JP2003117504A - Cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the cleaning efficiency of an internal circulation type cleaning device using convection, and to facilitate the loading and unloading of an article to be cleaned. SOLUTION: This cleaning device stores the article W to be cleaned in an airtightly sealed cleaning tank 1, and cleans the article W by bringing supercritical CO2 into contact with the article W within the cleaning tank 1. A circulation flow passage where the CO2 is circulated by the convection is formed by providing a cooling coil 2 at the upper part in the cleaning tank 1 and providing a heating coil 3 at the lower part. The article W is arranged at the down side of the cooling coil 2 in a downward flow passage 4 of the circulation flow passage, and the stay part 8 of a contaminant extracted is provided at the lower part of the cleaning tank 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning device for cleaning microfabricated components such as semiconductor devices and liquid crystal displays using a cleaning fluid in a supercritical or subcritical state.

[0002]

2. Description of the Related Art In recent years, a cleaning device using a supercritical fluid has been attracting attention as a device for cleaning microfabricated parts such as semiconductor elements and liquid crystal displays. What is a supercritical fluid?
It refers to a fluid in the region above the critical temperature and critical pressure peculiar to a substance. This supercritical fluid has a viscosity, a diffusion coefficient, a density, and a dissolving power intermediate between those of gas and liquid. Also, originally
Since the gas is used after being compressed, it behaves as a gas when the pressure is returned to the normal pressure.

The use of a supercritical fluid having such properties as a cleaning medium is easier to deal with miniaturization than conventional wet cleaning. It is not restricted by the shape of the substance to be cleaned. No drying process is required, quick treatment is possible, waste liquid treatment is not required, dissolving power can be freely controlled by adding additional solvent, etc., device main unit can be downsized, extracted contaminants It has many advantages such as easy separation (especially when using carbon dioxide supercritical fluid).

Materials mainly used as a cleaning medium (cleaning fluid) for the supercritical fluid are carbon dioxide, sulfurous acid gas, nitrous oxide, ethane, propane, CFC gas and the like. For example, carbon dioxide often used becomes a supercritical fluid under the conditions of a temperature of 31.06 ° C. or higher and a pressure of 74.8 atm or higher.

As a cleaning device using this type of supercritical fluid, in the cleaning device disclosed in Japanese Patent Laid-Open No. 176504/1987, a cylinder wall is provided inside the cleaning tank, so that a cylinder is provided inside the cleaning tank. A circulation flow path is defined by a flow path inside the wall and a flow path outside, and a heating means is provided in the internal flow path for accommodating the object to be cleaned and a cooling means is provided in the external flow path. By generating an ascending flow of the fluid whose specific gravity is reduced by heating and a descending flow of the fluid whose specific gravity is increased by cooling in the outer flow path, internal circulation of the supercritical fluid by convection is generated to improve the cleaning effect. I try to raise it. Such an internal circulation type cleaning device has advantages that the amount of cleaning fluid used can be reduced and that a circulation pump is not required unlike the external circulation.

[0006]

By the way, JP-A-62-62
In the conventional cleaning device described in Japanese Patent Laid-Open No. 176504/1998, since the density is reduced by heating and the solubility of contaminants is reduced accordingly, the object to be cleaned is disposed in the fluid in the inner flow path, It is possible that the ability is not very high. Further, when attempting to remove contaminants including particles having low solubility, it is not suitable because effective cleaning ability cannot be exhibited. Also, since the heat exchange pipe as the heating means is arranged inside the cylindrical wall, when trying to load or unload the item to be cleaned from the upper part of the cleaning tank, the heat exchange pipe becomes an obstacle, and the item to be cleaned can be loaded or unloaded. It may be difficult to do.

In view of the above circumstances, it is an object of the present invention to provide a cleaning device of an internal circulation type by convection, which can improve the cleaning efficiency and facilitate the taking in and out of an object to be cleaned. And

[0008]

According to a first aspect of the present invention, an object to be cleaned is contained in an airtightly sealed cleaning tank, and the cleaning fluid is in a supercritical or subcritical state for the object to be cleaned in the cleaning tank. In the cleaning device for extracting and removing contaminants attached to or impregnated with the object to be cleaned by providing a cooling means at the upper part and a heating means at the lower part in the cleaning tank, the fluid circulates by convection. A circulation channel is formed, and a storage section for the object to be cleaned is secured below the cooling means of the descending channel in this circulation channel, and a retention section for the extracted contaminants is provided at the bottom of the cleaning tank. It is characterized by

According to the first aspect of the present invention, since the cooling means is arranged in the upper part of the cleaning tank and the heating means is arranged in the lower part, the circulation efficiency of the fluid is increased and the cleaning capacity is improved. In addition, since the storage portion for the object to be cleaned is provided below the cooling means, the fluid whose density is increased by cooling and whose solubility is increased can be directly contacted with the object to be cleaned, and the contaminant can be effectively used as a fluid. It can be dissolved in. Further, since the fluid is heated by the heating means provided in the lower part of the cleaning tank to lower the density of the fluid and reduce the solubility, contaminants dissolved in the fluid are effectively separated in the lower part of the cleaning tank. The cleaning ability can be improved by recirculating the fluid from which contaminants have been separated. In addition, since the contaminants separated here are collected in the retention part in the lower part of the cleaning tank, they can be appropriately taken out to the outside. Further, since the cooling means and the heating means are separately arranged at the upper part and the lower part of the cleaning tank, it is possible to integrate the upper cooling means with the upper lid of the cleaning tank, and the cooling means together with the upper lid. By removing it, the object to be cleaned can be easily put in and taken out of the cleaning tank.

According to a second aspect of the present invention, in the first aspect, a partition member extending in the vertical direction is provided inside the cleaning tank to define an ascending channel and a descending channel of the circulation channel. The heating means is arranged below the ascending passage and the cooling means is arranged above the descending passage.

In the invention of claim 1, the partition member is not particularly limited to the place where the ascending flow path and the descending flow path of the circulation flow path are defined by providing the partition member inside the cleaning tank. In the above, the point that the partition member extending in the vertical direction is provided inside the cleaning tank to define the ascending channel and the descending channel of the circulation channel is limited. The heating means is arranged below the ascending flow path, and the cooling means is arranged above the descending flow path. By thus clearly defining the ascending flow path and the descending flow path by the partition member, the circulation loss due to the contact between the ascending flow and the descending flow can be reduced. Moreover, since the heating means is arranged in the lower part of the ascending flow path and the cooling means is arranged in the upper part of the descending flow path, the ascending and descending flows can be effectively created, and the cleaning efficiency is improved by improving the circulation efficiency. Can be achieved.

According to a third aspect of the present invention, in the second aspect, the partition member has a downward flow passage on the inside and an upward flow passage on the outside.
In addition, it is characterized in that it is configured by a stepped cylindrical wall having an upper portion having a large diameter and a lower portion having a small diameter, the internal space of the large diameter portion serving as a storage portion for the object to be cleaned, and the heating means arranged outside the small diameter portion. .

According to the third aspect of the present invention, since the partition member is constituted by the stepped cylindrical wall whose upper portion has a large diameter and whose lower portion has a small diameter,
A fluid that has been cooled and has a high density can be retained inside the large-diameter portion, a sufficient contact time with the object to be cleaned can be secured, and the cleaning capacity can be improved. Further, since the heating means is arranged outside the small diameter portion, for example, even when the heating means is constituted by a heat exchange coil, the heating means can be arranged with a space margin.
The heating efficiency can be increased to create an effective upflow.

According to a fourth aspect of the present invention, in any one of the first to third aspects, below the cooling means of the descending flow path, there is provided a cleaning container in which the fluid cooled by the cooling means stays inside and overflows. The cleaning container is arranged, and the inside of the cleaning container is used as a housing portion for the object to be cleaned.

According to the fourth aspect of the present invention, since the fluid that has been constantly cooled and has a high density can be retained in the cleaning container, a sufficient contact time with the object to be cleaned can be ensured and the cleaning can be performed. The ability can be improved.

The invention of claim 5 is characterized in that, in claim 3 or 4, the periphery of the accommodation portion of the object to be cleaned is covered with a heat insulating material.

According to the fifth aspect of the present invention, since the accommodation portion of the article to be cleaned is surrounded by the heat insulating material, the temperature of the fluid in contact with the article to be cleaned can be kept constant, and high circulation ability can be maintained. Cleaning efficiency can be improved.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, a subcritical fluid is used as the cleaning fluid, and a cleaning tank is provided with a liquid level gauge for detecting the liquid level of the fluid. It is characterized by that.

According to the sixth aspect of the invention, since the fluid in the subcritical state is used as the cleaning fluid, it is possible to bring the fluid which has become liquid by cooling into contact with the object to be cleaned to effectively dissolve the contaminants in the liquid. At the same time, the dissolved contaminants can be effectively separated when the density is reduced by heating. Therefore, the action of extracting contaminants by dissolution and separation can be promoted. Further, by providing the liquid level meter, a predetermined amount of subcritical fluid can be used for cleaning.

The invention of claim 7 is characterized in that, in any one of claims 1 to 6, CO ₂ , nitrous oxide or SF ₆ is used as the fluid.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a cleaning device of an embodiment using CO ₂ in a supercritical state as a cleaning fluid. This cleaning device accommodates an object W to be cleaned in a cleaning tank 1 which is hermetically sealed, and supercritical C is applied to the object W to be cleaned in the cleaning tank 1.
By contacting with O ₂ , the contaminants adhering to or impregnated with the object to be cleaned W are extracted and removed. The cooling coil 2 as a cooling means is provided in the upper part of the cleaning tank 1, and the heating coil as a heating device is provided in the lower part. 3 is provided so that convection is caused in the cleaning tank 1.

Inside the washing tank 1, the inside is a descending flow path 4,
A cylindrical wall (partitioning member) 10 that forms a circulation flow path with the outside as the upward flow path 5 is arranged concentrically with the inner wall of the cleaning tank 1.
The cylindrical wall 10 has a stepped structure in which an upper portion is configured as a large diameter portion 11 and a lower portion is configured as a small diameter portion 12, and the inside of the upper large diameter portion 11 serves as a storage portion 7 for the article W to be cleaned. Has become. Further, a guide cylinder 13 is continuously provided above the large-diameter portion 11, and the cooling coil 2 is inserted into the inner circumference of the guide cylinder 13. The cleaning tank 1 is of an openable / closable type with an upper lid (not shown), and a cooling coil 2 is integrally provided on the upper lid. In addition, the heating coil 3 is arranged in a space that is secured around the outer circumference of the small diameter portion 12. As a result, the heating coil 3 is located below the ascending flow path 5, and the cooling coil 2 is located above the descending flow path 4.

The lower end of the small diameter portion 12 of the cylinder wall 10 is the cleaning tank 1
Is extended to a position where it reaches the retention part 8 of the contaminants secured in the lower part of the container, and the fluid descending to the retention part 8 is heated in the heating coil 3 by reversing its direction, and the density is lowered to rise. It is like this. A heat insulating material 18 is provided on the cylindrical wall 10 defining the descending flow path 4 to insulate it from the ascending flow path 5 on the outer periphery thereof. The heat insulating material 18 is provided so as to surround at least the storage portion 7 for the article W to be cleaned.

Inside the large diameter portion 11 of the cylindrical wall 10, a bottomed cylindrical cleaning container 15 is accommodated in a state where a flow path is secured between the large diameter portion 11 and the inner wall of the large diameter portion 11. This cleaning container 15
Is located below the cooling coil 2 and
It is arranged so that the fluid cooled by is retained inside, overflows from the upper edge portion, flows along the inner surface of the cylindrical wall 10 and flows to the small diameter portion 12. And
Inside the cleaning container 15, a bottomed cylindrical inner cleaning container 16 having an outflow hole 17 at the center of the bottom is arranged, and the object W to be cleaned is accommodated in the inner cleaning container 16. When the object W to be cleaned is taken in and out of the cleaning tank 1, the cleaning container 15 is put in and taken out.

Further, the supercritical C
An introduction line 20 for introducing O ₂ is connected via a valve 21.

Next, the operation will be described. When cleaning the object W to be cleaned with supercritical CO ₂ , first, the cleaning container 15 is installed in the large diameter portion 11 of the central cylindrical wall 10 in the cleaning tank 1, and the object W to be cleaned is placed therein. Put in. Next, close the top lid and wash tank 1
Is closed and CO ₂ is supplied into the cleaning tank 1 through the valve 21 to maintain a predetermined temperature and pressure (temperature 31 ° C. or higher, pressure 70 kg / cm ² or higher) that results in a supercritical state.

Next, the heating coil 3 heats the lower part of the cleaning tank 1 and the cooling coil 2 cools the upper part of the cleaning tank 1 to form a temperature distribution inside the cleaning tank 1, as shown by the arrow in FIG. It causes natural circulation by convection. In this case, the CO ₂ heated by the heating coil 3 rises to the upper part of the cleaning tank 1 due to the decrease in density (about 0.1 to 0.46), and the elevated CO ₂ is cooled by the cooling coil 2. Increased density (density 0.46-0.85)
Thus, it flows down into the cleaning container 15 below. For example,
If the pressure in the cleaning tank 1 is 100 kg / cm ² , the lower part is 200 ° C. and the upper part is 40 ° C.
g / cm ³ , the upper part is O. It becomes 8 g / cm ³ . this is,
It can be determined that the density of CO _{2 in} the supercritical state has temperature dependence as shown in FIG. In FIG. 2, C
Has a density of 0.8 (at a pressure of 100 kg / cm ² and a temperature of 40
C) high density region of CO ₂ , H has a density of 0.12 (pressure 1
CO ₂ low density region of 00 kg / cm ² at a temperature of 200 ° C.).

Since high-density CO ₂ flows into the cleaning container 15 one after another, contaminants (organic substances) adhering to or impregnating the object to be cleaned W are efficiently dissolved in CO ₂ and the object to be cleaned is W cleaning is performed. Moreover, to increase the cleaning effect of the CO _2, since that is a structure in which residence dense CO ₂ in the cleaning vessel 15, a certain amount of CO ₂ is in contact at all times to the object to be cleaned W, the washing of the high efficiency line Be seen. Then, the CO ₂ after cleaning overflows and falls through the small diameter portion 12 to the lower part of the cleaning tank 1. Therefore, the object W to be cleaned is always cleaned with fresh CO ₂ .

The CO ₂ flowing down to the lower part of the cleaning tank 1 is heated by the heating coil 3 in the lower part of the cleaning tank 1. At this time, the density of CO ₂ decreases as the fluid temperature rises, so that contaminants and CO ₂ are separated. The separated contaminants accumulate in the retention part 8 at the bottom of the cleaning tank 1, and the heated CO ₂ flows to the upper part of the cleaning tank 1 again. The contaminants accumulated in the lower part of the cleaning tank 1 are appropriately extracted as needed.
Then, after a predetermined time, heating and cooling are stopped, the inside of the cleaning tank 1 is decompressed, and the object W to be cleaned is taken out.

As described above, since the cooling coil 2 is arranged above the cleaning tank 1 and the heating coil 3 is arranged below the cleaning tank 1, the temperature difference between the cooling coil 2 and the cooling coil 2 is increased so that the circulation efficiency of the CO ₂ fluid is increased and the cleaning is performed. Ability is improved. Further, since the object W to be cleaned is arranged immediately below the cooling coil 2, high-density CO ₂ can be brought into direct contact with the object W to be cleaned. Further, since CO ₂ is heated by the heating coil 3 in the lower part of the cleaning tank 1 to reduce the density, the contaminants dissolved in the CO ₂ fluid can be efficiently separated in the lower part of the cleaning tank 1, The fluid from which the contaminants have been separated can be circulated again, and the cleaning ability can be improved.

Further, since the ascending flow path 5 and the descending flow path 4 are defined by the stepped cylindrical wall 10 with the upper part having a large diameter and the lower part having a small diameter, the circulation loss due to the contact between the ascending flow and the descending flow is reduced. In addition, it is possible to retain the cooled and high-density fluid inside the large-diameter portion 11 and inside the cleaning container 15, and to secure a sufficient contact time with the object W to be cleaned. The cleaning ability can be improved. Further, since the heat insulating material 18 surrounds the accommodation portion 7 for the article to be cleaned W, the temperature of the CO ₂ fluid in contact with the article to be cleaned W can be kept constant, and the cleaning efficiency can be improved.

Further, since the cooling coil 2 and the heating coil 3 are separately arranged on the upper and lower portions of the cleaning tank 1, the upper cooling coil 2 can be integrated with the upper lid of the cleaning tank 1. By removing the cooling coil 2 together with the upper lid, the object to be cleaned W can be easily put in and taken out from the cleaning tank 1, and the workability can be improved.

FIG. 3 is a block diagram of a cleaning system provided mainly with the cleaning tank 1. This cleaning system includes a CO ₂ storage tank 31, a pump 32, a CO ₂ supply tank 33, a pressure gauge 34,
From the heater 35, the cleaning tank 1, the CO ₂ introduction line 20 equipped with the valve 21, the retention section 8 in the lower part of the cleaning tank 1 to C after cleaning
CO ₂ discharge line 4 with valve 42 for discharging O ₂
1. A CO ₂ flash tank (gas-liquid separation tank) 43 for separating contaminants from the washed CO ₂ guided by the discharge line 41,
A return line 45 for recycling CO ₂ via a cooler 46 and an organic substance recovery tank 44 for recovering the contaminants separated in the CO ₂ flash tank 43 are provided.

In this system, C _{2 is} supplied from the CO ₂ storage tank 31 to the CO ₂ supply tank 33 via the pump 32 and the heater 35.
Supply O ₂ . Here, the CO ₂ supply tank 33 is under the same temperature and pressure conditions as the cleaning tank 1. When carrying out the cleaning operation, supercritical CO ₂ is introduced into the cleaning tank 1 from the CO ₂ supply tank 33 via the valve 21. Then, as described above, cleaning is performed while maintaining the cleaning tank 1 under a predetermined condition.

When the washing is completed, the washed CO ₂ is taken out through the pressure reducing valve 42, and the CO ₂ flash tank 43 separates the CO ₂ from the organic matter. Then, the separated CO ₂ is sent to the CO ₂ storage tank 31 for recycling through the cooler 46, and the contaminants are sent to the organic matter recovery tank 44.

Next, an embodiment in which subcritical CO ₂ is used as the cleaning fluid will be described. As shown in FIG. 4, the basic configuration of the cleaning device is exactly the same as the device using supercritical CO ₂ except that a liquid level gauge 25 is added.

Explaining the cleaning method, first, CO ₂ is supplied into the cleaning tank 1 through the valve 21 and is maintained in a subcritical state at a predetermined room temperature pressure (pressure 35 to 75 kg / cm ² ). At this time, the supply amount of CO ₂ is adjusted by the liquid level gauge 25 so that liquid CO ₂ and gas CO ₂ exist in two layers.

In this state, the cleaning tank 1 is heated by the heating coil 3.
Is heated and the upper part of the cleaning tank 1 is cooled by the cooling coil 2 to form a temperature distribution in the cleaning tank 1 to generate convection. In the cleaning under the subcritical condition, the lower part of the cleaning tank 1 becomes gas CO ₂ , and the upper part of the cleaning tank 1 and the inside of the cleaning container 15 become liquid CO ₂ . The washing conditions are as shown in Table 1 below.

[0039]

[Table 1]

For example, the CO ₂ filling condition is 17 ° C. and 6 MP
When it is a, the cleaning tank 1 is in a gas-liquid two phase, but the cleaning tank 1
The lower part of the gas is heated by the heating coil 3 and heated to 27 ° C or higher to gas C
When O ₂ is used and the upper part of the cleaning tank 1 is maintained at 17 ° C. or lower by the cooling coil 2, convection occurs inside the cleaning tank 1 and the liquid CO ₂ flows into the cleaning container 15. At this time, the cleaning container 15 is provided by the heat insulating material 18 and a cooler (not shown).
Is maintained below 17 ° C.

By maintaining such conditions, the liquid CO ₂ is retained in the cleaning container 15, so that the contaminants (organic substances) attached to the object W to be cleaned are efficiently dissolved in CO _2. Thus, the object W to be cleaned is cleaned.

The liquid CO ₂ overflowing from the washing container 15 passes through the small diameter portion 12 and drops to the lower portion of the washing tank 1, and is heated again by the heating coil 3 in the lower portion of the washing tank 1. At this time, since liquid CO ₂ becomes gas CO ₂ , the solubility of the pollutant (organic matter) is reduced and the pollutant and CO ₂ are separated. The separated contaminants are accumulated in the retention part 8 in the lower part of the cleaning tank 1, and the heated gas CO ₂ flows to the upper part of the cleaning tank 1 again. Incidentally, the contaminants accumulated in the retention section 8 below the cleaning tank 1 are appropriately extracted as necessary. Then, after a predetermined time, heating and cooling are stopped, the inside of the cleaning tank 1 is decompressed, and the object W to be cleaned is taken out.

In this cleaning apparatus, since fluids in the supercritical and subcritical states are used as cleaning fluids, the fluid having a high density due to cooling is brought into contact with the object to be cleaned to effectively dissolve contaminants in the liquid. In addition, the dissolved contaminants can be effectively separated when the density is lowered by heating, and a high cleaning effect can be exhibited.

In the above embodiment, the supercritical flow
CO as the body₂I explained about the case of using
Ming is not limited to this, nitrous oxide, SF
₆, C₂H_Four, C₂H₆, C₃H₆, CHClF₂, C
₃H₈, CCl₂F₂, NH ₃Such as stable and
Supercritical state can be easily created, and the critical temperature
Is close to room temperature, which makes the heating operation easier.
A fluid can be preferably used.

[0045]

As described above, according to the inventions of claims 1 to 7, since the cooling means is arranged in the upper part of the cleaning tank and the heating means is arranged in the lower part, the circulation efficiency of the fluid is enhanced. be able to. Further, since the object to be cleaned is arranged below the cooling means and the contaminated part is provided in the lower part of the cleaning tank, the cleaning capacity can be improved. Further, since the upper cooling means can be integrated with the upper lid of the cleaning tank, it is possible to facilitate the loading and unloading of the object to be cleaned.

According to the second aspect of the present invention, the partition member is provided inside the cleaning tank to define the ascending flow path and the descending flow path of the circulation flow path. Circulation loss can be reduced and cleaning efficiency can be improved by improving circulation efficiency.

According to the third aspect of the present invention, since the flow path is partitioned by the stepped cylindrical wall having an upper portion having a large diameter and a lower portion having a small diameter,
High density fluid can be retained inside the large diameter part,
The cleaning ability can be improved. Further, since the heating means is arranged outside the small diameter portion, the heating means can be arranged with a space margin. Further, according to the invention of claim 4, since a high-density fluid can be retained in the cleaning container, the cleaning capacity can be improved.

According to the fifth aspect of the present invention, since the temperature of the fluid that contacts the object to be cleaned can be kept constant by the heat insulating material, the cleaning efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a cleaning device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state of the cleaning device during cleaning.

FIG. 3 is a configuration diagram of a cleaning system including the cleaning device.

FIG. 4 is a configuration diagram of a cleaning device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a cleaning state of the cleaning apparatus.

FIG. 6 is a characteristic diagram showing the temperature dependence of the density of supercritical CO ₂ .

[Explanation of symbols]

1 cleaning tank 2 Cooling coil (cooling means) 3 heating coils (heating means) 4 descending channels 5 ascending channel 7 Storage area for objects to be cleaned 8 staying part 10 tube wall 11 Large diameter part 12 Small diameter part 15 Washing container 18 Insulation 25 level gauge W to be cleaned

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ko Hatakeyama             1002-14 Mukoyama, Naka-machi, Naka-gun, Ibaraki Prefecture             Terari Co., Ltd.             Inside (72) Inventor Kenji Nishimura             1002-14 Mukoyama, Naka-machi, Naka-gun, Ibaraki Prefecture             Terari Co., Ltd.             Inside F-term (reference) 3B201 AA02 AA03 AB43 BB04 BB82                       BB87 BB90 BB98                 4D056 AB11 AC24 BA16

Claims (7)

[Claims] 1. An object to be cleaned is housed in an airtightly sealed cleaning tank, and the cleaning fluid in the supercritical or subcritical state is brought into contact with the object to be cleaned in the cleaning tank to adhere to the object to be cleaned. Alternatively, in a cleaning device for extracting and removing impregnated contaminants, a cooling means is provided in an upper part of the cleaning tank, and a heating means is provided in a lower part of the cleaning tank to form a circulation flow path for circulating the fluid by convection. A cleaning device characterized in that a housing portion for the object to be cleaned is secured below the cooling means of the descending flow path, and a retaining portion for the extracted contaminants is provided below the cleaning tank. 2. A partition member extending in the up-down direction is provided inside the cleaning tank to define an ascending flow path and a descending flow path of the circulation flow path, and heat the lower part of the ascending flow path. The cleaning device according to claim 1, wherein a cooling means and a cooling means are disposed above the descending channel. 3. The partition member is constituted by a stepped cylinder wall having a downward flow passage on the inner side and an upward flow passage on the outer side, and an upper portion having a large diameter and a lower portion having a small diameter, and an internal space of the large diameter portion is formed. The cleaning device according to claim 2, wherein a heating means is disposed outside the small diameter portion as a housing portion for the object to be cleaned. 4. A cleaning container is disposed below the cooling means of the descending flow path, and the fluid cooled by the cooling means accumulates therein and then overflows, and the inside of the cleaning container accommodates an object to be cleaned. 4. The method according to claim 1, wherein
The cleaning device according to any one of 1. 5. The cleaning apparatus according to claim 3, wherein the housing of the object to be cleaned is covered with a heat insulating material. 6. A subcritical fluid is used as the cleaning fluid, and a liquid level gauge for detecting the liquid level of the fluid is provided in the cleaning tank. The cleaning device described. 7. The cleaning apparatus according to claim 1, wherein CO ₂ , nitrous oxide, or SF ₆ is used as the fluid.