Source: http://www.google.com/patents/US7879528?dq=5726663
Timestamp: 2017-03-26 13:55:59
Document Index: 160570438

Matched Legal Cases: ['§371', '§119', 'Application No. 2003', 'Application No. 2003', 'Application No. 2004', 'Application No. 2004']

Patent US7879528 - Resist composition for electron beam or EUV - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsA resist composition and a method of forming a resist pattern that enable contamination within the exposure apparatus to be prevented in lithography processes using an electron beam or EUV (extreme ultraviolet light). In this method, an organic solvent containing, as the principal component, one or more...http://www.google.com/patents/US7879528?utm_source=gb-gplus-sharePatent US7879528 - Resist composition for electron beam or EUVAdvanced Patent SearchTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents.Publication numberUS7879528 B2Publication typeGrantApplication numberUS 12/044,678Publication dateFeb 1, 2011Filing dateMar 7, 2008Priority dateOct 22, 2003Fee statusPaidAlso published asUS7407734, US20070077512, US20080176170, WO2005040921A1Publication number044678, 12044678, US 7879528 B2, US 7879528B2, US-B2-7879528, US7879528 B2, US7879528B2InventorsTakeo Watanabe, Hideo Hada, Hiroo KinoshitaOriginal AssigneeTokyo Ohka Kogyo Co., Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (45), Non-Patent Citations (2), Classifications (21), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetResist composition for electron beam or EUV
[Film thickness (1)−Film thickness (2)]/(150−130)(Å/° C.)≦0.2(Å/° C.) (I)
wherein, said film thickness (1) is a film thickness following application of said resist composition to a substrate in sufficient quantity to generate a film thickness of 2300 Å±10% and subsequent heating at 130° C. for 90 seconds, and said film thickness (2) is a film thickness following application of said resist composition to a substrate in sufficient quantity to generate a film thickness of 2300 Å±10% and subsequent heating at 150° C. for 90 seconds.
7. The method of forming a resist pattern according to claim 5, wherein a degree of variation in total pressure of atmosphere inside an exposure system between a state prior to exposure and a state following exposure is less than 4.0×10−5 Pa.
This application is a continuation of U.S. patent application Ser. No. 10/574,073, filed Mar. 30, 2006, which is the U.S. National Phase filing under 35 U.S.C. §371 of PCT/JP2004/015503, filed Oct. 20, 2004, which designated the United States and was published in a language other than English, which claims priority under 35 U.S.C. §119(a)-(d) to Japanese Patent Application No. 2003-362223, filed Oct. 22, 2003; Japanese Patent Application No. 2003-371111, filed Oct. 30, 2003; and Japanese Patent Application No. 2004-100206, filed Mar. 30, 2004. The content of these applications is incorporated herein by reference in their entireties.
However, a problem arises in processes using electron beams or EUV in that as exposure is continued, a phenomenon occurs wherein the exposure radiation reaching the substrate weakens, or stable exposure becomes impossible, or exposure itself becomes impossible.
In order to achieve the above object, the present invention includes the aspects described below. A first aspect is a resist composition for an electron beam or EUV, wherein an organic solvent containing as the principal component, one or more compounds selected from the group consisting of propylene glycol monomethyl ether (PGME), methyl amyl ketone (MAK), butyl acetate (BuOAc), and 3-methyl methoxy propionate (MMP) is used as the resist solvent.
By application of the present invention, contamination within the exposure apparatus can be prevented for processes that use an electron beam or EUV.
FIG. 1 is a graph showing the variation in film thickness relative to heating temperature for films obtained in the examples and comparative examples.
In contrast, if propylene glycol monomethyl ether acetate (PGMEA) and ethyl lactate (EL) are used, which until now have been the most widely used resist solvents, then contaminants are generated from within the resist film, and the object of the present invention cannot be achieved. The expression “an organic solvent containing, as the principal component” means that the one or more compounds selected from the group consisting of propylene glycol monomethyl ether (PGME), methyl amyl ketone (MAK), butyl acetate (BuOAc), and 3-methyl methoxy propionate (MMP) represent the main component of the solvent, and other optional solvents may also be added provided the effects of the present invention are retained.
[Film thickness (1)−Film thickness (2)]/(150−130)(Å/° C.)=0.2(Å/° C.) (I)
[In this formula, the film thickness (1) is the film thickness following application of the resist composition to a substrate in sufficient quantity to generate a film thickness of 2300 Å±10% and subsequent heating at 130° C. for 90 seconds, and the film thickness (2) is the film thickness following application of the resist composition to a substrate in sufficient quantity to generate a film thickness of 2300 Å±10% and subsequent heating at 150° C. for 90 seconds.]
The value represented by the formula (I) is the gradient of the variation in film thickness relative to the temperature, and smaller values for this gradient indicate a smaller degree of variation in the film thickness when heated within a range from 130 to 150° C. The value of the left-hand member of the above formula is typically no more than 0.2 (Å/° C.), preferably no more than 0.15 (Å/° C.), and even more preferably 0.1 (Å/° C.) or less. The smaller this value is the better, so there is no technical meaning in prescribing a lower limit value.
The reason for specifying heating at temperature conditions of 130° C. and 150° C. is due to consideration of the prebake temperature conditions used in electron beam or EUV lithography.
Setting the heating conditions to at least 130° C. facilitates the adjustments required to obtain favorable resist pattern characteristics such as contrast. Setting the temperature conditions to no more than 150° C. simply reflects the upper limit temperature in terms of the prebake operation and the heating apparatus used in the prebake.
The heating conditions in the method of forming a resist pattern described below are not restricted to the temperature range from 130 to 150° C., but setting the temperature within this range is preferred from the viewpoints of conducting stable exposure and obtaining a favorable resist pattern, and in terms of the apparatus and operation conditions.
The film thickness was set to a value of 2300 Å±10% based on the types of film thickness values used in processes that use an electron beam or EUV. The ±10% enables measurement error to be taken into consideration, and provided the value falls within this range, the value can be applied to the criterion determined by the formula (I).
The second condition requires that the degree of variation in the total pressure of the atmosphere inside the exposure system between the state prior to exposure and the state following exposure is less than 4.0×10−5 Pa. As mentioned above, exposure using an electron beam or EUV is conducted within a vacuum, but on exposure, the generation of contaminants causes an increase in the pressure inside the exposure system. The degree of variation in the aforementioned total pressure is preferably no more than 3.5×10−5 Pa, and even more preferably no more than 3.3×10−5 Pa. The smaller this value is the better, so there is no technical meaning in prescribing a lower limit value. In the future, reducing this pressure variation to the 10−7 Pa or 10−8 Pa level is feasible, and this invention includes these types of ultra low pressure levels.
The conditions for measuring the degree of variation in the total pressure are described below. These conditions represent the standard conditions for exposure in an apparatus that emits EUV or the like using current technology. In the future, there is a possibility of further improvements in the degree of vacuum. Currently, if the degree of variation satisfies the aforementioned numerical range under these conditions, then the object of the present invention can be satisfactorily achieved. Exposure conditions: temperature: room temperature (25° C.), NewSubaru radiation optical facility at the Himeji Institute of Technology, pressure: 1×10−7 to 1×10−5 Pa, and preferably 1×10−6 Pa, heat accumulation current of the ring: 200 mA, exposure wavelength: 13.5 nm, exposure time: 60 seconds, resist film thickness: 100 nm.
The inside of the exposure system is designed so as to maintain the pressure at the above value, but as described above, when exposure is conducted, the pressure inside the exposure system increases as a result of contaminant generation. The “degree of variation in the total pressure of the atmosphere inside the exposure system between the state prior to exposure and the state following exposure” defined in the second condition can be determined by calculating the difference between the two values. In other words, the degree of variation can be determined by subtracting the pressure within the system immediately prior to exposure from the pressure in the system following exposure.
In this description, the term “(meth)acrylic acid” is a generic term that includes both methacrylic acid and acrylic acid. Similarly, the term “(meth)acrylate” is a generic term that includes both methacrylate and acrylate. Furthermore, the term “structural unit” refers to a monomer unit that contributes to the formation of a polymer. The expression “structural unit derived from a (meth)acrylate ester” refers to a structural unit that is formed by the cleavage of the ethylenic double bond of the (meth)acrylate ester, and is hereafter also referred to as a (meth)acrylate structural unit.
First Example Resin Component
(wherein, R represents —H or —CH3)
Provided R represents either —H or —CH3, there are no particular restrictions.
There are no particular restrictions on the bonding position of the —OH group to the benzene ring, although the position labeled 4 in the formula (the para position) is preferred.
(wherein, R represents —H or —CH3, and X represents an acid dissociable, dissolution inhibiting group)
Examples of the acid dissociable, dissolution inhibiting group X include alkyl groups with a tertiary carbon atom in which the tertiary carbon atom is bonded to the ester group (—C(O)O—), as well as cyclic acetal groups such as a tetrahydropyranyl group and tetrahydrofuranyl group.
When acid is generated from the acid generator on exposure, the acid dissociable, dissolution inhibiting group dissociates from the unit (a2) under the action of the acid, thereby converting the structural unit (a2) to a (meth)acrylic acid structural unit [the term “(meth)acrylic acid structural unit is a generic term including a methacrylic acid structural unit and an acrylic acid structural unit], and as a result, improving the solubility of the resin in an alkali developing solution.
(wherein, R and R1 each represent, independently, —H or —CH3, R2 represents —CH3 or —C2H5, and R3 represents a lower alkyl group)
(wherein, R represents —H or —CH3, R4 represents a lower alkyl group, and n represents either 0 or an integer from 1 to 3)
Second Example Resin Component
a structural unit which contains a polycyclic group-containing acid dissociable, dissolution inhibiting group, and is derived from a (meth)acrylate ester (hereafter also referred to as the first structural unit),
a structural unit which contains a lactone-containing monocyclic or polycyclic group, and is derived from a (meth)acrylate ester (hereafter also referred to as the second structural unit), and
a structural unit which contains a hydroxyl group-containing polycyclic group, and is derived from a (meth)acrylate ester (hereafter also referred to as the third structural unit).
In such cases, the first structural unit is essential, and although resins containing two types of structural units, namely the first structural unit and either the second structural unit or third structural unit are suitable, resin components containing all of the first through third structural units are preferred in terms of factors such as etching resistance, resolution, and the adhesion between the resist film and the substrate.
a structural unit which contains a polycyclic group that is different from the polycyclic group-containing acid dissociable, dissolution inhibiting group of the first structural unit, the lactone-containing monocyclic or polycyclic group of the second structural unit, and the hydroxyl group-containing polycyclic group of the third structural unit, and is derived from a (meth)acrylate ester.
Accordingly, the combination of the first through fourth structural units can be adjusted appropriately in accordance with factors such as the desired characteristics.
If both structural units are included, then the molar ratio structural units (a11):structural units (a11′) is preferably 0.4 to 2.5, and even more preferably 0.6 to 1.5, as such ratios yield superior compatibility between the polymer containing the structural units (a11) and the polymer containing the structural units (a11′).
If both structural units are included, then the molar ratio structural units (a12) structural units (a12′) is preferably within a range from 0.2 to 5.0, and even more preferably 0.6 to 1.5, as such ratios yield superior compatibility between the polymer containing the structural units (a12) and the polymer containing the structural units (a12′).
If both structural units are included, then the molar ratio structural units (a13) structural units (a13′) is preferably within a range from 0.2 to 5.0, and even more preferably 0.6 to 1.5, as such ratios yield superior compatibility between the polymer containing the structural units (a13) and the polymer containing the structural units (a13′).
The structural unit represented by the above general formula (I′) represents the case wherein the carbon atom that is adjacent to the oxygen atom (—O—) of the ester function of the (meth)acrylate unit is a tertiary alkyl group that exists within the ring skeleton of an adamantyl group or the like.
The structural unit represented by the above general formula (II′) represents the case wherein the carbon atom that is adjacent to the oxygen atom (—O—) of the ester function of the (meth)acrylate unit is a tertiary alkyl group, and a ring skeleton such as an adamantyl group exists within this tertiary alkyl group.
The structural unit represented by the above general formula (III′) represents the case wherein the carbon atom that is adjacent to the oxygen atom (—O—) of a separate ester from the ester function of the (meth)acrylate unit is a tertiary alkyl group, and the (meth)acrylate ester and this separate ester are connected via a ring skeleton such as a tetracyclododecanyl group.
If the combination of the structural unit (a11) and the structural unit (a11′) accounts for 30 to 60 mol %, and preferably from 30 to 50 mot %, of the combined total of all the structural units that constitute the aforementioned resin component, then the resolution is superior, which is preferred.
Copolymer (ii): a copolymer that contains from 30 to 60 mol % of the structural unit (a11), from 20 to 60 mol % of the structural unit (a12), and from 1 to 50 mold %, and preferably from 5 to 40 mol %, of the structural unit (a13).
Moreover, in the copolymers (ii) and (iii), the inclusion of the structural unit (a 13) or the structural unit (a13′) respectively is optional.
Furthermore, as described above, the resin component preferably also includes, as the aforementioned fourth structural unit, a structural unit [the structural unit (a14)] which contains a polycyclic group that is “different from the aforementioned polycyclic group-containing acid dissociable, dissolution inhibiting group, the aforementioned lactone-containing monocyclic or polycyclic group, and the aforementioned hydroxyl group-containing polycyclic group”, and is derived from a (meth)acrylate ester.
The expression “different from the aforementioned polycyclic group-containing acid dissociable, dissolution inhibiting group, the aforementioned lactone-containing monocyclic or polycyclic group, and the aforementioned hydroxyl group-containing polycyclic group” means that the polycyclic group of the structural unit (a14) does not duplicate the polycyclic group-containing acid dissociable, dissolution inhibiting group of the first structural unit, the lactone-containing monocyclic or polycyclic group of the second structural unit, or the hydroxyl group-containing polycyclic group of the third structural unit, meaning, in other words, that the structural unit (a14) contains no polycyclic group-containing acid dissociable, dissolution inhibiting groups of the first structural unit, no lactone-containing, monocyclic or polycyclic groups of the second structural unit, and no hydroxyl group-containing polycyclic groups of the third structural unit.
Furthermore, in this copolymer (v), from the viewpoint of achieving favorable resolution and resist pattern shape, the structural unit (a11′) typically accounts for 30 to 60 mol %, and preferably from 30 to 50 mol %, the structural unit (a12) typically accounts for 20 to 60 mol %, and preferably from 20 to 50 mol %, the structural unit (a 13) typically accounts for 1 to 30 mol %, and preferably from 10 to 20 mol %, and the structural unit (a14) typically accounts for 1 to 25 mol %, and preferably from 10 to 20 mol % of the combination of these structural units (a11′), (a12), (a13), and (a14).
Specific examples of suitable onium salts include diphenyliodonium trifluoromethanesulfonate, (4-methoxyphenyl)phenyliodonium trifluoromethanesulfonate, bis(p-tert-butylphenyl)iodonium trifluoro methanesulfonate, triphenylsulfonium trifluoromethanesulfonate, (4-methoxyphenyl)diphenylsulfonium trifluoromethanesulfonate, (4-methylphenyl)diphenylsulfonium nonafluorobutanesulfonate, (p-tert-butylphenyl)diphenylsulfonium trifluoromethanesulfonate, diphenyliodonium nonafluorobutanesulfonate, bis(p-tert-butylphenyl)iodonium nonafluorobutanesulfonate, and triphenylsulfonium nonafluorobutanesulfonate. Of these compounds, onium salts containing a fluorinated alkylsulfonate ion as the anion are preferred.
Examples of suitable oxime sulfonate compounds include α-(methylsulfonyloxyimino)-phenylacetonitrile, α-(methylsulfonyloxyimino)-p-methoxyphenylacetonitrile, α-(trifluoromethylsulfonyloxyimino)-phenylacetonitrile, α-(trifluoromethylsulfonyloxyimino)-p-methoxyphenylacetonitrile, α-(ethylsulfonyloxyimino)-p-methoxyphenylacetonitrile, α-(propylsulfonyloxyimino)-p-methylphenylacetonitrile, and α-(methylsulfolnyloxyimino)-p-bromophenylacetonitrile. Of these, α-(methylsulfonyloxyimino)-p-methoxyphenylacetonitrile is preferred.
Namely, an aforementioned positive resist composition is first applied to the surface of a substrate such as a silicon wafer using a spinner or the like, a prebake is conducted under temperature conditions of 80 to 150° C., and preferably from 130 to 150° C., for a period of 40 to 120 seconds, and preferably for 60 to 90 seconds, the thus obtained film is then subjected to selective exposure in a vacuum (for example, 1×10−7 to 1×10−5 Pa), either through a desired mask pattern or via direct patterning, using an EUV or EB exposure apparatus or the like, and PEB (post exposure baking) is then conducted under temperature conditions of 80 to 150° C. for 40 to 120 seconds, and preferably for 60 to 90 seconds. Subsequently, a developing treatment is conducted using an alkali developing solution such as a 0.1 to 10% by weight aqueous solution of tetramethylammonium hydroxide. In this manner, a resist pattern that is faithful to the mask pattern can be obtained.
Composition of Resists
Component (B): 5.0 parts by weight of triphenylsulfonium nonafluorobutanesulfonate.
Other additives: 0.3 parts by weight of triethanolamine.
Each of the above resist compositions was applied to the surface of a silicon substrate of diameter 200 mm in sufficient quantity to generate a film thickness of 2300±10% Å, and the film thickness was then measured after heating for 90 seconds at temperature conditions of 90° C., 110° C., 130° C., and 150° C. respectively.
The values measured at 130° C. and 150° C. were used to determine the value of the left-hand member of the above formula (I).
Each of the above resist compositions was applied to the surface of a silicon substrate of diameter 200 mm in sufficient quantity to generate a film thickness of 2300±10% Å, and the film was then heated for 90 seconds under temperature conditions of 130° C.
Subsequently, under conditions including a pressure of 1×10−7 to 1×10−5 Pa, and a temperature of room temperature (25° C.), the NewSubaru radiation optical facility at the Himeji Institute of Technology was used to conduct a selective exposure (exposure time: 60 seconds) of the resist film, using light of 13.5 nm, a heat accumulation current value for the ring of 200 mA, and a resist film thickness of 100 nm.
(Å/° C.)
3.10 × 10−5 Example 2
3.29 × 10−5 Example 3
3.50 × 10−5 Example 4
3.50 × 10−5 Comparative
4.10 × 10−5 example 1
4.00 × 10−5 example 2
4.20 × 10−5 example 3
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