JP4231376B2 - Supercritical fluid processing apparatus and method - Google Patents

Description

  The present invention relates to a novel supercritical fluid processing apparatus and method for cleaning or drying LSIs, MEMS elements, and the like after development using a supercritical fluid.

  In order to manufacture large-scale and high-performance devices such as LSI and MEMS elements, ultrafine patterns are required. This ultrafine pattern is a resist pattern formed through exposure, development, rinse cleaning (hereinafter simply referred to as “rinse”) and drying, or an etching pattern formed through etching, water washing, rinsing / drying. A resist is a polymer material that is sensitive to light, X-rays, electron beams and the like.

  However, there has been a problem that the pattern collapses during the drying process in the formation stage of the ultrafine pattern, and a pattern that satisfies the performance cannot be formed. The cause of this is that the capillary force of the rinsing liquid remaining between the patterns during drying acts on the ultrafine pattern and causes the pattern to fall.

The capillary force is generated by the difference between the pressure in the rinse liquid remaining between the patterns and the atmospheric pressure, and is related to the surface tension of the rinse liquid. Therefore, as the surface tension of the rinsing liquid increases, the capillary force increases and the pattern tends to collapse. In order to solve this pattern collapse, the rinse liquid usually used is replaced with a rinse liquid having a low surface tension, and drying is performed from this state. The surface tension is generated in a state where an interface between liquid and gas is formed. Therefore, Patent Document 1 discloses a drying method using a supercritical fluid as a method for drying without causing a liquid-gas interface in order to eliminate surface tension. As a supercritical fluid generally used, there is safe carbon dioxide (CO ₂ ) having a low critical pressure and critical temperature.

  FIG. 4 is a block diagram of a conventional microstructure drying apparatus using this supercritical carbon dioxide. First, an object to be dried 106 to be dried is placed in a high-pressure drying processing container 103 equipped with a heating unit and a cooling unit. Next, the dry solvent (liquid / gas) is delivered by opening the valve 104 from a liquid collecting cylinder with a siphon tube for storing the dry solvent (liquid carbon dioxide) or a cylinder 100 including a cold evaporator (hereinafter CE). The solvent is compressed by a high-pressure pump 101 that compresses and delivers the solvent. At this time, impurities dissolved in moisture contained in the dry solvent and metal fine particles mixed from a liquid collecting cylinder with a siphon tube are filtered by the filtering means 102.

  Next, the inside of the high-pressure drying treatment vessel 103 is filled with filtered liquid carbon dioxide, and the object to be dried is completely covered with liquid carbon dioxide instead of the rinsing liquid. After washing and replacing the liquid with liquid carbon dioxide, the temperature of the high-pressure drying treatment vessel 103 is raised to a temperature and pressure above the critical point (critical condition of carbon dioxide: 31 ° C, 73 MPa), and liquefied carbon dioxide is supercritical. Convert to carbon dioxide. Finally, while maintaining the temperature of the high-pressure drying treatment vessel 103 at or above the supercritical temperature, the control valve 105 is opened to release supercritical carbon dioxide to the atmospheric pressure, and then the temperature of the high-pressure drying treatment vessel 102 is increased to about room temperature. Cool and finish drying.

  As a conventional drying method, a supercritical fluid has both gas diffusivity and liquid solubility (high density), and if it changes from a liquid to a gas via a supercritical state, it does not go through an equilibrium line. The state can be changed. Therefore, when the fluid is gradually discharged from the state filled with the supercritical fluid, the liquid / gas interface is not formed, and therefore, it is possible to dry without causing an effect due to the surface tension.

  The rinsing liquid that can be replaced with liquid carbon dioxide includes, for example, 2-propanol, ethanol, alcohol, and the like. If the rinsing liquid used for washing the object to be dried is immiscible with carbon dioxide, this rinsing liquid is used. Must be replaced with another rinsing solution having affinity for carbon dioxide.

  Further, Patent Documents 2 and 3 are known as cleaning methods using a supercritical fluid as a solvent for cleaning LSIs and MEMS elements. The washing method is performed in the same manner as the above drying.

JP 2002-33302 A Japanese Patent Laid-Open No. 10-50648 Japanese Patent Laid-Open No. 4-17333

  In conventional drying or washing of fine structures, liquid carbon dioxide containing a large amount of impurities dissolved in water contained in a solvent or metal fine particles dissolved from a liquid collecting cylinder with a siphon tube is pressurized / heated up. Supercritical fluid is generated. Impurities dissolved in the moisture contained in this solvent and metal fine particles that have dissolved out of the liquid collection cylinder with siphon tube are difficult to remove with a filter installed in the liquid carbon dioxide introduction path. It was difficult to obtain a high supercritical fluid.

  In addition, when a filter is installed in the liquid carbon dioxide introduction path to remove impurities dissolved in the water contained in the liquid carbon dioxide or metal fine particles dissolved from the liquid collection cylinder with a siphon tube, etc. Since carbon contains a large amount of impurities and metal fine particles, the load on the filter is large, and the filter life is significantly reduced. In addition, the highest filtration accuracy in the filter cannot be exhibited as the performance of removing impurities and metal fine particles. For example, the maximum filtration accuracy in the sintered filter is about 0.003 μm, but the liquid can only exhibit the removal performance at about 2 μm.

  Also, when liquid carbon dioxide is filtered through a filter, adiabatic expansion occurs when high-pressure liquefied gas leaves the filter housing, and the liquid carbon dioxide may solidify (dry ice), destroying the filter. There is a risk of doing.

  Furthermore, when the filtration performance of impurities and metal fine particles is prioritized and converted to gaseous carbon dioxide, and impurities and metal fine particles are converted back to liquid after filtration, the point of enthalpy (20 ° C, approx. 6Mpa) Liquid enthalpy is 114 (kcal / kg), b point (20 ℃, about 6Mpa) Gas enthalpy is 151 (kcal / kg), b point-a point = 151-114 = 37 (kcal / kg) It becomes. In addition, when converted from a supercritical point to a liquid, the c point-a point = 133-114 due to the enthalpy of the a point (20 ° C., about 6 MPa) liquid and the c point (31.1 ° C., 7.382 MPa) supercritical point. = 19 (kcal / kg), and the enthalpy when converted from gas to liquid is about twice that of liquefaction from supercritical, and energy consumption is large.

  An object of the present invention is to provide a supercritical fluid processing apparatus and method for preventing destruction of a filter, having high cleanliness, and further reducing energy consumption when cleaning or drying an object to be processed with a supercritical fluid. is there.

The present invention, the object to be treated is placed into a high-pressure vessel, the pressure vessel to atmospheric temperature and pressure in the processing object by introducing a solvent containing liquid in liquid or supercritical state under high pressure gas In a supercritical fluid processing apparatus to be cleaned or dried, a supercritical state storage means capable of storing the solvent supplied from the solvent supply source as a supercritical state, and the supercritical state solvent from the supercritical state storage means the solids in possess a filtering means for filtering,
Wherein between the filter means and the high pressure vessel, said filtration means supercritical fluid processing apparatus characterized by chromatic re liquid state storage means capable of storing a solvent liquid state again in the supercritical state which is filtered by It is in.

  The supercritical fluid processing apparatus of the present invention has liquid state storage means capable of storing the solvent supplied from the supply source as a liquid state between the solvent supply source and the supercritical state storage means, and the filtration A re-liquid state storage means capable of storing the supercritical solvent filtered by the filtering means as a liquid state again between the means and the high-pressure vessel; and the liquid state storage means liquefies the solvent Liquefying means, pressure application means for sending the liquefied solvent to the supercritical state storage means, the supercritical state storage means controlling the pressure and temperature at which the solvent is in a supercritical state It is preferable to have a control means.

  Furthermore, in the supercritical fluid processing apparatus of the present invention, the filtration means controls the pressure and temperature at which the filter has a mesh size of 3 μm to 3 nm, the heating means provided on the outer periphery thereof, and the solvent in a supercritical state. A plurality of stages of the filter and the heating means arranged in series, the liquid state storage means, the supercritical state storage means, the filtration means and the high pressure vessel are sequentially installed at a higher position. Being arranged so that the flow of the solvent is in the direction from the lower part to the upper part, the re-liquid state storage means being sequentially installed at a higher position between the filtration means and the high-pressure vessel, It is preferable that the solvent is introduced from a position lower than the object to be processed in the high-pressure vessel, and a discharge port for the solvent discharged from the high-pressure vessel to the atmosphere is provided in the upper portion of the high-pressure vessel. .

The present invention, the object to be treated is placed into a high-pressure vessel, the pressure vessel to atmospheric temperature and pressure in the processing object by introducing a solvent containing liquid in liquid or supercritical state under high pressure gas In the supercritical fluid processing method for washing or drying, the solvent supplied from the solvent supply source is stored as a supercritical state, and the supercritical state solvent stored in the supercritical state is stored in the supercritical state. A supercritical fluid characterized by filtering solid matter therein , storing the filtered supercritical solvent again in a liquid state, and supplying the stored liquid solvent to the high-pressure vessel It is in the processing method.

In the supercritical fluid processing method of the present invention, the solvent supplied from the supply source is stored in a liquid state , and the stored liquid state solvent is supplied to the storage in the supercritical state. The filtered supercritical solvent is stored again as a liquid state, the stored liquid state solvent is supplied to the high-pressure vessel, and the pressure and temperature at which the solvent is brought into a supercritical state are controlled. Performing the filtration, storing in the liquid state, storing in the supercritical state, performing the filtration and washing or drying of the object to be processed in a high-pressure vessel sequentially at a high position, the re-liquid state It is preferable to perform storage at a high position sequentially between the filtration and washing or drying of the object to be processed in a high-pressure vessel.

It is known that there are about 10 ⁸ pieces / cF of metal fine particles with a diameter of 0.3 μm or more, which are dissolved from water and impurities dissolved in moisture in 5N (99.999%) high purity liquefied carbon dioxide that is commercially available. ing. In addition, analysis of impurities and fine metal particles revealed that they are Al, Ca, Cr, Fe, Ni, Cu, Au, Na, etc., and that these specific substances are larger than supercritical carbon dioxide. It was. Therefore, according to the present invention, the solvent is temporarily stored in the supercritical state and the heavy metal fine particles are collected at the lower part of the container, so that only a very small amount of impurities and metal fine particles are filtered in the filter. Extremely expensive.

  In particular, according to the present invention, after the solvent is brought into a supercritical state, it is filtered through a filter connected upward from the primary side, and the solvent flow path is sequentially arranged at a higher position, thereby conveying impurities and metal fine particles themselves. Without being stagnated, it is possible to prevent the filter from being broken, to prevent the filter from being broken, and to perform processing with less energy consumption. Furthermore, in the present invention, since the cleaning performance of the supercritical fluid itself as the solvent is extremely high, the object to be processed can be washed or dried with high cleanliness.

  Further, in the present invention, a gas / liquid mixed state is taken out from a storage means for storing a solvent (carbon dioxide) for cleaning or drying the object to be processed, and liquefied into a liquid state by a sufficiently cooled liquid state storage means. And send it out with a delivery pump. After that, after storing in a supercritical state storage means that can be stored as a supercritical state from a liquid, impurities or cylinders dissolved in water contained in the solvent with a filter that is connected in the supercritical state from below to above. Filtration (separation) of metal fine particles that have melted away from the surface and other components is highly purified. Furthermore, the solvent is sent to the high-pressure vessel from the re-liquefied state storage means that can re-liquefy and store the highly purified solvent. The liquid state storage means, the supercritical state storage means, the filtration means, the reliquefied state storage means, and the high-pressure vessel are sequentially arranged at a high position so that impurities or siphon tubes dissolved in the water contained in the liquid carbon dioxide can be obtained. Using the difference in specific gravity with heavy metal fine particles that have melted out from a liquid collecting cylinder, etc., we have found a method that prevents them from being lifted up (not transported).

  In addition, by re-liquefying from the supercritical state, energy consumption when re-liquefying from gas was reduced to about half, and energy consumption could be reduced. Furthermore, it is possible to prevent the filter from being damaged due to adiabatic expansion in the filter portion.

  In particular, in the present invention, the object to be treated is placed in the high-pressure vessel in a state immersed or wet in a rinsing liquid, and the rinsing liquid is removed from the object to be treated by the fluid introduced into the high-pressure container. It is extremely effective when drying the workpiece.

  According to the present invention, it is possible to increase the cleanliness of a liquid or supercritical solvent, and it is possible to perform cleaning or drying with low particles after development of LSI or MEMS elements using a supercritical fluid, resulting in a high yield. improves. Moreover, solidification of the solvent in the filter portion can be prevented, damage to the filter can be prevented, and reliability can be improved. Furthermore, energy consumption at the time of reliquefaction can be suppressed, and cost reduction can be achieved.

The present invention, the object to be treated is placed into a high-pressure vessel, the pressure vessel said object to be processed under high pressure gaseous at normal temperature and normal pressure by introducing a solvent containing liquid in liquid or supercritical state during In a supercritical fluid processing apparatus for cleaning or drying, a supercritical fluid that can be stored with control means for controlling the pressure and temperature at which the solvent supplied from the solvent supply source is in a supercritical state and the solvent is in a supercritical state. A plurality of stages of filtration means arranged in series, comprising: a state storage means; a filter for filtering the solid matter in the supercritical state solvent from the supercritical state storage means; and a heating means provided on the outer periphery thereof; and The liquid state storage means capable of storing the solvent supplied from the supply source as a liquid state between the solvent supply source and the supercritical state storage means, and the filtration between the filtration means and the high pressure vessel. To the means Liquefied means for liquefying the solvent by re-filtering the filtered supercritical solvent again, re-liquid state storing means for storing, and pressure applying means for sending the liquefied solvent to the supercritical state storage means The liquid state storage means, the supercritical state storage means, the filtration means, the re-liquid state storage means and the high-pressure vessel are sequentially installed at a high position, and the flow of the solvent is from the lower part to the upper part. The supercritical fluid processing apparatus is characterized by being arranged in a direction.

Furthermore, the present invention is installed to be treated into the high pressure vessel, said at normal temperature and normal pressure in the high pressure vessel wherein the object to be processed by introducing a solvent containing liquid in liquid or supercritical state under high pressure in a gas In a supercritical fluid processing method for washing or drying an object, the solvent supplied from the solvent source is stored as a supercritical state, and the solvent stored in the supercritical state is stored in the supercritical state. the solid was characterized by filtering, further to the solvent supplied from the supply source and stored in a liquid state, supplying the solvent reservoir liquid state for storage of the supercritical state, The filtered supercritical solvent is stored again as a liquid state, the stored liquid state solvent is supplied to the high-pressure vessel, and the pressure and temperature at which the solvent is brought into a supercritical state are controlled. Performing the filtration Storage in the liquid state, storage in the supercritical state, filtration, storage in the re-liquid state, and washing or drying of the object to be processed in a high-pressure vessel are sequentially performed at a high position. A supercritical fluid processing method.
[Experimental Example 1]

FIG. 1 is a block diagram of the fine structure drying apparatus of this experimental example . As shown in FIG. 1, a liquid collecting cylinder with a siphon tube for storing a dry solvent or a cylinder 100 made of CE, a high-pressure pump 101 for sending the dry solvent, impurities or cylinders dissolved in water contained in the dry solvent, Filtration means 102 having a filter for filtering (separating) metal fine particles that have dissolved from, etc., a high-pressure drying treatment container 103 for holding and processing the object to be dried, a valve 104 for supplying a drying solvent, drying A control valve 105 for releasing the solvent, an object to be dried 106, and a supercritical state storage means 200 capable of storing the dry solvent sent from the high-pressure pump as a supercritical state. The filtering means 102 and the supercritical state storage means 200 have a heating means and a control means for controlling the pressure and temperature of the dry solvent.

Hereinafter, a method for drying an object to be dried in the fine structure drying apparatus shown in FIG. 1 will be described. This experiment is an example of a case of using liquid carbon dioxide as a dry solvent.
(1) The object to be dried 106 to be dried is carried and held in the high-pressure drying processing container 103, and the lid of the high-pressure drying processing container 103 is closed after completion.
(2) Next, the valve 104 of the overhead valve of the cylinder 100 is opened. When the valve 104 is opened, the gas / liquid mixed carbon dioxide delivers a flow rate required for the rinse replacement by the high-pressure pump 101.
(3) The gas / liquid mixed carbon dioxide delivered by the high-pressure pump 101 is controlled by the supercritical state storage means 200 to a supercritical pressure and temperature and converted to a supercritical state.
(4) The carbon dioxide that has reached the supercritical state is contained in the liquid carbon dioxide before the supercritical state by using two or more filters that match the roughness of the eyes to be removed, such as a sintered filter or membrane filter of the filtering means 102. Impurities dissolved in the water contained in the water and metal fine particles dissolved from the liquid collecting cylinder with siphon tube are filtered (separated) to be highly purified. There is a heater on the outer periphery of the filtering means 102, and the supercritical temperature state is maintained.

The highly purified supercritical carbon dioxide is supplied to the high-pressure drying treatment vessel 103 in the state of liquid carbon dioxide.

  When highly purified liquid carbon dioxide is introduced into the high-pressure drying treatment container 103, the material 106 to be dried is filled with liquid carbon dioxide, and the rinsing liquid remaining between the microstructures is liquid carbon dioxide. Is replaced by

  After completion of the rinsing liquid replacement, the temperature of the high-pressure drying treatment vessel 103 is controlled from 18 ° C. to 40 ° C. while maintaining the pressure of the dry solvent. Thereby, the liquid carbon dioxide becomes a supercritical state.

  After reaching the supercritical state, the control valve 105 is opened while maintaining the control temperature of 40 ° C., and the supercritical carbon dioxide in the high-pressure drying treatment vessel 103 is released. Thus, the drying can be completed in a highly clean state without going through the gas / liquid interface because the supercritical state is released.

As described above, moisture microstructure drying apparatus of the present real Kenrei, prior to feeding the dried solvent to the high-pressure drying chamber, the drying solvent as the supercritical state, which is contained in the liquid carbon dioxide in the filter at that time Filtering (separating) the impurities dissolved in the metal and the metal fine particles dissolved in the liquid collecting cylinder with siphon tube, etc., it is possible to increase the cleanliness of the dry solvent and to solidify the dry solvent in the filter part. Since it can prevent, it can clean without damaging the filter itself. In the present embodiment, the supercritical state storage means 200, the filtration means 102, and the high-pressure drying treatment container 103 are piped at the same height. However, these are sequentially installed at higher positions in the same manner as in Embodiment 3 described later. Metal fine particles can be removed with high cleanliness.
[Experimental Example 2]

FIG. 2 is a configuration diagram of a fine structure drying apparatus showing another example of the experimental example . As shown in FIG. 2, a liquid collecting cylinder with a siphon tube for storing a dry solvent or a cylinder 100 made of CE, a high-pressure pump 101 for sending the dry solvent, impurities or cylinders dissolved in moisture contained in the dry solvent, Filtration means 102 for filtering (separating) the metal fine particles that have dissolved from, etc., high-pressure drying processing container 103 for holding and processing the object to be dried, valve 104 for supplying the drying solvent, and opening the drying solvent A control valve 105 for drying, a to-be-dried object 106, a supercritical state storage means 200 capable of storing the dry solvent sent from the high pressure pump as a supercritical state, and a liquid state storage means 300 capable of liquefying and storing the dried solvent Have. The filtering means 102 and the supercritical state storage means 200 have heating means and control means for controlling pressure and temperature.

Hereinafter, a method for drying an object to be dried in the microstructure drying apparatus shown in FIG. 2 will be described. This experiment provides an example of a case of using liquid carbon dioxide as a dry solvent.
(1) First, the object to be dried 106 to be dried is carried and held in the high-pressure drying processing container 103, and the lid of the high-pressure drying processing container 103 is closed after completion.
(2) Next, the valve 104 of the overhead valve of the cylinder 100 is opened. When the valve 104 is opened, gas / liquid mixed carbon dioxide is introduced into the liquid state storage means 300. At this time, since the liquid state storage means 300 is kept at −10 ° C., the carbon dioxide which is a gas is cooled and becomes liquid.
(3) Next, liquefied carbon dioxide is sent out by the high-pressure pump 101 at a flow rate necessary for rinsing replacement.
(4) The liquid carbon dioxide delivered by the high-pressure pump 101 is controlled to the supercritical pressure / temperature by the supercritical state storage means 200 and converted to a supercritical state.
(5) The carbon dioxide in the supercritical state is water contained in the liquid carbon dioxide by two or more filters according to the roughness of the eyes to be removed, such as a sintered filter or a membrane filter of the filtering means 102. Filter (separate) and purify the impurities dissolved in the metal and metal fine particles dissolved in the liquid collecting cylinder with siphon tube.

  The highly purified supercritical carbon dioxide is supplied to the high-pressure drying treatment vessel 103 in the state of liquid carbon dioxide.

  When highly purified liquid carbon dioxide is introduced into the high-pressure drying treatment container 103, the material 106 to be dried is filled with liquid carbon dioxide in the liquid state, and the rinsing liquid remaining between the microstructures is liquid dioxide. Substituted by carbon.

  After completion of the rinsing liquid replacement, the temperature of the high-pressure drying treatment vessel 103 is controlled from 18 ° C. to 40 ° C. while maintaining the pressure of the dry solvent. Thereby, liquid carbon dioxide will be in a supercritical state.

  After reaching the supercritical state, the control valve 105 is opened while maintaining the control temperature of 40 ° C., and the supercritical carbon dioxide in the high-pressure drying treatment vessel 103 is released. Thus, the drying can be completed in a highly clean state without going through the gas / liquid interface because the supercritical state is released.

As described above, moisture microstructure drying apparatus of the present real Kenrei, prior to feeding the dried solvent to the high-pressure drying chamber, the drying solvent as the supercritical state, which is contained in the liquid carbon dioxide in the filter at that time Filtering (separating) the impurities dissolved in the metal and the metal fine particles dissolved in the liquid collecting cylinder with siphon tube, etc., it is possible to increase the cleanliness of the dry solvent and to solidify the dry solvent in the filter part. Since it can prevent, it can clean without damaging a filter. In addition, a heater is provided on the outer periphery of the filtering means 102 and is maintained in a supercritical temperature state.
In this experiment example, a liquid state storage means 300, a supercritical state storage means 200, although the filtering means 102 and the high-pressure drying chamber 103 is a pipe at the same height, by placing them in sequential high position As in Example 1 described later, the metal fine particles can be removed with high cleanliness.
[Example 1 ]

Figure 3 is a block diagram of a micro-fine structures drying apparatus of the present invention. As shown in FIG. 3, a liquid collecting cylinder with a siphon tube for storing a dry solvent or a cylinder 100 made of CE, a high-pressure pump 101 for sending the dry solvent, impurities or cylinders dissolved in water contained in the dry solvent. Filtration means 102 for filtering (separating) the metal fine particles that have dissolved from, etc., high-pressure drying processing container 103 for holding and processing the object to be dried, valve 104 for supplying the drying solvent, and opening the drying solvent A control valve 105 for drying, an object to be dried 106, a supercritical state storage means 200 that can store the dry solvent sent from the high-pressure pump as a supercritical state, a liquid state storage means 300 that can cool and store the dried solvent, Re-liquefied state storage means 400 that can cool and re-liquefy and store the highly purified dry solvent is provided. The filtering means 102 and the supercritical state storage means 200 have heating means and control means for controlling pressure and temperature.

  In the present embodiment, the supercritical state storage means 200, the filtration means 102, the liquid state storage means 300, the reliquefied state storage means 400, and the high-pressure drying treatment container 103 are arranged in this order in the liquid carbon dioxide. Using the difference in specific gravity with the impurities dissolved in the contained water and heavy metal fine particles dissolved from the siphon tube with a liquid collection cylinder, etc. The purified dry solvent can be supplied to the high-pressure drying treatment container 103.

Hereinafter, a method for drying an object to be dried in the microstructure drying apparatus shown in FIG. 3 will be described. Table 1 is a table showing the state of the dry solvent at each site in FIG. In Table 1, the temperature and pressure are examples when liquefied carbon dioxide is used as the drying solvent.

(1) The object to be dried 106 to be dried is carried and held in the high-pressure drying processing container 103, and the lid of the high-pressure drying processing container 103 is closed after completion.
(2) Next, the valve 104 of the overhead valve of the cylinder 100 is opened. When the valve 104 is opened, gas / liquid mixed carbon dioxide is introduced into the liquid state storage means 300. At this time, since the liquid state storage means 300 is kept at −10 ° C., the carbon dioxide that is a gas is also cooled to become a liquid (see 3 in Table 1).
(3) Next, the high-pressure pump 101 sends out a flow rate necessary for rinsing the liquefied carbon dioxide.
(4) The liquid carbon dioxide delivered by the high-pressure pump 101 is controlled to the supercritical pressure / temperature by the supercritical state storage means 200 and converted to the supercritical state (see 5 in Table 1).
(5) The carbon dioxide that has reached the supercritical state is water contained in the liquid carbon dioxide by two or more stages of filters, such as a sintered filter or a membrane filter of the filtering means 102, which are adjusted to the roughness of the eyes to be removed. Filter (separate) and purify the impurities dissolved in the metal and metal fine particles dissolved in the liquid collecting cylinder with siphon tube. There is a heater on the outer periphery of the filtering means 102, and the supercritical temperature state is maintained.
(6) The highly purified supercritical carbon dioxide is cooled in the reliquefied state storage means 400, reconverted into a liquid (see 7 in Table 1), and supplied to the high-pressure drying treatment vessel 103.
(7) When highly purified liquid carbon dioxide is introduced into the high-pressure drying treatment container 103, the object to be dried 106 is filled with carbon dioxide in a liquid state, and the rinsing liquid remaining between the fine structures Replaced with liquid carbon dioxide.
(8) After the replacement of the rinse liquid is completed, the temperature of the high-pressure drying processing vessel 103 is controlled from 18 ° C. to 40 ° C. while maintaining the pressure of the drying solvent. Thereby, the carbon dioxide which was a liquid will be in a supercritical state (refer to 8 and 9 in Table 1).
(9) After reaching the supercritical state, the control valve 105 is opened while maintaining the control temperature of 40 ° C., and the supercritical carbon dioxide in the high-pressure drying treatment vessel 103 is released. Thus, the drying can be completed in a highly clean state without going through the gas / liquid interface because the supercritical state is released.

  As described above, in the microstructure drying apparatus of the present embodiment, before supplying the drying solvent to the high-pressure drying processing vessel, the drying solvent is set to a supercritical state, and the moisture contained in the liquid carbon dioxide at that time by the filter Filtering (separating) the impurities dissolved in the metal and the metal fine particles dissolved in the liquid collecting cylinder with siphon tube, etc., it is possible to increase the cleanliness of the dry solvent and to solidify the dry solvent in the filter part. Since it can prevent, it can clean without damaging a filter.

  Also, liquid carbon dioxide can be obtained by arranging the liquid state storage means, supercritical state storage means, filter, and reliquefaction state storage means sequentially at a higher position, and further introducing a dry solvent from below and supplying from above. Improve the cleanliness of the dry solvent by stagnating at a low position without transporting the impurities dissolved in the water contained in it or the metal fine particles dissolved from the liquid collecting cylinder with siphon tube. Can do.

  Furthermore, since filtration (separation) is performed in a supercritical state, energy consumption during reliquefaction can be halved compared to filtration (separation) in a gas state. Needless to say, the configuration may not be such that the dry solvent is reused as in the present embodiment.

It is a block diagram which shows the fine structure drying apparatus of Experimental example 1. FIG. It is a block diagram which shows the fine structure drying apparatus of Experimental example 2. FIG. It is a block diagram which shows the fine structure drying apparatus of this invention. It is a block diagram which shows the conventional fine structure drying apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Cylinder, 101 ... High pressure pump, 102 ... Filter, 103 ... High pressure drying processing apparatus, 104 ... Valve, 105 ... Control valve, 106 ... To-be-dried object, 200 ... Supercritical state storage means, 300 ... Liquid state storage means, 400: Re-liquefied state storage means.

Claims (16)

The object to be treated is placed into a high-pressure vessel, thereby cleaning or drying the object to be treated by introducing a solvent containing liquid in liquid or supercritical state under high pressure gaseous at normal temperature and normal pressure in the high pressure vessel In supercritical fluid processing equipment,
Supercritical state storage means capable of storing the solvent supplied from the solvent supply source as a supercritical state; and filtration means for filtering solid matter in the supercritical state solvent from the supercritical state storage means. Yes, and
Wherein between the filter means and the high pressure vessel, said filtration means supercritical fluid processing apparatus characterized by chromatic re liquid state storage means capable of storing a solvent liquid state again in the supercritical state which is filtered by .   2. The supercritical fluid processing according to claim 1, further comprising a liquid state storage unit capable of storing the solvent supplied from the supply source as a liquid state between the solvent supply source and the supercritical state storage unit. apparatus. 3. The supercritical fluid according to claim 2 , wherein the liquid state storage means includes liquefaction means for liquefying the solvent, and pressure application means for sending the liquefied solvent to the supercritical state storage means. Processing equipment.   2. The supercritical fluid processing apparatus according to claim 1, wherein the supercritical state storage means includes heating means for bringing the solvent into a supercritical state, and control means for controlling the pressure and temperature of the solvent.   2. The filter means according to claim 1, wherein the filter has a coarseness of 3 μm to 3 nm, a heating means provided on the outer periphery thereof, and a control means for controlling a pressure and a temperature at which the solvent is brought into a supercritical state. A supercritical fluid processing apparatus, wherein the filter and the heating means are arranged in a plurality of stages in series.   In Claim 2, the liquid state storage means, the supercritical state storage means, the filtration means and the high pressure vessel are sequentially installed at a high position, and are arranged so that the flow of the solvent is in the direction from the bottom to the top. A supercritical fluid processing apparatus. 2. The supercritical fluid processing apparatus according to claim 1 , wherein the filtering unit, the re-liquid state storage unit, and the high-pressure vessel are sequentially installed at a high position.   2. The supercritical fluid processing apparatus according to claim 1, wherein the solvent is introduced from a position lower than the object to be processed in the high-pressure vessel.   2. The supercritical fluid processing apparatus according to claim 1, wherein a discharge port for the solvent discharged from the high pressure vessel to the atmosphere is provided at an upper portion of the high pressure vessel. In Claim 1, the said to-be-processed object is installed in the said high-pressure vessel in the state immersed or rinsed in the rinse liquid, and the said rinse liquid is removed from the said to-be-processed object with the said solvent introduced into the said high-pressure container. A supercritical fluid processing apparatus for drying the object to be processed. The object to be treated is placed into a high-pressure vessel, thereby cleaning or drying the object to be treated by introducing a solvent containing liquid in liquid or supercritical state under high pressure gaseous at normal temperature and normal pressure in the high pressure vessel In the supercritical fluid processing method,
The solvent supplied from the solvent supply source is stored in a supercritical state, the supercritical solvent stored in the supercritical state is filtered in the supercritical state, and the solids therein are filtered. A supercritical fluid processing method , wherein the stored supercritical solvent is stored again as a liquid state, and the stored liquid solvent is supplied to the high-pressure vessel . According to claim 1 1, ultra said solvent supplied from said source stored as a solvent in a liquid state, and supplying said solvent reservoir liquid state for storage of the supercritical state Critical fluid processing method. According to claim 1 1, supercritical fluid processing method and performing the filtration while controlling the pressure and temperature of the solvent into a supercritical state. In claim 1 2, super and performs the storage in the liquid state, the storage in the supercritical state, at the filtering and sequentially high position the washing or drying of the object to be processed in a high pressure vessel Critical fluid processing method. According to claim 1 1, wherein the storage in again a liquid state, said filtering and no line between the washing or drying of the object to be processed in a high pressure vessel, said filtration, said storage and said again a liquid state A supercritical fluid processing method , wherein cleaning or drying of the object to be processed in a high pressure vessel is sequentially performed at a high position. According to claim 1 1, together with the installed in the object to be treated inside the high pressure vessel at dipping or wet the rinse solution, removing the rinse solution from said object to be processed by the solvent introduced into the high pressure vessel A supercritical fluid processing method, wherein the object to be processed is dried.

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