JP3801193B2 - Method for forming fine pattern and method for manufacturing semiconductor device - Google Patents

Description

  The present invention relates to a fine separation resist pattern material for increasing the film thickness of a resist pattern when forming a resist pattern in a semiconductor process, a method for forming a fine separation pattern using the same, The present invention relates to a method for manufacturing a semiconductor device using a fine separation pattern, and a semiconductor device manufactured by this manufacturing method.

  Along with the high integration of semiconductor devices, the wiring and isolation width required for the manufacturing process have become very fine. In general, a fine pattern is formed by a method in which a resist pattern is formed by a photolithography technique, and various underlying substrates are etched using the formed resist pattern as a mask.

  Therefore, the photolithography technique is very important in forming a fine pattern. The photolithographic technique is composed of resist coating, mask alignment, exposure, and development, and there is a limit to the demand for miniaturization due to the limitation of the exposure wavelength.

  Furthermore, as the exposure wavelength is shortened, the resist material used has a decrease in etching resistance, and the resist film thickness tends to be reduced from the point of fine pattern formation. There is a limit.

  Therefore, as a technique for improving the etching resistance of the resist, a method of modifying the resist surface by performing a treatment such as silylation of the resist surface has been studied (M. Sebald, et al., SPIE, Vol. 1262, p.528 (1990)).

However, the silylation method cannot be applied when (1) resist removal after etching is difficult and particles are generated, (2) the pattern shape is bad and the etching selectivity is poor, and (3) the base is an oxide film. The problem remains.
As described above, in the conventional photolithographic technique using exposure, it is difficult to ensure etching resistance because there is a limit to increasing the thickness of the resist pattern due to restrictions on fine pattern formation.

  The present invention has been made to solve such a problem, and in order to improve etching resistance in miniaturization of separation patterns and hole patterns, the film thickness of a resist pattern already formed is increased. Therefore, a material for increasing the film thickness and a technique for increasing the film thickness are provided. Furthermore, the present invention provides a method for manufacturing a semiconductor device using the finely divided resist pattern forming technique.

  The method for forming a fine pattern according to the present invention includes a step of forming a first resist pattern with a first resist capable of generating an acid or containing an acid on a substrate, and dissolving the first resist pattern. A non-crosslinkable third resist that does not cause a reaction due to an acid is formed so as to fill the separation space of the first resist pattern, and then, water or an aqueous solution is formed on the first resist pattern. Forming a second resist that is soluble and includes a component that undergoes a crosslinking reaction in the presence of an acid and that undergoes a crosslinking reaction by the supply of an acid from the first resist pattern; and the first resist of the second resist. Forming a cross-linked layer at a portion in contact with the upper surface of the resist pattern, and removing the non-cross-linked portion of the second resist and the third resist to form a second resist pattern It is intended to include and that step.

According to the present invention, a finely divided resist pattern forming material capable of forming a pattern that exceeds the limit of etching resistance of the resist film thickness used in the miniaturization of a resist pattern, and a fine pattern forming method using the same Is obtained.
In addition, it is possible to increase the thickness of the fine resist pattern without degrading the resolution of the resist, and sacrifice the etching resistance to reduce the thickness of the resist film as the pattern becomes finer. Can be realized without any problem. Further, by using the finely divided resist pattern thus formed as a mask, finely separated spaces or holes can be formed on the semiconductor substrate, and a semiconductor device having finely separated spaces or holes is obtained. be able to.

Reference form.
FIG. 1 shows an example of a mask pattern for forming a finely separated resist pattern of interest in a reference form. 1 to 4 are process flow diagrams for explaining a finely divided resist pattern forming method according to a reference embodiment. Here, a positive resist is used.

  First, a method for forming a finely divided resist pattern according to a reference embodiment and a method for manufacturing a semiconductor device using the same will be described with reference to FIGS.

  As shown in FIG. 3, a first resist 1 having a mechanism for generating an acid therein is applied to a semiconductor substrate (semiconductor wafer) 7 by an appropriate heat treatment (for example, a thickness of 0.5 to 0.7 μm). degree).

  The first resist is applied onto the semiconductor substrate 7 by spin coating or the like, and then pre-baked (heat treatment at 70 to 110 ° C. for about 1 minute) to evaporate the solvent in the first resist 1.

  Next, in order to form a first resist pattern, g-line, i-line, Deep-UV, KrF excimer, ArF excimer, EB (electron beam), X-ray, etc. Using a light source corresponding to the sensitivity wavelength, projection exposure is performed using a mask including a pattern as shown in FIG.

  The material of the first resist used here may be a resist using a mechanism that generates an acidic component inside the resist by appropriate heat treatment, and may be either a positive type or a negative type.

  For example, examples of the first resist include a positive resist composed of a novolak resin and a naphthoquinonediazide-based photosensitizer.

  Furthermore, as the first resist, a chemically amplified resist using a mechanism that generates acid can be applied, and any other resist material that uses a reaction system that generates acid by heating may be used. . Examples of the chemically amplified resist include a positive resist composed of a polyhydroxystyrene resin and an onium salt acid generator.

  After the exposure of the first resist 1, PEB (post-exposure heating) is performed as necessary (for example, PEB temperature: 50 to 130 ° C.) to improve the resolution of the resist 1.

  Next, it develops using about 0.05-3.0 wt% alkaline aqueous solution, such as TMAH (tetramethylammonium hydroxide). FIG. 2 shows a first resist pattern formed using a positive chemically amplified resist.

  After the development processing, post-development baking may be performed as necessary (for example, the baking temperature is 60 to 120 ° C. for about 60 seconds). Since this heat treatment affects the subsequent mixing reaction, it is desirable to set the temperature appropriately in accordance with the first resist or the second resist material to be used.

  The process described above is the same as the formation of a resist pattern by a general resist process, except that the first resist 1 that generates an acid is used.

  Next, as shown in FIG. 3, on the semiconductor substrate 7, the second resist 2 mainly composed of a crosslinkable material that crosslinks in the presence of an acid and dissolved in a solvent that does not dissolve the resist pattern of FIG. Apply.

  The method for applying the second resist 2 is not particularly limited as long as it can be uniformly applied onto the first resist pattern 1a, and is applied by spraying, spin coating or dipping (dipping) in the second resist solution. ).

  Next, after the application of the second resist 2, this is pre-baked as necessary (for example, at 85 ° C. for about 60 seconds) to form the second resist layer 2.

  Next, as shown in FIG. 3, the first resist pattern 1a formed on the semiconductor substrate 7 and the second resist 2 formed thereon are heat-treated. The heating temperature is, for example, about 85 ° C. to 140 ° C., and is a temperature range in which the resist pattern 1a is not deformed. The heat treatment promotes acid diffusion from the first resist pattern 1a, supplies the acid into the second resist 2, and causes a crosslinking reaction at the interface with the second resist 2 in contact with the upper surface of the resist pattern 1a. . The heat treatment temperature / time in this case is, for example, 85 ° C. to 140 ° C./60 to 120 seconds, and may be set to an optimum condition depending on the type of resist material used and the required thickness of the reaction layer.

  A cross-linked layer 4 that has undergone a cross-linking reaction by this mixing baking is formed in the second resist 2 so as to cover the first resist pattern 1a.

  Next, as shown in FIG. 3, the non-crosslinked second resist 2 is developed and removed using a developer of water, an aqueous solution of a water-soluble organic solvent, or an alkaline aqueous solution such as TMAH. Second resist pattern 2a is formed. By the above processing, it is possible to obtain a resist pattern in which the hole inner diameter or the line pattern separation width is reduced or the area of the isolated pattern is enlarged.

  As described above, in the fine resist pattern forming method described with reference to FIG. 3, the first resist is formed by an appropriate heat treatment before or after the formation of the second resist layer 2 on the first resist pattern 1a. The method of generating an acid in the pattern 1a and diffusing it into the second resist 2 has been described.

  Next, a method for generating an acid by exposure instead of this heat treatment or prior to the heat treatment will be described.

  FIG. 4 is a process flow diagram for explaining a method for forming a finely separated resist pattern in this case.

  After forming the first resist layer 1a shown in FIG. 4, as shown in FIG. 4, the entire surface of the semiconductor substrate is exposed with a g-line, i-line or KrF excimer laser, and an acid is formed in the first resist pattern 1a. As a result, a crosslinked layer 4 is formed in the vicinity of the interface of the second resist 2 in contact with the first resist pattern 1a.

  Further, after the second resist layer 2 shown in FIG. 4 is formed, the entire surface of the semiconductor substrate is exposed with a g-line, i-line or KrF excimer laser to generate an acid in the first resist pattern 1a. It is also possible to form the crosslinked layer 4 in the vicinity of the interface of the second resist 2 in contact with the first resist pattern 1a.

  The exposure may be performed before or after the formation of the second resist, and is not particularly limited, and may be selected as necessary.

  The light source used for the exposure at this time can be an Hg lamp, a KrF excimer, an ArF excimer, or the like according to the photosensitive wavelength of the first resist 1, and is particularly limited as long as an acid can be generated by exposure. Instead, exposure may be performed using a light source and an exposure amount corresponding to the photosensitive wavelength of the first resist 1 used.

  Next, if necessary, the semiconductor substrate 7 is heat-treated (for example, 60 to 130 ° C., mixing baking). Thereby, the acid from the first resist pattern 1a is diffused and supplied into the second resist 2, and the crosslinking reaction is promoted at the interface between the second resist 2 and the first resist pattern 1a. The mixing baking temperature / time in this case is 60 to 130 ° C./60 to 120 seconds, and it may be set to an optimum condition depending on the type of resist material used and the required thickness of the reaction layer.

  By this mixing baking, a crosslinked layer 4 that has undergone a crosslinking reaction is formed in the second resist 2 so as to cover the first resist pattern 1a.

  Next, the process of FIG.4 (e) is the same as that of FIG.3 (d). By the above processing, it is possible to obtain a resist pattern having an increased resist pattern thickness without reducing the resolution of the resist pattern.

  Here, materials used for the second resist 2 will be described.

  As the second resist, a crosslinkable water-soluble resin alone or a mixture of two or more of them can be used. In addition, a water-soluble cross-linking agent alone or a mixture of two or more of them is used. Furthermore, a mixture of these water-soluble resins and water-soluble crosslinking agents is used.

  When a mixture is used as the second resist, the material composition thereof is not particularly limited as long as the optimum composition is set depending on the first resist material to be applied or the set reaction conditions. .

  Specific examples of the water-soluble resin composition used in the second resist include polyacrylic acid, polyvinyl acetal, polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene imine, polyethylene oxide, and styrene-maleic acid copolymer as shown below. , Polyvinylamine resin, polyallylamine, oxazoline group-containing water-soluble resin and the like can be applied particularly effectively. In addition, in the presence of an acidic component, a crosslinking reaction occurs, or a crosslinking reaction does not occur. If mixing with a crosslinking agent is possible, it will not specifically limit. Water-soluble melamine resins, water-soluble urea resins, alkyd resins, sulfonamide resins, and the like are also applicable. These may be used alone or as a mixture.

  These water-soluble resins may be used as one kind or a mixture of two or more kinds, and can be appropriately adjusted depending on the reaction amount, reaction conditions, etc. with the underlying first resist 1.

  Further, these water-soluble resins may be used in the form of a salt such as hydrochloride for the purpose of improving the solubility in water.

  Next, specific examples of water-soluble crosslinking agents that can be used for the second resist include urea derivatives, alkoxyethylene urea, N-alkoxyethylene urea, ethylene urea, ethylene urea carboxylic acid and the like as shown below. Urea-based cross-linking agents, melamine-based cross-linking agents such as melamine and alkoxymethylene melamine, and amino-based cross-linking agents such as benzoguanamine and glycoluril are applicable. However, the crosslinking agent is not particularly limited to an amino crosslinking agent, and is not particularly limited as long as it is a water-soluble crosslinking agent that causes crosslinking by an acid.

  Further, as a specific water-soluble resist material used for the second resist, a water-soluble resin as described above alone or a mixture thereof and a water-soluble crosslinking agent as described above alone or a mixture thereof are mixed with each other. It is also effective to use them.

  For example, specifically, as the second resist, a polyvinyl acetal resin is used as the water-soluble resin composition, and methoxymethylol melamine, ethylene urea, or the like is used as the water-soluble crosslinking agent. . In this case, since the water solubility is high, the storage stability of the mixed solution is excellent.

  Note that the material applied to the second resist is water-soluble or soluble in a water-soluble solvent that does not dissolve the first resist pattern and causes a crosslinking reaction in the presence of an acid component. There is no particular limitation.

  Next, it is important to control the crosslinking reaction between the first resist 1 and the second resist 2 and to control the thickness of the crosslinked layer 4 formed on the first resist pattern 1a. The control of the crosslinking reaction is optimized according to the reactivity between the first resist 1 and the second resist 2 to be applied, the shape of the first resist pattern 1a, the thickness of the required crosslinking reaction layer 4, and the like. It is desirable.

  Control of the crosslinking reaction between the first resist and the second resist includes a method by adjusting process conditions and a method by adjusting the composition of the second resist material.

  As a process control method for the crosslinking reaction, methods such as (1) adjusting the exposure amount to the first resist pattern 1a, (2) adjusting the MB (mixing baking) temperature, and the processing time are effective. . In particular, it is possible to control the thickness of the crosslinked layer by adjusting the time for crosslinking by heating (MB time), which can be said to be a method with very high reaction controllability.

  From the aspect of the material composition used for the second resist, (3) the amount of reaction with the first resist is controlled by mixing two or more appropriate water-soluble resins and adjusting the mixing ratio. (4) A method of controlling the amount of reaction with the first resist by mixing an appropriate water-soluble crosslinking agent with the water-soluble resin and adjusting the mixing ratio is effective.

  However, the control of these cross-linking reactions is not determined centrally, and (1) the reactivity between the second resist material and the first resist material to be applied, and (2) the first resist pattern. It needs to be determined in consideration of various conditions such as shape, film thickness, (3) required film thickness of the crosslinked layer, (4) usable exposure conditions or MB conditions, and (5) coating conditions.

  In particular, it has been found that the reactivity between the first resist and the second resist is affected by the composition of the first resist material. Therefore, in the actual application, the above-described factors are taken into consideration. It is desirable to optimize the second resist material composition.

  Therefore, the type and composition ratio of the water-soluble material used for the second resist are not particularly limited, and are optimized and used according to the type of material used, heat treatment conditions, and the like.

  Next, the solvent used for the second resist will be described.

  The solvent used for the second resist is required not to dissolve the pattern of the first resist and to sufficiently dissolve the water-soluble material, but is not particularly limited as long as the solvent satisfies this. Absent.

  For example, as the solvent for the second resist, water (pure water), an alcohol solvent such as water and IPA (isopropyl alcohol), or a water-soluble organic solvent such as N-methylpyrrolidone alone or a mixed solution may be used. That's fine.

  The solvent to be mixed with water is not particularly limited as long as it is water-soluble. For example, alcohols such as ethanol, methanol, isopropyl alcohol, γ-butyrolactone, acetone and the like can be used. In accordance with the solubility of the material used for the second resist, the first resist pattern may be mixed within a range that does not dissolve.

Embodiment 1 FIG.
FIG. 5 is a process flow diagram for illustrating the finely divided resist pattern forming method according to the first embodiment of the present invention. With reference to FIG. 5, a method of forming a finely divided resist pattern according to the first embodiment and a method of manufacturing a semiconductor device using the same will be described.

  First, as shown in FIG. 5, the first resist pattern 11 a is formed on the semiconductor substrate 7. Since the formation method described in the reference form is used effectively, detailed description is omitted to avoid duplication.

  Next, a resist 3 is formed which does not dissolve the pattern of the resist 11a and does not cause a reaction due to the presence of an acid, that is, does not interact with the resist pattern 11a.

  The resist 3 is formed so as to fill the separation space portion of the resist pattern 11a, and the upper surface portion of the resist pattern 11a is not covered or is diffused from the resist pattern 11a when covered. Thereafter, the film thickness is set such that the acid component to be sufficiently diffused into the resist 2 to be formed.

  As a material of the resist 3, PVA (polyvinyl alcohol) or PVP (polyvinyl pyrrolidone) can be applied as a water-soluble material. The material is not limited to these, and is not particularly limited as long as the material does not interact with the resist 11a.

  Next, a resist 2 is formed. Since the formation method and material of the resist 2 are described in a reference form, the details are omitted here.

Further, as shown in FIG. 5 (e), the non-crosslinked portion is washed and removed by rinsing, thereby increasing the resist pattern thickness without reducing the resolution of the resist 11a. A resist pattern with improved etching properties can be obtained.
By using the finely divided resist pattern thus formed as a mask, finely separated spaces or holes can be formed on the semiconductor substrate, and a semiconductor device having finely separated spaces or holes can be obtained. it can.

  Next, reference examples and examples related to the reference embodiment and the first embodiment will be described.

Production Example 1
A resist pattern was formed using a chemically amplified excimer resist manufactured by Tokyo Ohka Kogyo Co., Ltd. as the first resist.

  First, the resist was dropped onto a Si wafer and formed by spin coating. Next, pre-baking was performed at 90 ° C./90 seconds to dry the solvent in the resist. Subsequently, exposure was performed using a mask as shown in FIG. 1 using a KrF excimer reduction projection exposure apparatus.

  Next, PEB treatment is performed at 100 ° C./90 seconds, and subsequently development is performed using an alkali developer (manufactured by Tokyo Ohka Kogyo Co., Ltd., NMD-W), which is shown in FIG. A resist pattern like this was obtained.

Production Example 2
As a second resist material, a 1 L volumetric flask was used, and Sekisui Chemical Co., Ltd.'s polyvinyl acetal resin ESREC KW3, KW1, polyvinyl alcohol resin, polyvinylpyrrolidone, oxazoline-containing water-soluble resin (Nippon Shokubai Co., Ltd., Epocross) WS500) and styrene-maleic anhydride copolymer (manufactured by ARCO chemical, SMA1000, 1440H) were mixed with 90 g of pure water and stirred and mixed at room temperature for 3 hours to obtain respective 10 wt% aqueous solutions. .

Production Example 3
As a second resist material, using a 1 L volumetric flask, methoxymethylol melamine (manufactured by Mitsui Cyamide Co., Ltd., Cymel 370), (N-methoxymethyl) methoxyethylene urea, (N-methoxymethyl) hydroxyethylene urea, N 10 g of each methoxymethylurea and 90 g of pure water were stirred and mixed at room temperature for 6 hours to obtain 10 wt% aqueous solutions, respectively.

Production Example 4
As the second resist material, 60 g, 70 g and 80 g of 10 wt% aqueous solution of KW3 obtained in Production Example 2, and 40 g and 30 g of 10 wt% aqueous solution of (N-methoxymethyl) hydroxyethylene urea obtained in Production Example 3 were used. , 20 g were mixed to obtain a mixed solution of a water-soluble resin and a water-soluble crosslinking agent.

Production Example 5
Using a 1 L volumetric flask as a third resist material, 10 g each of polyvinyl alcohol resin and polyvinylpyrrolidone were mixed with 90 g of pure water, and stirred and mixed at room temperature for 3 hours to obtain respective 10 wt% aqueous solutions. .

Production Example 6
As a second resist material, 80 g of a 10 wt% aqueous solution of polyvinyl alcohol obtained in Production Example 2 and 20 g of a 10 wt% aqueous solution of methoxymethylol melamine obtained in Production Example 3 were stirred and mixed at room temperature for 3 hours to obtain a water-soluble resin and a water-soluble resin. A mixed solution of the functional crosslinking agent was obtained.

Reference Examples 1 to 4 and Comparative Example 1.
On the Si wafer on which the first resist pattern obtained in Production Example 1 is formed, the second resist material obtained in Production Example 4 is dropped and spin-coated, and then pre-baked at 85 ° C./70 seconds, A second resist film was formed.

  Next, heat treatment was performed under the respective conditions of 100 ° C., 110 ° C., and 120 ° C./60 seconds to advance the crosslinking reaction. Next, development is performed using pure water, and the uncrosslinked layer is developed and peeled off, followed by post-baking at 110 ° C./60 seconds to form a second resist crosslinked layer on the first resist pattern. As shown in FIG. 8, a second resist pattern was formed. In FIG. 8, the thickness of the second resist pattern was measured by changing the mixing ratio of the water-soluble resin and measuring the resist pattern size after the formation of the crosslinked layer. The results are shown in Table 1.

  In this case, it is possible to control the thickness of the crosslinked layer formed on the first resist by changing the mixing amount of the water-soluble resin and the water-soluble crosslinking agent and by changing the heat treatment temperature. I understand that.

Reference Examples 5-7.
On the Si wafer on which the first resist pattern obtained in Production Example 1 is formed, as shown in FIG. 9, the entire surface of the wafer is exposed with a dose of 0, ² , 5 mJ / cm ² using a KrF excimer exposure apparatus. Went. Next, a 10 wt% mixed solution of KW3 and (N-methoxymethyl) hydroxyethyleneurea obtained in Production Example 4 was dropped as a second resist material, spin-coated, and then pre-baked at 85 ° C./70 seconds, A second resist film was formed.

  Furthermore, heat treatment was performed at 120 ° C./60 seconds to advance the crosslinking reaction. Next, development is performed using pure water, and the uncrosslinked layer is developed and peeled off, followed by post-baking at 110 ° C./60 seconds, thereby forming the first resist pattern on the upper surface as shown in FIG. Two resist cross-linked layers were formed. Further, the resist pattern film thickness after the formation of the crosslinked layer was measured. The results are shown in Table 2. As a result, the first resist film thickness 0.71 μm before the formation of the cross-linked layer is increased in thickness, and the film thickness of the cross-linked layer increases as the exposure amount increases, It was found that the film thickness was increased.

Examples 1-3.
After dropping the polyvinyl alcohol aqueous solution obtained in Production Example 5 as a third resist material onto the Si wafer on which the first resist pattern obtained in Production Example 1 is formed as shown in FIG. And pre-baking at 85 ° C./70 seconds to form a third resist film. Next, a 20 wt% mixed solution of polyvinyl alcohol and methoxymethylol melamine obtained in Production Example 6 is dropped as a second resist material, spin-coated, and then pre-baked at 85 ° C./70 seconds to obtain a second resist film. Formed.

  Furthermore, heat treatment was performed at 110 ° C./60 seconds, 115 ° C./60 seconds, and 120 ° C./60 seconds to advance the crosslinking reaction. Next, development is performed using pure water, and the uncrosslinked layer is developed and peeled off, followed by baking at 110 ° C./60 seconds, thereby forming the first resist pattern on the upper surface as shown in FIG. Two resist cross-linked layers were formed. Further, the resist pattern film thickness after the formation of the crosslinked layer was measured. The results are shown in Table 3.

It is a figure of the mask pattern for demonstrating the resist pattern formation method of a reference form. It is a figure of the resist pattern for demonstrating the resist pattern formation method of a reference form. It is a process flowchart for demonstrating the resist pattern formation method of a reference form. It is a process flowchart for demonstrating the resist pattern formation method of a reference form. It is a process flowchart for demonstrating the resist pattern formation method of Embodiment 1 of this invention. It is a figure of the 1st mask pattern in Examples 1-3 of this invention and Reference Examples 1-7. It is a figure of the 1st resist pattern in Examples 1-3 of this invention, and Reference Examples 1-7. It is a process flowchart for demonstrating the resist pattern formation method in the reference examples 1-4. It is a process flowchart for demonstrating the resist pattern formation method in the reference examples 5-7. It is a process flowchart for demonstrating the resist pattern formation method in Examples 1-3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st resist, 1a, 11a 1st resist pattern, 2nd resist, 2a 2nd resist pattern, 3rd resist which does not interact with resist pattern 11a, 4 crosslinked layer, 5 not yet Cross-linked layer, 6 upper layer agent,
7 Semiconductor substrate (semiconductor wafer), 8 Mask pattern.

Claims (3)

A step of forming a first resist pattern with a first resist that can generate an acid or contains an acid on a substrate, and does not dissolve the first resist pattern and does not cause a reaction by an acid. A third resist is formed so as to fill the separation space of the first resist pattern, and then, on the first resist pattern, it is soluble in water or an aqueous solution and undergoes a crosslinking reaction in the presence of an acid. A step of forming a second resist that includes a component that causes a cross-linking reaction by supplying an acid from the first resist pattern, and a cross-linking layer is formed on a portion of the second resist that is in contact with the top surface of the first resist pattern. Forming a second resist pattern by peeling off the non-crosslinked portion of the second resist and the third resist, and forming a second resist pattern. The method of forming the over down. The method for forming a fine pattern according to claim 1, wherein the third resist is soluble in water or an aqueous solution. A method for manufacturing a semiconductor device, comprising: a step of etching a semiconductor substrate using a resist pattern obtained by the fine pattern forming method according to claim 1 or 2 as a mask.

Images