JP2002313773A - Supercritical drying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly perform supercritical drying by removing rinsing liquid remaining inside a pattern in a short time. SOLUTION: A substrate 101 is heated hotter than the temperature inside a processing container and the remaining rinsing liquid 103a impregnated inside the pattern 101a is quickly discharged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a supercritical drying method used for forming a fine pattern used for forming a semiconductor device, and more particularly to a supercritical drying method used for forming a fine pattern by a lithography technique.

[0002]

2. Description of the Related Art In order to manufacture large-scale and high-performance devices such as LSIs, it is necessary to form fine patterns. As a technique for forming a fine pattern, there is a lithography technique such as a resist pattern which undergoes exposure, development, and rinsing. The resist pattern formed by this lithography technique is made of a polymer material that is sensitive to light, X-rays, electron beams and the like. Further, there is an etching technique which involves etching, washing, and rinsing.

However, when an extremely fine pattern is formed by the above-described pattern forming technique, a phenomenon occurs in which the pattern collapses, and there has been a problem that a pattern satisfying an intended purpose cannot be formed. The phenomenon that this pattern collapses will be described. As shown in FIG. 4A, a resist pattern 402 formed on a substrate 401 is formed.
After immersion in the rinsing liquid 403, the rinsing liquid is removed, and as shown in FIG. 4B, the rinsing liquid 403a remains between the adjacent resist patterns 402 at fine intervals. In such a state, the capillary force 410 of the rinsing liquid 403a acts on the pattern 402, and the rinsing liquid 403a
After all of a is dried and removed, as shown in FIG.
The pattern 402 falls down.

[0004] The capillary force 410 generates a rinse liquid 403a remaining between a plurality of fine patterns arranged at fine intervals.
This is caused by the difference between the internal pressure and the atmospheric pressure, and is related to the surface tension of the rinsing liquid 403a. Therefore, the higher the surface tension of the rinsing liquid, the higher the capillary force and the more likely the pattern falls. In order to solve the pattern collapse caused by the capillary force, a rinsing process may be performed using a rinsing liquid having a small surface tension.

[0005] Surface tension is generated when an interface between a liquid and a gas is formed. Therefore, if the rinsing process can be performed without forming the interface between the liquid and the gas, the pattern collapse can be suppressed. As a method of performing the rinsing process without forming the interface between the liquid and the gas, there is a method using a supercritical fluid. In this method, after immersion in a rinsing liquid, the rinsing liquid is replaced with a supercritical fluid, and the supercritical fluid is vaporized while only the supercritical fluid is in contact with the pattern.

A supercritical fluid has both gas diffusivity and liquid solubility (high density), and can change into a gas state without passing through an equilibrium line. For this reason, as described above, if drying is performed from a state filled with a supercritical state, a liquid / gas interface where surface tension occurs during drying is not formed, and drying can be performed in a state where surface tension does not occur. . As a result, drying using a supercritical fluid (rinsing treatment)
Then, it is possible to suppress the pattern collapse.

[0007] Commonly used supercritical fluids include:
There is safe carbon dioxide that has a low critical point, which is a supercritical point, and is nonflammable. In a drying process using carbon dioxide in a supercritical state, first, as shown in FIG. 5A, a resist pattern 502 formed on a substrate 501 is immersed in a rinsing liquid 503, and then these are heated to a temperature lower than room temperature. As a state, the rinsing liquid 503 is replaced with liquefied carbon dioxide,
As shown in FIG. 5B, the resist pattern 502 is immersed in liquefied carbon dioxide 504. Substrate 501
And the pressure of the atmosphere of the resist pattern 502 is 6 MPa.
If it is on the order, carbon dioxide can be kept in a liquefied state.

When the liquefied carbon dioxide 504 is formed around the resist pattern 502, the pressure of the atmosphere of the substrate 501 and the resist pattern 502 is set to about 7.38 MPa.
By setting the temperature to 31.1 ° C. or higher, the liquefied carbon dioxide 504 is brought into a supercritical state, and the resist pattern 502 is brought into a state immersed in the supercritical carbon dioxide. Thereafter, if the pressure of the atmosphere of the substrate 501 and the resist pattern 502 is gradually reduced while maintaining the above temperature, the surrounding supercritical carbon dioxide is gradually vaporized, and the surrounding supercritical carbon dioxide is completely vaporized. As shown in FIG. 5C, the drying of the resist pattern 502 is completed. In this drying process, even if the ambient pressure is reduced, the supercritical carbon dioxide does not liquefy, so that the pattern collapse due to the surface tension does not occur.

In this supercritical drying method, the rinsing liquid is replaced with liquefied carbon dioxide, so that an alcohol or the like which is easily dissolved in liquefied carbon dioxide is used as the rinsing liquid. Further, the apparatus for performing supercritical drying has a configuration capable of sufficiently withstanding the above-mentioned high-pressure state and heating the temperature of the processing container to the supercritical temperature. Such a supercritical drying apparatus includes, for example, as shown in FIG. 6, a processing container 601 that can withstand high pressure, and a temperature controller 602 that adjusts the temperature of the processing container 601. A substrate table 603 on which a substrate to be processed is placed is disposed in the processing container 601.
Is provided.

The processing vessel 601 has an inlet 604 for introducing liquefied carbon dioxide and the like, and an outlet 605 for discharging the internal fluid. A pressure feeding device 607 communicates with the inlet 604 via a valve 606,
The liquefied carbon dioxide in 8 can be pumped into the processing vessel 601. In addition, the outlet 605 has a pressure control valve 6.
09 is in communication. In a state where the pressure control valve 609 is closed, the liquefied carbon dioxide is
01 and the pressure in the processing vessel 601 is 7.5MPa.
If a is set as a and the temperature of the processing container 601 is adjusted by the temperature controller 602 and the temperature in the processing container 601 is set to a critical point or higher, the processing container 601 is filled with supercritical carbon dioxide.

[0011]

However, in the conventional supercritical drying method, the rinsing liquid impregnated in the resist pattern is difficult to remove, and a long drying time is required to remove the rinsing liquid impregnated. If the drying is terminated while the resist pattern is impregnated with the rinsing liquid due to insufficient drying, the fine resist pattern may fall down.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the supercritical drying can be performed more quickly by removing the rinsing liquid remaining in the pattern in a shorter time. The purpose is to.

[0013]

The supercritical drying method according to the present invention comprises a first step of exposing a pattern layer having a predetermined pattern formed on a substrate to a rinsing liquid; In this state, the substrate is placed in a container, and a liquid of a substance that is a gas in the air atmosphere is introduced into the container, so that the pattern layer is exposed to the liquid of the substance.
And a third step of removing a rinsing liquid attached to the pattern layer in a state where the pattern layer is exposed to the liquid of the substance; and a supercritical state of the liquid of the substance introduced into the container in a supercritical state. A fourth step in which the pattern layer is exposed to the supercritical fluid as a fluid, and by discharging the supercritical fluid in the vessel to the outside of the vessel, the pressure inside the vessel is reduced, and the supercritical fluid is vaporized. And a fifth step of exposing the pattern layer to a gas. The third step is such that the substrate is heated to a temperature higher than the temperature of the container. According to the present invention, in the third step, the temperature of the liquid substance in the vicinity of the substrate becomes higher than that of the substance away from the substrate.

In the above invention, in the third step, the temperature of the container is set below the critical point of the substance, and the temperature of the substrate is set to a temperature at which the substance enters a subcritical state. In the fourth step, the temperature of the substrate is equal to or higher than the critical point of the substance.

In a supercritical drying method according to another aspect of the present invention, a first step of exposing a pattern layer having a predetermined pattern formed on a substrate to a rinsing liquid, and a rinsing liquid is attached to the pattern layer. In this state, the substrate is placed in a container, and a liquid of a substance that is a gas in the atmospheric atmosphere is introduced into the container, and a second pattern is obtained in which the pattern layer is exposed to the liquid of the substance.
And a third step of removing a rinsing liquid attached to the pattern layer in a state where the pattern layer is exposed to the liquid of the substance; and a supercritical state of the liquid of the substance introduced into the container in a supercritical state. A fourth step in which the pattern layer is exposed to the supercritical fluid as a fluid, and by discharging the supercritical fluid in the vessel to the outside of the vessel, the pressure inside the vessel is reduced, and the supercritical fluid is vaporized. And a fifth step of exposing the pattern layer to a gas, whereby the substrate is heated to a temperature higher than the temperature in the container in the fourth step. According to the invention,
In the fourth step, the temperature of the substance near the substrate becomes higher than the distance from the substrate, and a flow of the substance occurs between the vicinity of the substrate and the distance from the substrate. In the above invention, in the fourth step, the temperature of the substrate is set to a temperature equal to or higher than the critical point of the substance.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. The main cause of pattern collapse during drying after the rinsing process is the presence of capillary force due to the rinse liquid remaining between adjacent patterns. this is,
The problem can be solved by supercritical drying using a supercritical fluid. However, when the pattern is made of a polymer material such as a resist, the rinsing liquid impregnates the pattern in the rinsing process, and the pattern collapses due to the deformation of the pattern. This phenomenon occurs particularly in a resist pattern formed near the resolution limit, and is often seen in a pattern having a width of 10 nm or less.

However, since carbon dioxide used for supercritical drying has no polarity and is hardly impregnated into a pattern made of a polymer material, liquefied carbon dioxide does not easily replace the rinsing liquid impregnated inside the pattern. Therefore,
Even if the supercritical drying is simply used, the above-described problems of pattern deformation and pattern collapse due to the rinsing liquid remaining inside the pattern cannot be solved.

In the present embodiment, the rinsing liquid around the pattern is replaced with liquefied carbon dioxide, and then the substrate on which the pattern is formed is heated so that the inside of the container filled with liquefied carbon dioxide is heated. The pattern was heated to a temperature higher than or equal to the temperature, so that the rinsing liquid remaining inside the pattern was quickly released to the outside.

First, as shown in FIG.
After a pattern 101a made of a polymer material such as a positive photoresist is formed on the substrate 101 by a development process of 02, as shown in FIG.
By immersing the substrate 101 in the rinsing liquid 103, the pattern 101a is exposed to the rinsing liquid to stop the development (rinsing processing). Thereafter, the substrate 101 is taken out of the rinsing liquid 103, placed in a predetermined processing container (not shown), and liquefied carbon dioxide is introduced and filled into the processing container, as shown in FIG. The substrate 101 is immersed in the liquefied carbon dioxide 104, and the pattern 101a is
Expose to 4. This operation is completed within a time period in which the pattern 101a can be kept wet with the rinsing liquid.

Next, the substrate 101 is heated so as to be higher than the temperature in the processing container, and as shown in FIG. 1 (c '), the remaining rinsing liquid 1 impregnated in the pattern 101a.
03a is released quickly. The temperature inside the processing container filled with the liquefied carbon dioxide 104 is controlled to around normal temperature of about 23 ° C., for example, to keep the carbon dioxide in a liquid state. On the other hand, the substrate heating temperature for releasing the residual rinsing liquid 103a may be, for example, about 30 ° C.

Thereafter, the temperature in the processing vessel is raised to the critical point of 3 points.
1.1 ° C. and the pressure in the processing vessel is 7.5 M
By setting the pressure to about Pa, the liquefied carbon dioxide is brought into a supercritical state so that the pattern 101 is exposed to the supercritical carbon dioxide, and the substance in contact with the pattern 101 is brought into a state where only the supercritical carbon dioxide is present. Next, the pressure in the processing chamber is gradually reduced to evaporate the supercritical carbon dioxide, thereby forming a pattern 101a without pattern collapse on the substrate 101 as shown in FIG. And

Here, the problem when the rinsing liquid remains inside the above-described pattern will be considered. For example, the rinsing liquid 103 having polarity is, as shown in FIG.
The pattern 101a made of a polymer material is impregnated. As a result, the pattern 101a becomes the impregnated rinse liquid 103a.
As a result, as shown in FIG. 2B, the pattern 101b has an increased volume. When the pattern width is small, the swelling area 101c becomes narrow, and the swelling area 10
As shown in FIG. 2C, the pattern 101b cannot withstand the stress generated from 1d, and eventually falls down as shown in FIG. Even if the rinsing liquid 103 is replaced with liquefied carbon dioxide 103 and supercritical drying is performed, the stress does not disappear unless the rinsing liquid 103a that caused the swelling is removed inside the pattern 101b. As a result, FIG. As shown, the pattern collapse occurs.

Next, the heating of the substrate performed at the stage shown in FIG. 1 (c ') will be described in more detail. First, as described above, a method of heating the substrate at the stage of replacing the rinsing liquid with liquefied carbon dioxide and bringing the liquefied carbon dioxide in the vicinity of the pattern into a subcritical state to release the impregnated rinsing liquid will be described. I do. As described above, heating the substrate and the pattern immersed in liquefied carbon dioxide,
When the temperature is about 30 ° C., the carbon dioxide around the pattern is in a subcritical state.

In the case of carbon dioxide, it is about 30 ° C. under a pressure capable of forming a supercritical state, which is 1 to 1 below the critical temperature (31.1 ° C.).
If the temperature is lower by two degrees, the state becomes a subcritical state that is not completely in a supercritical state. The subcritical state is a state where the density is lower than liquefied carbon dioxide and higher than the supercritical state. The subcritical carbon dioxide is easily impregnated inside the pattern, and if carbon dioxide comes to impregnate inside the pattern, the rinsing liquid impregnated inside the pattern is replaced with carbon dioxide, and more quickly. The residual rinsing liquid can be released outside the pattern. As a result, the liquefied carbon dioxide is brought into a supercritical state, and the remaining rinsing liquid inside the pattern at the stage of vaporizing the liquefied carbon dioxide can be reduced.

Further, at the stage of replacing the rinsing liquid with the liquefied carbon dioxide, the rinsing liquid impregnated in the pattern can be released by heating to a temperature higher than the critical point of carbon dioxide. In this case, the temperature difference between the vicinity of the substrate and the place distant from the substrate becomes large, the flow of fluid from the vicinity of the substrate, that is, from the vicinity of the pattern to the periphery becomes large, and the discharge of the rinsing liquid remaining inside the pattern is promoted. become. As a result, also in the present method, the liquefied carbon dioxide is brought into a supercritical state, and the remaining rinsing liquid inside the pattern at the stage of vaporizing the liquefied carbon dioxide can be reduced.

In the above two methods, carbon dioxide at a distance from the substrate is in a liquid state, but carbon dioxide near the heated substrate is in a subcritical or supercritical state. For this reason, after replacing the rinsing liquid with liquefied carbon dioxide, the substrate is heated to release the rinsing liquid remaining in the pattern, and then the step of bringing the liquefied carbon dioxide in the processing vessel into a supercritical state is omitted. The carbon dioxide may be vaporized by gradually lowering the internal pressure. By doing so, it is not necessary to heat the inside of the processing container in order to bring carbon dioxide into a supercritical state, and the process can be simplified.

At the stage where the liquefied carbon dioxide in the container for supercritical drying is brought into a supercritical state, the substrate is heated to a temperature not lower than the temperature inside the container at this stage, and the rinse liquid impregnated in the pattern is released. You may do it. Even in this case, the temperature difference between the vicinity of the substrate and the place away from the substrate is large. For this reason, an airflow is generated from the vicinity of the pattern to the surroundings, and the release of the rinsing liquid remaining inside the pattern is promoted by the airflow.

The above-described supercritical drying method may use a supercritical drying apparatus as shown in FIG. The supercritical drying apparatus shown in FIG. 3 includes a processing vessel 301 capable of forming a high pressure such as 7.5 MPa, and the temperature of the processing vessel 301 can be adjusted by a vessel temperature controller 302. Since the processing container 301 withstands a pressure for forming a supercritical state,
It is made of stainless steel with a wall thickness of several cm.
A substrate table 303 on which a substrate to be processed is placed is provided in the processing container 301, and the temperature of the substrate placed on the substrate table 303 can be adjusted by a substrate temperature controller 304.

The processing vessel 301 has an inlet 305 for introducing liquefied carbon dioxide and the like, and an outlet 306 for discharging the internal fluid. A pressure feeding device 308 communicates with the inlet 305 via a valve 307, and the cylinder 30
The liquefied carbon dioxide 9 can be pumped into the processing vessel 301. The outlet 306 has a pressure control valve 3
10 are in communication.

In the supercritical drying apparatus shown in FIG. 3, while the pressure control valve 310 is closed, the liquefied carbon dioxide is pressure-fed into the processing vessel 301 from the pressure feeding device 308 and the processing vessel 30
When the pressure of 1 was set to 7.5 MPa, the temperature of the processing container 301 was adjusted by the container temperature controller 302, and the temperature in the processing container 301 was set to about 23 ° C., the inside of the processing container 301 was filled with liquefied carbon dioxide. State.

In this state, the substrate temperature is controlled to be about 30 ° C. by heating the substrate table 303 under the control of the substrate temperature controller 304 to heat the substrate thereon, as described above. Carbon dioxide can be brought into a subcritical state. Next, while maintaining the pressure in the processing container 301, the temperature of the processing container 301 is adjusted by the container temperature controller 302, and if the temperature in the processing container 301 is set to a critical point or higher, the inside of the processing container 301 becomes supercritical. It will be filled with carbon dioxide.

Thereafter, by closing the valve 307 and opening the pressure control valve 310 by a predetermined amount, the carbon dioxide in the processing vessel 301 is gradually discharged, and the pressure in the processing vessel 301 is reduced. The supercritical carbon dioxide in 301 evaporates. When all the supercritical carbon dioxide in the processing container 301 is vaporized, the supercritical drying is completed. Although not shown in FIG. 3, the processing container 301 includes an openable / closable gate valve for carrying in and out the substrate to be processed.

In the supercritical drying apparatus shown in FIG. 3, when the inside of the processing vessel 301 is to be filled with liquefied carbon dioxide, it is better to keep the temperature of the processing vessel 301 as low as possible. Is shortened. On the other hand, in order to bring the liquefied carbon dioxide filled in the processing container 301 into a supercritical state, it is conventionally necessary to set the temperature of the processing container to 31 ° C. or higher.

In order to be able to process a substrate having a diameter of 10 cm in the processing vessel 301, the internal volume of the processing vessel 301 needs to be as large as 4000 cm ³ or more. As described above, the processing container 301 has a wall thickness of several cm so as to withstand high pressure. Therefore, the processing vessel 301 is equal to a large volume of stainless steel. The temperature of the processing container 301 is set to 23
In order to greatly change the temperature from 0 ° C. to 31 ° C. or more, much time is required, and the processing time is delayed.

On the other hand, in the supercritical drying apparatus shown in FIG. 3, since the surrounding carbon dioxide can be quickly brought into the supercritical state by heating the substrate table 303, the temperature of the processing vessel 301 becomes liquefied. The temperature can be kept at 23 ° C. to maintain the carbonized carbon. Therefore, according to the supercritical drying apparatus shown in FIG. 3, the liquefied carbon dioxide around the substrate can be brought into a supercritical state without heating the processing vessel 301, so that the supercritical drying can be performed more quickly.

[0036]

<Embodiment 1> A detailed description will be given below based on an embodiment. First, ZEP-7000 (manufactured by Zeon Corporation) which is an electron beam resist is spin-coated on a silicon substrate,
A resist film having a thickness of 250 nm was formed. Next, after the formed resist film is exposed to an electron beam to form a desired latent image, development processing with normal hexyl acetate and rinsing processing with 2-propanol (rinse liquid) are performed to form a resist pattern on the silicon substrate. Formed. The formed pattern width was 10 to 100 nm.

Thereafter, the silicon substrate is placed on the substrate table 303 in the processing container 301 within a time period in which the resist pattern can be kept wet with the rinsing liquid.
, And with the pressure control valve 310 closed,
The liquefied carbon dioxide in the cylinder 309 was pumped into the processing vessel 301 by the pumping device 308, and the inside of the processing vessel 301 was filled with liquefied carbon dioxide. At this time, the temperature of the processing container 301 becomes 23 by the control of the container temperature controller 302.
° C.

Next, by controlling the pressure and amount of carbon dioxide pumped by the pumping device 308 and controlling the degree of opening of the pressure control valve 310, the pressure in the processing vessel 301 is increased to 7.
It was 5 MPa. The pressure in the processing vessel 301 is 7.5MP
After reaching a, the temperature of the substrate table 303 was set to 30 ° C. and the temperature of the silicon substrate was set to about 30 ° C. under the control of the substrate temperature controller 304, and this state was maintained for 20 minutes. At this time, the liquefied carbon dioxide is supplied to the processing vessel 3 by the pressure feeding device 308.
01 and continued to be introduced.

When the temperature of the silicon substrate is controlled to about 30 ° C., the carbon dioxide near the silicon substrate is in a subcritical state, and the carbon dioxide away from the silicon substrate is in a liquid state. I have. Also, the processing container 3
Since 01 is controlled at 23 ° C., the temperature is lower at a position farther from the silicon substrate than at a position near the silicon substrate. As a result, in the processing container 301, carbon dioxide flows from the vicinity of the substrate toward the periphery thereof.

Thereafter, the temperature of the substrate table 303 is set to 35 ° C. and the temperature of the silicon substrate is set to 35 ° C. under the control of the substrate temperature controller 304, and the pumping of carbon dioxide by the pumping device 308 is stopped almost simultaneously, and the valve 307 is closed. Controlling the degree of opening of the pressure control valve 310 to discharge carbon dioxide,
The pressure in the processing vessel 301 was reduced. At this time, on the silicon substrate, carbon dioxide in a supercritical state is vaporized, and a state of supercritical drying is performed. The resist pattern on the silicon substrate obtained as a result of the supercritical drying had no pattern collapse and a good pattern shape was obtained.

<Embodiment 2> Next, another embodiment will be described. First, HSQ (manufactured by Dow Corning), which is an electron beam resist, is spin-coated on a silicon substrate.
A 00 nm resist film was formed. Next, after the formed resist film is exposed to an electron beam to form a desired latent image,
Tetramethylammonium hydroxide (TMA
H) and a rinsing process with ethanol (rinse solution) were performed to form a resist pattern on the silicon substrate. These developing and rinsing processes were performed at a temperature of 23 ° C. under the control of the container temperature controller 302.
Went inside. At this time, under the control of the substrate temperature controller 304, the substrate table 303 on which the silicon substrate is placed is mounted.
Was also set to 23 ° C. The formed pattern width is 8 nm
Met.

After rinsing, the container temperature controller 3
02, the temperature of the processing vessel 301 was reduced to 20 ° C. or lower, and carbon dioxide in the cylinder 309 was introduced into the processing vessel 301 by the pumping device 308. The introduction of carbon dioxide was performed by controlling the degree of opening of the pressure control valve 310 until the pressure in the processing container 301 became 7.5 MPa. After the processing vessel 301 is filled with liquefied carbon dioxide and the pressure becomes 7.5 MPa, the substrate temperature controller 3
Under the control of step 04, the temperature of the substrate table 303 was set to 30 ° C., and carbon dioxide near the silicon substrate was brought into a subcritical state. Thereafter, the introduction of carbon dioxide is stopped, and the pressure control valve 310 is stopped.
Is released to discharge carbon dioxide in the processing vessel 301, and the pressure in the processing vessel 301 is set to the atmospheric pressure.
The silicon substrate was unloaded from the inside. As described above, the resist pattern on the supercritically dried silicon substrate did not collapse and a good pattern shape was obtained.

<Embodiment 3> Next, a third embodiment will be described. First, HSQ (manufactured by Dow Corning) which is a sagittal resist was spin-coated to form a resist film having a thickness of 100 nm. Next, after the formed resist film is exposed to an electron beam to form a desired latent image, development processing with tetramethylammonium hydroxide (TMAH) and rinsing processing with ethanol (rinse liquid) are performed.
A resist pattern was formed on a silicon substrate. These development and rinsing processes were performed in a processing container 301 at 23 ° C. under the control of the container temperature controller 302. At this time, under the control of the substrate temperature controller 304, the temperature of the substrate table 303 on which the silicon substrate is mounted is also set to 23 ° C. The formed pattern width was 8 nm.

After rinsing, the container temperature controller 3
02, the temperature of the processing vessel 301 was reduced to 20 ° C. or lower, and the carbon dioxide in the cylinder 309 was introduced into the processing vessel 301 by the pumping device 308. The introduction of carbon dioxide was performed by controlling the degree of opening of the pressure control valve 310 until the pressure in the processing container 301 became 7.5 MPa. After the processing vessel 301 was filled with liquefied carbon dioxide and the pressure became 7.5 MPa, this state was maintained for 20 minutes.

Twenty minutes later, the temperature of the processing vessel 301 was raised to 35 ° C. by the control of the vessel temperature regulator 302, and the temperature of the substrate table 303 was brought to 50 ° C. by the control of the substrate temperature regulator 304. Thereafter, the introduction of carbon dioxide is stopped, and the pressure control valve 310 is further opened to open the processing container 30.
1 was discharged, the pressure in the processing vessel 301 was set to atmospheric pressure, and the silicon substrate was carried out of the processing vessel 301. As described above, the resist pattern on the supercritically dried silicon substrate did not collapse and a good pattern shape was obtained. As described above, according to the present embodiment, the rinsing liquid remaining in the resist pattern can be efficiently removed, and a good pattern of 10 nm or less can be formed.

In the above-described embodiment, the resist is an electron beam resist such as ZEP-7000 or HSQ.
Using normal hexyl acetate and TMAH as a developing solution
And 2-propanol and ethanol were used as the rinsing liquid, but the present invention is not limited to this. Of course, the present invention can be applied to a rinsing liquid compatible with liquefied carbon dioxide. In addition, even when water is used as the rinsing liquid, the present invention can be applied if a surfactant or the like is used to make the liquid carbon dioxide compatible. In the above description, a resist pattern of a polymer material is used as an example of a pattern to be dried. However, the present invention may be applied to drying of a pattern made of silicon or a compound semiconductor. In the above description, carbon dioxide is used as the supercritical fluid. However, the present invention is not limited to this, and a substance having a critical point such as CHF ₃ or NO ₂ may be used.

[0047]

As described above, in the present invention, the temperature of the substrate on which the pattern is formed is higher than that of the container for performing the supercritical drying, so that the rinsing liquid remaining on the pattern can be removed more quickly. I made it. As a result, according to the present invention, an excellent effect that the rinsing liquid remaining in the pattern can be removed in a shorter time and supercritical drying can be performed more quickly can be obtained.

[Brief description of the drawings]

FIG. 1 is a process chart for explaining a supercritical drying method of the present invention.

FIG. 2 is a configuration diagram showing a schematic configuration of a supercritical drying apparatus for realizing the supercritical drying method of the present invention.

FIG. 3 is a process chart for explaining a conventional supercritical drying method.

FIG. 4 is a process chart for explaining a conventional drying method.

FIG. 5 is a process chart for explaining a supercritical drying method.

FIG. 6 is a configuration diagram illustrating a general configuration of a supercritical drying apparatus that performs a supercritical drying method.

[Explanation of symbols]

101: substrate, 101a: pattern, 102: developer,
103: rinsing liquid, 103a: residual rinsing liquid, 104:
Liquefied carbon dioxide.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/30 570 571 F-term (Reference) 2H096 AA25 GA17 GA20 JA04 3L113 AA01 AB02 AC28 AC45 AC46 AC57 AC63 AC67 BA34 CA04 CA08 CB19 CB28 DA10 5F046 LA13 LA14 LA19

Claims (5)

[Claims] A first step of exposing a pattern layer having a predetermined pattern formed on a substrate to a rinsing liquid, wherein the rinsing liquid adheres to the pattern layer;
A second step of disposing the substrate in a container, introducing a liquid of a substance that is a gas in the atmosphere into the container, and exposing the pattern layer to the liquid of the substance; A third step of removing a rinsing liquid attached to the pattern layer while being exposed to the liquid of the substance, and converting the liquid of the substance introduced into the container into a supercritical fluid in a supercritical state. A fourth step in which the pattern layer is exposed to the supercritical fluid; and discharging the supercritical fluid in the container to the outside of the container to reduce the pressure inside the container, A fifth step of evaporating a critical fluid to expose the pattern layer to a gas, wherein in the third step, the substrate is heated to a temperature higher than the temperature of the container. Critical drying method. 2. The supercritical drying method according to claim 1, wherein in the third step, the temperature of the container is lower than a critical point of the substance, and the temperature of the substrate is such that the substance is in a subcritical state. A supercritical drying method, wherein the drying is performed at a temperature. 3. The supercritical drying method according to claim 1, wherein in the fourth step, the temperature of the substrate is equal to or higher than a critical point of the substance. . 4. A first step of exposing a pattern layer having a predetermined pattern formed on a substrate to a rinsing liquid, wherein the rinsing liquid adheres to the pattern layer.
A second step of disposing the substrate in a container, introducing a liquid of a substance that is a gas in the atmosphere into the container, and exposing the pattern layer to the liquid of the substance; A third step of removing a rinsing liquid attached to the pattern layer while being exposed to the liquid of the substance, and converting the liquid of the substance introduced into the container into a supercritical fluid in a supercritical state. A fourth step in which the pattern layer is exposed to the supercritical fluid; and discharging the supercritical fluid in the container to the outside of the container to reduce the pressure inside the container, A fifth step of evaporating a critical fluid to expose the pattern layer to a gas, wherein in the fourth step, the substrate is heated to a temperature higher than the temperature in the container. Supercritical drying method. 5. The supercritical drying method according to claim 4, wherein in the fourth step, the temperature of the substrate is equal to or higher than a critical point of the substance.