JPH0770493A - Resist pattern formation method - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a method for forming a resist pattern capable of obtaining a high-resolution pattern for forming a fine pattern having an L & S pitch of a mask or less without complicating the manufacturing process of the pattern or the mask. The purpose is to do. [Structure] (i) A substrate or thin film is coated with a resist solution containing a hydroxystyrene-based oligomer (provided that at least a part of hydroxy groups is substituted with a functional group) and a photo-acid generator, (ii) ) The substrate or thin film coated with the resist solution is exposed through a mask having a desired pattern to generate an acid from the photo-acid generator and at an exposure amount sufficient to cause polymerization of the oligomer. After that, the resist pattern is formed by baking and (iii) treating the obtained exposed film with an alkali developing solution to form a resist pattern including a resist-removed portion and a resist-unremoved portion in one exposed portion. Forming method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming a resist pattern, and more particularly to a method of forming a new resist pattern which can have a finer pattern than the pattern of an exposure mask. INDUSTRIAL APPLICABILITY The present invention can provide both positive and negative resist characteristics by using a hydroxystyrene-based oligomer having a functional group introduced into a part of hydroxy groups as a resist solution and a photoacid generator. It is possible and is useful for forming a fine pattern of a semiconductor.

[0002]

2. Description of the Related Art In recent years,
The integration of semiconductor integrated circuits has advanced, and VLSI has been put to practical use rather than LSI. This is realized by miniaturization of conductor wiring, electrodes, etc., and currently, the minimum pattern is less than 1 μm (submicron). Even things have been put to practical use. At first, ultraviolet rays were used as an exposure light source for forming a fine resist pattern, but due to the limitation of wavelength, the light also shifts to a short wavelength and is exposed using radiation such as deep ultraviolet rays, electron beams, and X-rays. Came to be done. However, there is a problem that the output of the high-pressure mercury lamp is considerably lowered when it shifts to far-ultraviolet light, and studies are being made to use an excimer laser beam to address this problem. As described above, in order to obtain a fine pattern, the exposure wavelength is being shortened, but in the present technology, it is limited to obtain a line / space pitch pattern equivalent to twice the wavelength. However, attempts have been made to form even finer patterns by making full use of the phase shift technique or the modified illumination technique. However, in particular, since the manufacturing process of such a mask is complicated, it is desired to develop a method for obtaining a fine pattern without using the phase shift method.

On the other hand, in terms of materials, there has been proposed a chemically sensitized resist which can achieve higher sensitivity, higher resolution and stabilization of the pattern forming process. In such a chemically sensitized resist, a photoacid generator is usually mixed with a polymer, and a group existing in a polymer molecule is chained using a Bronsted acid generated from the photoacid generator by light irradiation as a catalyst. To be eliminated or hydrolyzed. As a result, the exposed portion becomes soluble in the alkaline developing solution and functions as a positive resist. Here, diaryl iodonium salts, triaryl sulfonium salts and their derivatives are used as the photo-acid generator.

FIG. 12 shows a sensitivity curve of a conventional chemically amplified resist. That is, when a light having a certain exposure amount or more is irradiated, the polymer group undergoes elimination or hydrolysis reaction and becomes soluble in an alkali developing solution. When this chemically amplified resist is used to perform exposure with the mask 10 on which a desired pattern is formed, as shown in FIG.
The light 11 that has passed through the mask 10 causes diffraction and interference and reaches the surface of the resist 12, and the exposed resist 12 is exposed.
Turns positive 12a. Then, when this resist 12 is developed with an alkaline developer, a desired resist pattern 13 can be formed as shown in FIG. When the resist pattern forming method using the above resist is applied to a contact hole, as shown in FIGS. 15 and 16 for the opening pattern 5a of the mask 5 similar to FIG. Then, the ring-shaped positive pattern 14a is removed to obtain the ring-shaped punching pattern 14.

The resist composition containing a photopolymerization initiator which generates an acid upon irradiation with light, which is disclosed in JP-A-58-109463, is limited to those which function as a positive type or a negative type. The present invention has been made in view of the above-mentioned problems, and can be performed within the pitch of the mask line / space or within one pattern of the mask without inviting a complicated manufacturing process of the pattern or a complicated manufacturing of the mask. It is an object of the present invention to provide a resist pattern forming method capable of obtaining a high-resolution resist pattern for forming a plurality of fine patterns.

[0006]

According to the present invention, (i) a hydroxystyrene-based oligomer (provided that at least a part of a hydroxy group is substituted with a functional group) and a photoacid generator are formed on a substrate or a thin film. A resist solution consisting of an agent, (ii) the substrate or thin film coated with the resist solution, through a mask having a desired pattern, to generate an acid from the photo-acid generator, the oligomer of the After exposure with an exposure amount sufficient to cause polymerization, baking is performed, and (iii) the obtained exposed film is treated with an alkali developing solution to form a resist-removed portion and a resist-unremoved portion in one exposed portion. A method for forming a resist pattern, which comprises forming a resist pattern containing:

According to the method of the present invention, a subquarter micron pattern can be formed. The resist film formed has both positive type and negative type characteristics. As the substrate used in the method of the present invention, if it can be usually used as a substrate,
It is not particularly limited, and examples thereof include a semiconductor substrate such as a silicon substrate or a compound semiconductor substrate. This substrate is cleaned, dehydrated, pre-baked, hydrophobized, etc.
It is preferably used after desired treatment. Also,
A desired element such as a transistor or a capacitor may be formed on these substrates. The thin film used in the method of the present invention may be, for example, an insulating film such as a silicon oxide film or a silicon nitride film formed on a substrate or a desired element, a semiconductor film such as a polysilicon film, aluminum or the like. A metal film such as titanium can be used.

The resist solution used in the forming method of the present invention comprises a hydroxystyrene-based oligomer (provided that at least a part of the hydroxy group is substituted with a functional group) and a photoacid generator. A hydroxystyrene-based oligomer has a molecular weight of about 5,000 to 15,000,
It is preferably 5,000 to 13,000 oligomers.
The functional group substituted in at least a part of the hydroxy group of the hydroxystyrene-based oligomer means a functional group capable of suppressing dissolution of a polymer produced from the oligomer in a developing solution used, and specific examples thereof are given. Is at least one group selected from the group consisting of t-butoxycarbonyl group, pyranyl group, t-butoxycarbonylmethyl group, trialkylsilyl group (wherein alkyl is, for example, methyl, ethyl, propyl, etc.), or isopropenyl Examples thereof include at least one group selected from the group consisting of an oxycarbonyl group, an acryl group, a vinyloxyalkyl group (where alkyl is, for example, methyl, ethyl, propyl, etc.), a vinyloxycarbonyl group, and the like. The oligomer having the above functional group,
A resist film having the same function as a positive resist is provided in a region where the exposure amount is low, and it can function as a negative resist in a region where the exposure amount is high above a certain level. On the other hand, the above oligomer having a functional group can function as a negative resist in a region where the exposure amount is low, and can function as a positive resist in a region where the exposure amount is higher than a certain level. The substitution ratio of these functional groups is 5 to 2
It is 0 mol%, more preferably 10 to 15 mol%. The preferred hydroxystyrene-based oligomer has a hydroxyl group of p
At a position of 5 to 20 mol% thereof, which is substituted with a t-butoxycarbonyl group or a p-tetrahydropyranyl group. However, a hydroxyl group may exist at the m-position or the o-position. Furthermore, the benzene ring may be substituted with a methyl group. The hydroxystyrene-based oligomer may be a mixture of oligomers having different kinds of functional groups, their contents, molecular weights and the like. Further, a phenol novolac resin (however, a molecular weight of about 5,000 to 15,000) in which 5 to 20 mol% of the hydroxyl groups are substituted with the above functional groups may be used.

The photo-acid generator used in the present invention has a function of generating an acid by photodecomposition and of initiating polymerization of the above-mentioned oligomer when irradiated with light having an exposure amount of a predetermined value or more. I have. Specifically, an onium salt-based or non-onium salt-based photoacid generator can be used. Examples of the onium salt-based photoacid generator include sulfonium trifluoromethanesulfonate (for example, P
h ₃ -SSO ₃ CF _3), Jifeniruyo - Doniumu based photoacid generators (for example, Ph ₂ -IPF ₅ or Ph ₂ -ISbF
₅ ) is preferred. The above-mentioned Ph ₃ -SSO ₃ C
F ₃ (triphenylsulfonium trifluoromethanesulfonate), Ph ₂ -IPF ₅ or Ph ₂ -ISb
When F ₅ ) is used, those phenyl groups may be substituted with a methyl group, a methoxy group, a thiophenyl group, or t- as a substituent.
A butyl group-introduced one can also be used, and a counter ion part having BF ₄ ⁻ or PF ₆ ⁻ can also be used. Furthermore, it has been confirmed that a compound obtained by combining the above-mentioned substituents and counter ions can be used as a photoacid generator. Similar results were also obtained with a diphenyliodonium-based acid generator.

The resist solution of the present invention further comprises
It may contain a dissolution inhibitor capable of preventing dissolution of the resist (polymer) produced by the oligomer in the alkaline developer. Specifically, it is characterized by having bisphenol A or phenolphthalein as a skeleton and having a functional group having a dissolution inhibiting effect in order to exert a dissolution inhibiting effect, and the functional group is the same as the above oligomer. Is preferred. For example, t-butoxycarbonylated bisphenol A, t-butoxycarbonylmethylated bisphenol A or tetrahydropyranylated bisphenol A
Etc. can be mentioned. The amount of the dissolution inhibitor added can be appropriately selected in relation to the substitution rate of the functional group, when the functional group introduced into the oligomer to impart the dissolution inhibitor is not sufficient.

Further, in order to prepare the resist solution, it is preferable to use methoxyisopropanol, ethoxyisopropanol, diglyme, ethyl lactate or the like as a solvent for dissolving the oligomer, the photoacid generator, the dissolution inhibitor and the like. In the case of using an oligomer having at least one group selected from the group consisting of t-butoxycarbonyl group, pyranyl group, t-butoxycarbonylmethyl group and trialkylsilyl group in the resist solution which can be used in the present invention. The oligomer (A)
And the ratio (weight fraction) of the photoacid generator (B) is 10 ≦ A ≦
20, 0.2 ≦ B ≦ 1.0, more preferably 14 ≦ A ≦
17, 0.4 ≦ B ≦ 0.8. The ratio (weight fraction) of the oligomer (A), the photoacid generator (B) and the dissolution inhibitor (C) is 10 ≦ A ≦ 20, 0.2 ≦ B ≦ 1.
2, 0 ≦ C ≦ 4, more preferably 14 ≦ A ≦ 17,0.
4 ≦ B ≦ 0.8 and 3.0 ≦ C ≦ 3.2. Also,
When an oligomer having at least one group selected from the group consisting of an isopropenyloxycarbonyl group, an acryl group, a vinyloxyalkyl group and a vinyloxycarbonyl group is used, the oligomer (A) and the photoacid generator (B ) Ratio (weight fraction) is 8 ≦ A ≦ 20, 0.2 ≦
B ≦ 1.2, more preferably 10 ≦ A ≦ 18, 0.4 ≦
B ≦ 1.0. In addition, the ratio (weight fraction) of the oligomer (A), the photoacid generator (B) and the dissolution inhibitor (C) is
8 ≦ A ≦ 20, 0.4 ≦ B ≦ 1.0, 0 ≦ C ≦ 4, more preferably 10 ≦ A ≦ 18, 0.4 ≦ B ≦ 1.0, 3.
0 ≦ C ≦ 3.2.

The method of applying the resist solution is not particularly limited, and a spin coating method, a spray method, a vapor phase coating method and the like can be used. The use of spin coating is preferred. In addition, after applying the resist solution, in order to mainly remove the solvent of the resist solution, 60 to 110 ° C.,
Prebaking is preferably performed for about 60 to 120 seconds.
When an oligomer having at least one group selected from the group consisting of an isopropenyloxycarbonyl group, an acrylic group, a vinyloxyalkyl group and a vinyloxycarbonyl group is used as the resist solution, the prebaking temperature is 50 to 90. It is preferably carried out in the temperature range of ° C. The resist film is preferably formed with a film thickness of about 0.5 to 2.0 μm.

In the present invention, a mask having a desired pattern is formed on a transparent substrate which can be used as a mask substrate, for example, chromium, tungsten, tantalum,
With molybdenum silicon, tungsten silicon, etc.,
A desired pattern can be used. The shape of the mask pattern is not particularly limited, and can be determined in consideration of the type of irradiation light, a desired pattern, and the like. For example, a line with a line width of about 0.2 to 1.0 μm /
It is preferable to use a pattern having a space pitch, or a pattern having various widths such as a line width or a space width between patterns of about 0.2 to 1.0 μm, and more preferably a line width of about 0.25 to 0. Those having a line / space pitch of 5 μm, or patterns having various widths of line width or space width between patterns of about 0.25 to 0.5 μm. Further, in order to form a donut-shaped punched pattern or a donut-shaped remaining pattern, it is preferable that one side has an opening or a closed portion of about 0.25 to 1.0 μm, and more preferably about 0.3 to. It is 0.4 μm. As the transparent substrate, a transparent substrate such as a quartz substrate, that is, a substrate that does not affect light transmission in a wavelength range used in a normal exposure light process or the like is preferable. The thickness of the transparent substrate at this time is not particularly limited, but 2.
About 0 to 8.0 mm is preferable.

The exposure amount of light exposed through the mask is preferably sufficient to generate an acid from the photo-acid generator and polymerize the oligomer, and the irradiation energy is 50 mJ / cm ^2. The above is preferable. Specifically, the irradiation energy is
(1) In the case of forming a resist pattern having a line / space pitch, or a resist pattern having various widths as a line width or a space width between patterns, a positive type resist in a region where the exposure amount is low. When using a resist that functions in the same manner as the negative resist in the high region and 50 mJ / cm ² or more in the region where the exposure amount is low, the same function as the negative resist is used in the high region and in the high region. When a resist that functions in the same manner as a positive resist is used, it is preferably 100 mJ / cm ² or more, and (2) when a donut-shaped punching pattern or a donut-shaped remaining pattern is formed, When using a resist that functions like a positive resist in a region where the exposure amount is low and that functions like a negative resist in a region where the exposure amount is high, In the case of using a resist having a function of 100 mJ / cm ² or more and a function of the negative type resist in a region where the exposure amount is low and a function of the positive type resist in a region where the exposure amount is high, it is preferably 200 mJ / cm ² or more. .

The exposure light is not particularly limited,
i-line (365 nm), g-line (436 nm), excimer laser light (KrF: 248 nm, ArF: 193 nm), etc. can be used. In either case, the temperature during exposure is preferably about 23 to 25 ° C., and the irradiation time is preferably about 0.1 to 0.3 seconds, although it varies depending on the amount of energy. In the present invention, a bake treatment may be performed after the exposure and before the development. The baking at this time is about 80-1.
It is preferable to perform the treatment in the temperature range of 00 ° C. for about 60 to 120 seconds.

Further, the developing solution used in the development in the method for forming a resist pattern of the present invention is not particularly limited, and can be appropriately adjusted depending on the type and molecular weight of the resist used. For example, a tetramethylammonium hydroxide (TMAH) developer (NMD-W: manufactured by Tokyo Ohka Kogyo Co., Ltd.) can be used. The development time can be appropriately adjusted depending on the oligomer used, the concentration of the developing solution, and the like.
About 0 to 120 seconds is preferable. When using an oligomer having a molecular weight of about 13,000, TMAH of about 2.38% is obtained.
It has been confirmed that the desired pattern can be formed with
When the molecular weight is 10,000 or less, the dissolution rate becomes 100 nm / sec or more in a 2.38% TMAH developing solution, and a stable development process cannot be performed.
It was confirmed that by using the developing solution, a pattern was formed in a developing time of about 60 seconds.

The fine resist pattern obtained by the method of forming a resist pattern of the present invention can be used for fine wiring in a semiconductor device or the like, a node electrode of a capacitor for securing capacitance, and the like.

[0018]

The resist solution used in the method for forming a resist pattern of the present invention can provide a resist having both positive type and negative type characteristics. That is, at least a part of the hydroxy group of the hydroxystyrene-based oligomer is substituted with at least one group selected from the group consisting of t-butoxycarbonyl group, pyranyl group, t-butoxycarbonylmethyl group and trialkylsilyl group. When such an oligomer is used, it can be used as a resist capable of functioning similarly to a positive type resist in a region having a low exposure amount and functioning similarly to a negative type resist in a region having a high exposure amount. The following is a description with reference to the drawings.

As shown in FIG. 1, the above resist is
In a region with a low exposure amount (A in FIG. 1), it functions similarly to the positive type resist. In the reaction, the photo-acid generator mixed with the oligomer generates Bronsted acid in the low exposure region, and the generated Bronsted acid chain-links the elimination reaction or hydrolysis reaction of the functional group in the oligomer. The exposed portion is made soluble in the alkaline developing solution. In addition, as the amount of exposure increases (B in FIG. 1), the amount of radicals generated by light irradiation increases, and oligomers with deviated functional groups are polymerized by a radical reaction to be polymerized, It will function as a negative resist that is insoluble in an alkali developing solution.

In the method of forming a resist pattern using the above resist, as shown in FIG. 2, the light 2 that has passed through the mask 1 undergoes diffraction and interference, and on the surface of the resist 3,
The signal is strong near the center of the mask opening 1a and weak around the opening 1a, so that a signal of 0 or 1 passing through the mask pattern does not reach the surface of the resist 3. When the resist 3 is exposed by utilizing this light intensity, the place where the light intensity is the highest becomes a negative 3a and the other exposed region becomes a positive 3b. By developing this, as shown in FIG. 3, a pattern 4 having a line / space pitch that is half the mask line / space pitch can be obtained.

When the resist pattern forming method using the resist described above is applied to a contact hole, the opening pattern 5a of the mask 5 as shown in FIG. As shown in FIG. 5, the center of the ring-shaped pattern is made negative 6a, and the positive 6b is removed to obtain a donut-shaped punching pattern 6.

On the other hand, at least a part of the hydroxy group of the hydroxystyrene-based oligomer is substituted with at least one group selected from the group consisting of an isopropenyloxycarbonyl group, an acryl group, a vinyloxyalkyl group and a vinyloxycarbonyl group. In this case, it can be used as a resist that functions similarly to a negative resist in a region where the exposure amount is low and functions like a positive resist in a region where the exposure amount is high.

As shown in FIG. 7, the above resist is
It functions similarly to the negative type resist (B in FIG. 7) in the region where the exposure amount is low. In the reaction, a Brønsted acid generated in the low-exposure region activates a functional group that is a substituent of the hydroxy group of the oligomer by the photo-acid generator mixed with the oligomer (that is, the unsaturated bond is cleaved). ), And by cross-linking the oligomer and increasing the molecular weight of the oligomer, the exposed area becomes insoluble in the alkaline developer.
Further, as the exposure amount increases (C in FIG. 7), the amount of Bronsted acid increases, and the Bronsted acid serves as a catalyst to chain the elimination reaction or hydrolysis reaction of the functional group in the oligomer. The exposed portion functions as a positive resist that is soluble in an alkaline developer. This reaction can be promoted by performing pre-baking after applying the resist solution in a relatively low temperature range of 50 to 90 ° C.

A method of forming a resist pattern using the above resist is as shown in FIG.
The signal of 0 or 1 according to the pattern does not reach the surface of the resist 3. When the resist 3 is exposed using this light intensity, the place where the light intensity is the strongest becomes a positive 3b, and the other exposed region becomes a negative 3a. By developing this, as shown in FIG. 9, a pattern with a line / space pitch that is half the mask line / space pitch.
7 will be obtained.

10 and 11 are applied to the opening pattern 5a of the mask 5 similar to that shown in FIG. 4, when the resist pattern forming method using the above resist is applied to the contact hole. As shown in FIG. 7, the center of the ring-shaped pattern is made positive 8b and the negative portion 8a remains, so that a donut-shaped remaining pattern 8 is obtained.

[0026]

EXAMPLE An example of the method of forming a resist pattern according to the present invention will be described. Example 1 Methoxyisopropanol as a solvent had a molecular weight of 1.
16% by weight of 30,000 poly (pt-butoxycarbonylhydroxystyrene) (t-butoxycarbonylation rate: 13%) as a base oligomer, and triphenylsulfonium trifluoromethanesulfonate (Ph _3- ) as a photoacid generator. A resist solution containing 0.8% by weight of SCF ₃ SO ₃ ) was prepared.

Hexamethyldisilazane (H
MDS) 120 ° C. in steam at 40 ° C., spin coated on a 6-inch silicon substrate that has been subjected to a hydrophobic treatment for 40 seconds at a rotation speed of 3000 rpm, and then on a hot plate at 100 ° C.
Pre-baking was performed for 20 seconds to form a resist film having a thickness of 1 μm. Next, the mask pattern is 0.60 μm 1: 1
A substrate coated with the above resist film using a mask that is a line / space is used for deep ultraviolet radiation (KrF of 248 nm).
An exposure amount of 100 mJ / cm ² was performed with a stepper having an NA of 0.45 with an excimer laser beam). Then, baking was performed at 80 ° C. for 60 seconds. Finally 2.3
8% tetramethylammonium hydroxide (TMAH) developer (NMD-W: Tokyo Ohka Kogyo Co., Ltd.)
Developed).

As a result, the mask pattern is 0.60 μm.
0.30 μm for 1: 1 line / space of
A 1: 1 line / space pattern can be formed on a silicon substrate. A silicon substrate having a resist film similar to that described above was irradiated with an exposure dose of 200 mJ / cm ² using a mask having an opening with an outer diameter of 0.60 μm, so that the outer diameter was 0.60 μm and the inner diameter was 0. .30
A resist pattern having a donut-shaped punching pattern of μm was obtained.

In this embodiment, the baking after the exposure was carried out at 80 ° C. for 60 seconds, but the pattern could be formed even at 90 ° C. for 60 seconds. The exposure amount at this time was about 90% as compared with 80 ° C. for 60 seconds.

Comparative Example 1: A resist pattern was formed in the same manner as in Example 1 except that the exposure amount was 1/2 of that in Example 1. As a result, the mask pattern is 0.60 μm,
0.60 μm 1: 1 for 1: 1 line / space
It was a line / space. Further, a resist pattern having an opening of 0.60 μm was formed with respect to the opening of the mask pattern of 0.60 μm.

Comparative Example 2: After exposure, the baking temperature was 6 at 70 ° C.
A resist pattern was formed in the same manner as in Example 1 except that it was set to 0 second. As a result, the mask pattern is 0.60.
μm: 0.60 μm for 1: 1 line / space
It was 1: 1 line / space. Also, for the contact hole opening with a mask pattern of 0.60 μm,
A resist pattern having an opening of 0.60 μm was formed.

Example 2 Methoxyisopropanol as a solvent had a molecular weight of 1.
16% by weight of 30,000 poly (pt-butoxycarbonylhydroxystyrene) (t-butoxycarbonylation rate: 13%) as a base oligomer, and triphenylsulfonium trifluoromethanesulfonate (Ph _3- ) as a photoacid generator. 0.8% by weight of SCF ₃ SO ₃ ) and t-butoxycarbonylated bisphenol A as a dissolution inhibitor.
3.2% by weight was dissolved to prepare a resist solution.

Next, in the same manner as in Example 1, this solution was applied to a silicon substrate, exposed and developed. As a result, a resist pattern of 0.20 μm and 1: 1 line / space could be formed on the silicon substrate with respect to the mask pattern of 0.40 μm and 1: 1 line / space.

A silicon substrate coated with the same resist solution as described above was irradiated with an exposure amount of 200 mJ / cm ² using a mask having an opening with an outer diameter of 0.40 μm, so that the outer diameter was 0. .40 μm, inner diameter 0.20 μm
A resist pattern having a donut-shaped punching pattern was obtained.

Comparative Example 3: A resist pattern was formed in the same manner as in Example 2 except that the exposure amount was 1/2 of that in Example 1. As a result, the mask pattern is 0.40 μm,
0.40 μm 1: 1 for 1: 1 line / space
It was a line / space. Further, a resist pattern having an opening of 0.40 μm was formed with respect to the opening of the mask pattern of 0.40 μm.

Comparative Example 4: Post-exposure bake temperature 6 at 70 ° C.
A resist pattern was formed in the same manner as in Example 2 except that the time was 0 second. As a result, the mask pattern is 0.4
0.40μ for 0μm and 1: 1 line / space
m1: 1 line / space. Further, a resist pattern having an opening of 0.40 μm was formed with respect to the opening of the mask pattern of 0.40 μm.

Example 3 A resist solution similar to that in Example 1 was prepared. This solution was applied onto a silicon substrate in the same manner as in Example 1 and prebaked to form a resist film having a thickness of 1 μm. next,
Using a mask having a 1: 1 line / space with a mask pattern of 0.8 μm, a resist-coated substrate was
After exposure with deep ultraviolet rays (i-line of 365 nm) with a stepper of NA: 0.54 at an exposure amount of 200 mJ / cm ² , baking was performed at 80 ° C. for 60 seconds. Then, it was developed in the same manner as in Example 1.

As a result, the mask pattern is 0.80 μm.
m, 0.40 μm for 1: 1 line / space,
A resist pattern of 1: 1 line / space could be formed on the silicon substrate. Further, an outer diameter of 0.80 was applied to a silicon substrate coated with the same resist solution as above.
Using a mask having an opening of μm, the exposure dose is 500
By irradiating with mJ / cm ² , the outer diameter is 0.80μ
A resist pattern having a donut-shaped punching pattern having a diameter of m and an inner diameter of 0.40 μm was obtained.

Comparative Example 5: A resist pattern was formed by the same steps as in Example 3 except that the exposure amount was 1/2 of that in Example 1. As a result, the mask pattern is 0.80 μm,
0.80 μm 1: 1 for 1: 1 line / space
It was a line / space. Further, a resist pattern having an opening of 0.80 μm was formed for the opening of the mask pattern of 0.80 μm.

Comparative Example 6: Post-exposure bake temperature 6 at 70 ° C.
A resist pattern was formed in the same manner as in Example 3 except that it was set to 0 second. As a result, the mask pattern is 0.80μ
m: 0.80 μm for 1: 1 line / space
It was 1: 1 line / space. Further, a resist pattern having an opening of 0.80 μm was formed for the opening of the mask pattern of 0.80 μm.

Example 4 A resist solution similar to that in Example 2 was prepared. This solution was applied onto a silicon substrate in the same manner as in Example 1 and prebaked to form a resist film having a thickness of 1 μm. next,
A pattern was formed in the same manner as in Example 3. As a result, it was possible to form a resist pattern of 0.25 μm and 1: 1 line / space on the silicon substrate with respect to the mask pattern of 0.50 μm and 1: 1 line / space.

Further, a silicon substrate coated with the same resist solution as described above is irradiated with an exposure dose of 500 mJ / cm ² using a mask having an opening having an outer diameter of 0.50 μm, so that the outer diameter becomes 0. .50 μm, inner diameter 0.25 μm
A resist pattern having a donut-shaped punching pattern was obtained.

Comparative Example 7: A resist pattern was formed by the same steps as in Example 4 except that the exposure amount was 1/2 of that in Example 1. As a result, the mask pattern is 0.50 μm,
0.50 μm 1: 1 for 1: 1 line / space
It was a line / space. Further, a resist pattern having an opening of 0.50 μm was formed with respect to the opening of the mask pattern of 0.50 μm.

Comparative Example 8: Bake temperature after exposure was 6 at 70 ° C.
A resist pattern was formed by the same steps as in Example 4 except that the time was 0 second. As a result, the mask pattern is 0.5
0.50μ for 0μm and 1: 1 line / space
m1: 1 line / space. Further, a resist pattern having an opening of 0.50 μm was formed with respect to the opening of the mask pattern of 0.50 μm.

Example 5 A solvent having a molecular weight of 50 was added to methoxyisopropanol.
Of poly (p-isopropenyloxycarbonylhydroxystyrene) of 00 (isopropenyloxycarbonylation rate: 20%) as a base oligomer and triphenylsulfonium trifluoromethanesulfonate (Ph _3- SCF ₃ SO ₃ ) to 0.
5% by weight was dissolved to prepare a resist solution.

This solution was applied on a silicon substrate in the same manner as in Example 1 and prebaked on a hot plate at 60 ° C. for 120 seconds to form a resist film having a thickness of 1 μm.
Next, the substrate coated with the resist was changed to deep ultraviolet rays (248 n
m KrF excimer laser light) was used to perform an exposure of 150 mJ / cm ^{2 with} a stepper having an NA of 0.45, followed by baking at 80 ° C. for 60 seconds. Then, it was developed in the same manner as in Example 1.

As a result, the mask pattern is 0.40 μm.
m, 0.20 μm for 1: 1 line / space,
It was possible to form a 1: 1 line / space resist pattern on a silicon substrate. Further, a silicon substrate coated with the same resist solution as above was irradiated with an exposure amount of 200 mJ / cm ² using a mask having an opening with an outer diameter of 0.40 μm, so that the outer diameter of 0.
A resist pattern having a donut-shaped remaining pattern of 40 μm and an inner diameter of 0.20 μm was obtained.

In this example, as the base oligomer,
Poly (p-isopropenyloxycarbohydroxystyrene) having a molecular weight of 5000 was used, but the molecular weight was 3000.
If it is up to 10,000, it can be used in this embodiment. In this embodiment, the prebaking step of the patterning process was performed at 60 ° C. for 120 seconds, but the pattern could be formed even at a temperature below this.

Comparative Example 9: Prebaking temperature was 100 ° C. and 1
A resist pattern was formed by the same steps as in Example 5 except that the time was 20 seconds. As a result, the mask pattern is 0.
0.30 for 30 μm and 1: 1 line / space
μm 1: 1 line / space. In addition, when the mask pattern has an opening of 0.35 μm, 0.35 μm
A resist pattern having an opening was formed. 00
38

Example 6 A solvent having a molecular weight of 50 was added to methoxyisopropanol.
No. 00 p-vinyloxyethoxystyrene and p-hydroxystyrene copolymer (copolymer ratio 10:90) (vinyloxyethoxylation ratio: 10%) as a base oligomer 10% by weight, as a photo-acid generator triphenyl Sulfonium trifluoromethanesulfonate (Ph ₃ -S
CF ₃ SO ₃ ) was dissolved in 0.5% by weight to prepare a resist solution.

This solution was applied onto a silicon substrate in the same manner as in Example 1 and prebaked on a hot plate at 80 ° C. for 120 seconds to form a resist film having a thickness of 0.8 μm. Next, the substrate coated with the resist is exposed to deep ultraviolet rays (24
After exposure with a stepper of NA: 0.45 at a dose of 150 mJ / cm ² with a KrF excimer laser light of 8 nm), baking was performed at 80 ° C. for 60 seconds. Then, it was developed in the same manner as in Example 1.

As a result, the mask pattern is 0.40 μm.
m, 0.20 μm for 1: 1 line / space,
It was possible to form a 1: 1 line / space resist pattern on a silicon substrate. Further, a silicon substrate coated with the same resist solution as above was irradiated with an exposure amount of 200 mJ / cm ² using a mask having an opening with an outer diameter of 0.40 μm, so that the outer diameter of 0.
A resist pattern having a donut-shaped remaining pattern of 40 μm and an inner diameter of 0.20 μm was obtained.

In this example, as the base oligomer,
A p-vinyloxyethoxystyrene having a molecular weight of 5000 and a p-hydroxystyrene copolymer (vinyloxyethoxylation rate: 10%) were used. If the molecular weight is 3000 to 10,000, use it in this example. You can In this embodiment, the prebaking step of the patterning process was performed at 80 ° C. for 120 seconds, but the pattern could be formed even at a temperature below this.

Comparative Example 10: A resist pattern was formed by the same steps as in Example 6 except that the prebaking temperature was 120 ° C. for 120 seconds. As a result, when the mask pattern is 0.30 μm and 1: 1 line / space,
The resolution was 30 μm 1: 1 line / space. In addition, for the opening having a mask pattern of 0.35 μm,
A resist pattern having an opening of 0.35 μm was formed.

[0055]

According to the method of forming a resist pattern of the present invention, the characteristics of both negative and positive resists can be utilized, and the exposure wavelength can be shortened without shortening the wavelength.
Further, it is possible to form a high-resolution resist pattern by a process substantially similar to the conventional manufacturing process without using the super-resolution technique.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a resist film residual ratio and an exposure amount in a resist used in a method for forming a resist pattern according to the present invention.

FIG. 2 is a schematic cross-sectional view for explaining changes in the exposure light passing through the mask and the resist in the method for forming a resist pattern according to the present invention.

FIG. 3 is a schematic cross-sectional view showing a resist pattern formed by the method of forming a resist pattern according to the present invention.

FIG. 4 is a plan view showing a mask used for forming a ring-shaped or donut-shaped pattern.

FIG. 5 is a schematic plan view showing a resist pattern formed by the method of forming a resist pattern according to the present invention.

6 is a schematic cross-sectional view of the resist pattern of FIG.

FIG. 7 is a graph showing the relationship between the resist film residual ratio and the exposure dose in a resist used in the method for forming a resist pattern according to the present invention.

FIG. 8 is a schematic cross-sectional view for explaining changes in the exposure light passing through the mask and the resist in the method for forming a resist pattern according to the present invention.

FIG. 9 is a schematic cross-sectional view showing a resist pattern formed by the method of forming a resist pattern according to the present invention.

FIG. 10 is a schematic plan view showing a resist pattern formed by the method for forming a resist pattern according to the present invention.

11 is a schematic cross-sectional view of the resist pattern of FIG.

FIG. 12 is a graph showing the relationship between the resist film residual ratio and the exposure dose in a resist used in a conventional resist pattern forming method.

FIG. 13 is a schematic cross-sectional view for explaining changes in the exposure light passing through the mask and the resist in the conventional resist pattern forming method.

FIG. 14 is a schematic cross-sectional view showing a resist pattern formed by a conventional resist pattern forming method.

FIG. 15 is a schematic plan view showing a resist pattern formed by a conventional resist pattern forming method.

16 is a schematic cross-sectional view of the resist pattern of FIG.

[Explanation of symbols]

 1 Mask 1a, 5a Opening 2 Light 3 Resist 3a, 6a, 8a Negative area 3b, 6b, 8b Positive area 4, 6, 7, 8 Resist pattern 5 Mask

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location G03F 7/028 7/30 7124-2H 7/38 511 7124-2H H01L 21/027

Claims (11)

[Claims] 1. (i) A hydroxystyrene-based oligomer (provided that at least one hydroxy group is present on the substrate or thin film).
Part is substituted with a functional group) and a resist solution consisting of a photoacid generator, and (ii) the substrate or thin film coated with the resist solution, through a mask having a desired pattern, While generating acid from the photo-acid generator,
After exposing with an exposure amount sufficient to cause the polymerization of the oligomer, baking is carried out, and (iii) the obtained exposed film is treated with an alkali developing solution to form a resist-removed part and a resist-uncoated part in one exposed part. A method of forming a resist pattern, comprising forming a resist pattern including a removed portion. 2. At least one part of the hydroxy group of the hydroxystyrene-based oligomer is at least one functional group selected from the group consisting of t-butoxycarbonyl group, pyranyl group, t-butoxycarbonylmethyl group and trialkylsilyl group. The method for forming a resist pattern according to claim 1, wherein the resist pattern is replaced with. 3. At least a part of the hydroxy group of the hydroxystyrene-based oligomer is substituted with at least one functional group selected from the group consisting of an isopropenyloxycarbonyl group, an acryl group, a vinyloxyalkyl group and a vinyloxycarbonyl group. The method of forming a resist pattern according to claim 1. 4. The exposure amount in step (ii) is 50 mJ / cm ^2.
The method for forming a resist pattern according to any one of claims 1 to 3, which is as described above. 5. The baking after exposure in step (ii) is 80 to 1
The method for forming a resist pattern according to claim 2, wherein the method is performed in a temperature range of 00 ° C. 6. The method for forming a resist pattern according to claim 3, wherein pre-baking is performed in a temperature range of 50 to 90 ° C. before the exposure in step (ii). 7. The method for forming a resist pattern according to claim 1, wherein the photoacid generator is an onium salt-based or non-onium salt-based photoacid generator. 8. The method for forming a resist pattern according to claim 7, wherein the photo-acid generator is triphenylsulfonium trifluoromethanesulfonate. 9. The method of forming a resist pattern according to claim 1, wherein the resist solution further contains a dissolution inhibitor that suppresses dissolution of a polymer produced after polymerization of the oligomer in a developer used. 10. The method for forming a resist pattern according to claim 9, wherein the dissolution inhibitor is bisphenol A or phenolphthalein having a t-butoxycarbonyl group, a pyranyl group or a t-butoxycarbonylmethyl group as a substituent. . 11. One of the exposed portions of the resist pattern has a resist-removed portion in the center thereof and a resist-unremoved portion in the periphery thereof, or has a resist-unremoved portion in the center thereof. The method for forming a resist pattern according to claim 1, wherein the resist removal portion is provided around the periphery.