JP3905890B2 - Supercritical processing method - Google Patents

Description

  The present invention relates to a supercritical processing method for improving the etching resistance of a resist pattern made of an organic polymer material.

  As is well known, in order to manufacture a large-scale and high-performance device such as an LSI, an extremely fine pattern is required. In particular, with the increase in scale of LSIs, pattern miniaturization in LSI manufacturing has been promoted, and now a pattern with a line width of less than 100 nm has been formed. This ultrafine pattern is, for example, a resist pattern made of an organic material that is sensitive to a light source such as light, an X-ray, or an electron beam, which is formed through exposure, development, and rinsing.

  The above-described resist pattern can be formed by processing a film of an organic material (photosensitive resist) having photosensitivity to the above-described light source by a lithography technique. When the photosensitive resist film is exposed, the molecular weight and molecular structure of the exposed area changes, and a difference in solubility in the developer occurs between the unexposed area and the difference in solubility is used. The developed pattern can form a finer pattern than the photosensitive resist film.

  The resist pattern formed as described above is used for the mask pattern 702 for selective etching of the lower layer film 701 as shown in FIG. With the progress of etching, the etching resistance is lowered and the situation where the etching cannot be endured has occurred.

  For example, in photolithography technology using ultraviolet light with a wavelength of 365 nm as a light-sensitive resist, the molecular structure has a conjugated double bond of carbon, such as a benzene ring in the skeleton such as a novolac-based synthetic resin. I was able to use what I did. A resist material having a conjugated double bond in the molecule has high etching resistance in an etching technique used for fine processing of LSI.

However, the conventional photosensitive resist having the above conjugated double bond hardly transmits far ultraviolet rays having a wavelength of about 193 nm, and thus is not suitable for forming an extremely fine pattern as described above. For this reason, for example, in lithography using an ArF excimer laser as a light source, an organic material that does not contain a benzene ring or the like is used as a photosensitive resist.
Therefore, in order to form a nanometer-size fine pattern, a resist pattern with low etching resistance is currently used.

  When a resist material having low etching resistance is used, the mask pattern 702 is damaged and deformed during the etching process as shown in FIG. 7B. As a result, as shown in FIG. The pattern 703 formed on the film 701 does not have a shape as designed, for example, partly shaved.

  As a technique for improving etching resistance, a technique in which a substance having high etching resistance is put in a resist film has been proposed (Patent Document 1). In this technique, fullerene is mixed into a resist solution as a substance having high etching resistance, and this is applied to form a resist film, which is exposed and developed to form a pattern.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
JP-A-10-282649

  However, when a material having high etching resistance is added to the resist material, problems such as difficulty in development occur. In many cases, in order to improve etching resistance, a cross-linking component or a substance having high etching resistance is added. However, these are factors that hinder developability.

  For these techniques, after forming a resist pattern, a method of immersing the pattern in a solution of a substance having high etching resistance and introducing a substance having high etching resistance into the pattern may be considered. However, it is not easy to apply a material having high etching resistance into a pattern by using it as a solution, such as poor controllability of a pattern dimension, for forming a nanometer size pattern.

  The present invention has been made to solve the above problems, and an object of the present invention is to enable formation of a nanometer-sized resist pattern having high etching resistance with good dimensional controllability by lithography.

The supercritical processing method according to the present invention provides a substrate having a resist pattern formed by patterning a resist having photosensitivity to a predetermined light source using a lithography technique, and a supercritical fluid in which an etching resistant substance is dissolved in the resist pattern. A supercritical processing method in which the material is immersed in a supercritical fluid, wherein a supercritical fluid is a gas that is a gas in the atmosphere, and an etching resistant material is composed of molecules containing carbon as a constituent element. It has been done.
According to this method, an etching resistant material is introduced into the resist pattern.

  In the supercritical processing method described above, the etching resistant material may be any material having a dimension of about 1 nm or less. In addition, the etching resistant substance may be composed of molecules having a benzene ring in the chemical structure, or composed of molecules in which a plurality of carbons are conjugated and bonded in a spherical shape.

  Further, the etching resistant substance may be composed of molecules having a reactive group that causes a chemical reaction with the functional group constituting the resist, and can be reacted by heating to obtain a supercritical state. In this heating, it is preferable to heat the substrate and the die on which the substrate is placed, rather than heating the entire container. In this case, after the resist pattern is immersed in a supercritical fluid in which an etching resistant material is dissolved, the resist pattern is irradiated with light and heated to react the etching resistant material introduced into the resist pattern. May be.

  Further, in the supercritical processing method, a step of developing a resist pattern to form a resist pattern, and after the developing process, the resist pattern is exposed to a liquid substance that is a gas in the atmosphere while the resist pattern is wet. The process of making the substance liquid adhere to the resist pattern, the process of making the substance liquid in a supercritical state and immersing the resist pattern in the supercritical fluid, and the supercritical fluid in which the etching resistant substance is dissolved Supercritical drying may be performed by a step of immersing the resist pattern and a step of vaporizing the supercritical fluid.

  As described above, according to the present invention, since an etching resistant substance is introduced into the resist pattern, an excellent effect that a nanometer-sized resist pattern with high etching resistance can be formed with good dimensional controllability can be obtained. .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a process diagram for explaining an example of a supercritical processing method according to an embodiment of the present invention.
First, as shown in FIG. 1A, a resist pattern 102 is formed on a silicon substrate 101. For example, an ArF excimer laser is coated with a photosensitive ArF resist (AR230: manufactured by JSR) on a silicon substrate 101 to form a resist film having a thickness of about 500 nm, and a predetermined light source using an ArF excimer laser as a light source is formed. The resist pattern 102 is formed by exposing the pattern image and developing it immediately thereafter. The resist pattern 102 is a line having a width of about 90 nm extending in the normal direction of the paper surface of FIG.

After the development, a rinsing process for stopping the development is performed, the pattern 102 is kept wet with the rinsing liquid used for the rinsing process, and the silicon substrate 101 is placed inside the high-pressure vessel. After sealing the high pressure vessel, SF ₆ is introduced into the high pressure vessel, the inside of the high pressure vessel is filled with SF ₆ , and the internal pressure is set to about 10 MPa. As a result, the inside of the high-pressure vessel is filled with the SF ₆ liquid. Thereafter, the internal temperature of the high-pressure vessel is increased from about 23 ° C. to 50 ° C. to set SF ₆ inside the high-pressure vessel to a supercritical state. As a result, as shown in FIG. 1B, the pattern 102 is immersed in the supercritical fluid 103 of SF ₆ .

In the process of becoming the supercritical state shown in FIG. 1B described above, the rinse liquid that has wetted the pattern 102 is replaced with the SF ₆ liquid and the supercritical fluid, and is removed from the surface of the pattern 102. . In the replacement of the rinse liquid, for example, a surfactant may be used to improve the replacement efficiency.
Next, SF ₆ to which dibutoxynaphthalic acid is added is introduced into the high-pressure vessel while maintaining the above-described supercritical state conditions, and as shown in FIG. In the supercritical fluid 103, an etching resistant substance 104 made of dibutoxynaphthalic acid is dissolved.

  When the etching resistant material 104 is dissolved in the supercritical fluid 103 in which the pattern 102 is immersed, the etching resistant material 104 is impregnated into the pattern 102 together with the supercritical fluid 103, and FIG. As shown, an etching resistant material 104 is introduced into the pattern 102.

  Next, the supercritical fluid is gradually discharged from the inside of the high-pressure vessel, the pressure inside the high-pressure vessel is lowered, and the supercritical fluid inside the high-pressure vessel is vaporized. As a result, as shown in FIG. 1E, the silicon substrate 101 on which the resist pattern 102 is formed is in a dry state without pattern collapse. Further, the resist pattern 102 is in a state where the etching resistant material 104 is introduced.

  Alternatively, only the supercritical fluid may be introduced into the high-pressure vessel, and the concentration of the etching resistant substance may be reduced or removed, and then the pressure may be reduced to be in a dry state. By doing in this way, precipitation of an etching resistant substance can be suppressed. For example, after making the state shown in FIG. 1D, helium pressurized to 10 MPa is introduced into the high-pressure vessel, and the supercritical fluid 103 in the high-pressure vessel and the etching resistant substance 104 remaining in the high-pressure vessel are released. You may do it.

  Here, the resist pattern becomes difficult to be etched only by introducing the etching resistant material into the resist pattern, but the resist pattern becomes stronger by reacting the polymer constituting the resist pattern with the etching resistant material. This reaction can be allowed to proceed by heating, which can utilize the heating used to bring it to a supercritical state. Therefore, it is possible to proceed with the above reaction in a supercritical state. Moreover, you may make it perform the said reaction in the air atmosphere after drying. The efficiency of the reaction can also be improved by heat in the air atmosphere.

  For example, the resist pattern 102 into which the etching resistant material 104 is introduced is irradiated with ultraviolet rays, and a heat treatment at 100 ° C. is applied. By this treatment, the benzene structure constituting the etching resistant material 104 and the side chain of the organic material constituting the resist pattern 102 are reacted to improve the resist pattern 102 to a state with high etching resistance.

  Thereafter, the silicon substrate 101 is selectively etched using the resist pattern 102 as a mask so that the silicon pattern 105 is formed on the silicon substrate 101. According to the present embodiment, the resist pattern 102 is suppressed from being greatly deformed by the etching process, and the silicon pattern 105 having a desired size is obtained.

Hereinafter, the etching resistance improvement of the resist pattern will be described in more detail.
In order to improve the dry etching resistance of the resist pattern, an etching resistant molecule such as having a benzene ring may be introduced into the resist pattern. According to this, since it is introduced into the resist pattern that has been patterned, exposure and development are not adversely affected.
However, it is not easy to introduce many molecules into the resist pattern so that the etching resistance is improved.

  Here, the organic polymer material constituting the resist pattern generally has innumerable gaps (free volumes) having a diameter of about 0.6 nm. Since the supercritical fluid can easily enter the gap, the supercritical fluid can easily diffuse into the resist pattern. Therefore, the etching resistant substance can be introduced into the resist pattern by mixing and dissolving the etching resistant substance in the supercritical fluid to act on the resist pattern.

Thus, according to this method, an etching resistant material can be easily introduced into the resist pattern, and the etching resistance of the resist pattern can be improved. In addition, according to this method, since the supercritical drying can be performed by introducing the etching resistant substance into the resist pattern and then vaporizing the supercritical fluid, it is possible to suppress the collapse of the fine pattern. As is well known, pattern collapse occurs due to surface tension generated at the gas-liquid interface in drying after liquid treatment, but drying without forming a gas-liquid interface is achieved by drying using a supercritical fluid. And pattern collapse can be suppressed.
Further, according to this method, a resist pattern having high etching resistance can be formed using a conventionally used high resolution resist.

By the way, in the above-described embodiment, supercritical helium in which the etching resistant substance is difficult to dissolve is introduced, so that the supercritical SF ₆ in which the etching resistant substance is dissolved is discharged from the inside of the high pressure vessel. By doing in this way, it can suppress that the etching tolerance substance introduce | transduced into the resist pattern comes out of a resist pattern. In addition to helium, a rare gas such as xenon can be used. Nitrogen can also be used. These gases have low solubility of the etching resistant substance, and have a supercritical point lower than that of fluorine compounds such as SF ₆ and carbon dioxide, and can easily be brought into a supercritical state.

The retention of the etching resistant material introduced into the resist pattern is not limited to the method described above.
For example, the pressure inside the high-pressure vessel may be lowered to a minimum pressure that can maintain the supercritical state, and a supercritical fluid in which the etching resistant substance is not dissolved may be introduced. By setting the minimum pressure at which the supercritical state can be maintained, the density of the supercritical fluid can be lowered and the solubility can be lowered. Further, the internal temperature of the high-pressure vessel may be set below the critical point, and the supercritical substance may be released in a liquid state. As a result, it is possible to suppress the deposition of the etching resistant material while maintaining the etching resistant material inside the resist pattern without using a different supercritical material such as helium.

In addition, after the etching resistant substance in the supercritical fluid is introduced into the resist pattern, the introduced etching resistant substance reacts with the constituent material of the resist pattern, and then the supercritical fluid in which the etching resistant substance is not dissolved is reacted. You may make it introduce.
Hereinafter, the reaction between the resist material and the etching resistant substance will be described.
In order to react the etching resistant substance introduced into the resist pattern with the resist material, a material having a reactive group that reacts with the functional group constituting the resist material may be used as the etching resistant substance.

For example, the ArF resist has a chemical structure as shown in FIG. 2, but etching resistance is controlled by the presence of the portion 201, wettability is controlled by the presence of the portion 202, and development by the presence of the portion 203. Resolution is controlled. Note that the structure shown in FIG. 2 is basic, and some structures are slightly different in order to improve each characteristic.
In a resist having such a structure, since there are OH groups and carboxyl groups in the chemical structure, it is sufficient that reactive groups that react with these groups are introduced into the etching resistant substance.

In addition, it is more effective if a group in which the reaction proceeds easily is introduced into the resist in advance. Reactions that proceed easily include “—OH + Cl− → −O− + HCl ↑”, “—COOH + HOOC− → —COOC− + H ₂ O ↑”, and the like.
Further, as described above, the reaction between the etching resistant substance introduced into the pattern and the resist material constituting the pattern may be performed after drying (supercritical drying). For example, a conjugated bond structure capable of obtaining etching resistance can be formed by a crosslinking reaction.

  In the case of a chemically amplified positive resist material, an acid generator (reaction accelerator) such as an onium salt that generates an acid by light irradiation remains in the pattern. Therefore, it is possible to generate an acid from the remaining acid generator by irradiating the resist pattern obtained after drying with light. After the acid is generated by light irradiation, the etching resistant substance introduced into the resist pattern can easily react with the functional group of the resist material by applying heat treatment.

For example, in a chemically amplified resist, when light is irradiated to generate an acid, a t-butoxycarbonyl group (—COO (CH ₃ ) ₃ ) or a t-butoxy group (which becomes the portion 203 of the structure shown in FIG. -C (CH ₃ ) ₃ ) is detached and is easily dissolved in the developer.
Therefore, if an etching resistant material having a t-butoxycarbonyl group in the side chain (see FIG. 3) is introduced into the resist pattern, the resist pattern is irradiated with light so that both the resist pattern material and the etching resistant material are used. The t-butoxycarbonyl group is eliminated, and active sites (active species) are generated in both of them, and these undergo a chemical reaction to cause crosslinking.

In addition, by introducing a bisazide compound such as diazide diphenyl and using a photoreaction of “—C═C— + N ₃ − → —C—N—C— + N ₂ ↑”, a crosslinked structure is generated. Also good.
A crosslinking reaction using a melamine compound such as hexamethoxymethylmelamine, which is known as a crosslinking reaction of a resist material, or a glycidyl compound may be used. Moreover, you may make it produce | generate a urethane bond and crosslink using isocyanate.

Next, the etching resistant material will be described.
The etching resistant material is a material having at least carbon as a constituent element, and is more effective as the number of carbon atoms in the total number of atoms constituting the molecule is larger. In addition, since the etching resistant substance is introduced into the free volume (gap) of the resist that is a polymer material, the molecular size is preferably about 0.6 nm, which is the same as the free volume.

  In the case where a large free volume exists such as a polymer state in a porous state, the size of the free volume is 1 nm, and therefore the molecular size of the etching resistant substance is preferably 1 nm or less. By using an etching resistant material having a size equal to or less than the free volume, an increase in the dimension of the resist pattern due to the introduction of the etching resistant material can be suppressed.

  By the way, the etching is performed by cutting the molecular chain of the target substance to form molecules with more stable bonds. Accordingly, molecules that are difficult to etch are molecules that have more stable bonds. Since the photosensitive resist used for forming a nanometer-sized pattern is basically a polymer material having a carbon chain, if a double bond is introduced into a conjugated system, the bond becomes strong. For example, a molecule having a benzene ring as shown in FIG. 4 is preferable as the etching resistant substance. As shown in FIGS. 4 (a), (b), (d), and (e), it may be composed of a plurality of benzene rings. As described above, the larger the number of carbon atoms in the total number of atoms, the more preferable as the etching resistant substance.

Further, as shown in FIG. 5, the etching resistant material may be composed of a cyclic structure compound known as a supramolecular structure or a cage structure compound.
Further, the etching resistant material may be composed of a carbon compound having a spherical surface combination structure known as fullerene. Fullerene having about 60 carbon atoms is a molecule having a diameter of about 0.7 nm, and is a suitable size considering the size of the free volume described above. In addition, fullerene has very high etching resistance. Moreover, the metal may contain. For example, the etching resistant material may be composed of a coordination compound in which a metal such as Si, Al, or Ti is surrounded by a carbon chain. In addition, it is more preferable that the metal used in the semiconductor process is generally used from the viewpoint of consistency with the process.

Further, an etching resistant material may be configured by introducing reactive substituents such as a t-butoxy group, a chloromethyl group, and a bisazide group into each structure described above. In addition, if fluorine or methyl silicon is introduced into the etching resistant substance, it can be easily dissolved in a supercritical fluid such as carbon dioxide. Moreover, you may make it use the etching resistant substance which has the effect | action of surfactant for improving the replacement efficiency of a rinse liquid. For example, a group such as OH, COOH, or COOCH ₃ having polarity may be introduced into the etching resistant material in the structure described above.

  In addition, what is necessary is just to comprise the processing apparatus for introducing an etching resistant substance as shown, for example in FIG. The processing apparatus shown in FIG. 6 includes an additive supply path 604 including an additive supply unit 603 between a supercritical processing unit 601 composed of a high-pressure vessel and a supercritical fluid supply system 602 that supplies a supercritical fluid. And a direct supply path 605. After carrying the substrate to be processed into the supercritical processing unit 601, first the supercritical fluid is supplied via the additive supply path 604, so that the supercritical fluid in which the etching resistant substance is dissolved in the supercritical processing unit 601. Can be introduced. Further, by supplying the supercritical fluid via the direct supply path 605, only the supercritical fluid can be introduced into the supercritical processing unit 601. In order to introduce several etching resistant substances into the supercritical processing unit 601, a plurality of additive supply units 603 and additive supply paths 604 may be provided in parallel.

Next, another example of the supercritical processing method in the embodiment of the present invention will be described.
First, a silicon oxide film is formed on a silicon substrate, and an electron beam resist ZEP-520 (manufactured by Nippon Zeon) is spin-coated on the silicon oxide film to form a resist film having a thickness of 500 nm. The formed resist film is subjected to electron beam exposure of a desired pattern, post-exposure development and rinsing treatment, and a resist pattern having a width of about 50 nm is formed on the silicon oxide film.

  Next, the silicon substrate on which the resist pattern is formed is placed inside a high-pressure vessel having an internal temperature of 23 ° C., and the high-pressure vessel is sealed. Next, while controlling the opening of the pressure control valve provided in the discharge part of the high-pressure vessel, liquefied carbon dioxide is introduced by a pressure pump, and the inside of the high-pressure vessel is filled with liquefied carbon dioxide having a pressure of about 20 Pa. And Liquefied carbon dioxide is always supplied into the high-pressure vessel and discharged from the discharge unit. By continuing this state for about 5 minutes, the rinse liquid adhering to the resist pattern is replaced with liquefied carbon dioxide. These steps are the same as those used in well-known supercritical drying.

  Next, the internal temperature of the high-pressure vessel is raised to 35 ° C., and the etching resistant substance made of fullerene in which the fluoropropyl group is modified is dissolved in the introduced liquefied carbon dioxide. As a result, the inside of the high-pressure vessel is filled with supercritical carbon dioxide, and an etching resistant substance is introduced. Therefore, the resist pattern formed on the silicon substrate is immersed in supercritical carbon dioxide in which the etching resistant substance is dissolved.

  Next, the internal pressure of the high pressure vessel is reduced to about 7.5 MPa, and only the carbon dioxide is supplied to the high pressure vessel. As a result, carbon dioxide in which the etching resistant substance is dissolved is discharged from the inside of the high-pressure vessel. Thereafter, for example, by stopping the supply of carbon dioxide and gradually increasing the opening of the pressure control valve, the internal pressure of the high-pressure vessel is reduced to about atmospheric pressure, and the processing is terminated. The obtained resist pattern has no pattern collapse. Further, when the silicon oxide film is etched using the resist pattern as a mask, deformation of the resist pattern is suppressed and a good silicon oxide film pattern is formed.

Next, another example of the supercritical processing method in the embodiment of the present invention will be described.
First, a silicon oxide film is formed on a silicon substrate, and an electron beam resist ZEP-520 (manufactured by Nippon Zeon) is spin-coated on the silicon oxide film to form a resist film having a thickness of 500 nm. The formed resist film is subjected to electron beam exposure of a desired pattern, post-exposure development and rinsing treatment, and a resist pattern having a width of about 50 nm is formed on the silicon oxide film.

Next, the silicon substrate on which the resist pattern is formed is placed inside a high-pressure vessel having an internal temperature of 23 ° C., and the high-pressure vessel is sealed. Next, while controlling the opening of the pressure control valve provided in the discharge portion of the high pressure vessel, fluoroform (CHF ₃ ) is introduced by a pressure pump, and the inside of the high pressure vessel is filled with fluoroform having a pressure of about 20 Pa. State. Fluoroform is always supplied into the high-pressure vessel and discharged from the discharge section. By continuing this state for about 5 minutes, the rinse liquid adhering to the resist pattern is replaced with fluoroform. These steps are the same as those used in well-known supercritical drying.

  Next, the internal temperature of the high-pressure vessel is raised to 30 ° C., and the etching resistant substance made of diphenyldicarboxylic acid is dissolved in the introduced fluoroform. As a result, the inside of the high-pressure vessel is filled with supercritical fluoroform and an etching resistant substance is introduced. Accordingly, the resist pattern formed on the silicon substrate is immersed in the supercritical fluoroform in which the etching resistant substance is dissolved.

  Next, helium pressurized to 20 MPa is supplied to the high-pressure vessel. As a result, the fluoroform in which the etching resistant substance is dissolved is discharged from the inside of the high-pressure vessel. Thereafter, for example, by stopping the supply of helium and gradually increasing the opening degree of the pressure control valve, the internal pressure of the high-pressure vessel is reduced to about atmospheric pressure, and the process ends. The obtained resist pattern has no pattern collapse. Further, when the silicon oxide film is etched using the resist pattern as a mask, deformation of the resist pattern is suppressed and a good silicon oxide film pattern is formed.

Another example of the supercritical processing method in the embodiment of the present invention will be described.
An ArF resist (AR230: manufactured by JSR) is applied on a silicon substrate to form a resist film having a thickness of about 500 nm, a predetermined pattern image is exposed using an ArF excimer laser as a light source, and developed immediately thereafter. Then, a resist pattern is formed. After the development, a rinsing process for stopping the development is performed, and after the rinsing process, drying is performed by, for example, spin drying that rotates the substrate.

  Next, the silicon substrate on which the pattern is formed is disposed inside the high-pressure vessel, and the high-pressure vessel is sealed. The internal temperature of the high-pressure vessel is about 50 ° C. Normal hexane in which a sorbitan compound is dissolved as an etching resistant substance is dissolved in supercritical carbon dioxide, and these are introduced into the high-pressure vessel. The internal pressure of the high-pressure vessel is set to about 15 MPa, and this state is maintained for 5 minutes. Thereafter, the internal pressure of the high-pressure vessel is gradually reduced. By these steps, the above-described etching resistant substance is introduced into the resist pattern.

In addition, an etching resistant substance may be introduced into the resist pattern by the following.
An ArF resist (AR230: manufactured by JSR) is applied on a silicon substrate to form a resist film having a thickness of about 500 nm, a predetermined pattern image is exposed using an ArF excimer laser as a light source, and developed immediately thereafter. Then, a resist pattern is formed. After development, rinsing with water is performed to stop development, and development is stopped.

After the rinse treatment, the formed pattern is kept wet with water, and the silicon substrate is placed inside the high-pressure vessel to seal the high-pressure vessel. The internal temperature of the high-pressure vessel is 23 ° C. Next, liquefied C ₂ HF ₅ is introduced into the high-pressure vessel, the inside of the high-pressure vessel is filled with liquefied C ₂ HF ₅ , and the internal pressure is set to about 5 MPa. As a result, the inside of the high-pressure vessel is filled with the C ₂ HF ₅ liquid, and the water adhering to the resist pattern is replaced with the C ₂ HF ₅ liquid.

Next, C ₂ HF _{5 in} which benzyl isocyanate is dissolved is introduced into the high-pressure vessel, and the temperature of the silicon substrate is raised to 90 ° C. As a result, benzyl isocyanate is introduced into the resist pattern and reacts with the constituent molecules of the resist pattern. Thereafter, the internal pressure of the high-pressure vessel is gradually reduced. By these steps, the above-described etching resistant substance is introduced into the resist pattern and a compound portion is formed.

In addition, an etching resistant substance may be introduced into the resist pattern by the following.
A resist (TDUR-P603: manufactured by Tokyo Ohka) is applied on a silicon substrate to form a resist film, a predetermined pattern image is exposed using a KrF excimer laser as a light source, and developed immediately thereafter to form a resist pattern. Form. After development, rinsing with water is performed to stop development, and development is stopped. After the rinsing process, the pattern is kept wet with water, and the silicon substrate is placed inside the high-pressure vessel.

After the rinse treatment, the formed pattern is kept wet with water, and the silicon substrate is placed inside the high-pressure vessel to seal the high-pressure vessel. The internal temperature of the high-pressure vessel is 23 ° C. Next, SF ₆ is introduced into the high-pressure vessel, the inside of the high-pressure vessel is filled with SF ₆ , and the internal pressure is set to about 5 MPa. As a result, the inside of the high-pressure vessel is filled with the SF ₆ liquid, and the water adhering to the resist pattern is replaced with the SF ₆ liquid. Thereafter, the internal temperature of the high pressure vessel is raised from about initial 23 ° C. to 50 ° C., with the pressure vessel interior of SF ₆ in a supercritical state, SF was dissolved Butokishinafutaru acid onium salt is added ₆ Is introduced into the high-pressure vessel.

For example, butoxynaphthalic acid to which onium salt has been added by a pressure pump while controlling the opening degree of the pressure control valve provided in the discharge part of the high-pressure vessel to make the discharge and introduction state Supply SF _{6 in} which is dissolved. After maintaining this state for 5 minutes, nitrogen of about 5 MPa is introduced into the high-pressure vessel, and butoxynaphthalic acid is discharged from the inside of the high-pressure vessel. Thereafter, the internal pressure of the high-pressure vessel is reduced, and the silicon substrate is carried out from the inside of the high-pressure vessel.

  Next, the resist pattern of the silicon substrate taken out is irradiated with ultraviolet rays and subjected to a heat treatment at 100 ° C. to form a resist with a benzene structure that constitutes an etching resistant substance introduced into the resist pattern. It reacts with the organic chain. As a result, the resist pattern is modified into a state resistant to etching, and even when the silicon substrate is etched, the resist pattern is suppressed from being reduced, and a good silicon pattern can be formed.

In addition, an etching resistant substance may be introduced into the resist pattern by the following.
An ArF resist (AR230: manufactured by JSR) is coated on a silicon substrate to form a resist film, a predetermined pattern image is exposed using an ArF excimer laser as a light source, and developed immediately thereafter to form a resist pattern To do. After development, rinsing with water is performed to stop development, and development is stopped.

After the rinsing process, the pattern is kept wet with water, and the silicon substrate is placed inside the high-pressure vessel.
After the rinse treatment, the formed pattern is kept wet with water, and the silicon substrate is placed inside the high-pressure vessel to seal the high-pressure vessel. The internal temperature of the high-pressure vessel is 23 ° C. Next, SF _{6 in} which butoxynaphthalic acid having a partially introduced carboxyl group is dissolved is introduced into the high-pressure vessel, the inside of the high-pressure vessel is filled, and the internal pressure is set to about 10 MPa. As a result, the inside of the high-pressure vessel is filled with the SF ₆ liquid, and the water adhering to the resist pattern is replaced with the SF ₆ liquid.

Next, the internal temperature of the high-pressure vessel is increased from about 23 ° C. to 50 ° C. to set SF ₆ inside the high-pressure vessel to a supercritical state. For example, while controlling the opening degree of the pressure control valve provided in the discharge part of the high-pressure vessel so that the discharge and the introduction are performed, SF _{6 in} which butoxynaphthalic acid is dissolved by the pressure pump is used. Supply and maintain the supercritical state. After maintaining this state for 5 minutes, only SF ₆ is supplied to the inside of the high-pressure vessel at a pressure of 3 MPa for 1 minute, and finally the internal pressure of the high-pressure vessel is reduced to the atmospheric pressure state.
Also by the above processing, the above-described etching resistant substance is introduced into the resist pattern.

  In the above-described embodiment, when the etching resistant material is introduced into the resist pattern, the pressure of the supercritical fluid is set higher than the critical point. This is because the solubility of the etching resistant substance in the supercritical fluid is improved by increasing the pressure and increasing the density of the supercritical fluid. However, when the pressure exceeds 20 MPa, the solubility of the etching resistant substance is not significantly changed. Therefore, it is not very effective to increase the pressure of the supercritical fluid beyond 20 MPa.

Further, the etching resistant substance may be dissolved at any time when a supercritical substance such as SF ₆ or carbon dioxide serving as a medium is introduced. For example, after rinsing, the supercritical material liquid is dissolved in the etching resistant material when it is introduced into the high-pressure vessel. After that, the supercritical material is brought into a supercritical state, and the etching resistant material is introduced into the resist pattern. You may make it make it. In this case, the rinsing liquid is replaced in the state where the etching resistant substance exists in the atmosphere of the resist pattern.

The etching resistant substance may be introduced alone or in a state dissolved in another solvent. Further, a reaction accelerator mixed with an etching resistant substance may be introduced into the supercritical fluid and used. By adding the reaction accelerator, the reaction between the etching resistant substance and the resist constituent material can be performed more rapidly.
All of these additions may be simultaneously dissolved in a supercritical material that becomes a supercritical fluid and introduced into the high-pressure vessel, or individually introduced into the high-pressure vessel and mixed in the high-pressure vessel. Also good. Alternatively, the substances to be added may be individually dissolved in a supercritical substance, and each of them may be transported to a high-pressure vessel and introduced into the high-pressure vessel step by step.

  When the purpose is to introduce an etching resistant material into the resist pattern, after the resist pattern is formed and dried, a supercritical fluid in which the etching resistant material is dissolved may act on the resist pattern. For example, after a substrate on which a resist pattern is formed is carried into a high-pressure vessel, a supercritical fluid in which an etching resistant material is dissolved is introduced into the high-pressure vessel to fill the high-pressure vessel, and the resist pattern dissolves the etching resistant material. In a supercritical fluid. After maintaining this state for a predetermined time, the supercritical fluid may be discharged from the high-pressure vessel.

In the above description, SF ₆ , carbon dioxide, and fluoroform are exemplified as the supercritical material that is a gas and is a supercritical fluid in the air atmosphere, but is not limited thereto. For example, a fluorine compound such as C ₂ HF ₅ or CHF ₂ OCF ₃ may be used as the supercritical material. Further, N ₂ O may be used as a supercritical material. Note that the air atmosphere is an atmosphere generally referred to as standard air, and is, for example, a state where the atmospheric (ground) atmospheric pressure is 1013.15 hPa and the ground temperature is 15 ° C.

It is process drawing which shows an example of the supercritical processing method in embodiment of this invention. It is a structural diagram which shows the structural example of an etching resistant substance. It is explanatory drawing which shows the structural example of an etching resistant substance. It is explanatory drawing which shows the structural example of an etching resistant substance. It is explanatory drawing which shows the structural example of an etching resistant substance. It is a block diagram which shows roughly the apparatus structure for implement | achieving a supercritical processing method. It is process drawing for demonstrating the problem of the etching process which used a resist pattern as a mask.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Silicon substrate, 102 ... Resist pattern, 103 ... Supercritical fluid, 104 ... Etching-resistant substance, 105 ... Silicon pattern.

Claims (7)

Prepare a substrate provided with a resist pattern formed by patterning a photosensitive resist in a predetermined light source by lithography technology,
A supercritical processing method in which the resist pattern is immersed in a supercritical fluid in which an etching resistant substance is dissolved,
The supercritical fluid is a substance that is a gas in an air atmosphere in a supercritical state,
The supercritical processing method, wherein the etching resistant substance is composed of molecules having carbon as a constituent element. The supercritical processing method according to claim 1,
The etching resistant material is composed of molecules having a dimension of 1 nm or less. In the supercritical processing method according to claim 1 or 2,
The etching resistant material is composed of molecules having a benzene ring in a chemical structure. In the supercritical processing method according to claim 1 or 2,
The etching resistant substance is composed of molecules in which a plurality of carbons are conjugated and bonded in a spherical shape. In the supercritical processing method of any one of Claims 1-4,
The etching resistant substance is composed of molecules having a reactive group that causes a chemical reaction with a functional group constituting the resist. In the supercritical processing method according to claim 5,
After the resist pattern is immersed in the supercritical fluid in which the etching resistant material is dissolved,
A supercritical processing method, wherein the resist pattern is irradiated with light and heated. In the supercritical processing method according to any one of claims 1 to 6,
A step of developing to form the resist pattern;
After the development process, the resist pattern is exposed to a liquid of the substance that is a gas in the atmosphere while the resist pattern is wet, and the liquid of the substance is attached to the resist pattern; ,
A step of bringing the liquid of the substance into a supercritical state and immersing the resist pattern in a supercritical fluid; and
A step of immersing the resist pattern in the supercritical fluid in which the etching resistant substance is dissolved;
A supercritical processing method comprising at least a step of vaporizing the supercritical fluid.

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