JP2001324263A - Supercritical drier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to carry out supercritical drying in a state wherein occurrence of pattern failure is inhibited as much as possible. SOLUTION: A diagonal flow plate 112 opposite to a substrate disposing table 103 is provided between a nozzle 108 and the substrate disposing plate 103. The diagonal flow plate 112 is disposed substantially in parallel with a substrate 104 disposed on the table 103.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supercritical drying apparatus for performing supercritical drying for suppressing the collapse of fine patterns due to the surface tension of a rinsing liquid in drying after rinsing.

[0002]

2. Description of the Related Art In recent years, with the increase in scale of MOS LSI,
The miniaturization of patterns in LSI manufacturing has been promoted along with the increase in size of chips, and patterns having a line width of less than 100 nm have now been formed. Reducing the line width results in the formation of a pattern having a large aspect ratio (height / width). Thus, LSI
In order to manufacture large-scale and high-performance devices such as, an ultrafine pattern is required.

The ultrafine pattern is, for example, a resist pattern formed through exposure, development, and rinsing and having sensitivity to light, X-rays, or electron beams. Also,
This is an etching pattern made of an inorganic material such as an oxide formed through etching, water washing, and rinsing by selective etching using the resist pattern as a mask. The above-described resist pattern can be formed by processing a film of a photosensitive resist which is an organic material by a lithography technique. When the photosensitive resist film is exposed, the molecular weight and molecular structure of the exposed area change, and a difference in solubility in a developing solution occurs between the exposed area and the unexposed area. By the treatment, a finer pattern than the photosensitive resist film can be formed.

In the above-described development processing, if the development is continued, the unexposed areas will soon begin to dissolve in the developer and the pattern will disappear, so that the development is stopped by performing a rinsing treatment with a rinsing liquid. . Finally, by drying and removing the rinsing liquid, a resist pattern as a processing mask can be formed on the resist film. As a major problem at the time of drying in forming such a fine pattern, FIGS.
There is a pattern collapse as shown in the process diagram of C.

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 by the resist. For example, in the case where a substrate is etched using a resist pattern as a mask to form a substrate pattern having a high aspect ratio, the substrate is washed after the etching, and FIG.
As shown in (1), the substrate pattern 902 together with the substrate 901 is immersed in water 903 and rinsed. Thereafter, drying is performed.

However, as shown in FIG. 9B, during drying, a bending force (capillary force) 9 is caused by a pressure difference between water 903 remaining between substrate patterns 902 and external air 904.
05 works. As a result, as shown in FIG.
1, pattern collapse of the substrate pattern 902 occurs.
This falling phenomenon becomes more remarkable as the pattern becomes higher in aspect ratio. It has been reported that the capillary force depends on the surface tension generated at a gas-liquid interface between a rinsing liquid such as water and a pattern (Reference: Applied Physics.
Letters, 66, 2655-2657, 1995
Year).

This capillary force not only defeats a resist pattern made of an organic material but also distorts a stronger pattern made of an inorganic material such as silicon. The problem is important. The problem caused by 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 the rinsing liquid, the surface tension of water is about 72 × 10 ⁻³ N / m, but the surface tension of methanol is about 23 × 10 ⁻³ N / m. When the ethanol is dried after replacing the water with ethanol, the degree of pattern collapse is suppressed.

Further, if perfluorocarbon having a surface tension of 20 × 10 ⁻³ N / m is used and the perfluorocarbon is replaced with a rinsing liquid and then the perfluorocarbon is dried, the pattern collapse can be more effectively suppressed. It is a target. 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, the pattern collapse cannot be eliminated because the liquid has a certain surface tension. In order to solve the problem of 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.

A supercritical fluid is a liquid having a surface tension of zero. A supercritical fluid is a substance at a temperature and pressure above the critical temperature and critical pressure, and has a dissolving power close to that of a liquid, but exhibits properties similar to that of a gas, such as tension and viscosity. It can be called a liquid. 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 is eliminated. A supercritical fluid has both gas diffusivity and liquid solubility (high density), and can change state from liquid to gas without passing through an equilibrium line. For this reason, when this supercritical fluid is gradually released from the state filled with the supercritical fluid, a liquid / gas interface is not formed. Can be.

As a supercritical fluid, safe carbon dioxide having a low critical point is used in many cases. When a supercritical fluid is used for drying, a rinsing process using alcohol as a final rinse is performed, and thereafter, the rinsing liquid adhering to the substrate surface is replaced with liquefied carbon dioxide in a sealed container. Started with Carbon dioxide is 6MP
If it is pressurized to about a, it liquefies at room temperature,
This is performed in a state where the pressure in the container is increased to about 6 MPa. After the rinsing liquid adhering to the substrate is completely replaced by liquefied carbon dioxide, the inside of the container is heated to a temperature and pressure higher than the critical point of carbon dioxide (critical point of carbon dioxide: 31 degrees, 7.3MPa).
In step a), liquefied carbon dioxide is converted to supercritical carbon dioxide.

Finally, while maintaining the above temperature, a part of the vessel is opened to release supercritical carbon dioxide to the outside, the pressure in the vessel is reduced to atmospheric pressure, and the supercritical carbon dioxide in the vessel is vaporized. Then, the drying is completed. At the time of the pressure reduction, the carbon dioxide is vaporized without being liquefied, so that a gas-liquid interface where surface tension should be applied is not formed on the substrate. For this reason, these can be dried without causing the superfine patterns on the substrate to collapse.

[0012] The apparatus for the above-mentioned supercritical drying includes:
For example, as shown in FIG. 10, there is a device in which a cylinder 1003 containing liquefied carbon dioxide is connected via a valve 1004 to a reaction chamber 1002 in a sealable container 1001. In this apparatus, a valve 10 on the liquefied carbon dioxide introduction side is used.
04 is opened, liquefied carbon dioxide is introduced into the container 1001, and the nozzle 100
The liquefied carbon dioxide is discharged from the front end 5 and the liquefied carbon dioxide is injected onto the substrate placed in the reaction chamber 1002.
At this time, the discharge side valve 1006 is adjusted to
The pressure in the reaction chamber 1002 is controlled by limiting the amount of liquefied carbon dioxide discharged from 002. If, for example, an automatic pressure valve or the like is used as the discharge side valve 1006, the above pressure control becomes possible.

As described above, while the liquefied carbon dioxide is being injected onto the substrate by the nozzle 1005, the container 10
01 is heated to, for example, about 31 ° C., and the pressure in the reaction chamber 1002 is set to 7.5 MPa or more, the liquefied carbon dioxide injected onto the substrate in the reaction chamber 1002 enters a supercritical state. The pressure in the reaction chamber 1002 can be increased by adjusting the valve 1006 to reduce the amount of liquefied carbon dioxide discharged from the reaction chamber 1002. Thereafter, the valve 1004 is closed and the valve 1006 is opened, the pressure in the reaction chamber 1002 is reduced, and the supercritical carbon dioxide injected on the substrate in the reaction chamber 1002 is vaporized, so that the supercritical drying is performed. Ends.

[0014]

However, even if liquefied carbon dioxide is injected onto the substrate in the reaction chamber using a nozzle or the like, the rinse liquid adhering to the pattern layer on the substrate may not be completely replaced. there were. As described above, when the rinsing liquid remains, pattern collapse occurs due to the surface tension of the rinsing liquid even when supercritical drying is performed. For example, as shown in FIG. 11A, a substrate 1101 on which a pattern 1101a is formed is immersed in a rinsing liquid 1102 to perform a rinsing process, and then the substrate 1101 is placed in a reaction chamber (not shown) of a predetermined sealable container. And liquefied carbon dioxide was introduced into the reaction chamber, and as shown in FIG.
101a is immersed in liquefied carbon dioxide 1104.

However, at this stage, the rinsing liquid 1102
May remain between the patterns 1101a. In this way, when a part of the rinsing liquid 1102 remains, at the stage where the liquefied carbon dioxide is brought into a supercritical state, as shown in FIG.
And a rinsing liquid 1102, a surface tension is generated at the interface, and a force 1106 for tilting the pattern 1101a is generated. As a result, after the supercritical drying, the pattern 110a collapses as shown in FIG. 11D. The remaining rinsing liquid that cannot be completely replaced by the above-mentioned liquefied carbon dioxide increases as the pattern interval becomes narrower. In addition, when the substrate to be subjected to supercritical drying becomes large, the remaining rinse liquid due to insufficient replacement of liquefied carbon dioxide is more likely to occur.

The present invention has been made in order to solve the above problems, and has as its object to enable supercritical drying to be performed in a state where occurrence of pattern collapse is suppressed as much as possible.

[0017]

According to the present invention, there is provided a supercritical drying apparatus comprising: a hermetically sealable container having a reaction chamber in which a substrate to be processed is placed; A liquid supply means for supplying, a nozzle disposed above a central portion of the substrate in the reaction chamber, and a nozzle for discharging a liquid of the substance supplied by the liquid supply means onto an upper portion of the substrate in the reaction chamber, and a nozzle disposed between the nozzle and the substrate And a diagonal flow plate having a plurality of openings for changing the direction in which the substance discharged from the nozzle flows to less than 90 ° with respect to the surface of the substrate and to the direction of the circumference having the center as the center of the substrate. Discharge means for discharging the fluid introduced into the reaction chamber, control means for controlling the pressure in the reaction chamber to a pressure at which the substance becomes a supercritical state, and temperature control for controlling the temperature in the reaction chamber to a predetermined temperature Means. According to the present invention, the liquid of the substance discharged from the nozzle flows obliquely into the substrate in the direction of the circumference whose center is the center of the substrate whose flow direction is changed by the diagonal flow plate, On the substrate, a circumferential flow of the liquid material is formed around the center of the substrate.

Further, the supercritical drying apparatus according to the present invention comprises a hermetically sealable container having a reaction chamber for mounting a substrate to be processed, and a liquid supply means for supplying a liquid of a substance which is a gas in the atmosphere to the reaction chamber. And a nozzle disposed on the side of the substrate above the substrate arrangement position in the reaction chamber, for discharging the liquid of the substance supplied by the liquid supply means in the direction of the substrate, and a discharge means for discharging the fluid introduced into the reaction chamber And control means for controlling the pressure in the reaction chamber to a pressure at which the substance becomes a supercritical state, and temperature control means for controlling the temperature in the reaction chamber to a predetermined temperature. According to this invention, the liquid of the substance discharged from the nozzle flows into the substrate from one end of the substrate and flows out to the other end of the substrate, and flows from one end to the other end of the substrate. It is formed.

In the above invention, the direction in which the substance discharged from the nozzle is disposed between the nozzle and the substrate is defined as:
By providing a diffusion plate for diffusing the entire area of the substrate, the liquid substance is diffused throughout the entire area of the substrate. In the above invention, the liquid supply means may be constituted by a cylinder for containing the liquid of the substance and a pumping means for pressure-feeding the liquid of the substance contained in the cylinder into the reaction chamber via a pipe. Further, the above substance is carbon dioxide, and the supercritical state includes a subcritical state.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. 1 is a sectional view showing a configuration of a supercritical drying apparatus according to an embodiment of the present invention. The supercritical drying apparatus comprises a sealable container 101, and the container 101 includes an upper part 10 of the container.
1a and a container lower part 101b. Container 10
1, a reaction chamber 102 is formed, and a container lower part 101b is formed.
A substrate mounting table 103 is fixed inside the reaction chamber 102,
A substrate 104 to be processed is mounted on the substrate mounting table 103. Further, as shown in FIG. 1B, the container upper part 101a and the container lower part 101b can be divided, and the container 101 is configured so that the reaction chamber 102 can be opened to the outside. In addition,
The container may be integrally formed, provided with a loading / unloading port which can be opened and closed and communicated with the reaction chamber, and the substrate mounting table may be loaded and unloaded from the loading / unloading port together with the substrate.

Liquefied carbon dioxide is stored in the cylinder 105, and liquefied carbon dioxide delivered from the cylinder 105 is pumped through a pipe 107 by a pressure pump 106.
The liquefied carbon dioxide fed under pressure is injected from a nozzle 108 communicating with a pipe 107 onto a substrate 104 on a substrate mounting table 103. A valve 109 for controlling the flow rate of liquefied carbon dioxide transported in the pipe 107 is provided in the middle of the pipe 107. In addition, without using the pressure pump 106,
A configuration in which liquefied carbon dioxide is directly supplied from the cylinder 105 may be adopted. The liquefied carbon dioxide introduced into the reaction chamber 102 is discharged from the outlet 110 to the outside of the container 101.
The outlet 110 is provided with a valve 111 for controlling the amount of discharge from the reaction chamber 102. The reaction chamber 10 is determined based on the amount of pressure supplied from the pump 106 and the amount of opening and closing of the valve 111.
2 can be controlled.

In addition, in the supercritical drying apparatus according to the present embodiment, a mixed flow plate 112 is provided between the nozzle 108 and the substrate mounting table 103 so as to face the substrate mounting table 103. The diagonal flow plate 112 is disposed so as to be substantially parallel to the substrate 104 mounted on the substrate mounting table 103. As shown in the plan view of FIG. 2A, for example, the diagonal flow plate 112 has a plurality of openings 121 that radially extend outward from the center of the disk. Further, as shown in the side views of FIGS. 2A and 2B, fins 122 opened in the same circumferential direction of the disk at the same angle (for example, 10 ° with respect to the plane of the diagonal flow plate 112) are provided in the respective openings 121. It has a formed structure. Further, as shown in FIG. 1A, the diagonal flow plate 112 holds the fixing member 1 such that the fins 122 spread in the direction in which the substrate 104 is placed.
13 and is fixed to the container 101a.

The liquefied carbon dioxide pumped to the container 101 is discharged from the nozzle 108 and flows into the mixed flow plate 112, and the liquefied carbon dioxide flowing into the mixed flow plate 112 is diffused on the mixed flow plate 112 in all directions. Then, the liquefied carbon dioxide diffused in all directions on the mixed flow plate 112 flows from the opening 121 to the mixed flow plate 112.
It flows toward the lower substrate 104. At this time, the opening 1
Since the fin 122 is provided in the opening 21, the opening 1
The liquefied carbon dioxide flowing out below 21 is
22 allows the liquid to flow obliquely into the substrate 104. The openings 121 are arranged radially from the center of the mixed flow plate 112, that is, the center of the substrate 104, and the fins 122 face in the circumferential direction of the mixed flow plate 112.

Therefore, on the surface of the substrate 104, a flow of the inflowing liquefied carbon dioxide is formed in a circumferential direction of a circle whose center is the center of the substrate 104. Therefore, the mixed flow plate 1
The liquefied carbon dioxide that has flowed into the substrate 104 via the substrate 12 flows outward from the center of the substrate so as to rotate on the substrate 104 (FIG. 3). As a result, when the substrate 104 on which the fine pattern on which the rinsing liquid is adhered as a result of the rinsing process is processed by the present apparatus, the liquefied carbon dioxide newly flowing in causes the The liquefied carbon dioxide mixed with the liquid is pushed to the outer periphery of the substrate. Also, the diagonal flow plate 112 is
If the substrate 104 is formed to have the same size as that of the substrate 04, the liquefied carbon dioxide can be uniformly supplied to the entire substrate even if the substrate 104 has a large diameter of 300 mm. Contrary to the above, a flow of liquefied carbon dioxide may be formed from the outer periphery of the substrate toward the inner periphery of the substrate, and if a state where liquefied carbon dioxide flows without convection over the entire substrate is obtained,
Similar effects can be obtained.

Next, a supercritical drying method using the present supercritical drying apparatus will be described. Hereinafter, a case in which a pattern is formed on a substrate using an electron beam positive resist ZEP-7000 (manufactured by Nippon Zeon Co., Ltd.), and a supercritical drying is performed after a rinsing process in the pattern formation will be described.
The pattern was formed by applying the above resist on a substrate to a thickness of about 250 nm. The pattern width and pattern interval are 5
A plurality were formed in the range of 0 to 200 nm. In the rinsing treatment, 2-propanol was used as a rinsing liquid.

First, as shown in FIG.
The substrate 104 wet with 1 or 2-propanol is placed on the substrate platform 103 (FIG. 1A),
Is closed, the pressure pump 106 is operated, the valve 109 is opened, liquefied carbon dioxide is pressure-fed from the cylinder 105 to the nozzle 108, and liquefied carbon dioxide is discharged from the tip of the nozzle 108 at about 100 ml / min. Further, by controlling the opening amount of the valve 111, the pressure inside the reaction chamber 102, that is, the pressure around the substrate 104 and the pattern 104a is set to 7.5 MPa,
The inside temperature was 23 ° C.

The liquefied carbon dioxide discharged from the nozzle 108 reaches the substrate 104 via the mixed flow plate 112,
As shown in B, the surface of the substrate 104 is liquefied carbon dioxide 40
2 is immersed. At this time, as described above,
The flow of liquefied carbon dioxide flowing outward from the center of the substrate so as to rotate on the substrate 104 is formed, and the pattern 10
The rinsing liquid between 4a is also efficiently replaced with liquefied carbon dioxide.

After performing the substitution process for 20 minutes, the pressure in the reaction chamber 102 is maintained at 7.5 MPa, and the temperature of the liquefied carbon dioxide is increased to 35 ° C. to bring the substrate 104 into a supercritical state. 4C, and
As shown in FIG. 7, the periphery of the pattern 104a is supercritical carbon dioxide 403. Thereafter, by increasing the opening amount of the valve 111 and lowering the pressure in the reaction chamber 102 to vaporize the supercritical carbon dioxide, as shown in FIG. 4D, no rinsing liquid remains between the patterns 401a, The substrate 104 on which the pattern 104a is formed without a pattern collapse
Can be dried.

On the other hand, when supercritical drying was performed without using a mixed flow plate, pattern collapse occurred. As described above, when the supercritical drying value of the present embodiment is used, the supercritical drying can be performed in a state where the pattern does not collapse due to the function of the mixed flow plate. In addition, the effect of obliquely flowing the liquefied carbon dioxide by the mixed flow plate increases as the pressure of the liquefied carbon dioxide increases. For example, when the pumping speed of liquefied carbon dioxide is set to 20 ml / min, even if a mixed flow plate is provided, the inflow angle of the liquefied carbon dioxide to the substrate becomes almost vertical, so that the above effect is not obtained much. However, when the pumping speed of the liquefied carbon dioxide is set to 100 ml / min, the inflow angle of the liquefied carbon dioxide to the substrate becomes larger from the vertical angle by arranging the mixed flow plate, so that the replacement of the rinsing liquid can be performed. It will be done more efficiently.

The diagonal plate may have the structure shown in FIGS. 5, 6, and 7. The mixed flow plate 501 shown in the plan view of FIG. 5A.
Is formed in a disk shape and has a plurality of openings 50 on the same circumference.
2 and fins 503 formed in each opening 502 in the same circumferential direction. FIG. 5B
FIG. 5A shows a cross section taken along line XX of FIG. 5A, and FIG. 5A shows a state viewed from above in FIG. 5B. The liquefied carbon dioxide that has flowed into the center of the mixed flow plate 501 spreads around the mixed flow plate 501,
It flows from the opening 502 to the fin 503 formation side, and the fin 5
Due to 03, the flow becomes a diagonal flow directed in the circumferential direction of the diagonal flow plate 501 and flows downward.

The mixed flow plate 601 shown in the plan view of FIG. 6A has a plurality of openings 602. FIG. 6B shows a side surface of the opening 602 viewed from the direction of arrow Y, and FIG.
The side surface of the opening 602 viewed from the direction of arrow X is shown. The convex portion forming the opening 602 is formed on the side on which the substrate to be processed is placed. Opening 602
Are in the same direction in four regions divided into four by orthogonal coordinates passing through the center of the disk-shaped mixed flow plate 601. In FIG. 6A, an opening 602 arranged in the upper right area
Indicates the direction of the x-axis of the rectangular coordinates. The opening 602 arranged in the lower right region faces the direction of the y-axis of the rectangular coordinates. The opening 602 arranged in the upper left area faces the direction of the y-axis of the rectangular coordinates. The opening 602 arranged in the lower left area is oriented in the direction of the x-axis of the rectangular coordinates.

A mixed flow plate 701 shown in the plan view of FIG. 7 is an impeller in which a plurality of blades 702 are fixed to a substantially frustoconical hub 703, for example, an impeller used for a mixed flow blower. If liquefied carbon dioxide flows into the mixed flow plate 701 from the front of FIG. 7, the flow direction of the liquefied carbon dioxide is changed by the wings 702. The same effect can be obtained.

Embodiment 2 Next, another embodiment of the present invention will be described. FIG. 8A
1 is a cross-sectional view illustrating a configuration of a supercritical drying device according to the present embodiment. The supercritical drying apparatus is a container 1 that can be sealed.
The container 101 is composed of a container upper portion 101a and a container lower portion 101b. In the container 101,
A reaction chamber 102 is formed, and the reaction chamber
A substrate mounting table 103 is fixed inside 02, and a substrate 104 to be processed is mounted on the substrate mounting table 103. Also in this embodiment, similarly to the above-described embodiment, the container upper part 101a and the container lower part 101b can be divided, and the container 101 is configured so that the reaction chamber 102 can be opened to the outside.

The cylinder 105 contains liquefied carbon dioxide, and the liquefied carbon dioxide is supplied to a pressure pump 106.
, And is injected from the side of the substrate mounting table 103 from a nozzle 108 a communicating with the pipe 107.
A valve 109 for controlling the flow rate of liquefied carbon dioxide transported in the pipe 107 is provided in the middle of the pipe 107. The liquefied carbon dioxide introduced into the reaction chamber 102 is discharged from the outlet 110 to the outside of the container 101.
The outlet 110 is provided with a valve 111 for controlling the amount of discharge from the reaction chamber 102. The reaction chamber 10 is determined based on the amount of pressure supplied from the pump 106 and the amount of opening and closing of the valve 111.
2 can be controlled.

In addition, in the supercritical drying apparatus of the present embodiment, the diffusion plate 812 is provided between the nozzle 108a provided on the side of the container 101 and the substrate mounting table 103. As shown in the top view of FIG. 8B, the diffusion plate 812 is provided with a plurality of openings 821, and each opening 821 has a fin that opens at a predetermined angle in a direction that spreads from the center of the diffusion plate 812 to both sides. 822 are formed. Therefore, the liquefied carbon dioxide discharged from the nozzle 108 a is spread over the entire area of the substrate 104 by the diffusion plate 812 and is supplied onto the substrate 104. The liquefied carbon dioxide diffused by the diffusion plate 812 flows into the substrate 104 from one end of the substrate 104, passes through the entire area of the substrate 104, and flows to the other end of the substrate 104.

As a result, as a result of the rinsing process, the substrate 10 on which the fine pattern to which the rinsing liquid is adhered is formed.
When 4 is processed by the present apparatus, the liquefied carbon dioxide that has already flowed in onto the substrate and mixed with the rinsing liquid due to the newly-introduced liquefied carbon dioxide is flushed to the outer periphery of the substrate. Further, if the width of the diffusion plate 812 is formed to be substantially the same length as the substrate 104, even if the substrate 104 has a large diameter of 300 mm, liquefied carbon dioxide can be uniformly supplied to the entire substrate. .

Next, a supercritical drying method using the present supercritical drying apparatus will be described. Hereinafter, a case in which a pattern is formed on a substrate using an electron beam positive resist ZEP-7000 (manufactured by Nippon Zeon Co., Ltd.), and a supercritical drying is performed after a rinsing process in the pattern formation will be described.
The pattern was formed by applying the above resist on a substrate to a thickness of about 250 nm, exposing it to an electron beam, and developing it with normal hexyl acetate. Pattern width and pattern interval are 50 ~
A plurality were formed in a range of 200 nm. In the rinsing treatment, 2-propanol was used as a rinsing liquid.

First, the substrate 104 wet with the rinsing liquid, ie, 2-propanol, is placed on the substrate mounting table 103 (FIG. 8A).
After placing the reaction chamber 102 in a sealed state, the pressure pump 106 is operated and the valve 109 is opened, liquefied carbon dioxide is pressure-fed from the cylinder 105 to the nozzle 108a, and liquefied carbon dioxide is About 100
Discharge at milliliter / min. Also, the valve 11
By controlling the opening amount of 1, the pressure in the reaction chamber 102,
That is, the pressure around the substrate 104 and the pattern 104a was 7.5 MPa, and the temperature inside the reaction chamber 102 was 23 ° C.

The liquefied carbon dioxide discharged from the nozzle 108a reaches the substrate 104 via the diffusion plate 812, and the surface of the substrate 104 is immersed in the liquefied carbon dioxide.
At this time, as described above, a flow of liquefied carbon dioxide flowing from one end to the other end on the substrate 104 is formed,
The rinse liquid between the patterns 104a is also efficiently replaced with liquefied carbon dioxide.

After performing the substitution process for 20 minutes, the pressure in the reaction chamber 102 is maintained at 7.5 MPa, and the temperature of the liquefied carbon dioxide is set to 35 ° C. to bring the substrate 104 into a supercritical state. Is in a state of flowing. Thereafter, by increasing the opening amount of the valve 111 and reducing the pressure in the reaction chamber 102 to vaporize the supercritical carbon dioxide,
The substrate 104 on which the pattern 104a has been formed can be dried without leaving a rinse liquid between the patterns 401a and without causing the pattern to collapse.

In the above embodiment, a pattern is formed by developing with normal hexyl acetate using the electron beam resist ZEP-7000, and a rinsing process is performed with 2-propanol. It is not limited. The present invention is also applicable to a case where a pattern is formed with another developing solution using another resist and a rinsing process is performed using another processing solution. Also,
Even if the pattern is made of silicon or a compound semiconductor material, the collapse of the pattern can be suppressed by performing the supercritical drying using the supercritical drying apparatus of the present invention. In addition, in the above embodiment, carbon dioxide is used as the supercritical fluid. However, the present invention is not limited to this.
The same applies when various liquid fluids having a critical point such as F ₃ and NO ₂ are used.

[0042]

As described above, according to the present invention,
Since the rinse liquid attached to the pattern layer can be efficiently replaced with a liquid such as carbon dioxide, supercritical drying can be performed while minimizing the occurrence of pattern collapse. Is obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a supercritical drying apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view A and a side view B showing a configuration of a mixed flow plate 112 in the supercritical drying apparatus of the embodiment.

FIG. 3 shows a substrate 1 in the supercritical drying apparatus according to the embodiment.
It is a perspective view which shows the state in the vicinity of 04 upper part.

FIG. 4 is a process diagram illustrating a supercritical drying method using the supercritical drying apparatus according to the embodiment.

FIG. 5 is a plan view A and a cross-sectional view B showing another embodiment of the mixed flow plate.
It is.

FIG. 6 is a plan view A and sectional views B and C showing another embodiment of the mixed flow plate.

FIG. 7 is a plan view showing another embodiment of the mixed flow plate.

FIG. 8 is a configuration diagram illustrating a configuration of a supercritical drying apparatus according to another embodiment of the present invention.

FIG. 9 is a process chart showing pattern collapse in drying after a rinsing process.

FIG. 10 is a configuration diagram showing a configuration of a conventional supercritical drying apparatus.

FIG. 11 is a process chart showing a conventional supercritical drying method.

[Explanation of symbols]

101: Container, 101a: Upper container, 101b: Lower container, 102: Reaction chamber, 103: Substrate mounting table, 104: Substrate, 105: Cylinder, 106: Pumping pump, 107: Piping, 108: Nozzle, 109: Valve, Reference numeral 110 denotes a discharge port, 111 denotes a valve, 112 denotes a diagonal plate, 113 denotes a fixing member, 121 denotes an opening, and 122 denotes a fin.

Claims (6)

[Claims] 1. A sealable container having a reaction chamber on which a substrate to be processed is placed, a liquid supply means for supplying a liquid of a substance which is a gas in the atmosphere to the reaction chamber, and A nozzle that is disposed above a substrate central portion and discharges the liquid of the substance supplied by the liquid supply unit onto the substrate in the reaction chamber, and is disposed between the nozzle and the substrate; A diagonal flow plate having a plurality of openings in which the direction of flow of the ejected substance is less than 90 ° with respect to the surface of the substrate, and is changed to a direction of a circumference whose center is the center of the substrate. Discharging means for discharging the fluid introduced into the reaction chamber; control means for controlling the pressure in the reaction chamber to a pressure at which the substance becomes a supercritical state; and controlling the temperature in the reaction chamber to a predetermined temperature. Temperature control to control Supercritical drying apparatus characterized by comprising a means. 2. A sealable container having a reaction chamber on which a substrate to be processed is mounted, liquid supply means for supplying a liquid of a substance which is a gas in the atmosphere to the reaction chamber, and the substrate in the reaction chamber. A nozzle that is disposed on the side of the substrate above an arrangement position and discharges the liquid of the substance supplied by the liquid supply unit in a direction toward the substrate; and a discharge unit that discharges a fluid introduced into the reaction chamber. A control means for controlling the pressure in the reaction chamber to a pressure at which the substance becomes a supercritical state; and a temperature control means for controlling the temperature in the reaction chamber to a predetermined temperature. Critical drying equipment. 3. The supercritical drying apparatus according to claim 2, further comprising: a diffusion plate disposed between the nozzle and the substrate, for diffusing a direction in which the substance discharged from the nozzle flows into the entire area of the substrate. A supercritical drying device, comprising: 4. The supercritical drying apparatus according to claim 1, wherein the liquid supply unit includes: a cylinder that stores the liquid of the substance; and a container that stores the liquid of the substance. A pressure-feeding means for feeding the liquid into the reaction chamber via a pipe. 5. The supercritical drying apparatus according to claim 1, wherein the substance is carbon dioxide. 6. The supercritical drying apparatus according to claim 1, wherein the supercritical state includes a subcritical state.