JP3633763B2 - Vaporizer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vaporizer used in, for example, a thin film vapor phase growth apparatus using a liquid as a raw material, and more particularly to a vaporizer suitable for vaporizing a high dielectric material such as barium titanate / strontium or a ferroelectric thin film material. .
[0002]
[Prior 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 with a gigabit order in the future from the current megabit order has been conducted. As a dielectric thin film used for manufacturing a large capacity element necessary for manufacturing such a DRAM, a silicon oxide film or a silicon nitride film having a dielectric constant of 10 or less, tantalum pentoxide (Ta ₂ O having a dielectric constant of about 20). ₅ ) Instead of thin films, 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. Has been. In addition, ferroelectric thin film materials such as PZT, PLZT, and Y1, which have a higher dielectric constant, are also promising.
[0003]
Chemical vapor deposition (CVD) is a promising method for depositing such a material, and in this case, it is necessary to stably supply a source gas to the deposition target substrate in the deposition reaction tank. is there. As the source gas, Ba (DPM) ₂ , Sr (DPM) _2, etc., which are solid at room temperature, are dissolved in an organic solvent (for example, THF) and liquefied to heat and vaporize.
[0004]
Such a liquid raw material changes in quality when it receives heat for a longer time than necessary, or only the organic solvent that is mainly the solvent is vaporized first, and the concentration of the organic metal itself is increased and polymerized. It may become difficult to vaporize. For example, in a liquid raw material in which Ba (DPM) ₂ and Sr (DPM) ₂ are dissolved in THF as an organic solvent, the liquid phase range of the solvent is the region shown in FIG. The phase range is (a + c). Therefore, when passing through the region (c) in order to vaporize the raw material in the region (a), only the solvent is vaporized and the raw material is deposited, which blocks the passage and causes quality deterioration due to concentration change. At that time, it is considered necessary to bring the liquid raw material to the high temperature region at once.
[0005]
[Problems to be solved by the invention]
However, unless the heat necessary for vaporizing the liquid raw material is supplied in the shortest possible time, the temperature reacts and fluctuates particularly sensitively to fluctuations in the supply amount of the liquid raw material, and the raw material enters the region (c). It may stay and change the composition, or may vaporize and condense after the vaporization. In addition, in the vaporizer, it is necessary to control a minute flow rate depending on the situation, but if the vaporized state is unstable, it is difficult to control the flow rate.
[0006]
An object of the present invention is to provide a vaporizer capable of stably and efficiently vaporizing a liquid material having a complex vaporization characteristic as a high dielectric material or a ferroelectric material.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is a first region for maintaining the liquid from the supply source in a liquid state, and a second region that is provided adjacent to the downstream side of the first region and vaporizes the liquid. Pressure holding means for holding the pressure in the first region higher than that in the second region; and the liquid in the first region is lower than the vaporization temperature at the pressure in the first region, and the second region a first heating means for heating a temperature higher than the vaporization temperature at a pressure of, have a second heating means to compensate for the heat of vaporization of the liquid in said second region, said first or second heating means a vaporizer, wherein the heating medium der Rukoto having fluidity.
[0008]
Thereby, the temperature of the liquid in the first region is raised to the maximum temperature at which the raw material does not deteriorate or deteriorate, and the temperature and pressure conditions are maintained so that the liquid state is maintained. The amount of heat necessary for evaporation can be accumulated to the maximum in the first region.
[0009]
A sufficient amount of heat is supplied in advance in the first region, and the liquid is in a superheated state above the gas phase line under the pressure condition in the second region. Get. Accordingly, it is possible to prevent vaporization from becoming unstable due to a temperature drop due to a shortage of heat. In addition, when moving from the first region to the second region, vaporization is instantaneously performed, and the previous first region is maintained at a sufficiently high pressure, so that partial vaporization of the solvent may occur. Is prevented.
As the heating medium, for example, by using a predetermined chemically synthesized oil, efficient and stable heating is performed with a sufficient heat capacity.
[0010]
The invention according to claim 2 has pressure holding means for holding the pressure of the first region higher than the vapor pressure of the liquid at the temperature of the second region. It is a vaporizer.
[0012]
A third aspect of the present invention is the vaporizer according to the first aspect, wherein the pressure holding means is a check valve. For example, by forming a contact line between the valve body and the valve seat extending in the circumferential direction, a predetermined vaporization passage can be formed and a certain vaporization efficiency can be ensured while forming a large pressure gradient. .
[0013]
According to a fourth aspect of the present invention, there is provided means for introducing a carrier gas, a solvent, a cleaning gas or a solvent for conveying the vaporized gas to the first region or the second region. 1. The vaporizer according to 1. Thereby, the effect | action of the increase in vaporization efficiency and the stability improvement of vaporization is acquired.
[0014]
A heating medium before Symbol second heating means has a fluidity, the heat transfer path to the second region is mainly the valve body of the check valve, the valve body has a portion of the sheet You may do it .
[0015]
Before SL sites on the sheet of liquid may be disposed in a direction to receive by gravity.
[0016]
The invention according to claim 5 is a structure in which the liquid suddenly expands in volume before and after the boundary between the second region and the first region, and immediately after the liquid flows into the second region, or immediately inflated once abruptly flows into the second region is a vaporization apparatus according to claim 1, characterized in Rukoto to have a go slowly passage cross-sectional area increases structures.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show a vaporizer according to an embodiment of the present invention. FIG. 1 (a) is a sectional view of the whole, FIG. 1 (b) is an AA arrow view, and FIG. It is a figure which expands and shows the principal part. 1 shows a state in which the valve is fully opened, and FIG. 2 shows a state in which the valve is closed. Vaporization is normally performed in a state close to FIG.
[0019]
This vaporizer is configured by connecting an upper casing 10 and a lower casing 12 with a diaphragm (valve element) 14 interposed therebetween. In the upper casing 10, a liquid raw material supply channel 18 surrounded by the first heating medium space 16 is formed at the center, and this opens to the lower surface of the upper casing 10. As shown in FIG. 1B, a flat circular recess 22 surrounded by a ridge (diaphragm pressing portion) 20 extending in the circumferential direction and the diaphragm 14 is formed on the lower surface of the upper casing 10. The diaphragm 14 is preferably made of a material that does not break even when made thin, such as a Co alloy, and has good sealing properties. The liquid raw material supply channel 18 is structured such that the liquid raw material is supplied in a fixed amount from the liquid raw material supply unit using a mass flow controller, a metering pump, or the like. The liquid raw material supply channel 18 is designed to be sufficiently thin so that the time required for the liquid raw material to pass therethrough is not unnecessarily long.
[0020]
As shown in FIG. 1B, the recess 22 on the lower surface of the upper casing 10 is further formed with a second protrusion (valve seat) 24 concentrically on the inner side, and the inner side is a liquid raw material supply. A liquid space 26 in which the flow path 18 opens, and a vaporization space 28 on the outside. The vaporization space 28 is an annular space, and an exhaust port 32 of an exhaust passage 30 formed in the upper casing 10 is opened on one side, and a carrier gas passage 34 that supplies a carrier gas such as Ar to the other side. A carrier gas port 36 is open. The carrier gas port 36 may supply a cleaning gas or solvent. The liquid source supply channel 18 and the liquid space 26 constitute a first region, and the vaporization space 28 and the exhaust channel 30 constitute a second region.
[0021]
A valve device V is incorporated in the lower casing 12. That is, a valve hole 40 is formed in the center of the lower casing 12, and a shaft 44 having a valve support 42 attached to the top is accommodated therein so as to be movable up and down. The valve support 42 is a flat surface having the same diameter as the valve seat 24 or a curved surface having a large curvature, and the edge is a tapered surface 46 that is gently inclined. A second heating medium space 48 is formed so as to surround the periphery of the valve support 42, and a heat medium inflow channel 50 and an outflow channel 52 are in communication with the second heating medium space 48. Heat medium circulation piping is connected.
[0022]
This valve device V urges the valve support 42 upward at a predetermined pressure by the pressing means so that the liquid raw material oozes into the vaporization space 28 when the pressure on the liquid raw material side becomes larger than this. In this embodiment, two pressing means, that is, a spring device 54 and an air cylinder device 56 are provided. That is, a spring space 58 that surrounds the shaft 44 is formed at the center in the height direction of the lower casing 12, and a coil spring 62 that biases the shaft 44 upward via the spring retainer 60 is accommodated therein. . In addition, an air cylinder space 68 having air ports 64 and 66 on the upper and lower sides is formed in the lower portion, in which a piston plate 70 attached to the shaft 44 is slidably accommodated, and a seal member is disposed at a necessary portion. Has been.
[0023]
It should be noted that the operating pressure of the valve device V is set, and the temperature of the heat medium in the valve controller, the first heating medium space 16 and the second heating medium space 48 that controls the valve to operate according to the set pressure. Although a temperature control unit and the like for controlling are provided, details thereof are omitted. The heat medium temperature in the first heating medium space 16 is set to a temperature higher than the vaporization temperature in the pressure of the gas space 28. The heat medium temperature in the second heating medium space 48 heats the valve support 42 and the diaphragm 14 to a temperature higher than the vaporization temperature in the pressure of the gas space 28 of the liquid raw material.
[0024]
Hereinafter, an operation of the vaporizer configured as described above will be described. The temperature and pressure of each part are set to predetermined values in advance, and a downstream film forming apparatus or the like is connected to the exhaust port. The liquid raw material flows into the liquid space 26 from a raw material supply unit (not shown) via the thin tubular raw material supply channel 18. In the pressure feed pump of the raw material supply unit, the supply pressure is adjusted to be slightly larger than the urging force of the valve support 42 by the pressing means 54 and 56. As a result, a small amount of liquid raw material is collected from the minute gap formed by the minute difference between the supply pressure and the valve body pressing force along the contact line between the valve body 14 and the valve seat 24 supported by the valve support 42. The vaporized space 28 is supplied.
[0025]
On the secondary side of the boundary between the first region and the second region, the pressure is instantaneously released and enters the low pressure region. In this process, a part of the raw material is instantly vaporized, but the insufficient vaporization heat at this time is supplied by the heating medium from the back side of the sheet-like valve body 14. Since the valve body 14 is in the form of a thin sheet, the heat supply speed is sufficiently high. In this embodiment, since the sheet surface is on the lower side, the material that could not be vaporized immediately after inflow also rides on the heated sheet surface. Sufficient heat will be supplied. Since the carrier gas has a structure in which it is discharged via the above-described portion of the unvaporized portion, the raw material vapor pressure at that portion is lowered, thereby improving the vaporization efficiency.
[0026]
In the present invention, as described above, increasing the pressure gradient (pressure difference) before and after the contact line between the valve body 14 and the valve seat 24 allows the raw material to retain more heat in a liquid state. Although it is preferable, it is preferably 15 kgf / cm ² in order for the invention to exert the above-described action. In addition, for the gas after passing through the second region, if there is a sudden pressure fluctuation, the supply of heat of vaporization is insufficient, the temperature drops, and vaporization becomes unstable. Therefore, a structure in which the cross-sectional area of the passage from the second region toward the exhaust passage 30 is gradually increased to suppress a sudden volume expansion and prevent a temperature drop is desirable.
[0027]
FIG. 3 shows a second embodiment of the present invention, in which the carrier gas supply channel 72 is merged with the liquid source supply channel 76 via the mixer 74, and the carrier gas is premixed with the liquid source. I am doing so. Thereby, since the carrier gas passes through the boundary between the first region and the second region, the replacement of the raw material vapor with the carrier gas is sufficiently performed, so that the liquid raw material can be vaporized more efficiently.
[0028]
FIG. 4 shows a third embodiment of the present invention, in which a carrier gas channel 78 and a liquid source supply channel 80 are opened in the liquid space 26 as a double pipe structure, and the carrier gas and the liquid source are supplied. At the same time, the liquid space 26 is supplied. Also by this, as in the case of FIG. 3, the vapor substitution efficiency of the liquid raw material is increased, so that the vaporization is performed efficiently.
[0029]
FIG. 5 shows a fourth embodiment of the present invention. In the previous embodiments, the space where the raw material circulates and the space on the valve device side are partitioned by the diaphragm 14 itself which is a valve body. However, in this embodiment, a bellows 82 is used. That is, a valve body 84 having the same shape as the previous valve support is attached to the tip of the shaft 44, and the upper end of the bellows 82 is attached to the lower edge portion of the valve body 84. The lower end of the bellows 82 is the valve housing of the casing 86. It is attached to the inner end of the annular plate 90 protruding from the inner surface of the hole 88.
[0030]
The space inside the bellows 82 is a second heating medium space 92, and the heat medium supplied through the flow paths 94 and 96 heats the shaft 44 and the valve body 84 to replenish the heat of vaporization. ing. In this embodiment, the vaporization space 28 is configured as a cylindrical space surrounding the valve body 84 and the bellows 82, and the outer surface of the bellows itself also acts as a heating surface.
[0031]
FIG. 6 shows a fifth embodiment of the present invention. In the fourth embodiment, the carrier gas flow path 72 is combined with the liquid source supply flow path 76 via the mixer 74. It is. FIG. 7 shows a sixth embodiment of the present invention. In the fourth embodiment, the carrier gas flow path 78 and the liquid source supply flow path 80 have a double tube structure. .
[0032]
8 and 9 show still another embodiment of the present invention. In these embodiments, the difference between the temperature in the first region and the vaporization temperature of the raw material at the pressure in the second region, that is, the degree of superheating (= ΔT), corresponds to the first region. The degree of expansion of the flow path in the portion of the boundary area toward the second area is changed.
[0033]
The seventh embodiment of FIG. 8 is suitable when ΔT is set relatively small, and the angle θ ₁ between the valve seat 24 and the valve body 14 is set small. In this case, since the amount of heat that the liquid material has as sensible heat is not so large, by adopting the configuration as described above, volume expansion due to rapid channel expansion is prevented, and vaporization due to gas temperature drop is prevented. Prevent instability.
[0034]
On the other hand, the eighth embodiment of FIG. 9 is suitable when ΔT is set relatively large, and the angle θ ₂ between the valve seat 24 and the valve body 14 is also set large. In this case, since the amount of heat that the liquid material has as sensible heat is large, it is possible to increase the vaporization efficiency by performing rapid deposition expansion. It should be noted that how much ΔT can be set differs depending on the target raw material, and for a raw material having a small range between the vaporization temperature and the reaction temperature, ΔT cannot be set large.
[0035]
【The invention's effect】
As described above, according to the present invention, vaporization is instantaneously performed when moving from the first region to the second region having a lower pressure while maintaining the first region at a high pressure to prevent deterioration of the liquid. Therefore, it is possible to prevent vaporization and partial vaporization of the liquid raw material having complicated vaporization characteristics as a high dielectric material or a ferroelectric material, and to vaporize stably and efficiently. In addition, since sufficient heat of vaporization is given to the liquid prior to vaporization, it is possible to prevent clogging in the vaporizer and piping due to temperature instability due to insufficient heat in the vaporization region, and stable vaporization operation. Can be performed while accurately controlling the minute flow rate.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view showing the overall configuration of a vaporizer according to a first embodiment of the present invention, and FIG.
FIG. 2 is an enlarged view showing a main part of the apparatus shown in FIG.
FIG. 3 is a sectional view of a vaporizer according to a second embodiment of the present invention.
FIG. 4 is a sectional view of a vaporizer according to a third embodiment of the present invention.
FIG. 5 is a sectional view of a vaporizer according to a fourth embodiment of the present invention.
FIG. 6 is a sectional view of a vaporizer according to a fifth embodiment of the present invention.
FIG. 7 is a sectional view of a vaporizer according to a sixth embodiment of the present invention.
FIG. 8 is a sectional view of a vaporizer according to a seventh embodiment of the present invention.
FIG. 9 is a sectional view of a vaporizer according to an eighth embodiment of the present invention.
FIG. 10 is a state diagram showing characteristics of a liquid raw material.
[Explanation of symbols]
10 Upper casing 12 Lower casing 14 Diaphragm (valve)
16 1st heating-medium space 18,76,80 Liquid raw material supply flow path 20 Diaphragm pressing part 22 Recess 24 Valve seat 26 Liquid space (1st area | region)
28 Vaporization space (second area)
30 Exhaust flow path 32 Exhaust ports 34, 72, 78 Carrier gas flow path 42 Valve bodies 48, 92 Second heating medium space 54 Spring device 56 Air cylinder device V Valve device

Claims (5)

A first region for maintaining liquid from a source in a liquid state;
A second region that is provided adjacent to the downstream side of the first region and vaporizes the liquid;
Pressure holding means for holding the pressure in the first region higher than that in the second region;
First heating means for heating the liquid in the first region to a temperature lower than the vaporization temperature at the pressure in the first region and higher than the vaporization temperature at the pressure in the second region;
Have a second heating means to compensate for the heat of vaporization of the liquid in said second region,
Vaporizing device said first or second heating means and said heating medium der Rukoto having fluidity. 2. The vaporizer according to claim 1, further comprising pressure holding means for holding the pressure in the first region higher than the vapor pressure of the liquid at the temperature in the second region. 2. The vaporizer according to claim 1, wherein the pressure holding means is a check valve. 2. The vaporizer according to claim 1, further comprising means for introducing a carrier gas, a solvent, a cleaning gas, or a solvent for conveying the vaporized gas to the first region or the second region. A structure in which the liquid suddenly expands in volume before and after the boundary between the second region and the first region ;
Wherein said liquid, characterized in Rukoto to have a said immediately flowed into the second region, or immediately after once expands rapidly flows into the second region will slowly passage cross-sectional area increases structural Item 2. The vaporizer according to Item 1.

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