JPH09139374A - Surface treating method and apparatus and element obtained from them - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid deforming a microstructure in a drying step by dissolving a liq. deposited to the surface of a washed element in a liq. or supercritical fluid of specified compd. in a pressure vessel and lowering the pressure in this vessel held above a critical temp. below a critical pressure to gasify and remove this fluid. SOLUTION: Component elements of a high density integrated circuit to which specified treatment or washing is applied are housed in a housing 2 of a pressure vessel 1 and contacted with a liq. or supercritical fluid entered into the vessel 1 through a pump 14, valve 18 and entrance line 19 from a tank 11 to dissolve the liq. deposited to the surface of the element in the liq. or supercritical fluid of specified compd. While the temp. in the vessel 1 is held above the critical temp. of the specified compd. by a temp. adjuster 7, the pressure is reduced below the critical pressure to gasify and remove the supercritical fluid whereby the elements of a microstructure can be taken out without deformation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment method for an element that undergoes processes such as coating, exposing, developing, etching and cleaning of a photosensitive material on a solid substrate which is a work piece, a treatment apparatus and a method for obtaining the same. Related elements, for example, a microstructure in which a part or all of a region of a processed product is separated from a solid substrate which is a workpiece by etching in a liquid, or a contact with a solid substrate which is a workpiece. It is useful for forming microfabrication patterns etc. where the area of the non-contact part with the solid substrate is large compared to the area of the part
It is also useful for preventing so-called watermark, which is a problem in the manufacturing process of semiconductor devices.

[0002]

2. Description of the Related Art In the formation of microstructures by lithography or in the manufacture of semiconductor devices, it is common practice to make the final formation, whether bonded to the support substrate or completely separated from the support substrate. The process is performed by applying a photosensitive material onto a solid substrate that is a workpiece, exposing, developing, etching, cleaning, etc., and finally drying and removing the liquid adhering to the periphery of the microstructure. In some cases, after washing with pure water, the liquid is replaced with another liquid having a higher evaporation rate and then dried in the atmosphere.

[0003]

When the whole or a part of the target pattern-formed product is separated from the surface of the supporting substrate, as the processing size becomes smaller and the shape becomes more complicated, the conventional pure water is used. Serious obstacles appear during the drying process of liquids such as organic solvents that have replaced it. That is, although the pattern-formed product as designed is obtained at the stage where the liquid is attached to the periphery of the fine pattern, significant deformation or destruction occurs after drying. Also,
Even when the bottoms of the fine patterns are all bonded to the surface of the substrate, the same obstacle appears even when the ratio of the height and width of the fine patterns, which is called the aspect ratio, is large.

As a result of observing the drying process in detail with an optical microscope, this deformation or destruction is caused by the surface tension of the droplets when the surrounding liquid that wets the microstructure is dried and the diameter of the droplets is reduced. It became clear that this is because a large stress was applied to the microstructure. This effect is most prominent in the case of water having a large surface tension, but the same phenomenon occurs in the case of a liquid having a smaller surface tension than water such as an organic solvent that replaces the water.

Freeze-drying is conceivable as one means for overcoming such problems, but the volume of a liquid generally changes during freezing. Therefore, it is not an essential solution because stress is applied to the sample during freezing.

Further, in the process of manufacturing semiconductors, so-called watermarks are formed on the surface of silicon or aluminum after being dried by a predetermined process, which is one of the causes of lowering the yield of products.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have earnestly studied for the purpose of preventing deformation and destruction of a microstructure formed by etching or washing in a liquid during the drying process and preventing the formation of a watermark. Then, the present invention was obtained.

The present inventors have focused their attention on supercritical fluids. A supercritical fluid is one of the phases that each substance takes under a temperature and pressure that are higher than the values unique to each substance called critical temperature and critical pressure.In this state, other liquids and solids Although it has almost the same dissolving power as the liquid state of the substance, it has a peculiar property that its viscosity is extremely small and its diffusion coefficient is extremely large. Supercritical fluid is rapidly gasified by reducing the ambient pressure below the critical pressure.

It is possible to utilize a supercritical fluid having a peculiar property of a large dissolving power and a small viscosity for removing a photosensitive material in a semiconductor fine processing step.
30, JP-A-1-220828, JP-A-2-20972
9, JP-A-3-127832 and the like. It is described in JP-A-5-47732 that carbon dioxide, which has a particularly low critical temperature and is easy to handle, has an advantage of having a small effect on the global environment.

It is known that the viscosity of each supercritical fluid is generally about 1/100 or less of that of the corresponding liquid. In contrast, there are no reliable surface tension measurements for each supercritical fluid. However, both the viscosity and the surface tension are due to the interaction force between the atoms and molecules forming the liquid or fluid. Therefore, in a supercritical fluid with low viscosity, its surface tension is also extremely small,
The inventors have estimated that it is about one hundredth or less than the corresponding liquid. Therefore, it is expected that the stress applied to the sample in the process of gasification thereof is extremely small. Experimental facts set forth in the examples below demonstrate that this assumption is correct.

In the present invention, a microstructure or a microfabricated pattern having a large aspect ratio, which is wholly or partially separated from the surface of the supporting substrate by the etching treatment in the microfabrication process, is directly used for cleaning or for cleaning. After passing through the liquid of the above, or after substituting with another liquid as will be described later, these liquids are turned into supercritical fluids by contacting them with the supercritical fluids in the pressure vessel with the liquids attached to the surface. Remove by dissolving. Then, while maintaining the container temperature at or above the critical temperature, the pressure inside the container is reduced to below the critical pressure to gasify and remove the supercritical fluid, and the microstructure is taken out into the atmosphere. Since the surface tension of the supercritical fluid is extremely small, the stress exerted on the microstructure by the surface tension of the supercritical fluid when it is removed from the surface of the microstructure is negligible. Therefore, the microstructure is not deformed or destroyed. In the manufacture of semiconductors, cleaning liquid and the like attached during processing are effectively removed. Hereinafter, the present invention will be described mainly with respect to an example of forming a fine structure by fine processing.

A feature of the present invention is to bring the liquid into contact with the supercritical fluid while the liquid remains attached to the surface or the periphery of the constructed element. Once the microstructure is dried by evaporation of the liquid, stress is applied to the microstructure at that stage, causing deformation or destruction. Therefore, it is necessary to prevent the sample from drying before removing the liquid using the supercritical fluid. This is the greatest difference between the present invention and a series of conventional inventions that use supercritical fluids for cleaning purposes.

For this purpose, the liquid adhering to the periphery of the microstructure must have a low evaporation rate, and liquids with high vapor pressure such as ethyl alcohol and acetone are not suitable. Therefore, when the organic solvent or the like is used to remove the residue of the photosensitive organic compound used for the fine processing, it is effective to replace the organic solvent or the like with another liquid after the operation. . It is essential that the liquid used for such replacement has a low evaporation rate and is not corrosive or toxic, and preferably has high compatibility with the liquid used for cleaning.

The studies conducted by the present inventors have revealed that water is one of the most preferable compounds satisfying these conditions. Therefore, when selecting the liquid, it is necessary that the evaporation rate is equal to or lower than that of water, that is, the vapor pressure at room temperature is equal to or lower than that of water. As the liquid other than water used in the present invention,
Higher alcohols, polyhydric alcohols, linear hydrocarbons having 8 or more carbon atoms, and the like are preferable.

Although the dissolving power of a supercritical fluid is almost equal to that of the corresponding liquid, a liquid generally has a larger dissolving power. On the other hand, in order to improve the efficiency of the production process, it is required that the time required for drying the microstructure is short. for that reason,
The microstructure to which the liquid adheres may first be brought into contact with the liquid of the predetermined compound to remove it, and then the temperature in the pressure vessel may be raised to bring the liquid into a supercritical state and then depressurized. It is also possible to periodically change the temperature inside the container above and below the critical temperature in order to take full advantage of the characteristics of both the liquid state, which has a higher dissolving power, and the supercritical fluid, which has a low viscosity and tends to enter small gaps. Is the preferred method. However, the important point is that when the pressure in the pressure resistant vessel is reduced and gasified, the temperature in the vessel must always exceed the supercritical temperature.

When a supercritical fluid is used to remove a non-volatile substance such as a residue of a photosensitive organic compound used for microfabrication, if the cleaning is completed, a state in which the supercritical fluid is changed to a liquid It doesn't matter even if the pressure is reduced with. However, in the case of removing a volatile liquid such as water for the purpose of preventing the deformation of the microstructure, it must be in a supercritical state. Therefore, the temperature inside the pressure resistant container needs to be strictly controlled, and the pressure resistant container according to the present invention preferably has a temperature control mechanism.

When the liquid that wets the microstructure is replaced or removed by the liquid of a predetermined compound or supercritical fluid, the removal of the liquid that wets the surface of the microstructure used for cleaning is substantially completed. It is useful to know what you have done. It is not preferable from the viewpoint of production efficiency to keep the liquid of the predetermined compound or the supercritical fluid flowing for a longer time than necessary. Further, if taken out into the atmosphere in an insufficiently dried state, irreversible deformation of the sample is caused, and even if it is returned to the supercritical fluid, the original shape is not restored. Therefore, it is preferable to measure the concentration of the liquid discharged from the pressure vessel or the liquid to be removed in the supercritical fluid in real time. For measuring the concentration, absorptance of light of a predetermined wavelength, a change in dielectric constant, mass spectrometry, or the like is used, but the selection of such concentration measuring means does not limit the content of the present invention.

The liquid to be removed according to the present invention is a liquid that is condensed or physically adsorbed in the gaps of the microstructure as droplets. An extremely small amount of liquid that is chemically adsorbed as a monolayer on the surface of a solid is difficult to remove by this method, but even if it remains, it does not deform or break due to stress. Also, this is unlikely to be the cause of the watermark. Therefore, any of the above methods is sufficient for measuring the concentration of the liquid to be removed in the present invention. That is, since the drying of the microstructure ends when the concentration of the liquid to be removed reaches the detection limit or less, the microstructure is not deformed or destroyed after being taken out into the atmosphere. If it is necessary to remove the liquid chemically adsorbed on the surface of the microstructure, it goes without saying that another method such as heating in vacuum is adopted.

As the supercritical fluid, many substances such as carbon dioxide, ammonia, water, alcohols, low molecular weight saturated aliphatic hydrocarbons, benzene, diethyl ether, etc., which have been confirmed to be in a supercritical state, are used. can do. Among these, carbon dioxide having a supercritical temperature of 31.3 ° C., which is close to room temperature, is one of the preferable substances because it is easy to handle and the sample does not need to be at a high temperature. In addition, the compatibility with the water used for washing is great,
Alcohols that easily dissolve this are also preferable substances. The water used in the washing step can also be used in a supercritical state.

The present invention will be described with reference to the phase diagram of the pure substance shown in FIG. In FIG. 1, the horizontal axis represents temperature and the vertical axis represents pressure. Solid and liquid are melting curves ab passing through triple point a
The liquid and the gas are separated by an evaporation curve a-c that passes through the triple point a and the critical point c. In the supercritical state, a line dc in which the temperature and the pressure exceed the critical temperature Tc and the critical pressure Tp, respectively.
It exists in the area surrounded by -e. In the case of carbon dioxide, the critical temperature is 31.3 ° C and the critical pressure is 72.9 atm, where the density is 0.45 g / ml.

At the stage of removing the liquid adhering to the microstructure, the inside of the pressure resistant container may be either point A or point B in the figure, but after the processing is completed, the line from point B must be drawn. c-
After entering the gaseous state via one point on e, 1 at room temperature
It has to be reached to point C, which corresponds to atmospheric pressure. When the pressure inside the container is reduced and the pressure is reduced through the evaporation curves ac, the liquid and the gas coexist there, and the sample is deformed. When using a supercritical fluid for the purpose of only removing the residues of photosensitive organic compounds used for microfabrication,
There is no problem even if it goes through the evaporation curves ac. In fact, simply introducing a supercritical fluid whose temperature is adjusted outside the pressure vessel into the pressure vessel may cause the temperature inside the vessel to become lower than the critical temperature due to adiabatic expansion and radiation of heat from the pressure vessel at that stage. is there. Therefore, for the purpose of the present invention, it is preferable to control the temperature of the pressure resistant container.

FIG. 2 is a schematic view of a drying device as a main part of the processing system according to the present invention. The pressure-resistant container is a container body 1 that can be opened upward for exchanging a microstructure that is a sample, a container 2 for the microstructure in the container, and a pressure container lid that hermetically seals the opening of the container. 3 and the sample container 2 has a mesh-shaped bottom. A pressure gauge 4 and a thermometer 5 are connected to the container body 1, and the temperature of the container body 1 is controlled by a temperature controller 7 through a feedback circuit 6. The supercritical fluid is sent from the tank 11 to the heat exchanger 16 through the flowmeter 13 and the pump 14. 1
2 is a valve and 15 is a check valve. The supercritical fluid, which is controlled to a predetermined temperature, has a valve 18 and an introduction line 1.
9 to the container body. Reference numeral 17 is a pressure regulator. Supercritical fluid containing impurities such as water is drain line 2
After passing through 1, the densitometer 22 and the filter 23, the heat exchanger 25 deposits a dissolved substance and then reuses it through the circulation line 27. If necessary, the exhaust valve 24
May be released into the atmosphere through. The exhaust valve may be installed between the densitometer 22 and the filter 23.
Reference numeral 26 is a check valve. Although not shown in the figure, it is also effective to provide a pulse buffer on the way when the sample may be damaged by the pulsating flow generated during the supply.

The target of the drying method using the supercritical fluid according to the present invention is a microstructure in which a part of the supporting solid substrate side of the fine pattern is separated from the supporting solid substrate, or Even if there is no separation part from the solid substrate, it is a microstructure having a large ratio of pattern height to width called an aspect ratio. The former is a minute driving component called a micromachine, and the latter is an indispensable component of a high-density integrated circuit. Especially in the latter,
This includes not only conventional microfabrication products in which a fine pattern formed through an etching process exists as convex portions on the substrate surface, but also microfabrication products having deep groove portions close to each other. A specific example of such a structure is, for example, Symposium on V in which a dynamic random access memory with a storage capacity of 256 kilobits was held in 1995.
See pages 15 to 16 of the proceedings of LSI Technology.

Related to the deformation and breakage of the liquid due to surface tension is a property called bending strength of the constituent materials. For the main materials to be microfabricated, this value is in the region of approximately 10 Kgf / mm. Actually, the presence or absence of deformation during drying by the conventional method mainly depends on the size of the microfabrication region, not on the material of the solid substrate which is the workpiece. More specifically, not the ratio of the height to the width of the minute portion, which is called the aspect ratio, but the ratio of the height to the square of the width of the minute portion exceeds a certain value, the deformation during drying becomes remarkable. It was revealed. The present invention is used to dry these samples.

In the case of a fine pattern convexly formed on the upper surface of the substrate, the ratio of the height to the square of the width of the fine portion is 25.
If it exceeds, the possibility of deformation is significantly increased by the conventional drying method. Further, even if the width of the minute portion is slightly larger than this, if the distance between two adjacent minute portions is small, it is easily deformed. In another case, when a plurality of thin and deep grooves are formed near the substrate surface, the deformation becomes remarkable when the ratio of the groove depth to the square of the distance between the grooves is 25 or more. In any of these sample forms, according to the present invention, it becomes possible to dry the microstructure portion without deforming it. In the above description, the unit of length is micrometer.

The present invention can also be applied to a process of drying an artificial microstructure formed by a method other than the lithography technique or a microstructure existing in nature. For example, needle-shaped single crystals called whiskers or whiskers are formed not only by condensation from the vapor phase but also by precipitation from solution. Its small thickness is a few nanometers, and its length can reach a few centimeters. The whiskers themselves are ideally near-perfect crystals with very high strength. However, at the boundary with the solid surface on which it grows, it does not always have sufficient strength due to lattice mismatch and defects. Therefore, such whiskers may break at their roots when removed from the solution in which they were grown. The present invention is also effective in the process of drying such needle crystals. In addition, artificial or natural fiber is a solid whose length is infinite compared to its width. The density and the aggregated state dominate the characteristics of the fiber, but the present invention is also effective for preventing aggregation of the fiber in the drying process after washing or surface treatment in a liquid. The present invention is also effective for drying the porous body.

In the present invention, the liquid adhering to the surface of the microstructure is dissolved and removed in the supercritical fluid and then gasified and removed. Since the surface tension of the supercritical fluid is small, the microstructure cannot be deformed or destroyed during the gasification process.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION

Example 1 A U-shaped pattern formed product whose plan view is shown in FIG. 3 was formed by the following steps. The material is amorphous silicon whose surface is coated with silicon nitride and has a thickness of 2 μm. First, silicon nitride was deposited to a thickness of 0.1 μm on the surface of a silicon wafer, and then amorphous silicon was deposited to a thickness of 2 μm. Then, the amorphous silicon layer was left in a U shape by lithography. Silicon nitride was again deposited on this surface to a thickness of 0.1 micrometer. At this stage, the U-shaped amorphous silicon layer has its upper and lower sides and side surfaces covered with silicon nitride.
Next, the silicon nitride other than that covering the U-shaped amorphous silicon layer was removed again by lithography. The silicon wafer is dissolved by immersing the wafer in an aqueous solution of potassium hydroxide, and the U-shaped minute formations covered with silicon nitride are separated. After replacing the potassium hydroxide aqueous solution with pure water, the micro-formed product was transferred together with the container to the pressure resistant container shown in FIG. Carbon dioxide in a supercritical state was continuously supplied thereto, and pressure was reduced after water was no longer detected in the discharged supercritical carbon dioxide, and the pattern formed product was taken out in a dried state. It was confirmed with an optical microscope that the pattern-formed product had a size and shape as designed and was not deformed or destroyed at all. In the pattern-formed product having the same specifications, which was washed with water and then naturally dried in the atmosphere, both ends of the U-shape were adhered due to deformation.

Example 2 By the same process as in Example 1, a pattern of FIG. 4A made of amorphous silicon whose periphery was covered with a silicon nitride layer was formed on the surface of the silicon wafer. Its thickness is 2 microns. Then, the silicon wafer was gradually dissolved by immersing the silicon wafer in an aqueous solution of potassium hydroxide. When the silicon on the lower side of the narrow portion in the pattern of FIG. 4A was removed, the alkaline aqueous solution was transferred to pure water for cleaning. Next, this silicon wafer was transferred to a sample storage part of a pressure resistant container, and carbon dioxide in a supercritical state was promptly supplied before it was dried. After water was no longer detected in the discharged supercritical carbon dioxide, the pressure was reduced and the pattern-formed product was taken out in a dry state. The cross-section is shown in Fig. 4 by scanning electron microscope observation.
It was confirmed that it was (b). In FIG. 4B, 3
Reference numeral 1 is amorphous silicon, 32 is silicon nitride, and 33 is a silicon substrate. In the wide portion of the main pattern, the silicon layer below the silicon layer remains, and only the narrow portion of the main pattern is separated from the silicon substrate. In the pattern-formed product having the same specifications, which was naturally dried in the air after being washed with water, the narrow portion was broken and adhered to the substrate surface.

Example 3 A silicon wafer whose both surfaces are mirror-polished has a film thickness of 0.1 on one surface.
Micron-meter silicon nitride and amorphous silicon with a film thickness of 2 micrometers were sequentially deposited. Lithographically, the amorphous silicon / silicon nitride layer was left in a rectangle having a width of 5 μm and a length of 15 μm, and the other portion was removed. Next, silicon nitride having a film thickness of 0.1 μm is deposited on both surfaces of the silicon wafer by the low pressure vapor phase synthesis method, and then the silicon nitride film is formed by lithography as shown in FIG.
A pattern as shown in the sectional view of FIG. This silicon wafer was etched from the back side with an aqueous solution of potassium hydroxide and then washed with water. Then, this was soaked in 1-butanol and dried in the same manner as in Example 2 using carbon dioxide in a supercritical state. It was confirmed by observation with an optical microscope that the structure shown in FIG. 5B was obtained.
That is, as a result of locally progressing the etching of the silicon wafer from the region where the silicon nitride layer on the back side is removed, the rectangular amorphous silicon layer on the upper surface remains with a part thereof fixed to the silicon wafer. . With a pattern-formed product of the same specification that was naturally dried in the air after being washed with water,
The pattern portion was broken and adhered to the etched portion on the side surface of the silicon wafer.

Example 4 An organic material layer made of an electron beam resist or the like having a line width of 0.4 μm and an interval of 0.3 μm was provided on a silicon wafer having a diameter of 200 mm by electron beam drawing.
A portion of the wafer not covered with the organic layer was etched to a depth of 2 μm by reactive ion etching, and the organic layer was removed by oxygen plasma. Then, after sequentially washing with an ozone / sulfuric acid aqueous solution, pure water, diluted hydrofluoric acid, and pure water, this wafer was transferred to the pressure vessel shown in FIG. 2 while the entire surface was wet with water. The container temperature was kept at 27 ° C., and liquid carbon dioxide at the same temperature was circulated and supplied. During this period, liquid carbon dioxide was decompressed in another container to precipitate dissolved water, and then reused. Finally, the container temperature was raised to 40 ° C., the pressure was reduced, and the silicon wafer was taken out. It was confirmed by an optical microscope observation that there was no deformed pattern on the wafer. Deformation points were found on silicon wafers of the same shape that were naturally dried in the air after being washed with water or forcedly dried by rotation.

Example 5 A line width of 0..0 was formed on a silicon wafer by ultraviolet lithography using a phase shift mask and reactive ion etching.
Grooves having a depth of 6 μm and a depth of 20 μm were formed at intervals of 0.6 μm. Next, this was sequentially immersed in thin hydrofluoric nitric acid, pure water, and thin hydrofluoric acid, and finally thoroughly washed with pure water. Thereafter, it was dried in the same manner as in Example 1. As a result of observing the side surface obtained by breaking the sample taken out into the air with a scanning electron microscope, it became clear that there was no defect. Deformation points were found on silicon wafers of the same specifications that were naturally dried in the atmosphere. Similar results were obtained when holes having the same depth and having sides of 0.3 μm and 0.6 μm were formed at intervals of 0.6 μm.

In all of the above, the prevention of deformation of the microstructure was mainly described, but it goes without saying that no watermark was observed in any of the examples.

[0034]

According to the present invention, since the droplets attached to the surface of the microstructure are replaced with the supercritical fluid having a small surface tension and then dried, the microstructure is not deformed or destroyed in the atmosphere. Can be taken out.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state diagram of a pure substance for explaining the principle of the present invention.

FIG. 2 is a diagram showing a schematic view of a main part of a processing system according to the present invention.

FIG. 3 is a diagram showing a plan view of a minute pattern created in Example 1;

4A is a plan view of a minute pattern created in Example 2, and FIG. 4B is a sectional view.

5A is a cross-sectional view of a silicon wafer before etching formed in Example 3, and FIG. 5B is a cross-sectional view after etching with an alkaline solution.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Container main body, 2 ... Micro structure accommodating part, 3 ... Pressure container lid, 4 ... Pressure gauge, 5 ... Thermometer, 6 ... Feedback circuit, 7 ... Temperature controller, 11 ... Tank, 12 ... Valve 13
... Flowmeter, 14 ... Pump, 15 ... Backflow prevention valve, 16 ... Heat exchanger, 17 ... Pressure regulator, 18 ... Valve, 19 ... Introduction line, 21 ... Discharge line, 22 ... Concentration meter, 23 ... Filter, 24 ... Exhaust valve, 25 ... Heat exchanger, 26 ...
Check valve, 27 ... Circulation line, 31 ... Amorphous silicon, 32 ... Silicon nitride, 33 ... Silicon substrate.

Claims (7)

[Claims] 1. A surface treatment method for an element formed through a predetermined treatment process on an object to be treated, wherein a liquid which has been subjected to the predetermined treatment or cleaning is an element which has been subjected to the predetermined treatment or cleaning treatment. While adhering to the liquid, the liquid adhering to the device surface is dissolved in the liquid or supercritical fluid of the predetermined compound by contacting with the predetermined compound in the liquid or supercritical fluid state in the pressure resistant container, and then the temperature in the pressure resistant container is set to the predetermined compound. The surface treatment method is characterized in that the supercritical fluid is gasified and removed by lowering the pressure to the critical pressure or lower while maintaining the temperature above the critical temperature. 2. A liquid or a supercritical fluid in a pressure resistant container after the liquid adhered to the periphery of the element by the predetermined treatment or cleaning is replaced with water or another liquid having a vapor pressure at room temperature lower than that of water. The surface treatment method according to claim 1, wherein the surface treatment method is brought into contact with a predetermined compound in a state. 3. An element is formed through a predetermined treatment process on an object to be treated, and the element subjected to the predetermined treatment or cleaning treatment is placed in a pressure resistant container in a state in which a liquid used therefor is attached. Carrying in, introducing a predetermined compound in a liquid or supercritical fluid state into the pressure vessel to dissolve the liquid adhering to the device surface in the liquid or supercritical fluid of the predetermined compound, the liquid in the pressure vessel or the supercritical fluid Continuously or intermittently updating a predetermined compound in a critical fluid state, detecting the concentration of a liquid compound to be removed in a liquid or a predetermined compound in a supercritical fluid state that comes out of a pressure resistant container during the updating, After the concentration becomes equal to or lower than a predetermined value, the pressure in the pressure vessel is kept at the critical temperature of the predetermined compound or higher, and the pressure is lowered to the critical pressure or lower to gasify the supercritical fluid. Surface treatment wherein the more becomes possible with Kukoto. 4. When carrying an element into a pressure resistant container, the liquid attached to the periphery of the element by the predetermined treatment or cleaning is replaced with water or another liquid having a vapor pressure at room temperature lower than that of water. The surface treatment method according to claim 3. 5. An element to be processed is a microstructure formed by microfabrication on a solid substrate, and a part of the microstructure is separated from the substrate by etching the solid substrate in a solution. The surface treatment method according to any one of claims 1 to 4. 6. A means for forming an element through a predetermined treatment process on an object to be treated, a pressure-resistant container for holding a predetermined compound in a liquid or supercritical fluid state, and the predetermined treatment or cleaning treatment in the pressure-resistant container. A means for carrying in the device, a means for detecting the concentration of a liquid compound to be removed in a predetermined compound in a liquid or supercritical fluid state, a pressure in a state where the temperature inside the pressure vessel is kept above the critical temperature of the predetermined compound. And a means for lowering the supercritical fluid to a critical pressure or lower to gasify and remove the supercritical fluid. 7. A method of coating a photosensitive material on a solid substrate, exposing the same,
A microstructure formed through processes such as development, etching, and cleaning, wherein the microstructure has a convex portion with respect to the substrate surface or a width of a portion of the continuous two or more concave portions bonded to the substrate, Alternatively, the ratio of the maximum height of the convex portion or the concave portion from the substrate surface in the micrometer unit to the square of the smaller value in the micrometer unit between the two adjacent convex portions or the concave portion is 25 or more, the microstructure dissolves the liquid adhering to the surface at the time of construction in a liquid of a predetermined compound or a supercritical fluid, and keeps the temperature below the critical temperature of the predetermined compound, and the pressure is kept below the critical pressure. An element characterized in that the supercritical fluid is reduced and gasified to be removed.