JP3553838B2 - Supercritical drying method - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a supercritical drying method used when forming a fine pattern used for forming a semiconductor device, and particularly to a supercritical drying method used when forming a fine pattern by a lithography technique.
[0002]
[Prior art]
In recent years, with the increase in the scale of MOS LSIs, the miniaturization of patterns in LSI manufacturing has been promoted along with the enlargement of chips, and patterns having line widths of less than 100 nm have now been formed. Then, the fact that the line width is reduced results in the formation of a pattern having a large aspect ratio (height / width).
In addition, forming a fine pattern means that a resist pattern as a processing mask used for the etching process necessarily has a high aspect ratio. This resist pattern can be formed by processing a resist film, which is an organic material, by lithography. When the resist film is exposed, the molecular weight and molecular structure of the exposed area change, and a difference in solubility in the developing solution occurs between the exposed area and the unexposed area. A pattern can be formed on the resist film.
[0003]
In the above-described development processing, if the development is continued, the unexposed area eventually begins to dissolve in the developer and the pattern disappears. Therefore, the rinsing processing with the rinsing liquid is performed to stop the development. Finally, by drying and removing the rinsing liquid, a resist pattern as a processing mask can be formed on the resist film.
A major problem during drying in forming such a fine pattern is the collapse of the pattern 501 as shown in the sectional view of FIG.
[0004]
A fine resist pattern having a large aspect ratio is formed through development, rinsing, and drying. A fine pattern having a large aspect ratio is formed other than the resist. For example, after the substrate is etched using the resist pattern as a mask, the substrate is washed, rinsed (washed with water), and dried to form a substrate pattern having a high aspect ratio. The pattern 501 collapses during drying after the rinsing process, and this collapse phenomenon becomes more prominent as the pattern 501 has a higher aspect ratio.
[0005]
As shown in FIG. 6, the above-mentioned phenomenon that the pattern collapses is caused by a bending force (capillary force) 610 acting due to a pressure difference between the rinsing liquid 602 remaining between the patterns 601 and the external air 603 when the resist or the substrate is dried. It is due to. It is reported that the capillary force 610 depends on the surface tension generated at the gas-liquid interface between the rinsing liquid 602 and the pattern 601 (Reference: Applied Physics Letters, Vol. 66, 2655-2657). Pp. 1995).
[0006]
This capillary force not only defeats a resist pattern made of an organic material, but also distorts a pattern stronger than a resist pattern made of silicon or the like made of an inorganic material. The problem is important. The problem due to the capillary force can be solved by performing the treatment using a rinsing liquid having a small surface tension. For example, when water is used as a rinsing liquid, the surface tension of water is about 72 dyn / cm, but the surface tension of methanol is about 23 dyn / cm. The degree of pattern collapse is suppressed by drying.
[0007]
Furthermore, if perfluorocarbon having a surface tension of 20 dyn / cm is used and the perfluorocarbon liquid is replaced with the rinsing liquid and then the perfluorocarbon is dried, it is more effective to suppress pattern collapse. However, the use of a rinsing liquid having a low surface tension can reduce the occurrence of pattern collapse. However, as long as the liquid is used, pattern collapse cannot be eliminated because the liquid has a certain surface tension. In order to solve the problem of the pattern collapse, it is necessary to use a rinsing liquid having a zero surface tension, or to replace the rinsing liquid with a liquid having a zero surface tension, and then dry the replaced liquid.
[0008]
A supercritical fluid is a liquid having a surface tension of zero. A supercritical fluid is a substance at a temperature and pressure exceeding the critical temperature and pressure, and has a dissolving power similar to a liquid, but has a tension and viscosity similar to those of a gas, and maintains a gas state. It can be called a liquid. Then, since the supercritical fluid does not form a gas-liquid interface, the surface tension becomes zero. Therefore, if drying is performed in a supercritical state, the concept of surface tension is lost, and pattern collapse does not occur. Usually, carbon dioxide is used as the supercritical fluid. Since carbon dioxide has a low critical point (7.3 MPa, 31 ° C.) and is chemically stable, it has already been used as a critical fluid for biological sample observation.
[0009]
Conventionally, supercritical drying using a supercritical state of carbon dioxide has been performed as follows. First, liquefied carbon dioxide is introduced into a predetermined processing vessel in advance, and drainage is repeated to replace the rinse liquid. After the rinsing liquid is replaced with carbon dioxide, the liquefied carbon dioxide in the vessel is turned into supercritical carbon dioxide by heating the processing vessel to a temperature and pressure above the critical point. Here, the operation of flowing in and out of the supercritical carbon dioxide is not particularly performed. Finally, in a state where only the supercritical carbon dioxide is attached to the fine pattern, the pressure inside the container is reduced, and the supercritical carbon dioxide is vaporized and dried.
[0010]
[Problems to be solved by the invention]
By the way, in the development and drying process, in general, the substrate is often washed with water and then dried. However, since water cannot be directly replaced with carbon dioxide, the water is replaced with ethanol which is relatively easily mixed with carbon dioxide, and then the substrate is dried. Critical drying was performed. However, even though it is easily miscible, the solubility of ethanol and carbon dioxide is not sufficient, so that it takes a long time to perform replacement, and there is a problem that some of the components cannot be replaced. Further, in the case of forming a pattern made of a polymer material that dissolves in alcohol, the pattern is dissolved when alcohol is used, so that the above-described supercritical drying method cannot be applied.
[0011]
The present invention has been made to solve the above problems, and an object of the present invention is to reduce pattern collapse in supercritical drying as compared with the related art.
[0012]
[Means for Solving the Problems]
In the supercritical drying method of the present invention, first, a pattern layer having a predetermined pattern formed on a substrate is exposed to water, and then the pattern layer is exposed to an alcohol liquid with water attached to the pattern layer. The water adhering to the layer is dissolved in the alcohol liquid to make the alcohol liquid adhere to the pattern layer, and then the pattern layer is aliphatic carbonized while the alcohol liquid adheres to the pattern layer. Exposure to a liquid of hydrogen dissolves the alcohol liquid adhering to the pattern layer in the aliphatic hydrocarbon liquid to make the aliphatic hydrocarbon liquid adhere to the pattern layer. The pattern layer is exposed to a liquid of a nonpolar substance which is a gas in the air atmosphere with the aliphatic hydrocarbon liquid attached, and the aliphatic hydrocarbon liquid attached to the pattern layer is exposed. Dissolved in a non-polar substance liquid to make the non-polar substance liquid adhere to the pattern layer, then put the non-polar substance adhering to the pattern layer into a supercritical state, and then adhere to the pattern layer It is intended to vaporize the non-polar substance in the supercritical state.
According to the present invention, the alcohol adhering to the pattern layer formed on the substrate is replaced with an aliphatic hydrocarbon, and at the stage where the non-polar substance liquid adheres to the pattern layer, the pattern layer contains an aliphatic hydrocarbon. Is attached.
[0013]
In the supercritical drying method of the present invention, first, a pattern layer having a predetermined pattern formed on a substrate is exposed to water, and then the pattern layer is made of an aliphatic hydrocarbon with water adhered to the pattern layer. Exposure to liquid, emulsify the water and aliphatic hydrocarbon liquid attached to the pattern layer to make the aliphatic hydrocarbon liquid adhere to the pattern layer, and then apply the aliphatic hydrocarbon to the pattern layer When the pattern layer is exposed to the non-polar substance liquid, which is a gas in the atmosphere, with the liquid attached, the aliphatic hydrocarbon liquid adhering to the pattern layer is dissolved in the non-polar substance liquid to form a pattern. The liquid layer of the nonpolar substance is attached to the layer, then the nonpolar substance adhering to the pattern layer is brought to the supercritical state, and then the supercritical nonpolar substance adhering to the pattern layer Vaporize Those were Utoshi.
According to the present invention, the water adhering to the pattern layer formed on the substrate is replaced with an aliphatic hydrocarbon, and at the stage where the non-polar substance liquid adheres to the pattern layer, the pattern layer contains an aliphatic hydrocarbon. Is attached.
[0014]
In the above invention, water and an aliphatic hydrocarbon liquid are emulsified by adding a surfactant to the aliphatic hydrocarbon. Further, by adding a surfactant to water, the water and the liquid of the aliphatic hydrocarbon are emulsified. This surfactant is a non-ionic surfactant.
In the above invention, the aliphatic hydrocarbon is either normal hexane or normal heptane. The non-polar substance is carbon dioxide.
Further, in the above invention, all the steps may be performed in the same container.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
In the present invention, before performing supercritical drying, an aliphatic hydrocarbon such as n-hexane (normal hexane) is attached to the pattern surface. As used herein, the term "aliphatic hydrocarbon" refers to an aliphatic hydrocarbon that is in a liquid state in an atmospheric atmosphere, such as at 20 to 30 ° C. under atmospheric pressure.
As described above, in supercritical drying using carbon dioxide, carbon dioxide used as a supercritical fluid has no polarity, and has low solubility in a polar alcohol. Therefore, in order to supercritically dry the fine pattern to which the alcohol is attached, even if an attempt is made to replace the attached alcohol with liquefied carbon dioxide, a region where the alcohol cannot be partially replaced and the alcohol remains remains. Since supercritical drying is not performed in the region where the alcohol remains, pattern collapse occurs as shown in FIG.
[0016]
In contrast, if the object to be replaced with liquefied carbon dioxide is a nonpolar aliphatic hydrocarbon, the solubility for carbon dioxide is high, and the aliphatic hydrocarbon remains without being completely replaced with liquefied carbon dioxide. It is suppressed, and pattern collapse does not occur. Therefore, if the substrate to be dried is rinsed with a non-polar aliphatic hydrocarbon and then subjected to supercritical drying using carbon oxide, pattern collapse can be greatly suppressed. In addition, n-hexane, cyclohexane, etc. are suitable because a lower molecular weight aliphatic hydrocarbon has higher compatibility with liquefied carbon dioxide.
Hereinafter, an embodiment will be described in more detail.
[0017]
【Example】
(Example 1)
First, a supercritical drying apparatus for performing supercritical drying will be described. In the supercritical drying apparatus, as shown in FIG. 1, a substrate 101 to be processed is fixed in a reaction chamber 102 where supercritical drying is performed, and is processed. The reaction chamber 102 includes a liquefied carbon dioxide cylinder 103 connected to the reaction chamber 102 via a pump unit 104. The reaction chamber 102 is provided with a discharge pipe 105 and a valve 106 between the pump unit 104 and the reaction chamber 102. In addition, a pressure control valve 107 for automatically controlling the pressure in the reaction chamber 102 is provided in the discharge pipe 105. The temperature inside the reaction chamber 102 is controlled by a temperature control device 108.
[0018]
Next, the supercritical drying of the first embodiment using the above-described supercritical drying apparatus will be described.
First, as shown in FIG. 2A, the surface of the silicon substrate 101 having a (110) plane is thermally oxidized to form an oxide film 201 with a thickness of about 30 nm, and as shown in FIG. A thin resist pattern 202 is formed. As the resist pattern 202, a pattern having a width of about 30 nm was formed at intervals of 30 nm using a known lithography technique. Next, after the oxide film 201 is dry-etched using the resist pattern 202 as a mask, the resist pattern 202 is removed, and a mask pattern 201a made of silicon oxide is formed on the silicon substrate 101 as shown in FIG. 2C.
[0019]
Next, as shown in FIG. 3D, the silicon substrate 101 is immersed in a potassium hydroxide aqueous solution 203, and the surface of the silicon substrate 101 is etched using the mask pattern 201a as a mask. Since the surface of the silicon substrate 101 is the (110) plane, the etching with the potassium hydroxide aqueous solution 203 proceeds only in a direction perpendicular to the surface of the silicon substrate 101. Accordingly, as shown in FIG. 3D, a rectangular pattern 204 having a vertically long cross section can be formed on the silicon substrate 101.
[0020]
When the height of the pattern 204 became about 150 nm, as shown in FIG. 3E, the substrate 101 was immersed in water 205 to stop etching, and washed with water.
Next, the reaction chamber 102 shown in FIG. 1 was filled with ethanol, the substrate 101 washed with water was introduced into the reaction chamber 102 before the surface was dried, and the silicon substrate was sealed as shown in FIG. 3F. 101 is immersed in ethanol 206, and the water remaining on the surface of the pattern 204 is replaced with ethanol 206.
[0021]
Next, n-hexane was introduced into the above-mentioned reaction chamber 102, ethanol was discharged, and the inside of the reaction chamber 102 was filled with n-hexane. The pattern 204 is immersed in the n-hexane 207 around the pattern 204, and the ethanol existing around the pattern 204 is replaced with the n-hexane 207.
Next, liquefied carbon dioxide is introduced into the reaction chamber 102 from the cylinder 103 shown in FIG. 1 and replaced with n-hexane, and the silicon substrate 101 is immersed in liquefied carbon dioxide 208 as shown in FIG. 3H. State. As a result, the pattern 204 is immersed in the liquefied carbon dioxide 208.
[0022]
Thereafter, the delivery pressure of liquefied carbon dioxide by the pump unit 104 and the reaction chamber 10 by the pressure control valve 107. 2 Chamber 10 by the temperature controller 108 2 Each temperature in the reaction chamber is adjusted, 2 The internal pressure is 7.5 MPa and the reaction chamber 10 2 By setting the internal temperature to 35 ° C., the reaction chamber 10 2 The carbon dioxide inside was brought into a supercritical state. Reaction chamber 10 2 After the carbon dioxide in the reactor is brought into a supercritical state, the reaction chamber 10 2 The supercritical carbon dioxide in the reactor is discharged at a rate of 1 liter / min. 2 The inside was dried. As a result, as shown in FIG. 3I, a fine silicon pattern 204 having a width of about 30 nm and a height of 150 nm was formed on the silicon substrate 101 without pattern collapse.
[0023]
By the way, in the case of forming a resist pattern that dissolves in alcohol, as described above, after washing the formed fine pattern with water, the water cannot be replaced with alcohol. In such a case, an aliphatic hydrocarbon may be emulsified in water or a water may be emulsified in an aliphatic hydrocarbon by using a surfactant (surfactant). If a surfactant is used, it is possible to form a resist pattern and wash it with water, and then replace this water with an aliphatic hydrocarbon.
[0024]
A surfactant is an amphipathic substance basically composed of a hydrocarbon chain which is a lipophilic group and a hydrophilic group such as a polar group, and causes significant adsorption at an oil / water interface. Therefore, for water washing of the resist pattern, using water in which a surfactant is dissolved, or by using an aliphatic hydrocarbon in which a surfactant is dissolved, after washing a fine pattern formed with an aliphatic hydrocarbon, Can replace the moisture. When a surfactant is added to an aliphatic hydrocarbon, the surfactant remains on the substrate (pattern) unless the surfactant used is dissolved in liquefied carbon dioxide. In such a case, the substrate may be washed with an aliphatic hydrocarbon in which the surfactant has not been melted before introducing the liquefied nitrogen dioxide.
[0025]
The types of surfactants that can be used include, for example, those that are easily soluble in an organic solvent, hydrate the OH groups in the molecular structure, and emulsify water. Non There are ionic surfactants. Considering hydrophilicity, those having an ether skeleton are suitable. For example, those containing polyoxyethylene, in particular, polyoxyalkylene alkyl ethers such as polyoxyethylene noniphenol ether are excellent in emulsifying water for aliphatic hydrocarbons.
[0026]
Also, sorbitan fatty acid esters such as sorbitan laurate and sorbitan stearate can be used as the surfactant. Sorbitan fatty acid esters have less emulsifiability of water with respect to aliphatic hydrocarbons than polyoxyalkylene alkyl ethers, but have less influence on polar macromolecules such as resists of aliphatic hydrocarbons with added sorbitan fatty acid esters. In the case of a polyoxyalkylene alkyl ether-based surfactant, a polar polymer becomes soluble because water has a micellar structure when emulsified. On the other hand, the sorbitan-based surfactant hardly forms micelles with water, so that the polar polymer does not have solubility. Surfactants that can be used are not limited to those described above, and include fatty acid ester-type surfactants such as polyoxyethylene sorbitan fatty acid esters. Non Ionic surfactants can also be used.
[0027]
(Example 2)
Hereinafter, the supercritical drying of the second embodiment using the supercritical drying apparatus of FIG. 1 will be described.
First, as shown in FIG. 4A, an electron beam is exposed to an electron beam resist thin film 401 made of NEB-31 (Sumitomo Chemical Industries) coated on a silicon substrate 101 to form a latent image of a desired pattern. Next, as shown in FIG. 4B, the silicon substrate 101 is immersed in a developing solution 402 composed of a 2.38% aqueous solution of tetraammonium hydroxide and developed to form a resist pattern 401a on the silicon substrate 101. The resist pattern 401a was formed to have a width of 30 nm and a height of 150 nm, and an interval with an adjacent pattern was formed to be 30 nm.
[0028]
Next, as shown in FIG. 4C, after the silicon substrate 101 is immersed in water 403 to stop the development and washed, the silicon substrate 101 is filled with n-hexane to which sorbitan monolaurate is added by 3% (weight ratio). The substrate 101 is fixed in the reaction chamber 102 (FIG. 1). The movement of the substrate 101 into the reaction chamber 102 is performed in a state where the water on the surface of the substrate 101 is not dried. As shown in FIG. 4D, the substrate 101 is immersed in n-hexane 404 to which sorbitan monolaurate is added. As a result, moisture on the surface of the resist pattern 401a is emulsified in n-hexane 404 due to the presence of sorbitan monolaurate, and moisture is removed from the vicinity of the resist pattern 401a, that is, from the surface of the substrate 101.
[0029]
Next, the above-mentioned reaction chamber 102 is sealed, and liquefied carbon dioxide is introduced into the reaction chamber 102 from the cylinder 103 shown in FIG. 1 and is replaced with n-hexane. As shown in FIG. It is assumed that it is immersed in carbon 405. As a result, the resist pattern 401a is immersed in the liquefied carbon dioxide 405, and the n-hexane 404 on the surface of the substrate 101 is replaced with the liquefied carbon dioxide 405.
Thereafter, the delivery pressure of liquefied carbon dioxide by the pump unit 104 and the reaction chamber 10 by the pressure control valve 107. 2 Chamber 10 by the temperature controller 108 2 Each temperature in the reaction chamber is adjusted, 2 The internal pressure is 7.5 MPa and the reaction chamber 10 2 By setting the internal temperature to 35 ° C., the reaction chamber 10 2 The carbon dioxide inside was brought into a supercritical state.
[0030]
And the reaction chamber 10 2 After the carbon dioxide in the reactor is brought into a supercritical state, the reaction chamber 10 2 The supercritical carbon dioxide in the reactor is discharged at a rate of 0.5 liter / min. 2 The inside was dried. As a result, as shown in FIG. 4F, a fine resist pattern 401a was formed. silicon The substrate 101 was dried without pattern collapse. Here, by setting the discharge rate of the supercritical carbon dioxide to 0.5 liter / min, the pressure change in the reaction chamber was moderated, and the pattern collapse due to the rapid pressure change was suppressed. When liquefied carbon dioxide is introduced, it is replaced with n-hexane to which sorbitan monolaurate has been added, and is in a state substantially free of moisture. Therefore, pattern expansion due to moisture remaining in the resist pattern during supercritical drying with supercritical carbon dioxide can be suppressed.
[0031]
In the first embodiment, the case where the silicon pattern is dried is taken as an example. R Although described, the present invention is not limited to this, and can be similarly applied to a pattern of a compound semiconductor or the like. Further, the present invention is not limited to the resist pattern used in the second embodiment, but may be applied to a pattern made of another polymer material. Further, the supercritical fluid is not limited to carbon dioxide, and a supercritical fluid of a nonpolar substance such as ethane or propane may be used.
[0032]
(Example 3)
When observing a biological sample with a scanning electron microscope, the biological sample needs to be dry. The drying of the biological sample can also be performed by supercritical drying. In supercritical drying of a biological sample, first, a biological sample in water is taken out, placed in a 5% n-hexane solution of polyoxyethylene nonylphenyl ether, and water is replaced with a hexane solution. Next, after rinsing the biological sample with a pure hexane solution, the reaction chamber 10 of the supercritical drying apparatus shown in FIG. 2 In the reaction chamber 10 2 Liquefied carbon dioxide was introduced inside. Reaction chamber 10 2 After the hexane is replaced and discharged by liquefied carbon dioxide, the reaction chamber 10 2 The internal pressure was 7.5 MPa, the temperature was 35 ° C., and the reaction chamber 10 2 The carbon dioxide inside was made supercritical. Thereafter, while maintaining the temperature at 35 ° C., supercritical carbon dioxide is supplied to the reaction chamber 10 at a rate of 1 liter / min. 2 Discharged from inside. As a result, a dried biological sample can be obtained in a favorable state with less deformation as compared with the alcohol substitution.
[0033]
【The invention's effect】
As described above, in the present invention, first, a pattern layer having a predetermined pattern formed on a substrate is exposed to water, and then the pattern layer is exposed to a liquid of alcohol with water attached to the pattern layer, The water adhering to the pattern layer is dissolved in an alcohol liquid to make the alcohol liquid adhere to the pattern layer, and then the pattern layer is made aliphatic with the alcohol liquid adhering to the pattern layer. Exposure to the hydrocarbon liquid, dissolve the alcohol liquid adhering to the pattern layer in the aliphatic hydrocarbon liquid to make the aliphatic hydrocarbon liquid adhere to the pattern layer, and then apply When the aliphatic hydrocarbon liquid is attached, the pattern layer is exposed to a liquid of a non-polar substance which is a gas in an atmospheric atmosphere such as carbon dioxide, and adheres to the pattern layer. Dissolve the aliphatic hydrocarbon liquid in the non-polar substance liquid to make the non-polar substance liquid adhere to the pattern layer, and then put the non-polar substance adhering to the pattern layer in the supercritical state. Thereafter, the non-polar substance in a supercritical state adhering to the pattern layer is vaporized.
[0034]
According to the present invention, the alcohol adhering to the pattern layer formed on the substrate is replaced with an aliphatic hydrocarbon, and at the stage where the non-polar substance liquid adheres to the pattern layer, the pattern layer contains an aliphatic hydrocarbon. Is attached. Compared with the compatibility between the alcohol and the nonpolar substance, the compatibility between the alcohol and the aliphatic hydrocarbon and the compatibility between the aliphatic hydrocarbon and the nonpolar substance are higher. For this reason, each of the above substitutions is easily performed, and at the stage of bringing the liquid of the nonpolar substance into the supercritical state, almost no alcohol remains in the pattern layer, and according to the present invention, Pattern collapse in supercritical drying can be further reduced.
[0035]
Further, in the present invention, first, a pattern layer having a predetermined pattern formed on a substrate is exposed to water, and then the pattern layer is exposed to an aliphatic hydrocarbon liquid in a state where water is attached to the pattern layer. The water and aliphatic hydrocarbon liquid adhering to the layer are emulsified so that the aliphatic hydrocarbon liquid adheres to the pattern layer, and then the aliphatic hydrocarbon liquid adheres to the pattern layer. The pattern layer is exposed to a liquid of a non-polar substance which is a gas in an atmospheric atmosphere such as carbon dioxide while dissolving the liquid of the aliphatic hydrocarbon adhering to the pattern layer in the liquid of the non-polar substance. The liquid layer of the nonpolar substance is attached to the layer, then the nonpolar substance adhering to the pattern layer is brought to the supercritical state, and then the supercritical nonpolar substance adhering to the pattern layer To And so as to of.
[0036]
According to the present invention, the water adhering to the pattern layer formed on the substrate is replaced with an aliphatic hydrocarbon, and at the stage where the non-polar substance liquid adheres to the pattern layer, the pattern layer contains an aliphatic hydrocarbon. Is attached. As described above, without using alcohol, at the stage where the liquid of the nonpolar substance is brought into the supercritical state, water is substantially suppressed from remaining in the pattern layer. Pattern collapse can be further reduced.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of a supercritical drying apparatus used in an embodiment of the present invention.
FIG. 2 is a process diagram illustrating a supercritical drying method in Embodiment 1 of the present invention.
FIG. 3 is a process diagram illustrating a supercritical drying method according to the first embodiment of the present invention, following FIG. 2;
FIG. 4 is a process diagram illustrating a supercritical drying method in Embodiment 2 of the present invention.
FIG. 5 is a cross-sectional view showing a state in which a fine pattern is collapsed.
FIG. 6 is a cross-sectional view showing a state in which a rinsing liquid is present between fine patterns.
[Explanation of symbols]
Reference Signs List 101: substrate, 102: reaction chamber, 103: cylinder, 104: pump unit, 105: discharge pipe, 106: valve, 107: pressure control valve, 108: temperature controller, 201: oxide film, 202: resist pattern, 203 ... aqueous potassium hydroxide solution, 204 ... pattern, 205 ... water, 206 ... ethanol, 207 ... n-hexane, 208 ... liquefied carbon dioxide.

Claims (8)

A first step of exposing a pattern layer having a predetermined pattern formed on the substrate to water;
After the first step, the pattern layer is exposed to an alcohol liquid in a state where the water adheres to the pattern layer, and the water adhering to the pattern layer is dissolved in the alcohol liquid to form the pattern layer. A second step of causing the alcohol liquid to adhere to the
After this second step, the pattern layer is exposed to an aliphatic hydrocarbon liquid in a state where the alcohol liquid is attached to the pattern layer, and the alcohol liquid attached to the pattern layer is removed from the fatty liquid. A third step of dissolving the aliphatic hydrocarbon liquid in the aliphatic hydrocarbon liquid to cause the aliphatic hydrocarbon liquid to adhere to the pattern layer;
After the third step, the pattern layer is exposed to a liquid of a non-polar substance which is a gas in an air atmosphere in a state where the liquid of the aliphatic hydrocarbon is attached to the pattern layer. A fourth step of dissolving the liquid of the aliphatic hydrocarbon having been dissolved in the liquid of the nonpolar substance to make the liquid of the nonpolar substance adhere to the pattern layer;
After the fourth step, a fifth step of bringing the nonpolar substance attached to the pattern layer into a supercritical state,
After the fifth step, at least a sixth step of vaporizing a non-polar substance in a supercritical state adhering to the pattern layer. A first step of exposing a pattern layer having a predetermined pattern formed on the substrate to water;
After the first step, the pattern layer is exposed to an aliphatic hydrocarbon liquid with the water attached to the pattern layer, and the water and the aliphatic hydrocarbon liquid attached to the pattern layer are exposed to water. A second step of emulsifying the liquid to make the aliphatic hydrocarbon liquid adhere to the pattern layer,
After the second step, the pattern layer is exposed to a liquid of a nonpolar substance which is a gas in an air atmosphere in a state where the aliphatic hydrocarbon liquid is attached to the pattern layer, and adheres to the pattern layer. A third step of dissolving the liquid of the aliphatic hydrocarbon being dissolved in the liquid of the non-polar substance to make the liquid of the non-polar substance adhere to the pattern layer;
After this third step, a fourth step of bringing the nonpolar substance attached to the pattern layer into a supercritical state,
After the fourth step, at least a fifth step of vaporizing the non-polar substance in a supercritical state adhering to the pattern layer. The supercritical drying method according to claim 2,
A supercritical drying method, wherein in the second step, a surfactant is added to the aliphatic hydrocarbon to emulsify the water and the liquid of the aliphatic hydrocarbon. The supercritical drying method according to claim 2,
The supercritical drying method, wherein in the second step, a surfactant is added to the water to emulsify the water and the liquid of the aliphatic hydrocarbon. The supercritical drying method according to claim 3 or 4,
The supercritical drying method, wherein the surfactant is a nonionic surfactant. The supercritical drying method according to any one of claims 1 to 5,
The supercritical drying method, wherein the aliphatic hydrocarbon is one of normal hexane and normal heptane. The supercritical drying method according to any one of claims 1 to 6,
The said nonpolar substance is carbon dioxide, The supercritical drying method characterized by the above-mentioned. The supercritical drying method according to any one of claims 1 to 7,
A supercritical drying method, wherein all the steps are performed in the same container.

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