. . The supplied liquid comes into contact with the upper surface 9a of the porous body 9, is sucked into the porous body 9 by a negative pressure, a capillary phenomenon, and the like, and vaporizes by passing through the porous body 9 while passing therethrough. In this example, when the liquid raw material is transferred from the supply section A to the vaporization section B, it is instantaneously moved from the low-temperature supply section A to the high-temperature vaporization section B, so that the temperature transition region is almost eliminated. Therefore, situations such as separation of the solvent in the raw material and precipitation of other components are suppressed.

In this embodiment, since the heating medium flow path P ₂ is formed so as to penetrate the center of the porous body 9, the heat of vaporization is also deprived of the inside of the porous body 9 and the temperature is lowered. Heat is smoothly supplied to the locations, and the temperature inside the porous body 9 is less uneven. Therefore, efficient vaporization using the entire region of the porous body 9 is performed. FIG. 2 (b)
It may of course be formed a heat medium flow path P ₂ to a plurality of through as shown in FIG.

FIG. 3 shows another embodiment of the present invention, in which the porous body 19 is formed in a tapered shape such that the diameter of the porous body 19 increases from the top to the bottom. In order to prevent the flow rate from increasing on the downstream side and increasing the pressure loss on the inlet side as the vaporization of the liquid material progresses, the diameter on the downstream side is increased to decrease the flow rate. Things. Accordingly, in order to balance the internal and external temperatures of the enlarged diameter portion to form an internal heat medium passage P ₄ in the lower central portion of the porous body 19.

In this embodiment, the internal heat medium flow path P ₄
Has longitudinal flow paths 20 along the axis and cross flow paths 21 and 22 on the upstream and downstream sides. As shown in FIG. 4, the cross flow paths 21 and 22 are located at the same height. _May be provided. In this case, the longitudinal flow path 20a is wider than the transverse flow paths 21 and 22, in which the heat medium flows and the heat medium circulates by convection.

FIG. 5 shows still another embodiment of the present invention, in which the porous body 23 used has a flat disk shape as compared with the previous embodiment. In this example,
Not provided the heat medium flow path through the interior of the porous body 23, in its instead, not jackets 24a constituting the first external heat medium flow path P _6, 24b only the side surface of the porous body 23 The outer edges of the upper and lower surfaces 23a and 23b are also in contact with each other. That is, the jackets 24a and 24b sandwich the edge of the porous body 23 between the annular concave portions 25a and 25b. Also, the jacket 26 constituting the second external heat medium passage P ₇ is provided to protrude in the central portion of the discharge pipe C, the top surface covers the central portion of the exhaust surface 23b.

In the vaporizer having such a structure, the liquid raw material is supplied from the nozzle 3 to the center of the liquid receiving surface 23a of the porous body 23, and the inside of the porous body 23 is reduced by a negative pressure and a capillary phenomenon. It flows radially in the radial direction, and evaporates by obtaining heat of vaporization along the way. The vaporized gas is supplied to the annular exhaust surface 23b.
Flows to the discharge pipe C and is supplied to the next step. Since the porous body 23 has a flat disk shape, sufficient heating is performed by heat input from the edge and the center of the lower surface, stable vaporization without clogging is performed, and the manufacturing cost is low because of the simple shape. In this embodiment, the outer jacket 24
Since the porous bodies 23 are fixed by sandwiching the porous body 23 by dividing the upper and lower parts a and 24b, the work of attaching, cleaning, and removing for replacement is easy.

[0036]

As described above, according to the present invention, the porous body is efficiently heated by the heat medium flow passage to promote the vaporization in the porous body, and the entire area of the porous body is effectively used. Efficient vaporization is used. In addition, the material supply section is configured separately from the vaporization section, and a temperature maintaining mechanism for maintaining the material supply path at a predetermined temperature or less is provided, thereby preventing heat conduction from the high-temperature vaporization section to the material supply path. Thus, smooth vaporization can be performed. Further, by providing the pressure adjusting section for adjusting the pressure of the liquid raw material immediately before the vaporizing section, the liquid raw material is prevented from being deteriorated before reaching the vaporizing section. As a result, it is possible to efficiently and smoothly vaporize a liquid raw material having complicated characteristics.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of one embodiment of the present invention.

FIG. 2A is a view taken in the direction of the arrow II, and FIG.
FIG.

FIG. 3 is a sectional view of another embodiment of the present invention.

FIG. 4 is a sectional view of a main part of another example of the invention shown in FIG. 3;

FIG. 5 is a sectional view showing the overall configuration of still another embodiment of the present invention.

FIG. 6 is an example of a graph showing physical properties of a liquid raw material.

[Explanation of symbols]

1 feed channel 2 pressure regulator 4 temperature maintaining mechanism 9,19,23 porous body 9a, 19a, 23a liquid-receiving surface 9b, 19b, 23b exhaust surface L ₂ heating medium A vaporization section B material supply section C discharging pipe P _{1, P 3, P 6,} P 7 external heat medium passage P _2, P _4, P ₅ the internal heat medium channel

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

Claims (13)

[Claims] A vaporizer having a porous body having a liquid receiving surface and an exhaust surface facing each other; a raw material supply unit having a raw material supply path for supplying a liquid raw material to the liquid receiving surface of the porous body; A heat medium flow path thermally contacting a porous body, and a heat medium supply system for flowing a heat medium heated to a temperature equal to or higher than the vaporization temperature of the liquid raw material through the heat medium flow path. . 2. The vaporizer according to claim 1, wherein the heat medium flow path has an external heat medium flow path that covers a side surface of the porous body. 3. The heat medium flow path has an internal heat medium flow path penetrating the porous body.
The carburetor according to claim 1. 4. The vaporizer according to claim 3, wherein the internal heat medium flow path has a transverse flow path extending in a direction intersecting the axis of the porous body. 5. The vaporizer according to claim 3, wherein the internal heat medium flow path has a vertical flow path extending in a direction parallel to an axis of the porous body. 6. The internal heat medium flow path has a stagnant portion expanding at the center of the porous body.
The carburetor according to claim 1. 7. The vaporizer according to claim 1, wherein the heat medium flow path is provided so as to cover at least one edge of the liquid receiving surface and the exhaust surface of the porous body. vessel. 8. The vaporizer according to claim 2, wherein the jacket forming the external heat medium flow passage has a divided structure sandwiching an edge of the porous body. 9. The vaporizer according to claim 2, further comprising a second external heat medium passage which covers a central portion of at least one of the liquid receiving surface and the exhaust surface. 10. The vaporizer according to claim 1, wherein a carrier gas supply path for supplying a carrier gas toward the liquid receiving surface is formed. 11. The apparatus according to claim 1, wherein the raw material supply section is formed separately from the vaporizing section, and a temperature maintaining mechanism for maintaining the raw material supply path at a temperature equal to or lower than a vaporization temperature of the liquid raw material is provided. The carburetor according to claim 1. 12. The vaporizer according to claim 1, wherein a pressure regulator for regulating the pressure of the liquid raw material is provided in the raw material supply path immediately before the vaporizer. 13. The vaporizer according to claim 12, further comprising a heat retaining mechanism for heating or cooling the pressure adjusting section.