JPH1116824A - Method and device for development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a fine pattern of higher aspect ratio by preventing a resist pattern from breaking due to surface tension when a rinse liquid is dried. SOLUTION: The device is so configured as to develop a pattern on a substrate 2. Here, with heating mechanisms 18 and 24 provided, one or more of the substrate 2, a final rinse liquid, and a dry air, are heated for processing the method, a process is provided where, when the final rinse liquid 13 or the dry air is supplied to the substrate 2, the temperature of one or more of the substrate 2, the final rinse liquid 13, and the air for drying, are made higher than that of the substrate 2 and a solvent used in the process before the final rinse liquid 13 is supplied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing apparatus and a developing method used for forming a fine pattern using a resist for ultrafine processing such as a super LSI.

[0002]

2. Description of the Related Art In the ultra LSI processing technology, patterns have been miniaturized, and are now entering a region of 0.2 μm or less in a development stage. A dry etching process is employed in LSI substrate processing, and a fine pattern is usually transferred to a substrate using a resist as a mask. In order to use this resist pattern as a mask for dry etching, a certain thickness (usually, about 0.5 μm) is required, and a certain film thickness is required to eliminate defects such as pinholes during resist coating. It is necessary to secure the thickness. In this case, as the pattern becomes finer, the ratio between the height and width of the resist pattern (called the aspect ratio) increases, and a phenomenon occurs in which adjacent patterns are stuck together during the development process and collapse. This pattern collapse is caused by the mechanical force acting on the fine resist pattern due to the surface tension of the solvent when the final rinse liquid is dried. In order to reduce this problem, a method of freeze-drying the final rinse solution has been proposed.However, the use of liquid nitrogen and the need for a vacuum drying process have resulted in significant cost increases and the effects of residual impurities. You. On the other hand, as a simpler method for preventing pattern collapse, there is a method in which a low surface tension solvent is used for the final rinse liquid. The most suitable as such a solvent is a perfluorocarbon solvent such as perfluoropentane, perfluorohexane and perfluoroheptane having a surface tension at room temperature of 15 dyn / cm or less. If a perfluorocarbon solvent is used for the final rinse,
The aspect ratio, which was limited to 3-4, can be improved to 4-5.

However, if the minimum pattern dimension is reduced to 0.1 μm or less while maintaining the currently used resist film thickness of about 0.5 μm, the aspect ratio becomes 5 or more, and the perfluorocarbon solvent is usually used. Even when used as a final rinsing liquid, stable pattern formation becomes difficult.

[0004] When forming various fine elements using ultra-fine processing of 0.1 μm or less besides the VLSI, as the miniaturization progresses, even if an extremely thin resist of about 100 nm is used, this pattern collapse may occur. Since the actual resolution is determined, essentially the same problem as in the above-mentioned LSI manufacturing is encountered.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a developing apparatus and a developing method for preventing a resist pattern from collapsing due to surface tension when a rinsing liquid is dried to form a fine pattern having a higher aspect ratio. The challenge is to provide

[0006]

In order to solve the above problems, according to the present invention, when the rinsing liquid is dried, the surface temperature of the final rinsing liquid is reduced by increasing the drying temperature of the final rinsing liquid. This prevents the pattern from collapsing upon drying. In the conventional developing method, a developing solution and a rinsing liquid (sometimes divided into an intermediate rinse and a final rinse) are sequentially supplied to the exposed resist on the substrate to be processed, and finally, the substrate is dried with dry air or nitrogen gas. However, at this time, the temperature of the developing solution and the rinsing solution are controlled at a temperature around room temperature.
In many cases, the temperature is kept constant, and heating is not particularly performed at a high temperature. In the present invention, as a means for improving the drying temperature of the final rinsing liquid, the substrate to be processed, or the final rinsing liquid, or any of a drying gas such as dry air or nitrogen,
Alternatively, by heating a plurality of these,
It has been found that an ultrafine pattern with a higher aspect ratio can be formed. The solvent used as the final rinsing liquid depends on the type of the resist. Generally, pure water is used for a photomask resist comprising an alkali-soluble resin such as a novolak resin and a photosensitive agent, and alcohol such as isopropyl alcohol is used for an electron beam resist such as polymethyl methacrylate and CMS. It is known that the surface tension of a substance decreases with increasing temperature. Therefore, the surface tension of pure water at room temperature (23 ° C.) is about 75 × 10
^-3 N / m, and 0.14 × 10 ^-3 N /
Since the value of m surface tension decreases, it can be reduced to about 70 × 10 ⁻³ N / m when dried at 60 ° C. In the case of isopropyl alcohol, the surface tension is about 23 × 1 at room temperature (23 ° C.).
0 ^-3 is N / m, 1 ℃ rise when about 0.08 × 10 ^-3
Since drying at 45 ° C. reduces the surface tension to about 21 × 10 ⁻³ N / m because the surface tension of N / m decreases. On the other hand, as a representative of a perfluorocarbon solvent which is a solvent having the lowest surface tension as a general-purpose solvent, the value of the surface tension of perfluorohexane is about 14 × 10 ⁻³ N / at room temperature (23 ° C.).
m and about 0.094 × 10 ⁻³ N / m when the temperature rises by 1 ° C.
Surface tension value decreases. Therefore, when the temperature is raised to 23 ° C., which is a normal developing condition, and dried at 55 ° C. near the boiling point, the surface tension decreases to about 11 × 10 ⁻³ N / m. Thus, by raising the temperature at the time of final rinse liquid drying,
This has the effect of considerably reducing the surface tension.

[0007] As a heating means at the time of drying, three methods can be used. First, by raising the substrate temperature, the effect can be obtained most easily in terms of the device. However, the temperature at the time of development may increase, and it is necessary to change the conventional development process. On the other hand, a method of heating the final rinse liquid is also effective. In particular, when pure water is used as the final rinse, the load on the apparatus is small, but with organic isopropyl alcohol, it is necessary to enhance fire extinguishing equipment. In addition, since the perfluorocarbon solvent is nonflammable, there is no problem of fire extinguishing. However, since the vapor pressure is high, it is necessary to pay attention to the pressure. Compared with these, dry air, nitrogen gas, and argon gas used for final drying are also easier to heat, and in particular, nitrogen gas and argon gas are most advantageous because they are safe to heat. Furthermore, by combining a plurality of these three methods, the heating temperature during drying can be increased. In practice, the heating means is selected depending on the type and properties of the final rinse liquid.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. The developing device of the present embodiment is characterized in that a mechanism for heating the final rinsing liquid and the drying gas to reduce the surface tension of the final rinsing liquid when drying the final rinsing liquid is provided. This example is shown in FIG.

In this developing apparatus, a wafer support 3 for holding a wafer 2 as a substrate to be processed and a motor 4 having the support 3 fixed on a rotating shaft are arranged in a developing cup 1. Above the table 3, a developer nozzle 8 for supplying the developer 7 onto the wafer 2, a final rinse nozzle 16 for supplying a final rinse liquid 13 onto the wafer 2, and a dry gas onto the wafer 2. And a dry gas nozzle 23 to be sprayed. Further, the developing cup 1 is provided with a drain 5 for discharging a developing solution and a rinsing solution in the cup.

The pipeline of the developing solution nozzle 8 is inserted into the developing solution tank 6 via an electromagnetic valve 9. Developer tank 6
Is provided with a high-pressure gas supply port 11 for supplying a high-pressure gas for pressure-feeding the developer into the tank via a pressure gauge 10. By supplying a high-pressure gas from the supply port 11 and opening the electromagnetic valve 9, the developer 7 in the tank 6 is supplied onto the wafer 2 through the developer nozzle 8.

The conduit of the final rinse nozzle 16 is
7 and is inserted into the final rinse tank 12. The final rinse tank 12 is provided with a high-pressure gas supply port 15 for supplying a high-pressure gas for pressure feeding into the tank via a pressure gauge 14. A high-pressure gas having a predetermined pressure is supplied from the supply port 15, and the solenoid valve 17 is opened.
The final rinsing liquid 13 is supplied to the wafer 2 through the nozzle 16. Further, the final rinsing tank 12 is provided with a temperature adjusting means including a heater 18 and a temperature measuring device 19. By this temperature adjusting means, the final rinsing liquid 13 in the tank 12 can be heated to a constant temperature and supplied to the wafer 2 from the nozzle 16. As the final rinsing liquid 13, perfluoropentane, perfluorohexane, perfluoroheptane and a mixture thereof are effective, but those having an even larger number of carbon atoms, such as 8, 9, 10, 11, 12, 13, etc. Perfluorocarbon solvents and mixtures thereof are used.

The duct of the dry gas nozzle 23 is connected to the gas cylinder valve 21 of the high-pressure gas cylinder 20 via a temperature measuring means 25, a heater 24 and a pressure gauge 22. When the gas cylinder valve 21 is opened, the dry gas is supplied from the inside of the high-pressure gas cylinder 20 to the wafer 2 through the nozzle 23. Further, the heater 2 provided in the pipeline of the nozzle 23
4 and a temperature control means comprising a temperature measuring device 19,
The drying gas passing through the pipe of the nozzle 23 is heated to a certain temperature and can be supplied to the wafer 2 from the nozzle 23. As the dry gas, nitrogen gas, argon gas, dry air, or the like is used, and nitrogen gas is particularly preferably used.

The temperatures of the final rinsing liquid 13 and the dry gas are adjusted and controlled so as to be at least 20 ° C. higher than the temperature of the developing liquid 7 and lower than the boiling point of the final rinsing liquid 13.
Heaters 18, 24 linked to temperature measuring devices 19, 25
Is heated and adjusted. In addition, the wafer 2 may be heated. In that case, a heater may be built in the wafer support 3 to heat the wafer 2.

An embodiment of the developing method according to the present invention will be described by taking the case where the above-described developing device is used as an example. In this embodiment, the temperature of the final rinsing liquid 13 and the temperature of the drying gas are higher than the temperatures of the substrate and the solvent used in the step prior to the final rinsing step when the drying is performed by the final rinsing step or the drying gas spraying. The method is characterized by including a step of setting a temperature. A wafer 2 as a substrate to be processed is suction-held on a wafer support 3 in a developing cup 1. The wafer 2 is obtained by spin-coating a resist having an appropriate thickness, baking it under appropriate conditions, and then drawing a fine pattern. The motor 4 is driven and the wafer 2
Is rotated at a desired speed, and the developer 7 is supplied to the wafer 2 through the developer nozzle 8. Subsequently, the final rinsing liquid 13 at a higher temperature than the solvent (the developing liquid 7) in the previous developing step is supplied through the nozzle 16. The developer 7 and the final rinse 13 supplied from the nozzle 8 are discharged from the drain 5. After supplying the final rinsing liquid 13 to the wafer 2, the wafer 2 is dried by blowing a dry gas heated to the same temperature as the final rinsing liquid 13, for example, a nitrogen gas or dry air.

In the final rinsing step and the drying step,
By heating the temperature of the final rinsing liquid 13 and the drying gas to a temperature higher than the temperature of the solvent (developer 7) in the previous developing step, and increasing the drying temperature of the final rinsing liquid 13, the surface of the final rinsing liquid 13 is heated. The tension can be reduced, and the pattern size at which pattern collapse occurs can be reduced. This developing method is effective for any type of rinsing liquid, but the most effective is that the main component of the final rinsing liquid is a single perfluorocarbon solvent or two or more types. Of a mixture of perfluorocarbon solvents. As the perfluorocarbon solvent, the number of carbons is 5, 6, 7
The perfluoropentane, perfluorohexane, perfluoroheptane and mixtures thereof are effective, but have a larger number of carbon atoms, that is, 8,9,10,1.
Perfluorocarbon solvents such as 1, 12, 13 and the like and mixtures thereof can also be used. Also, the final rinse liquid 1
It is desirable that the temperature of 3 and the dry gas be higher than the temperature of the developing solution 7 by 20 ° C. or more and lower than the boiling point of the final rinsing liquid 13. In the above-described embodiment, the final rinse liquid and the dry gas are heated. However, if at least one of the wafer (substrate), the final rinse liquid, and the dry gas is heated, the final rinse liquid and the dry gas are heated. The purpose of reducing the surface tension during drying can be achieved, and the same effect can be obtained.

As still another embodiment, when a middle rinsing liquid is supplied to the wafer 2 after the developing step and then a final rinsing liquid 13 is supplied, a supply mechanism (supply mechanism) for supplying the developing liquid 7 is used. An intermediate rinsing supply mechanism having the same configuration as the tank 6, the solenoid valve 7, the nozzle 8, the pressure gauge 10, and the high pressure gas supply port 11) is provided, and the intermediate rinsing nozzle is arranged on the wafer 2 to perform development. A developing device configured to supply an intermediate rinsing liquid to the wafer 2 like the liquid 7 is used.
In the present embodiment, after supplying the unheated developer 6 and the intermediate rinsing liquid onto the wafer 2, the heated final rinsing liquid 13 is supplied, and then the heated dry gas is blown to the final rinsing liquid. 13 is dried. Also in the embodiment in which the step of supplying the intermediate rinsing liquid is added, the temperatures of the final rinsing liquid 13 and the drying gas are heated to a higher temperature than the solvent (the developing liquid 7 and the intermediate rinsing liquid) in the previous developing step. By increasing the temperature at the time of drying the final rinsing liquid 13, the surface tension of the final rinsing liquid 13 is reduced, and the effect of reducing the pattern size at which pattern collapse occurs can be obtained.

[0017]

Next, the present invention will be described more specifically with reference to examples. Example 1 A chemically amplified X-ray resist SEPR-44-D (manufactured by Shin-Etsu Chemical Co., Ltd.) was deposited on a 6-inch silicon substrate by 0.5.
After spin coating to a film thickness of μm and pre-baking at 100 ° C. for 120 seconds, using an SOR beam line,
X-ray exposure was performed. After exposure, post-baking was performed at 75 ° C. for 120 seconds. The used X-ray mask has a window of 20 mm square, in which a 0.4 μm thick tantalum line and space pattern having a line and space ratio of 1: 1 from 100 nm to 300 nm in 10 nm steps. Are formed on a 2 × 2 matrix at an interval of 10 mm in both the X and Y directions. Two substrates were prepared, and one substrate was supplied with a 2.1% aqueous solution of tetramethylammonium hydroxide at 23 ° C. while rotating at a rotation speed of 100 rpm.
After developing for 60 seconds, pure water at 23 ° C. was supplied as a rinsing liquid for 60 seconds, and dried by blowing nitrogen gas at 23 ° C. The second substrate is supplied with a 2.1% aqueous solution of tetramethylammonium hydroxide at 23 ° C. while rotating at a rotation speed of 100 rpm, and is developed for 60 seconds.
Then, pure water at 23 ° C. was supplied as an intermediate rinse for 60 seconds, then pure water heated to 60 ° C. was supplied for 20 seconds, and finally, nitrogen gas at 60 ° C. was blown and dried. These two
When the resolution of the sample was compared with an electron microscope, the first sample, which was rinsed with pure water at 23 ° C. and dried with nitrogen gas at 23 ° C., had a line and space pattern having a period of 250 nm at the periphery of the substrate. Until then, resolution was possible without pattern collapse where adjacent patterns stick together. The second sample, which was finally rinsed with pure water at 60 ° C. and dried with nitrogen gas at 60 ° C., could be resolved up to a line and space pattern with a period of 220 nm without adjacent patterns sticking together. As is apparent from this result, a finer line and space pattern can be resolved by heating the final rinse liquid, pure water, and heating the nitrogen gas used for drying. This is because the surface tension of pure water as the final rinsing liquid was reduced by increasing the drying temperature.

Example 2 Z on a 4-inch silicon substrate
An EP-520 resist is spin-coated to a thickness of 0.4 μm and baked in an oven at 165 ° C. for 30 minutes, and then an electron beam exposure apparatus (JBX-5FE manufactured by JEOL Ltd.)
Was used to draw a fine pattern. The drawn pattern is 1
A line and space pattern is drawn from the 00 nm cycle to the 300 nm cycle in increments of 5 nm over a length of 2 mm with an exposure amount of 10 levels in each cycle as one set, and drawn on the entire wafer in a matrix at an interval of 10 mm in both the XY directions. did. Two substrates were prepared, and one substrate was rotated at a rotation speed of 100 rpm while maintaining the substrate temperature at 23 ° C., and ZED-
N50 (manufactured by Zeon Corporation) is supplied at 23 ° C. and development is performed for 5 minutes. Then, isopropyl alcohol (abbreviated as IPA) is supplied as a rinse solution at 23 ° C. for 60 seconds, and nitrogen gas is blown at 23 ° C. And dried. The second substrate is a ZED-N50 (manufactured by Zeon Corporation) at 23 ° C. at a rotation speed of 100 rpm while maintaining the substrate temperature at 23 ° C.
And developing for 5 minutes, and then supplying the IPA at 23 ° C. as an intermediate rinse for 60 seconds to raise the substrate temperature to 45 ° C.
Temperature. Thereafter, IPA at 45 ° C. was supplied for 20 seconds, and finally nitrogen gas at 45 ° C. was blown to dry. When the resolution of these two samples was compared with an electron microscope, the first sample, which was rinsed with 23 ° C. IPA and dried with 23 ° C. nitrogen gas, had 20% at the periphery of the substrate.
It was possible to resolve a line and space pattern having a cycle of 0 nm without causing a pattern collapse in which adjacent patterns were stuck together. 4
The final sample was rinsed with 45 ° C. IPA at 5 ° C. substrate temperature and dried with 45 ° C. nitrogen gas.
Up to a line and space pattern with a period of 5 nm, the pattern could be resolved without causing the pattern collapse where the adjacent patterns were stuck. As is apparent from this result, a finer line and space pattern can be resolved by heating the substrate, heating the final rinse liquid IPA, and heating the nitrogen gas used for drying. This is because the surface tension of IPA, which is the final rinse liquid, was lowered by increasing the drying temperature.

[Embodiment 3] Z on a 4-inch silicon substrate
EP-520 mixed with fullerene C60 (manufactured by MER) at a ratio of 10% by weight based on the weight of the resist polymer was spin-coated to a thickness of 0.25 μm,
After baking in an oven at a temperature of 30 ° C. for 30 minutes, a fine pattern was drawn using an electron beam exposure apparatus (JBX-5FE manufactured by JEOL Ltd.). The drawn pattern is a set of a line and space pattern drawn at an exposure amount of 10 levels in each cycle from the 50 nm cycle to the 150 nm cycle in increments of 5 nm over a length of 2 nm and a cycle of 10 levels.
Writing was performed on the entire surface of the wafer in a matrix at mm intervals. Two substrates were prepared and developed. The developing method is such that the first substrate is kept at 23 ° C., and while rotating at a rotation speed of 100 rpm, ZED-N which is a developing solution of a ZEP resist is used.
50 (manufactured by ZEON CORPORATION) at 23 ° C. and development for 7 minutes, then IPA as an intermediate rinse at 23 ° C. for 60 seconds, followed by 6 minutes of 23 ° C. perfluorohexane.
The solution was supplied for 0 second, and finally dried by blowing nitrogen gas at 23 ° C. The second substrate is kept at 23 ° C.
While rotating at a rotation speed of rpm, ZED-
N50 (manufactured by Nippon Zeon) was supplied and developed for 7 minutes, then IPA was supplied as an intermediate rinse at 23 ° C. for 60 seconds, then perfluorohexane was supplied at 23 ° C. for 60 seconds, and finally at 60 ° C. Dried with nitrogen gas. When the resolution of these two samples was compared with an electron microscope, the first sample dried with nitrogen gas at 23 ° C. showed a line and space pattern up to a 90 nm cycle, and the pattern collapse where the adjacent patterns stuck together. In contrast, the second sample dried with nitrogen gas at 60 ° C resolved the line and space pattern up to a period of 75 nm without causing adjacent patterns to stick together. done. As is apparent from this result, a finer line and space pattern can be resolved by heating the used nitrogen gas. This is because the surface tension of perfluorohexane, which is the final rinsing liquid, was reduced by increasing the drying temperature. In particular, in this example, since a high-temperature drying was performed using perfluorohexane, which is a low surface tension solvent, as the final rinsing liquid, an extremely fine pattern with an aspect ratio of 6.5 or more was obtained, and the effect of the present invention was obtained. highest.

As described above, in the above-described embodiment, the case where the chemically amplified resist SEPR-44-D is exposed to X-rays, the case where ZEP or Z
Although the case where the EP is subjected to electron beam exposure has been described, it is apparent that high resolution can be obtained even if the EP is applied to light exposure using another type of resist or excimer laser. Although nitrogen gas is used as the drying gas, the same effect can be obtained by using an inert gas such as dry air or argon. In the embodiment, pure water, I
Although PA and perfluorohexane were used, similar effects can be obtained with other solvents. In particular, as a low surface tension solvent perfluorocarbon solvent, the number of carbons is 5,
Effective are perfluoropentane, perfluorohexane, perfluoroheptane and mixtures thereof corresponding to 6,7,8,9,9,1
Perfluorocarbon solvents such as 0, 11, 12, and 13 and mixtures thereof can also be used. Further, by providing a temperature difference of 20 ° C. or more as a temperature of a substrate, a rinsing liquid, or a gas to be dried as well as a temperature used typically (room temperature) as well as the temperature used in the embodiment, A clear decrease in surface tension occurred, with a similar effect. The upper limit of the temperature may be the boiling point of the rinsing liquid. Needless to say, these must be lower than the temperature at which the resist hardens and cannot be removed by development.

[0021]

According to the present invention, it is possible to prevent the pattern from collapsing due to the development process in the ultra-fine region of the resist pattern used for ultrafine processing, and to substantially improve the resolution. As a result, a great effect can be obtained in the manufacture of an VLSI, the manufacture of an X-ray mask used therefor, and the manufacture of optical components such as a fine diffraction grating.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of a developing device according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 development cup 2 wafer (substrate) 3 wafer support 4 motor 5 drain 6 developer tank 7 developer 8 developer nozzle 9,17 solenoid valve 10,14,22 pressure gauge 11,15 high pressure gas supply port 12 final rinse tank 13 Final Rinse Liquid 16 Final Rinse Nozzle 18, 24 Heater (Heating Mechanism) 19, 25 Temperature Measuring Device (Control Means) 20 High Pressure Gas Cylinder 21 Gas Cylinder Valve 22 Pressure Gauge 23 Dry Gas Nozzle

Claims (5)

[Claims] 1. A developing solution and two or more rinsing liquids of a final rinsing liquid or an intermediate rinsing liquid and a final rinsing liquid are supplied onto a substrate to which a resist pattern has been transferred, and the final rinsing liquid is dried with a dry gas. A developing device for drying and developing a pattern on the substrate, comprising a mechanism for heating one or more of the substrate, a final rinsing liquid, and a dry gas. 2. The developing device according to claim 1, wherein the heating mechanism sets one or more of the temperature of the substrate, the final rinsing liquid, or the dry gas to the temperature of the developing liquid and the intermediate rinsing liquid. A developing device having a means for adjusting and controlling the temperature to be at least 20 ° C. higher than the boiling point of the final rinse liquid. 3. A developing solution and two or more rinsing liquids of a final rinsing liquid or an intermediate rinsing liquid and a final rinsing liquid are supplied onto the substrate to which the resist pattern has been transferred, and the final rinsing liquid is dried with a dry gas. In a developing method for drying and developing a pattern on the substrate, one or more temperatures of the substrate, the final rinsing liquid, or the gas used for drying are adjusted by supplying the final rinsing liquid or the drying gas to the substrate. A developing method comprising: a step of raising the temperature of a substrate and a solvent used in a step before supplying a rinsing liquid to higher temperatures. 4. The developing method according to claim 3, wherein the high temperature is higher than the temperature of the substrate and the solvent used in the step before supplying the final rinsing liquid by 20 ° C. or more, and is higher than the boiling point of the final rinsing liquid. A low temperature. 5. The developing method according to claim 3, wherein a main component of the final rinsing liquid is a single perfluorocarbon solvent or a mixture of two or more perfluorocarbon solvents. Development method.