JPH08150301A - Distillation apparatus and operation thereof - Google Patents

Abstract

PURPOSE: To restrain the occurrence of mist and to remove metal ions and high boiling point organic materials in a distillation apparatus in which a heat source and a liquid chemical vapor condenser are installed in the lower part and in the upper part respectively by installing a means for blowing inert gas into liquid chemicals. CONSTITUTION: A distillation apparatus 10 for removing metal impurities and high boiling point organic materials in liquid chemicals consists of a heater 3 for vaporizing liquid chemicals 2 stored in the lower part of a body 1 and a liquid chemical vapor condenser 6 for condensing liquid chemical vapor in the upper part thereof. In the lower part of the vapor condenser 6, a pan 11 for recovering the condensed liquid chemicals is installed. Between a part for storing the liquid chemicals 2 and the liquid chemical vapor condenser 6, a demister 4 is installed. In this case, inert gas feeding piping 8 in which blow-in ports 9 for blowing inert gas such as nitrogen and helium into the liquid chemicals to be distilled are formed in the liquid chemicals 2 is installed. In this way, the bumping and the occurrence of mist are restrained to reduce the occurrence of heavy metal contamination, water mark or the like of the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distillation apparatus for efficiently removing metal impurities, high-boiling point organic substances and the like in a chemical solution, and a method of operating the distillation apparatus.

[0002]

2. Description of the Related Art Generally, a method of using a chemical solution such as 2-propanol for cleaning and drying semiconductor wafers and liquid crystal panels is widely known. In the purification of 2-propanol, the chemical liquid was evaporated under atmospheric pressure and the generated vapor was condensed to remove metal impurities and high-boiling organic substances.

[0003]

When used for semiconductor wafers in the cleaning / drying operations using the above chemicals, deterioration of device performance due to heavy metal contamination and defects called watermarks occur, and When used for liquid crystals, lenses, etc., haze may occur, which is a big problem.

[0004]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that one of the causes of heavy metal contamination, watermarks and haze is the distillation process of a chemical solution used during cleaning and drying. It was found that heavy metals, etc. were mixed in the chemical liquid due to the entrainment of minute droplets,
The present invention was found to suppress heavy metal contamination of the device and the generation of watermarks and haze by suppressing the generation of mist by blowing an inert gas into the chemical liquid in the distillation process.

That is, the gist of the present invention is that in a distillation apparatus having at least a heat source for vaporizing the chemical liquid stored in the lower portion and a chemical vapor condenser for condensing the chemical vapor in the upper portion, the distillation apparatus is not In a distillation apparatus, characterized in that a means for blowing an active gas is provided, and in the method for operating the distillation apparatus, an inert gas of 0.05 to 0.3 Nm ³ / hr per 1 m ² of heat transfer surface is contained in a chemical solution. It exists in the operating method of the distillation apparatus characterized by blowing.

The present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view for explaining one embodiment of the present invention. The distillation apparatus 10 includes a substantially cylindrical main body 1, a heater 3 as a heat source for vaporizing the chemical liquid stored in the lower portion of the main body 1, and a chemical liquid vapor condenser for condensing the chemical liquid vapor in the upper portion of the main body 1. It consists of 6 and 6. At the bottom of the chemical vapor condensing device 6, a receiving tray 11 for collecting the condensed chemical liquid is provided, from which the condensate is extracted through a condensate extracting pipe 12. A fibrous demister 4 is provided between the portion for storing the chemical liquid and the chemical vapor condenser 6. Although the demister is not always necessary, the provision of the demister makes it easier to suppress the entrainment of microdroplets.

A chemical solution 2 is stored in the lower portion of the distillation apparatus body 1. The chemical liquid is not particularly limited, but 2-propanol (isopropyl alcohol), ethanol, trichloroethane and the like can be exemplified. The chemical liquid 2 is heated by the heater 3 and vaporized. The chemical vapor 5 rises and condenses on the surface of the condenser 6. An example of the chemical vapor condenser 6 is one in which a cooling medium is made to flow a refrigerant.

A feature of the present invention is that a means for blowing an inert gas into the chemical liquid to be distilled is provided. Examples of the inert gas include nitrogen, helium, neon and argon, and may be air as long as the chemical liquid is stable to air. It is preferable to pass the inert gas through a filter so that the inert gas does not become a source for bringing particles into the distillation apparatus. As the filter, a filter having a pore diameter of 1 μm or less, particularly 0.1 μm or less is preferable.

In FIG. 1, as an inert gas blowing means,
An inert gas supply pipe 8 provided with a blowing port 9 in the chemical liquid is illustrated. The blowing port 9 has a diameter of 0.1 to 0.
The surface density is 5 mm and the surface density is 20 to 70 per 1 m ^{2 of} heat transfer surface. The blowing port is preferably provided in the vicinity within 20 mm from the heat transfer surface. In FIG. 1, the heater 3
Is provided over the entire bottom surface of the main body 1, so the heat transfer surface means the entire bottom surface, and the blowing port 9 is located at 5
It is provided at mm. The heating by the heater can be performed from the side surface instead of from the bottom surface, and in this case, the blowing port can be provided in a ring shape near the side surface. However, when the heat transfer surface is a side surface, that is, when heating from the side surface, the peripheral portion and the central portion of the side surface have different vaporization rates of the chemical liquid, and especially when the main body has a cylindrical shape, a curved surface that is difficult to process Since there are cases where a heater having a heater is used, the heat transfer surface is usually the bottom surface.

The amount of the inert gas blown in is preferably 0.05 to 0.3 Nm ³ / hr per 1 m ² of heat transfer surface. If the amount of the inert gas blown in is too small, the effect of the present invention will not be sufficiently obtained, and if it is too large, it will cause the generation of mist, which is not preferable.

[0011]

In the conventional distillation apparatus, mist is generated due to bumping of the chemical liquid, and the mist is mixed into the condensed chemical liquid, which is a cause of heavy metal contamination of the device and generation of watermarks and the like. In the present invention, by blowing a small amount of an inert gas, bumping can be suppressed, and by suppressing the generation of mist, it is possible to reduce the heavy metal contamination of the device and the generation of watermarks.

Further, since the amount of particles entrained in the mist can be reduced, the occurrence of defects such as semiconductors can be suppressed.

[0013]

EXAMPLES The present invention will now be described in more detail with reference to examples. Example 1 and Comparative Example 1 In FIG. 1, the inner diameter of the heat transfer surface of the main body 1 was 50 cm, and 2-propanol was used as the chemical liquid 2.

Nitrogen gas is used as the inert gas, and
It was used through a microfiltration filter capable of almost completely removing particles having a particle size of 09 μm or more. The blowing port 9 has a hole diameter of 0.3 mm, and a total of seven blowing ports 9 (35 per 1 m ^{2 of} heat transfer surface) are provided in the chemical solution. As the demister for suppressing the entrainment of fine droplets, a woven stainless fiber having a diameter of 100 mm and a height of 150 mm was used.

First, as Comparative Example 1, when the distillation apparatus was operated without blowing nitrogen, 2-propanol obtained by distillation contained 2 ppb of sodium ions, 5 ppb of iron ions, and 7 ppb of chlorine ions. Next, in Example 1, nitrogen was added at 0.5 Nl / min (0.03
Nm ³ / hr, the heat transfer surface 1m ² per 0.153Nm ³ / h
When operated while blowing at a flow rate of r), the amounts of sodium ion, iron ion and chlorine ion in 2-propanol condensed in the chemical vapor condenser 6 were all 0.1.
It decreased to less than ppb.

[0016]

INDUSTRIAL APPLICABILITY In the distillation apparatus of the present invention, by suppressing the generation of mist, metal ions and high boiling point organic substances are removed, the generation of defects such as watermarks and haze is suppressed, and the amount of particles entrained is also reduced. It is particularly useful for cleaning and drying electronic industrial equipment, which can be reduced in density and can be highly densified.

[Brief description of drawings]

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

[Explanation of symbols]

 1 Distilling device main body 2 Chemical liquid 3 Heater 4 Demister 5 Chemical liquid vapor 6 Chemical liquid vapor condenser 7 Chemical liquid vapor rising limit surface 8 Inert gas supply pipe 9 Inert gas blowing port 12 Condensate extraction pipe

Claims (3)

[Claims] 1. A distillation apparatus having at least a heat source for vaporizing a chemical solution stored in a lower portion and a chemical vapor condenser for condensing the chemical vapor in an upper portion, a means for blowing an inert gas into the chemical solution. A distillation device characterized by being provided. 2. An inert gas blowing port having a diameter of 0.1 to 0.5 mm is provided in the vicinity of the heat transfer surface in the chemical liquid in an amount of 20 to 70 per 1 m ^{2 of the} heat transfer surface. Distillation equipment. 3. A method of operating a distillation apparatus having at least a heat source for vaporizing a chemical solution stored in a lower portion and a chemical vapor condenser for condensing a chemical vapor in an upper portion, wherein a heat transfer surface of 1 m is contained in the chemical solution. 0.05 to 0.3 Nm ³ per ²
A method for operating a distillation apparatus, which comprises blowing in an inert gas of / hr.