JP2003168651A - Apparatus and method for feeding liquid source material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for feeding a liquid source material capable of easily feeding a CVD liquid source material to a vaporizing/ feeding apparatus without discontinuing feeding of the vaporized CVD liquid source material to a CVD apparatus in feeding the vaporized CVD liquid source material. <P>SOLUTION: This apparatus for feeding a liquid source material is a portable liquid-source-material feeding apparatus, which comprises a CVD liquid-source- material container and a cleaning-liquid container. The CVD liquid-source- material container is provided with a heating means, a CVD liquid-source- material feeding tube for feeding the CVD liquid source material to the outside, and an inlet tube for compressed gas for transportation. The cleaning-liquid container is provided with a cleaning-liquid feeding tube for feeding the cleaning liquid to the CVD liquid-source-material feeding tube and an inlet tube for compressed gas for transportation. Besides, to the CVD liquid-source-material feeding tube, a discharge tube for discharging residual cleaning liquid to the outside is connected. The CVD liquid source material is fed to the vaporizing/ feeding apparatus by using the portable liquid-source-material feeding apparatus. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for supplying a liquid CVD raw material to a liquid CVD raw material container of a vaporization supply device. More specifically, liquid CVD
The present invention relates to an apparatus and a method for easily supplying a raw material to a liquid CVD raw material container of a vaporization supply device without contacting the atmosphere.

[0002]

2. Description of the Related Art In recent years, along with the development of the semiconductor industry, the performance and integration of semiconductor devices have advanced, and in place of the hydride gas and halide gas that have been used conventionally,
Various liquid organometallic compounds have come to be used as CVD raw materials. The insulating thin film of a semiconductor device includes SiO ₂ as a gate insulating film, Si ₃ N _{4 as} a capacitor insulating film, PSG (phosphorus silicon glass) as an interlayer insulating film, and BPSG (boron phosphorus silicon silicon).
Glass), for example, tetraethoxysilicon (Si (OC ₂ H ₅ ) ₄ ) is used as a CVD raw material for the SiO ₂ film.
However, trimethoxyboron (B (OCH ₃ ) ₃ ) and trimethoxyphosphorus (PO (O
CH ₃ ) ₃ ) and the like are used.

In a metal film of a semiconductor device, dimethyl aluminum hydride (Al (CH ₃ ) ₂ H) is used as a CVD raw material for an aluminum film, and hexafluoroacetylacetone copper vinyltrimethylsilane ((CF ₃ CO) ₂ CHCu · C
H ₂ CHSi (CH ₃ ) ₃ ) and bis (ethylcyclopentadienyl) ruthenium (Ru (C ₅ H ₄ C ₂ H ₅ ) ₂ ) are used as a CVD raw material for the ruthenium film.

These liquid organometallic compounds are indispensable materials in semiconductor manufacturing, but most of them are highly toxic or have not been confirmed to be safe. Moreover, organoaluminum and the like explode with air, water and explosion. It is extremely dangerous because it reacts dynamically. These liquid CVD raw materials are usually filled in a relatively small and highly airtight metal container having an internal capacity of several tens to several hundreds of g. It is supplied to the vaporizer via the mass flow controller by the pressure of the gas, made into a gas state in the vaporizer, and then supplied to the CVD apparatus.

[0005]

As described above, many liquid CVD raw materials are highly toxic and highly reactive, and liquid CV
If the reactants such as the liquid CVD raw material and water are generated and powdered or adhered in the pipe before the raw material D is supplied to the vaporizer, the vaporization supply, the vapor phase growth reaction, or the quality of the semiconductor thin film is adversely affected. Therefore, when replacing a used liquid CVD raw material container with a new liquid CVD raw material container, even if these are liquid CVD raw materials of the same type, the liquid C
Liquid C remaining on the inner wall of the pipe before removing the VD raw material container
It is necessary to wash and remove the VD raw material, and after the replacement, it is necessary to supply a carrier gas to the inside of the pipe to completely remove air and ensure airtightness and safety.

Therefore, in the conventional vaporization supply of the liquid CVD raw material, the vaporization supply must be interrupted in order to replace the liquid CVD raw material container, and there is a disadvantage that it takes time to restart the vaporization supply. Therefore, the problem to be solved by the present invention is to provide a liquid raw material supply capable of easily replenishing the liquid CVD raw material to the vaporization supply device without interrupting the vaporization supply to the CVD device in the vaporization supply of the liquid CVD raw material. An apparatus and a liquid raw material supply method are provided.

[0007]

As a result of intensive studies to solve these problems, the inventors of the present invention used a portable liquid raw material supply device equipped with a liquid CVD raw material container and a cleaning liquid container to obtain this liquid. While supplying the liquid CVD raw material from the raw material supply device to the liquid CVD raw material container of the vaporization supply device,
Since the post-treatment after the supply of the liquid CVD raw material is completed is performed by cleaning the pipe in the portable liquid raw material supply device, it is possible to easily perform the liquid CVD raw material without interrupting the vaporization supply. It has been found that the vaporization supply device can be supplemented with the present invention, and the present invention has been completed.

That is, the present invention comprises a liquid CVD raw material container and a cleaning liquid container, and the liquid CVD raw material container has a heating means and a liquid CVD raw material supply pipe for supplying the liquid CVD raw material to the outside and pressure feeding. A gas introducing pipe is connected, a cleaning liquid supply pipe for supplying a cleaning liquid to the liquid CVD raw material supply pipe and a pressure-feeding gas introducing pipe are connected to the cleaning liquid container, and the liquid CVD raw material supply pipe is further connected to the liquid CVD raw material supply pipe. A portable liquid raw material supply device characterized in that a discharge pipe for discharging the residual cleaning liquid to the outside is connected.

The present invention also provides a portable liquid source supply device comprising a liquid CVD source container filled with a liquid CVD source and a cleaning liquid container filled with a cleaning liquid.
Liquid C in a liquid CVD raw material container other than the liquid raw material supply device
After supplying the VD raw material, the cleaning liquid is supplied from the cleaning liquid container into the liquid CVD raw material supply pipe of the liquid raw material supply device used for supplying the liquid CVD raw material to wash away the remaining liquid CVD raw material, and then the The liquid raw material supply method is also characterized in that the cleaning residual liquid remaining in the liquid CVD raw material supply pipe is removed by heating and / or decompressing the inside of the liquid CVD raw material supply pipe.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a liquid C of a vaporization and supply device.
The present invention is applied to an apparatus and a method for supplying a liquid CVD raw material of the same type as the liquid CVD raw material filled in the liquid CVD raw material container to the VD raw material container. The liquid raw material supply device of the present invention includes a liquid CVD raw material container and a cleaning liquid container,
The liquid CVD raw material container has a heating means and has a liquid CV outside.
The liquid CVD raw material supply pipe for supplying the D raw material and the pressurized gas introduction pipe are connected, and the cleaning liquid container is connected with the cleaning liquid supply pipe and the pressurized gas introduction pipe for supplying the cleaning liquid to the liquid CVD raw material supply pipe. Further, the liquid CVD raw material supply device is a portable liquid raw material supply device in which a discharge pipe for discharging the cleaning residual liquid to the outside is connected to the liquid CVD raw material supply pipe.

In the liquid raw material supply method of the present invention, the liquid CVD raw material is supplied from the portable liquid raw material supply device to the liquid CVD raw material container other than the liquid raw material supply device, and then the liquid CVD is performed. A cleaning liquid is supplied into the liquid CVD raw material supply pipe of the liquid raw material supply device used to supply the raw material to wash away the remaining liquid CVD raw material, and then the liquid CVD raw material supply pipe is heated and / or depressurized to perform liquid CVD. This is a liquid raw material supply method for removing the residual cleaning liquid remaining in the raw material supply pipe.

Liquid raw material supply device and liquid raw material supply of the present invention
Liquid CVD raw materials applicable to the feeding method are liquid at room temperature.
Even the body is a solid dissolved in a solvent
Also, there is no particular limitation as long as it can maintain a liquid state.
It is appropriately selected and used depending on the way. For example Tetra Iso-P
Ropoxy titanium (Ti (OCH (CH₃)₂)_Four), Tet
La n-propoxy titanium (Ti (OC₃H₇)_Four), Tetra t
ert-butoxy zirconium (Zr (OC (C
H₃)₃)_Four), Tetra-n-butoxyzirconium (Zr
(OC_FourH₉)_Four), Tetramethoxy vanadium (V (O
CH₃)_Four), Trimethoxyvanadyl oxide (VO (O
CH₃)₃), Pentaethoxyniobium (Nb (OC₂H_Five)
_Five), Pentaethoxy tantalum (Ta (OC₂H_Five)_Five),
Trimethoxyboron (B (OCH₃)₃), Tri iso-pro
Poxyaluminum (Al (OCH (CH₃)₂) ₃),
Tetraethoxy silicon (Si (OC₂H_Five)_Four), Tetra
Ethoxy germanium (Ge (OC₂H_Five)_Four), Tetra
Methoxy tin (Sn (OCH₃)_Four), Trimethoxyphosphorus
(P (OCH₃)₃), Trimethoxyphosphine oxide
(PO (OCH₃)₃), Triethoxyarsenic (As (OC
₂H_Five)₃), Triethoxy antimony (Sb (OC
₂H_Five)₃) And other liquid alkoxides at room temperature
You can

In addition to the above, trimethyl aluminum (Al (CH ₃ ) ₃ ), dimethyl aluminum hydride (Al (CH ₃ ) ₂ H), tri-iso-butyl aluminum (Al (iso-C ₄ H ₉ ) ₃ ), Hexafluoroacetylacetone copper vinyl trimethylsilane ((CF ₃ CO) ₂
CHCu.CH ₂ CHSi (CH ₃ ) ₃ ), hexafluoroacetylacetone copper allyltrimethylsilane ((CF
₃ CO) ₂ CHCu.CH ₂ CHCH ₂ Si (CH ₃ ) ₃ ),
Bis (an iso-propyl cyclopentadienyl) tungsten dihalide _{((iso-C 3 H 7} C 5 H 5) 2 WH 2), tetradimethylamino zirconium (Zr (N (C
H ₃ ) ₂ ) ₄ ), pentadimethylamino tantalum (Ta
_{(N (CH 3) 2)} 5), penta diethylamino tantalum _{(Ta (N (C 2 H} 5) 2) 5), tetra dimethylamino titanium _{(Ti (N (CH 3)} 2) 4), tetra diethylamino titanium ( A raw material that is liquid at room temperature, such as Ti (N (C ₂ H ₅ ) ₂ ) ₄ ) can be exemplified.

Further, hexacarbonyl molybdenum (M
o (CO)₆), Dimethyl pentoxy gold (Au (C
H₃)₂(OC_FiveH₇)), Bis (2,2,6,6, -tetramethyl-
3,5 heptane dionite) barium (Ba ((C (C
H₃)₃)₂C₃HO₂)₂), Bis (2,2,6,6, -tetramethy
Le-3,5 heptane dionite) strontium (Sr
((C (CH₃)₃)₂C₃HO₂)₂), Tetra (2,2,6,6,
-Tetramethyl-3,5 heptandionite) Titanium
(Ti ((C (CH₃)₃)₂C₃HO₂)_Four), Tetra (2,
2,6,6, -Tetramethyl-3,5 heptane dionite) Zirco
Nium (Zr ((C (CH₃ )₃)₂C₃HO₂)_Four),Screw
(2,2,6,6, -Tetramethyl-3,5 heptandionite) Lead
(Pb ((C (CH₃)₃)₂C₃HO₂)₂), (Jittersi
Arybutoxide bis) (2,2,6,6, -tetramethyl-3.5.
Heptane dionite) titanium, (di-isopropoxy
Si) (2,2,6,6, -tetramethyl-3,5, -heptanedionai
G) Titanium, tetrakis (isobutyryl pivaloyl)
Methanate) zirconium, or (isopropoxy)
Tris (2,2,6,6, -tetramethyl-3,5, -heptane diona
For example, a raw material that is solid at room temperature, such as zirconium
You can However, these are usually 0.1 to 1.0 mo
It is necessary to dissolve it in an organic solvent at a concentration of about 1 / L before use.
is there.

The organic solvent used as a solvent for the solid CVD raw material usually has a boiling point of 40 ° C to 140 ° C.
Is an organic solvent. As those organic solvents, for example,
Ethers such as propyl ether, methyl butyl ether, ethyl propyl ether, ethyl butyl ether, trimethylene oxide, tetrahydrofuran, tetrahydropyran, alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, acetone, ethyl methyl ketone, iso-propyl methyl ketone ,
ketones such as iso-butyl methyl ketone, propylamine,
Examples thereof include amines such as butylamine, diethylamine, dipropylamine and triethylamine, esters such as ethyl acetate, propyl acetate and butyl acetate, and hydrocarbons such as hexane, heptane and octane.

The liquid raw material supply apparatus and the liquid raw material supply method of the present invention will be described below in detail with reference to FIGS. 1 and 2, but the present invention is not limited thereto.
1 and 2 are configuration diagrams showing an example of the liquid raw material supply device of the present invention. The liquid raw material supply device of the present invention is shown in FIG.
As shown in FIG.
Is a portable liquid raw material supply device. Further, the liquid CVD raw material container 2 is connected to a liquid CVD raw material supply pipe 6 for supplying the liquid CVD raw material 1 to the outside and a pressure-feeding gas introduction pipe 7, and the cleaning liquid container 4 is filled with the cleaning liquid 3. A cleaning liquid supply pipe 8 for supplying the liquid CVD raw material supply pipe 6 and a pressure-feeding gas introduction pipe 7 are connected. Further, the liquid CVD raw material supply pipe 6 is connected to a discharge pipe 9 for discharging the residual cleaning liquid to the outside.

In the liquid raw material supply apparatus of the present invention, preferably, as shown in FIG. 2, the cleaning liquid discharge pipe 10 for facilitating the discharge of the cleaning liquid remaining in the cleaning liquid supply pipe 8 to the outside, and the liquid. Bypass pipe 1 for facilitating the discharge of the cleaning residual liquid remaining in the CVD raw material supply pipe 6 to the outside
1 is provided. Further, the heating means is provided to heat the inside of the liquid CVD raw material supply pipe to facilitate removal of the residual cleaning liquid, but preferably it is provided in a part of the cleaning liquid supply pipe and a part of the discharge pipe as shown in FIG. Is also provided. As the heating means, a method of winding a ribbon heater on the outside of the pipe, a method of covering with a block heater matching the shape of the pipe,
Alternatively, there is a method of circulating hot air or a liquid heat medium.
The heating temperature varies depending on the vapor pressure of the liquid CVD raw material and the cleaning liquid, but is usually about 40 to 250 ° C.

Liquid C in the liquid raw material supply apparatus of the present invention
The VD raw material container has a structure in which the liquid CVD raw material is supplied to the liquid CVD raw material supply pipe by the pressure of the pressurized gas supplied from the pressurized gas supply pipe. Similarly, the cleaning liquid container is also configured such that the cleaning liquid is supplied to the liquid CVD raw material supply pipe by the pressure of the compressed gas supplied from the compressed gas supply pipe 5. As the pressure-feeding gas in the present invention, an inert gas such as helium, nitrogen or argon is usually used. The pressurized gas supply pipe is usually connected to an external inert gas pipe or an inert gas cylinder when supplying the liquid CVD raw material.

By the liquid raw material supply method of the present invention, liquid C
When the VD raw material is supplied to the liquid CVD raw material container of the vaporization supply device, after the pressure-feeding gas is supplied from the pressure-feeding gas supply pipe in advance, the inside of the liquid CVD raw material supply pipe and the inside of the cleaning liquid supply pipe are under the pressure-feeding gas atmosphere. The liquid CVD raw material supply pipe is connected to the liquid CVD raw material container of the external vaporization supply device.
Then, the pressure of the pressure-fed gas supplied from the pressure-fed gas supply pipe causes the liquid CVD raw material to be supplied to the liquid CVD raw material container of the external vaporization supply device via the liquid CVD raw material supply pipe.

In the liquid raw material supply method of the present invention, after the supply of the liquid CVD raw material is completed, the liquid CVD raw material supply pipe is separated from the liquid CVD raw material container of the external vaporization supply device, Cleaning is performed. The cleaning of the liquid CVD raw material supply pipe in the present invention is performed by supplying the cleaning liquid from the cleaning liquid container to wash away the remaining liquid CVD raw material. The liquid CVD raw material and the cleaning liquid are discharged from the discharge pipe to the outside. Next, the inside of the liquid CVD raw material supply pipe is heated and / or depressurized to remove the cleaning residual liquid remaining in the liquid CVD raw material supply pipe. When reducing the pressure, a pressure reducing means such as a vacuum pump is usually connected to the discharge pipe via a cooling trap.

When the liquid raw material supply method of the present invention is carried out by using the liquid raw material supply device having the structure shown in FIG. 2, the cleaning liquid is supplied from the pressurized gas supply pipe before the liquid CVD raw material supply pipe. It is also possible to supply a pressure-feeding gas and push back the liquid CVD raw material remaining in the liquid CVD raw material supply pipe to the liquid CVD raw material container. Further, after the cleaning liquid is supplied to wash away the liquid CVD raw material, it is possible to remove the residual cleaning liquid by flowing the pressure-fed gas while heating the inside of the liquid CVD raw material supply pipe.

As the cleaning liquid in the liquid raw material supply method of the present invention, ethers, alcohols, ketones, amines, esters, hydrocarbons and the like having a boiling point of 40 ° C. to 140 ° C. are usually used. Examples of such cleaning liquid include propyl ether, methyl butyl ether, ethyl propyl ether, ethyl butyl ether, trimethylene oxide, tetrahydrofuran, ethers such as tetrahydropyran, methyl alcohol, alcohols such as ethyl alcohol, propyl alcohol and butyl alcohol, acetone, Ketones such as ethyl methyl ketone, iso-propyl methyl ketone, iso-butyl methyl ketone, propylamine, butylamine, diethylamine,
Examples thereof include amines such as dipropylamine and triethylamine, esters such as ethyl acetate, propyl acetate and butyl acetate, and hydrocarbons such as hexane, heptane and octane.

[0023]

EXAMPLES Next, the present invention will be specifically described by way of examples, but the present invention is not limited to these.

Example 1 A liquid raw material supply device having a structure as shown in FIG. 2 was manufactured.
The liquid CVD raw material container is an electrolytic polishing specification stainless steel container having an inner diameter of 300 mm and a height of 610 mm, and is filled with tetraethoxysilicon as a liquid CVD raw material. The cleaning liquid container is an electrolytic polishing specification stainless steel container having an inner diameter of 150 mm and a height of 300 mm, and is filled with hexane as a cleaning liquid. The pipes, joints, and valves used were made of stainless steel with electrolytic polishing specifications. A block heater suitable for the shape of the pipe was used as the heating means.

Next, after connecting the pressure-feeding gas supply pipe to an external helium gas pipe and supplying helium from the pressure-feeding gas supply pipe to make the inside of the liquid CVD raw material supply pipe and the inside of the cleaning liquid supply pipe under a helium gas atmosphere, The liquid CVD raw material supply pipe was connected to an external liquid CVD raw material container. After that, helium was supplied from the pressure-feeding gas supply pipe to the liquid CVD raw material container, and 10 L of tetraethoxysilicon was supplied by the pressure.
It was supplied to an external liquid CVD raw material container via a liquid CVD raw material supply pipe.

After the supply of tetraethoxysilicon is completed, the liquid CVD raw material supply pipe is separated from the external liquid CVD raw material container, and tetraethoxysilicon in the liquid CVD raw material supply pipe is dropped by gravity into the liquid CVD raw material container. Further, helium was supplied via a bypass pipe and pushed back into the liquid CVD raw material container. Next, after closing the valve of the bypass pipe and opening the valve of the discharge pipe, 100 mL of hexane was supplied from the cleaning liquid container into the liquid CVD raw material supply pipe to wash away the remaining tetraethoxysilicon into the discharge pipe. Further, the inside of the liquid CVD raw material supply pipe is heated to 70 ° C., and helium is added to
The liquid was supplied for 0 minutes to remove the cleaning residual liquid remaining in the liquid CVD raw material supply pipe.

After the liquid CVD raw material container was removed from the liquid CVD raw material supply pipe, the inside of the liquid CVD raw material supply pipe was examined. As a result, tetraethoxysilicon which is the liquid CVD raw material, its reaction product, and hexane which is the cleaning liquid were detected. However, it was confirmed that the inside of the liquid CVD raw material supply pipe was sufficiently cleaned.

Example 2 A liquid raw material supply apparatus was manufactured in the same manner as in Example 1 except that tetra iso-propoxy titanium was used as the liquid CVD raw material and iso-propyl alcohol was used as the cleaning liquid. Using this liquid raw material supply device, iso-propoxy titanium was supplied to an external liquid CVD raw material container in the same manner as in Example 1.
After completion of supply of iso-propoxy titanium, liquid CVD
The raw material supply pipe was separated from the external liquid CVD raw material container, and the vacuum pump was connected to the discharge pipe via the liquid nitrogen cooling trap.

After iso-propoxy titanium in the liquid CVD raw material supply pipe was dropped into the liquid CVD raw material container by gravity, helium was further supplied through the bypass pipe and pushed back into the liquid CVD raw material container. Next, after closing the valve of the bypass pipe and opening the valve of the discharge pipe, 300 mL of iso-propyl alcohol was supplied from the cleaning liquid container into the liquid CVD raw material supply pipe to wash away the residual iso-propoxytitanium to the discharge pipe. It was Further, the inside of the liquid CVD raw material supply pipe was heated to 70 ° C. and the vacuum pump was operated for 30 minutes to remove the cleaning residual liquid remaining in the liquid CVD raw material supply pipe.

After removing the liquid CVD raw material container from the liquid CVD raw material supply pipe, the inside of the liquid CVD raw material supply pipe was examined. As a result, iso-propoxytitanium as the liquid CVD raw material, its reaction product, and iso- Propyl alcohol was not detected, and it was confirmed that the inside of the liquid CVD raw material supply pipe was sufficiently washed.

[0031]

According to the liquid raw material supply apparatus and the liquid raw material supply method of the present invention, the liquid CVD raw material can be easily replenished to the vaporization supply apparatus without interrupting the vaporization supply to the CVD apparatus. .

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a liquid raw material supply device of the present invention.

FIG. 2 is a configuration diagram showing an example of a liquid raw material supply apparatus other than FIG. 1 of the present invention.

[Explanation of symbols]

1 Liquid CVD raw material 2 Liquid CVD raw material container 3 cleaning liquid 4 Cleaning liquid container 5 heating means 6 Liquid CVD raw material supply pipe 7 Compressed gas introduction pipe 8 Cleaning liquid supply pipe 9 discharge pipe 10 Cleaning liquid discharge pipe 11 Bypass pipe

Claims (5)

[Claims] 1. A liquid CVD raw material container and a cleaning liquid container are provided, and the liquid CVD raw material container has a heating means and a liquid CVD raw material supply pipe for supplying the liquid CVD raw material to the outside and a pressurized gas introduction pipe. And a cleaning liquid supply pipe for supplying a cleaning liquid to the liquid CVD raw material supply pipe and a pressure-feeding gas introduction pipe are connected to the cleaning liquid container,
Further, the liquid CVD raw material supply pipe is connected to a discharge pipe for discharging the cleaning residual liquid to the outside, which is a portable liquid raw material supply device. 2. The liquid raw material supply device according to claim 1, further comprising a cleaning liquid discharge pipe connecting the cleaning liquid supply pipe and the discharge pipe. 3. A bypass pipe for connecting the liquid CVD raw material supply pipe and the pressure-feeding gas introduction pipe is further provided.
The liquid raw material supply device according to. 4. A liquid CVD in which a liquid CVD raw material is filled.
A liquid CVD raw material is supplied from a portable liquid raw material supply device including a raw material container and a cleaning liquid container filled with a cleaning liquid to a liquid CVD raw material container other than the liquid raw material supply device, and then a liquid CVD raw material is supplied. The cleaning liquid is supplied from the cleaning liquid container into the liquid CVD raw material supply pipe of the liquid raw material supply device used for washing away the remaining liquid CVD raw material, and then the liquid CVD raw material supply pipe is heated and / or depressurized. A method for supplying a liquid raw material, characterized in that the residual cleaning liquid remaining in the liquid CVD raw material supply pipe is removed. 5. The cleaning liquid has a boiling point of 40 ° C. to 14 ° C.
The liquid raw material supply method according to claim 4, which is one or more selected from ethers, alcohols, ketones, amines, esters, and hydrocarbons at 0 ° C.