U.S. patent application number 14/610096 was filed with the patent office on 2015-12-31 for compositions comprising carboxy component and processes for photolithography.
The applicant listed for this patent is Rohm and Haas Electronic Materials, LLC. Invention is credited to George G. Barclay, Charles R. Szmanda, Deyan Wang, Cheng-Bai Xu.
Application Number | 20150378255 14/610096 |
Document ID | / |
Family ID | 41818664 |
Filed Date | 2015-12-31 |
United States Patent
Application |
20150378255 |
Kind Code |
A1 |
Wang; Deyan ; et
al. |
December 31, 2015 |
COMPOSITIONS COMPRISING CARBOXY COMPONENT AND PROCESSES FOR
PHOTOLITHOGRAPHY
Abstract
New photoresist compositions are provided that are useful for
immersion lithography. Preferred photoresist compositions of the
invention comprise one or more block copolymers. Particularly
preferred photoresists of the invention can exhibit reduced
leaching of resist materials into an immersion fluid contacting the
resist layer during immersion lithography processing.
Inventors: |
Wang; Deyan; (Hudson,
MA) ; Szmanda; Charles R.; (Westborough, MA) ;
Barclay; George G.; (Jefferson, MA) ; Xu;
Cheng-Bai; (Southboro, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Rohm and Haas Electronic Materials, LLC |
Marlborough |
MA |
US |
|
|
Family ID: |
41818664 |
Appl. No.: |
14/610096 |
Filed: |
January 30, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12592155 |
Nov 19, 2009 |
8975006 |
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14610096 |
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61199696 |
Nov 19, 2008 |
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Current U.S.
Class: |
430/270.1 ;
430/322 |
Current CPC
Class: |
G03F 7/2041 20130101;
G03F 7/0048 20130101; G03F 7/0382 20130101; G03F 7/038 20130101;
G03F 7/0392 20130101; G03F 7/0046 20130101 |
International
Class: |
G03F 7/038 20060101
G03F007/038; G03F 7/20 20060101 G03F007/20 |
Claims
1. A method for processing a photoresist composition, comprising:
(a) applying on a substrate a photoresist composition comprising:
(i) one or more resins, (ii) a photoactive component, and (iii) one
or more block copolymers that are distinct from the one or more
resins; and (b) immersion exposing the photoresist layer to
radiation activating for the photoresist composition.
2. The method of claim 1 wherein the one or more block copolymers
are substantially non-mixable with the one or more resins.
3. The method of claim 1 wherein one or more of the block
copolymers comprise (1) a developer affinity block and (2) a
hydrophobic block.
4. The method of claim 1 wherein one or more of the block
copolymers comprise at least three distinct blocks or domains.
5. The method of claim 1 wherein the one or more block copolymers
comprise hetero-substituted multi-ring carbocyclic aryl groups,
sulfonamide and/or carboxy groups.
6. The method of claim 1 wherein the one or more block copolymers
comprise one more fluorine groups or fluorine-substituted
groups.
7. The method of claim 1 wherein the one or more block copolymers
comprise aqueous base-solubilizing groups and/or one or more
photoacid-labile groups.
8. A coated substrate system comprising: a substrate having
thereon: a coating layer of a photoresist composition, the
photoresist composition comprising: (i) one or more resins, (ii) a
photoactive component, and (iii) one or more block copolymers that
are distinct from the one or more resins.
9. The system of claim 8 wherein an immersion lithography fluid
contacts the top surface of the photoresist coating layer
10. The system of claim 8 further comprising an immersion
photolithography exposure tool.
11. The system of claim 8 wherein one or more of the block
copolymers comprise (1) a developer affinity block and (2) a
hydrophobic block.
12. A photoresist composition comprising: one or more resins, (ii)
a photoactive component, and (iii) one or more one or more block
copolymers that are distinct from the one or more resins.
13. The photoresist composition of claim 12 herein the one or more
block copolymers are substantially non-mixable with the one or more
resins.
Description
[0001] The present invention relates to new photoresist
compositions that are particularly useful in immersion lithography
processes. Preferred photoresist compositions of the invention
comprise one or more with block copolymers. Preferred block
copolymers can be substantially non-mixable with a resin component
of the resist. Particularly preferred photoresists of the invention
can exhibit reduced defects following development with an aqueous
alkaline solution.
[0002] Photoresists are photosensitive films used for transfer of
an image to a substrate. A coating layer of a photoresist is formed
on a substrate and the photoresist layer is then exposed through a
photomask to a source of activating radiation. The photomask has
areas that are opaque to activating radiation and other areas that
are transparent to activating radiation. Exposure to activating
radiation provides a photoinduced chemical transformation of the
photoresist coating to thereby transfer the pattern of the
photomask to the photoresist coated substrate. Following exposure,
the photoresist is developed to provide a relief image that permits
selective processing of a substrate. See U.S. Patent Application
Publication 200610246373.
[0003] The growth of the semiconductor industry is driven by
Moore's law which states that the complexity of an IC device
doubles on average every two years. This necessitates the need to
lithographically transfer patterns and structures with ever
decreasing feature size.
[0004] While currently available photoresists are suitable for many
applications, current resists also can exhibit significant
shortcomings, particularly in high performance applications such as
formation of highly resolved sub-quarter micron and even sub-tenth
micron features.
[0005] We now provide new photoresist compositions and processes.
Photoresist compositions comprise one or more block copolymers.
[0006] More particularly, preferred photoresists of the invention
may comprise:
[0007] (i) one or more resins,
[0008] (ii) a photoactive component which may suitably comprise one
or more photo acid generator compounds, and
[0009] (iii) one or more block copolymers. Preferably, the one or
more block copolymers are substantially non-mixable with the one or
more resins,
[0010] Preferred block copolymers comprise at least two domains or
blocks (1) and (2):
[0011] (1) developer-solublizing block that comprises developer
soluble moieties such as photoacid-labile groups (e.g.
photoacid-labile ester or acetal groups) or other developer
solubilizing groups such as carboxy (--COOH), fluoroalcohols such
as --C(OH)(CF.sub.3).sub.2, or optionally substituted
sulfonamide;
[0012] (2) a hydrophilic block that comprises repeat units will
hydrophilic groups such as longer chain alkyl groups (e.g.
optionally substituted C.sub.4-25alkyl) including branched alkyl
groups (e.g. optionally substituted branched C.sub.4-25alkyl) such
as polymerized 2,3,3-trimethyl butylacrylate.
[0013] Preferred block copolymers may comprise additional blocks or
domains in addition to (1) and (2), i.e. the copolymers may be
triblocks, tetrablocks or other higher order multi-block polymers.
For at least certain applications, a dual-block polymer (total of 2
domains or blocks) will be suitable. Thus, references herein to
block copolymers are inclusive of polymers that comprise 2, 3, 4 or
more distinct blocks or domains. As should be understood, the term
"block" polymer or copolymer as referred to herein indicates a
polymer that comprises one or more section of a first chemical
structure separated by one or more sections of a different chemical
structure or composition.
[0014] The size or molecular weight of each block or domain of a
block copolymer of a photoresist of the invention may vary rather
widely. For at least certain applications, each block of a
copolymer may have a Mw of at least 50 or 100, more preferably at
least about 200, 300, 400, 500, 600, 700, 800, 900, 10000, 1100,
1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900 or 2000. Each block
of a block copolymer may have differing molecular weights, or
approximately equal (e.g. within about 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 15, 20 or 25 percent) molecular weights.
[0015] Each block of a block copolymer can vary in composition. For
example, suitable will be blocks that consist essentially of (e.g.
at least 70, 80, 90, 95 or 98 weight percent) of a single repeat
unit. Also suitable will be blocks that are alternating or random
polymer units of 2, 3, 4, 5 or more distinct polymerized
monomers.
[0016] Block copolymers used in photoresists of the invention may
contain a variety of moieties including e.g. fluorinated groups
such as fluoroalkyl including fluoro(C.sub.1-25alkyl) including
perfluoro(C.sub.1-25alkyl) such as F.sub.3C-- and
F.sub.3CF.sub.2C--; fluoroalcohols such as
fluoro(C.sub.1-25alcohols) including (F.sub.3C).sub.2C(OH)--;
sulfonamides including fluorinated sulfonamides; extended alkyl
groups e.g. C.sub.4-20alkyl including branched alkyl such as
t-butyl; and Si-substituted groups such as Si(C.sub.1-20alkyl);
hetero(N, O or S)-substituted carbocyclic aryl units, particularly
hetero(N, O or S)-substituted multi-ring carbocyclic aryl units
such as hydroxynaphthyl groups. Block polymers that comprise
polymerized acrylate groups (including acrylate groups that contain
photoacid-labile and/or fluorinated moieties) also are
preferred.
[0017] Particularly preferred photoresists of the invention can
exhibit reduced defects associated with a resist relief image
formed from the photoresist composition. In certain aspects,
micro-bridging between lines of the formed resist relief image can
be minimized or avoided.
[0018] As referred to herein, one or more block copolymers that are
substantially non-mixable with the one or more photoresist resins
can be any block polymer added to a photoresist that results in
reduced defects upon aqeuous alkaline development.
[0019] Suitable block co polymers (including substantially
non-mixable block copolymers) for use in photoresists of the
invention include compositions that comprise silicon and/or
fluorine substitution.
[0020] Preferred block copolymers (which can be substantially
non-mixable materials) for use in photoresists of the invention
also may comprise optionally substituted sulfonamide groups,
including groups such as RS(.dbd.O)(X)NR'.sub.2 where R is a
non-hydrogen substituent, particularly --OH (to provide
--SO.sub.3H), optionally substituted C.sub.1-20alkyl, and an
electron-withdrawing group such as halogen especially fluoro or
haloalkyl such as fluoralkyl e.g. F.sub.3C--. In the formula
RS(.dbd.O)(X)NR'.sub.2, X is a spacer (e.g. a chemical bond or a 1
to 8 carbon linkage), and each R' is independently a hydrogen or
non-hydrogen substituent such as optionally substituted
C.sub.1-20alkyl including a group as defined for R above. Such
sulfonamide groups suitably may be present on an alkyl linkage
(e.g. C.sub.1-12alkyl), a polymerized acrylate group, or other
moiety.
[0021] It thus should be understood that references herein to
"sulfonamide" are inclusive of where a sulfono (SO.sub.2) moiety is
directly linked (e.g. X in formula RS(.dbd.O)(X)NR'.sub.2 is
chemical bond) to nitrogen as well as where a sulfono (SO.sub.2)
moiety is spaced by 1, 2, 3 or more atoms (such as carbon atoms,
e.g. X in formula RS(.dbd.O)(X)NR'.sub.2 is (--CH.sub.2--).sub.1-3)
from the nitrogen of the sulfonamide group.
[0022] In certain aspects of the invention, preferred are
photoresist compositions that comprise materials that comprise
sulfonamide group(s) where a sulfono (--SO.sub.2) moiety is spaced
by 1, 2, 3 or more non-nitrogen atoms from the most adjacent
nitrogen of the sulfonamide moiety.
[0023] Additional preferred block copolymers (which can be
substantially non-mixable materials) for use in photoresists of the
invention also may comprise carboxy (--COOH) groups, such as may be
present on alkyl groups e.g. --(CH.sub.2)--COOH where n is suitably
from 1 to 20, or polymerized acid acrylate groups such as may be
provided by polymerization of acrylic acid or methacrylic acid or
by a group
(CH.sub.3).sub.n(CH.sub.m.dbd.CH.sub.2)C(.dbd.O)O(CH.sub.2).sub.pCOOH
where n is 0 or 1, m is 2 or 3, p is an integer of from 1 to
12.
[0024] Still further preferred block copolymers (which can be
substantially non-mixable materials) for use in photoresists of the
invention also may comprise hetero-substituted carbocyclic aryl
units, particularly carbocyclic aryl units substituted by oxygen or
sulfur-containing moieties such as hydroxyl, e.g. multi-ring
substituted carbocyclic aryl units such as hydroxyl naphthyl.
[0025] Also preferred are those block copolymers (including
substantially non-mixable block copolymers) that comprise
photoacid-labile groups, such as photoacid-labile ester or acetal
groups, including such groups as described herein employed in a
resin component of a chemically amplified photoresist.
[0026] Preferred substantially non-mixable block polymers for use
in photoresists of the invention also will be soluble in the same
organic solvent(s) used to formulate the photoresist
composition.
[0027] Particularly preferred block copolymers (including
substantially non-mixable block copolymer) for use in photoresists
of the invention also will have lower surface energy and/or smaller
hydrodynamic volume than the one or more resins of the
photoresist's resin component, or at least one or more distinct
blocks of the polymer will have such a lower surface energy and/or
smaller hydrodynamic volume than the one or more resins of the
photoresist's resin component. The lower surface energy can
facilitate segregation or migration of the block copolymer to top
or upper portions of an applied photoresist coating layer.
Additionally, relative smaller higher hydrodynamic volume also can
be preferred because it can facilitate efficient migration (higher
diffusion coefficient) of the block polymers to upper regions of
the applied photoresist coating layer.
[0028] Preferred block polymers for use in photoresists of the
invention also will be soluble in photoresist developer
compositions (e.g. 0.26N aqueous alkaline solution such as 0.26N
tetramethyl ammonium hydroxide aqueous developer). Thus, in
addition to photoacid-labile groups as discussed above, other
aqueous base-solubilizing groups may be included in the
substantially non-mixable materials such as hydroxyl, fluoroalcohol
(e.g. --CH(CF.sub.3).sub.2), carboxy and the like.
[0029] Suitable block copolymers for use in photoresists of the
invention also may be in the form of particles. Such particles may
include block polymers that are polymerized in the form discrete
particles, i.e. as separate and distinct polymer particles. Such
polymer particles typically have one or more different
characteristics from linear or ladder polymers such as linear or
ladder silicon polymers. For example, such polymer particles may
have a defined size and a low molecular weight distribution. More
particularly, in a preferred aspect, a plurality of the polymer
particles may be employed, in a photoresist of the invention with a
mean particle size (dimension) of from about 5 to 3000 angstroms,
more preferably from about 5 to 2000 angstroms, still more
preferably from about 5 to about 1000 angstroms, yet more
preferably from about 10 to about 500 angstroms, even more
preferably from 10 to 50 or 200 angstroms. For many applications,
particularly preferred particles have a mean particle size of less
than about 200 or 100 angstroms.
[0030] Additional suitable block copolymers may have Si content,
including silsesquioxane materials, materials with Si0.sub.2
groups, and the like.
[0031] Preferred imaging wavelengths of lithographic systems of the
invention include sub-300 nm wavelengths e.g. 248 nm, and sub-200
nm wavelengths e.g. 193 nm. In addition to one or more block
copolymers, particularly preferred photoresists of the invention
may contain a photoactive component (e.g. one or more photoacid
generator compounds) and one or more resins (which resins are
distinct from the one or more block copolymers) that are suitably
chosen from among:
[0032] 1) a phenolic resin that contains acid-labile groups that
can provide a chemically amplified positive resist particularly
suitable for imaging at 248 nm. Particularly preferred resins of
this class include: i) polymers that contain polymerized units of a
vinyl phenol and an alkyl acrylate, where the polymerized alkyl
acrylate units can undergo a deblocking reaction in the presence of
photoacid. Exemplary alkyl acrylates that can undergo a
photoacid-induced deblocking reaction include e.g. t-butyl
acrylate, t-butyl methacrylate, methyladamantyl acrylate, methyl
adamantyl methacrylate, and other non-cyclic alkyl and alicyclic
acrylates that can undergo a photoacid-induced reaction, such as
polymers in U.S. Pat. Nos. 6,042,997 and 5,492,793, incorporated
herein by reference; ii) polymers that contain polymerized units of
a vinyl phenol, an optionally substituted vinyl phenyl (e.g.
styrene) that does not contain a hydroxy or carboxy ring
substituent, and an alkyl acrylate such as those deblocking groups
described with polymers i) above, such as polymers described in
U.S. Pat. No. 6,042,997, incorporated herein by reference; and iii)
polymers that contain repeat units that comprise an acetal or ketal
moiety that will react with photoacid, and optionally aromatic
repeat units such as phenyl or phenolic groups; such polymers have
been described in U.S. Pat. Nos. 5,929,176 and 6,090,526,
incorporated herein by reference, as well as blends of i) and/or
ii) and/or iii);
[0033] 2) phenolic resins that do not contain acid-labile groups
such as poly(vinylphenol) and novolak resins that may be employed
in I-line and G-line photoresists together with a
diazonaphthoquinone photoactive compound and have been described
e.g. in U.S. Pat. Nos. 4,983,492; 5,130,410; 5,216,111; and
5,529,880;
[0034] 3) a resin that is substantially or completely free of
phenyl or other aromatic groups that can provide a chemically
amplified positive resist particularly suitable for imaging at
sub-200 nm wavelengths such as 193 nm. Particularly preferred
resins of this class include: i) polymers that contain polymerized
units of a non-aromatic cyclic olefin (endocyclic double bond) such
as an optionally substituted norbornene, such as polymers described
in U.S. Pat. Nos. 5,843,624, and 6,048,664, incorporated herein by
reference; ii) polymers that contain alkyl acrylate units such as
e.g. t-butyl acrylate, t-butyl methacrylate, methyladamantyl
acrylate, methyl adamantyl methacrylate, and other non-cyclic alkyl
and alicyclic acrylates; such polymers have been described in U.S.
Pat. No. 6,057,083; European Published Applications EP01008913A1
and EP00930542A1; and U.S. pending patent application Ser. No.
09/143,462, all incorporated herein by reference, and iii) polymers
that contain polymerized anhydride units, particularly polymerized
maleic anhydride and/or itaconic anhydride units, such as disclosed
in European Published Application EP01008913A1 and U.S. Pat. No.
6,048,662, both incorporated herein by reference, as well as blends
of i) and/or ii) and/or iii);
[0035] 4) a resin that contains repeat units that contain a hetero
atom, particularly oxygen and/or sulfur (but other than an
anhydride, i.e. the unit does not contain a keto ring atom), and
preferable are substantially or completely free of any aromatic
units. Preferably, the heteroalicyclic unit is fused to the resin
backbone, and further preferred is where the resin comprises a
fused carbon alicyclic unit such as provided by polymerization of a
norborene group and/or an anhydride unit such as provided by
polymerization of a maleic anhydride or itaconic anhydride. Such
resins are disclosed in PCT/US01/14914 and U.S. application Ser.
No. 09/567,634.
[0036] 5) resins that contain Si-substitution including
poly(silsequioxanes) and the like and may be used with an
undercoated layer. Such resins are disclosed e.g. in U.S. Pat. No.
6,803,171.
[0037] 6) a resin that contains fluorine substitution
(fluoropolymer), e.g. as may be provided by polymerization of
tetrafluoroethylene, a fluorinated aromatic group such as
fluoro-styrene compound, compounds that comprise a
hexafluoroalcohol moiety, and the like. Examples of such resins are
disclosed e.g. in PCT/US99/21912.
[0038] Preferred photoresists of the invention include both
chemically-amplified positive-acting and negative-acting
photoresists. Typically preferred chemically-amplified positive
resists include one or more resins that comprise photoacid-labile
groups such as photoacid-labile ester or acetal groups.
[0039] The invention further provides methods for forming a
photoresist relief image and producing an electronic device using
photoresists of the invention. The invention also provides novel
articles of manufacture comprising substrates coated with a
photoresist composition of the invention.
[0040] Other aspects of the invention are disclosed infra.
[0041] As discussed above, particularly preferred photoresists of
the invention can exhibit reduced defects following aqueous
alkaline development. Such defects can include reduced organic
residues in areas bared of photoresist upon development as well as
reduced microbridging between images resist lines or other
features.
[0042] As discussed above, suitable block copolymers of
photoresists of the invention that substantially non-mixable (as
referred to herein) with the resist resin component can be readily
identified by simple testing. In particular, as referred to herein,
preferred substantially non-mixable block copolymers will provide a
decreased occurrence or amount of defects upon aqueous alkaline
development relative to a comparable photoresist relative to the
same photoresist system that is processed into the same manner, but
in the absence of the candidate substantially non-mixable
material(s). Assessment of defects (or absence thereof) can be made
via scanning electron micrography. Detection of photoresist
material in the immersion fluid can be conducted as described in
Example 2 of U.S. Patent Publication 2006/0246373 and includes mass
spectroscopy analysis of the immersion fluid before and after
exposure to the photoresist. In such analysis, the immersion fluid
directly contacts the tested photoresist composition layer for
about 60 seconds during exposure. Preferably, addition of one or
more block copolymers provides at least a 10 percent reduction in
photoresist material (again, acid or organics as detected by mass
spectroscopy) residing in the immersion fluid relative to the same
photoresist that does not employ such block polymer(s), more
preferably the one or more block polymer(s) provide at least a 20,
50, or 100, 200, 500, or 1000 percent reduction photoresist
material (again, acid and/or organics) residing in to the immersion
fluid relative to the same photoresist that does not contain the
candidate block polymer(s).
[0043] Preferred photoresists of the invention will result in less
than 1.6 X E-10 (mole/cm.sup.2/sec) of photoacid generator material
being leached into deionized water or other overcoating immersion
fluid for 60 seconds during exposure by the analysis method
described in Example 2 of U.S. Patent Publication 2006/0246373.
Preferred photoresists of the invention may have preferred water
contact angles.
[0044] As referred to herein, water contact angles, such as static,
receding, advancing sliding, developer static can be determined in
accordance with the producers disclosed in Burnett et al., J. Vac.
Sci. Techn. B, 23(6), pages 2721-2727 (November/December 2005).
Preferred photoresists (as determined as a spin-coated layer with
solvent removed by soft-bake) will have a receding angle of at
least 65.degree., more preferably at least 70.degree..
Additionally, preferred substantially non-mixable materials (as
determined as a spin-coated layer with solvent removed by
soft-bake) will have a receding angle of at least 65.degree., more
preferably at least 70.degree..
[0045] As discussed above, suitable block copolymers for use in
polymers of the invention may comprise a variety of moieties
functionalities. For instance, block copolymers may comprise
non-aromatic units such as provided by polymerization of an
acrylate or an optionally substituted cyclic olefin (particularly
carbon alicyclic or heteroalicyclic group) such as a polymerized
optionally substituted norbornene. Suitably, at least one of the
resin repeat units contains a photoacid-labile moiety such as a
photoacid-labile ester or acetal moiety. For use in a photoresist
imaged at 193 nm, particularly preferred block polymers are
substantially free of any aromatic moieties other than the hydroxy
naphthyl groups or other hetero-substituted carbocyclic aryl
groups.
[0046] Additional preferred polymer units may be provided by
polymerization of an anhydride such as maleic anhydride or itaconic
anhydride; or lactones such as provided by polymerization of a
suitable acrylate e.g. acryloxy-norborene-butyrolactone and the
like.
[0047] Preferred substituted hetero-substituted carbocyclic aryl
units for incorporation into a block copolymer are naphthyl groups
as well as other substituted carbocyclic aryl moieties such as
hetero-substituted phenyl, anthracenyl, acenaphthyl, phenanthryl,
and the like. Generally, hetero-substituted carbocyclic aryl groups
having multiple fused rings (e.g. 2 or 3 fused rings, at least one
of which is a carbocyclic aryl) are preferred such as
hetero-substituted naphthyl, anthracenyl, acenaphthyl, phenanthryl,
and the like.
[0048] A carbocyclic group may have a variety of
hetero-substituents, with oxygen- and sulfur-containing
substituents being generally preferred. For instance, preferred
hetero-substituted carbocyclic aryl groups of resins of the
invention include those aryl groups having one or more hydroxy
(--OH), thin (--SH), alcohol (e.g. hydroxyC.sub.1-6alkyl),
thioalkyl (e.g. HSC.sub.1-6alkyl), alkanoyl (e.g. C.sub.1-6alkanoyl
such as formyl or acyl), alkylsulfide such as
C.sub.1-6alkylsulfide, carboxylate (including C.sub.1-12ester),
alkyl ether including C.sub.1-8ether, and the like. Preferably, at
least one hetero atom of the hetero-containing substituent has a
hydrogen substituent (e.g. hydroxy is preferred over alkoxy). It is
also preferred that the hetero group has the hetero atom directly
linked to the carbocyclic ring (such as a hydroxy or thio ring
substituents), or a hetero atom is a substituent of an activated
carbon such as a ring substituent of --CH.sub.2OH or --CH.sub.2SH,
or other primary hydroxy or thio alkyl.
[0049] Preferred substituted carbocyclic aryl units for
incorporation into a block polymer are naphthyl groups substituted
with one or more hydroxy (--OH), thio (--SH), alcohol (e.g.
hydroxyC.sub.1-6alkyl), thioalkyl (e.g. HSC.sub.1-6alkyl), alkanoyl
(e.g. C.sub.1-6alkanoyl such as formyl or acyl), alkylsulfide such
as C.sub.1-6alkylsulfide, carboxylate (including C.sub.1-12ester),
alkyl ether including C.sub.1-8ether, and the like. Preferably, at
least one hetero atom of the hetero-containing substituent has a
hydrogen substituent (e.g. hydroxy is preferred over alkoxy). It is
also preferred that the hetero group has the hetero atom directly
linked to the carbocyclic ring (such as a hydroxy or thio ring
substituents), or a hetero atom is a substituent of an activated
carbon such as a ring substituent of --CH.sub.2OH or --CH.sub.2SH,
or other primary hydroxy or thio alkyl. A hydroxynapthyl group such
as provided by polymerization of vinyl hydroxyl naphthyl is a
preferred unit of a block copolymer for use in a photoresist of the
invention.
[0050] A block copolymer may suitably contain a relatively wide
range of amounts of hydroxy naphthyl units or other
hetero-substituted carbocyclic aryl groups. Suitably, a block
copolymer may contain quite minor amounts of the hydroxy naphthyl
units. For example, a block copolymer may suitably contain less
than about 50 or 40 mole percent of hetero-substituted carbocyclic
aryl units based on total units of a resin, or even less than about
30, 20, 15 or 10 mole percent of hetero-substituted carbocyclic
aryl units based on total units of the block polymer. Indeed, a
block polymer may suitably contain about 0.5, 1, 2, 3, 4, 5, 6, 7
or 8 mole percent of hydroxy naphthyl units based on total units of
the resin. Typically, a block copolymer will contain at least about
1, 2, 3, 4 or 5 mole percent of hetero-substituted carbocyclic aryl
units such as hydroxy naphthyl units based on total resin units, if
the block copolymer contains such units. Generally preferred are
block copolymers that contain at least or up to about 5, 10, 20,
30, 40, or 45 hetero-substituted carbocyclic aryl units such as
hydroxy naphthyl units based on total resin units.
[0051] Block copolymer are preferably employed in photoresists
imaged at 193 rim and suitably will be substantially free of any
phenyl or other aromatic groups other than the hetero-substituted
carbocyclic aryl units. For example, preferred block copolymers
contain less than about 5 mole percent aromatic groups other than
the hetero-substituted carbocyclic aryl units, more preferably less
than about 1 or 2 mole percent aromatic groups hetero-substituted
carbocyclic aryl units.
[0052] As discussed, various moieties of block copolymers and other
materials may be optionally substituted. A "substituted"
substituent may be substituted at one or more available positions,
typically 1, 2, or 3 positions by one or more suitable groups such
as e.g. halogen (particularly F, Cl or Br); cyano; C.sub.1-8alkyl;
C.sub.1-8 alkoxy; C.sub.1-8 alkylthio; C.sub.1-8alkylsulfonyl;
C.sub.2-8 alkenyl; C.sub.2-8 alkynyl; hydroxyl; nitro; carbocyclic
aryl such as phenyl, napthyl, acenaphthyl, anthracenyl; alkanoyl
such as a C.sub.1-6 alkanoyl e.g. acyl and the like; etc.
[0053] Block copolymers for use in photoresists of the invention
may be prepared by known procedures including a free radical
polymerization process such as disclosed in U.S. Pat. Nos.
6,515,088 and 6,379,874. A preferred synthesis is also set forth in
the examples which follow. Preferred initiators include
1-octylperoxy-9-borafluoene and can promote so-called "living" free
radical polymerization.
[0054] Preferably a block copolymer will have a weight average
molecular weight (Mw) of about 800 or 1,000 to about 100,000, more
preferably about 2,000 to about 30,000, still more preferably from
about 2,000 to 15,000 or 20,000, with a molecular weight
distribution (Mw/Mn) of about 3 or less, more preferably a
molecular weight distribution of about 2 or less. Molecular weights
(either Mw or Mn) of the resins of the invention are suitably
determined by gel permeation chromatography.
[0055] It is also preferred that the molar ratio of (1) developer
affinity block(s) to (2) hydrophobic block(s) of a particular block
copolymer be approximately equal, e.g. with a relative range of
65:35, more preferably 60:40, more preferably 55:45 or even more
preferably about 50:50. Such relative ranges can avoid undesired
micelle formation.
[0056] Specifically preferred block copolymers for use in
photoresists of the invention include the following:
##STR00001## ##STR00002##
[0057] As discussed above, suitable block copolymers may include
Si-containing materials. Suitable block copolymers include
nanostructured compositions, which are commercially available from
groups such as Hybrid Plastics (Fountain Valley, Calif.),
Sigma/Aldrich, and others. Such materials may include molecular
silicas which have a Si--O core enveloped by organic groups;
silanols; and polymers and resins which include silsesquioxane
cage-structured compounds and may be silicones, styrenics,
acrylics, alicyclics such as norbornenes and others.
[0058] Particles (including organic particles) useful as block
copolymers include Si-containing and fluorinated materials. Such
particles are commercially available, or can be readily
synthesized, e.g. by reaction of one or more monomers together with
a crosslinking agent and an initiator compound if desired. The
reacted monomers may have substitution as desired e.g. fluorine, Si
groups, photoacid-labile groups such as photoacid-labile esters or
acetals, other base-solubilizing groups such as alcohols and the
like. See Example 1 of U.S. Patent Application Publication
2006/0246373 for an exemplary synthesis of such particles produced
with multiple distinct monomers, where one of the monomers provides
a photoacid-labile group to the resulting polymer particle.
[0059] The block copolymer(s) may be present in a photoresist
composition in relatively small amounts and still provide effective
results. For instance, the one or more block polymers may be
suitably present in about 0.1 to 20 weight percent based on total
weight of a fluid photoresist composition. Suitable amounts also
are provided in the examples which follow.
[0060] In certain aspects of the invention, excluded are
photoresists that contain a fluorinated surfactant material where
the surfactant material contains from 30 to 60 mass % of fluorine
atoms, or even 20 mass % fluorine atoms, or up to 70 mass percent
fluorine atoms.
[0061] As discussed above, preferred photoresists for use in
accordance with the invention include positive-acting or
negative-acting chemically amplified photoresists, i.e.
negative-acting resist compositions which undergo a
photoacid-promoted crosslinking reaction to render exposed regions
of a coating layer of the resist less developer soluble than
unexposed regions, and positive-acting resist compositions which
undergo a photoacid-promoted deprotection reaction of acid labile
groups of one or more composition components to render exposed
regions of a coating layer of the resist more soluble in an aqueous
developer than unexposed regions. Ester groups that contain a
tertiary non-cyclic alkyl carbon (e.g. t-butyl) or a tertiary
alicyclic carbon (e.g. methyladamantyl) covalently linked to the
carboxyl oxygen of the ester are often preferred photoacid-labile
groups of resins employed in photoresists of the invention. Acetal
photoacid-labile groups also will be preferred.
[0062] Preferred photoresists of the invention typically comprise a
resin component and a photoactive component. Preferably the resin
has functional groups that impart alkaline aqueous developability
to the resist composition. For example, preferred are resin binders
that comprise polar functional groups such as hydroxyl or
carboxylate. Preferably a resin component is used in a resist
composition in an amount sufficient to render the resist
developable with an aqueous alkaline solution.
[0063] For imaging at wavelengths greater than 200 nm, such as 248
nm, phenolic resins are typically preferred. Preferred phenolic
resins are poly (vinylphenols) which may be formed by block
polymerization, emulsion polymerization or solution polymerization
of the corresponding monomers in the presence of a catalyst.
Vinylphenols useful for the production of polyvinyl phenol resins
may be prepared, for example, by hydrolysis of commercially
available coumarin or substituted coumarin, followed by
decarboxylation of the resulting hydroxy cinnamic acids. Useful
vinylphenols may also be prepared by dehydration of the
corresponding hydroxy alkyl phenols or by decarboxylation of
hydroxy cinnamic acids resulting from the reaction of substituted
or nonsubstituted hydroxybenzaldehydes with malonic acid. Preferred
polyvinylphenol resins prepared from such vinylphenols have a
molecular weight range of from about 2,000 to about 60,000
daltons.
[0064] Also preferred for imaging at wavelengths greater than 200
nm, such as 248 nm are chemically amplified photoresists that
comprise in admixture a photoactive component and a resin component
that comprises a copolymer containing both phenolic and
non-phenolic units. For example, one preferred group of such
copolymers has acid labile groups substantially, essentially or
completely only on non-phenolic units of the copolymer,
particularly alkylacrylate photoacid-labile groups, i.e. a
phenolic-alkyl acrylate copolymer. One especially preferred
copolymer binder has repeating units x and y of the following
formula:
##STR00003##
[0065] wherein the hydroxyl group be present at either the ortho,
meta or para positions throughout the copolymer, and R' is
substituted or unsubstituted alkyl having 1 to about 18 carbon
atoms, more typically 1 to about 6 to 8 carbon atoms. Vert-butyl is
a generally preferred R' group. An R' group may be optionally
substituted by e.g. one or more halogen (particularly F, Cl or Br),
C.sub.1-8 alkoxy, C.sub.2-8 alkenyl, etc. The units x and y may be
regularly alternating in the copolymer, or maybe randomly
interspersed through the polymer. Such copolymers can be readily
formed. For example, for resins of the above formula, vinyl phenols
and a substituted or unsubstituted alkyl acrylate such as
t-butylacrylate and the like may be condensed under free radical
conditions as known in the art. The substituted ester moiety, i.e.
R'--O--C(.dbd.O)--, moiety of the acrylate units serves as the acid
labile groups of the resin and will undergo photoacid induced
cleavage upon exposure of a coating layer of a photoresist
containing the resin. Preferably the copolymer will have a M.sub.w
of from about 8,000 to about 50,000, more preferably about 15,000
to about 30,000 with a molecular weight distribution of about 3 or
less, more preferably a molecular weight distribution of about 2 or
less. Non-phenolic resins, e.g. a copolymer of an alkyl acrylate
such as t-butylacrylate or t-butylmethacrylate and a vinyl
alicyclic such as a vinyl norbornyl or vinyl cyclohexanol compound,
also may be used as a resin binder in compositions of the
invention. Such copolymers also may be prepared by such free
radical polymerization or other known procedures and suitably will
have a M.sub.w of from about 8,000 to about 50,000, and a molecular
weight distribution of about 3 or less.
[0066] Other preferred resins that have acid-labile deblocking
groups for use in a positive-acting chemically-amplified
photoresist of the invention have been disclosed in European Patent
Application 0829766A2 of the Shipley Company (resins with acetal
and ketal resins) and European Patent Application EP0783136A2 of
the Shipley Company (terpolymers and other copolymers including
units of 1) styrene; 2) hydroxystyrene; and 3) acid labile groups,
particularly alkyl acrylate acid labile groups such as
t-butylacrylate or t-butylmethacrylate). In general, resins having
a variety of acid labile groups will be suitable, such as acid
sensitive esters, carbonates, ethers, imides, etc. The photoacid
labile groups will more typically be pendant from a polymer
backbone, although resins that have acid labile groups that are
integral to the polymer backbone also may be employed.
[0067] As discussed above, for imaging at sub-200 nm wavelengths
such as 193 nm, preferably a photoresist is employed that contains
one or more polymers that are substantially, essentially or
completely free of phenyl or other aromatic groups. For example,
for sub-200 urn imaging, preferred photoresist polymers contain
less than about 5 mole percent aromatic groups, more preferably
less than about 1 or 2 mole percent aromatic groups, more
preferably less than about 0.1, 0.02, 0.04 and 0.08 mole percent
aromatic groups and still more preferably less than about 0.01 mole
percent aromatic groups. Particularly preferred polymers are
completely free of aromatic groups. Aromatic groups can be highly
absorbing of sub-200 nm radiation and thus are undesirable for
polymers used in photoresists imaged with such short wavelength
radiation.
[0068] Suitable polymers that are substantially or completely free
of aromatic groups and may be formulated with a PAG of the
invention to provide a photoresist for sub-200 nm imaging are
disclosed in European application EP930542A1 and U.S. Pat. Nos.
6,692,888 and 6,680,159, all of the Shipley Company.
[0069] Suitable polymers that are substantially or completely free
of aromatic groups suitably contain acrylate units such as
photoacid-labile acrylate units as may be provided by
polymerization of methyladamanatylacrylate,
methyladamantylmethacrylate, ethylfenchylaclylate,
ethylfenchylmethacrylate, and the like; fused non-aromatic
alicyclic groups such as may be provided by polymerization of a
norbornene compound or other alicyclic compound having an
endocyclic carbon-carbon double bond; an anhydride such as may be
provided by polymerization of maleic anhydride and/or itaconic
anhydride; and the like.
[0070] Preferred negative-acting compositions of the invention
comprise one or more materials (such as a crosslinker component
e.g. an amine-based materials such as a melamine resin) that will
cure, crosslink or harden upon exposure to acid, and a photoactive
component of the invention. Particularly preferred negative acting
compositions comprise a resin binder such as a phenolic resin, a
crosslinker component and a photoactive component of the invention.
Such compositions and the use thereof has been disclosed in
European Patent Applications 0164248 and 0232972 and in U.S. Pat.
No. 5,128,232 to Thackeray et al. Preferred phenolic resins for use
as the resin binder component include novolaks and
poly(vinylphenol)s such as those discussed above. Preferred
crosslinkers include amine-based materials, including melamine,
glycolurils, benzoguanamine-based materials and urea-based
materials. Melamine-formaldehyde resins are generally most
preferred. Such crosslinkers are commercially available, e.g. the
melamine resins sold by Cytec under the trade names Cymel 300, 301
and 303. Glycoluril resins are sold by Cytec under trade names
Cymel 1170, 1171, 1172, urea-based resins are sold under the trade
names of Beetle 60, 65 and 80, and benzoguanamine resins are sold
under the trade names Cymel 1123 and 1125.
[0071] For imaging at sub-200 nm wavelengths such as 193 nm,
preferred negative-acting photoresists are disclosed in WO 03077029
to the Shipley Company.
[0072] Photoresists of the invention also may contain other
materials. For example, other optional additives include actinic
and contrast dyes, anti-striation agents, plasticizers, speed
enhancers, sensitizers (e.g. for use of a PAG of the invention at
longer wavelengths such as Mine (i.e. 365 nm) or G-line
wavelengths), etc. Such optional additives typically will be
present in minor concentration in a photoresist composition except
for fillers and dyes which may be present in relatively large
concentrations such as, e.g., in amounts of from 5 to 30 percent by
weight of the total weight of a resist's dry components.
[0073] A preferred optional additive of resists of the invention is
an added base, e.g. a caprolactam, which can enhance resolution of
a developed resist relief image. The added base is suitably used in
relatively small amounts, e.g. about 1 to 10 percent by weight
relative to the PAG, more typically 1 to about 5 weight percent.
Other suitable basic additives include ammonium sulfonate salts
such as piperidinium p-toluenesulfonate and dicyclohexylammonium
p-toluenesulfonate; alkyl amines such as tripropylamine and
dodecylamine; aryl amines such as diphenylamine, triphenylamine,
aminophenol, 2-(4-aminophenyl)-2-(4-hydroxyphenyl)propane, etc.
[0074] The resin component of resists of the invention is typically
used in an amount sufficient to render an exposed coating layer of
the resist developable such as with an aqueous alkaline solution.
More particularly, a resin binder will suitably comprise 50 to
about 90 weight percent of total solids of the resist. The
photoactive component should be present in an amount sufficient to
enable generation of a latent image in a coating layer of the
resist. More specifically, the photoactive component will suitably
be present in an amount of from about 1 to 40 weight percent of
total solids of a resist. Typically, lesser amounts of the
photoactive component will be suitable for chemically amplified
resists.
[0075] The resist compositions of the invention also comprise a
photoacid generator (i.e. "PAG") that is suitably employed in an
amount sufficient to generate a latent image in a coating layer of
the resist upon exposure to activating radiation. Preferred PAGs
for imaging at 193 run and 248 nm imaging include imidosulfonates
such as compounds of the following formula:
##STR00004##
wherein R is camphor, adamantane, alkyl (e.g. C.sub.1-12 alkyl) and
periluoroalkyl such as perfluoro(C.sub.1-12alkyl), particularly
perfluorooctanesulfonate, perfluorononanesulfonate and the like. A
specifically preferred PAG is
N-[(perfluorooctanesulfonyl)oxy]-5-norbornene-2,3-dicarboximide.
[0076] Sulfonate compounds are also suitable PAGs, particularly
sulfonate salts. Two suitable agents for 193 nm and 248 nm imaging
arc the following PAGS 1 and 2:
##STR00005##
[0077] Such sulfonate compounds can be prepared as disclosed in
European Patent Application 96118111.2 (publication number
0783136), which details the synthesis of above PAG 1.
[0078] Also suitable are the above two iodonium compounds complexed
with anions other than the above-depicted camphorsulfonate groups.
In particular, preferred anions include those of the formula
RSO.sub.3-- where R is adamantane, alkyl (e.g. C.sub.1-12 alkyl)
and perfluoroalkyl such as perfluoro (C.sub.1-12alkyl),
particularly perfluorooctanesulfonate, perfluorobutanesulfonate and
the like.
[0079] Other known FAGS also may be employed in photoresists used
in accordance with the invention. Particularly for 193 nm imaging,
generally preferred are FAGS that do not contain aromatic groups,
such as the above-mentioned imidosulfonates, in order to provide
enhanced transparency.
[0080] Photoresists of the invention also may contain other
optional materials. For example, other optional additives include
anti-striation agents, plasticizers, speed enhancers, etc. Such
optional additives typically will be present in minor
concentrations in a photoresist composition except for fillers and
dyes which may be present in relatively large concentrations, e.g.,
in amounts of from about 5 to 30 percent by weight of the total
weight of a resist's dry components.
[0081] The photoresists used in accordance with the invention are
generally prepared following known procedures. For example, a
resist of the invention can be prepared as a coating composition by
dissolving the components of the photoresist in a suitable solvent
such as, e.g., a glycol ether such as 2-methoxyethyl ether
(diglyme), ethylene glycol monomethyl ether, propylene glycol
monomethyl ether; propylene glycol monomethyl ether acetate;
lactates such as ethyl lactate or methyl lactate, with ethyl
lactate being preferred; propionates, particularly methyl
propionate, ethyl propionate and ethyl ethoxy propionate; a
Cellosolve ester such as methyl Cellosolve acetate; an aromatic
hydrocarbon such toluene or xylene; or a ketone such as methylethyl
ketone, cyclohexanone and 2-heptanone. Typically the solids content
of the photoresist varies between 5 and 35 percent by weight of the
total weight of the photoresist composition. Blends of such
solvents also are suitable.
[0082] Liquid photoresist compositions may be applied to a
substrate such as by spinning, dipping, roller coating or other
conventional coating technique. When spin coating, the solids
content of the coating solution can be adjusted to provide a
desired film thickness based upon the specific spinning equipment
utilized, the viscosity of the solution, the speed of the spinner
and the amount of time allowed for spinning.
[0083] Photoresist compositions used in accordance with the
invention are suitably applied to substrates conventionally used in
processes involving coating with photoresists. For example, the
composition may be applied over silicon wafers or silicon wafers
coated with silicon dioxide for the production of microprocessors
and other integrated circuit components. Aluminum-aluminum oxide,
gallium arsenide, ceramic, quartz, copper, glass substrates and the
like are also suitably employed. Photoresists also may be suitably
applied over an antireflective layer, particularly an organic
antireflective layer.
[0084] Following coating of the photoresist onto a surface, it may
be dried by heating to remove the solvent until preferably the
photoresist coating is tack free.
[0085] The photoresist layer (with overcoated barrier composition
layer, if present) in then exposed in an immersion lithography
system, i.e. where the space between the exposure tool
(particularly the projection lens) and the photoresist coated
substrate is occupied by an immersion fluid, such as water or water
mixed with one or more additives such as cesium sulfate which can
provide a fluid of enhanced refractive index. Preferably the
immersion fluid (e.g., water) has been treated to avoid bubbles,
e.g. water can be degassed to avoid nanobubbles.
[0086] References herein to "immersion exposing" or other similar
term indicates that exposure is conducted with such a fluid layer
(e.g. water or water with additives) interposed between an exposure
tool and the coated photoresist composition layer.
[0087] The photoresist composition layer is then suitably patterned
exposed to activating radiation with the exposure energy typically
ranging from about 1 to 100 mJ/cm.sup.2, dependent upon the
exposure tool and the components of the photoresist composition.
References herein to exposing a photoresist composition to
radiation that is activating for the photoresist indicates that the
radiation is capable of forming a latent image in the photoresist
such as by causing a reaction of the photoactive component (e.g.
producing photoacid from the photoacid generator compound).
[0088] As discussed above, photoresist compositions are preferably
photoactivated by a short exposure wavelength, particularly a
sub-400 nm, sub-300 and sub-200 nm exposure wavelength, with I-line
(365 nm), 248 nm and 193 nm being particularly preferred exposure
wavelengths as well as EUV and 157 nm.
[0089] Following exposure, the film layer of the composition is
preferably baked at temperatures ranging from about 70.degree. C.
to about 160.degree. C. Thereafter, the film is developed,
preferably by treatment with an aqueous based developer such as
quaternary ammonium hydroxide solutions such as a tetra-alkyl
ammonium hydroxide solution; various amine solutions preferably a
0.26 N tetramethylammonium hydroxide, such as ethyl amine, n-propyl
amine, diethyl amine, di-n-propyl amine, triethyl amine, or
methyldiethyl amine; alcohol amines such as diethanol amine or
triethanol amine; cyclic amines such as pyrrole, pyridine, etc. In
general, development is in accordance with procedures recognized in
the art.
[0090] Following development of the photoresist coating over the
substrate, the developed substrate may be selectively processed on
those areas bared of resist, for example by chemically etching or
plating substrate areas bared of resist in accordance with
procedures known in the art. For the manufacture of microelectronic
substrates, e.g., the manufacture of silicon dioxide wafers,
suitable etchants include a gas etchant, e.g. a halogen plasma
etchant such as a chlorine or fluorine-based etchant such a
Cl.sub.2 or CF.sub.4/CHF.sub.3 etchant applied as a plasma stream.
After such processing, resist may be removed from the processed
substrate using known stripping procedures.
[0091] The following non-limiting examples are illustrative of the
invention. All documents mentioned herein are incorporated by
reference herein in their entirety.
EXAMPLE 1
Di-block copolymer synthesis:
Poly(2-(((trifluoromethyl)sulfonyl)amino)ethyl
2-methylacrylate-block-2,3,3-trimethyl butyl acrylate)
[0092] The title block copolymer having the following structure was
prepared as described below:
##STR00006## [0093] A. Monomer solution 1: 30 weight percent
(CH.sub.3)CH.dbd.CH.sub.2(C.dbd.O)O(CH.sub.2).sub.2NHSO.sub.2CF.sub.3
in anhydrous tetrahydrofuran [0094] B. Monomer solution 2: 30
weight percent
CH.sub.2.dbd.CH.sub.2(C)O(CH)(CH.sub.3).sub.2C(CH.sub.3).sub.3 in
anhydrous tetrahydrofuran [0095] C. Initiator Solution: 1M of
1-octylperoxy-9-borafluoene in anhydrous THF
[0096] A 100 ml flask with a magnetic stir bar is heated under
vacuum to remove residual moisture and then sealed under dry
nitrogen, Add to the sealed flask 23.3 g (26.8 mM) of Monomer
solution 1 and place the flask in a bath at 20.degree. C. Transfer
6 ml of Initiator solution to the flask and stir the mixture in the
flask for 5 hours. Then add 15.2 g (26.8 mM) of Monomer solution 2
to the flask and continue stirring for another 5 hours followed by
quenching of the reaction with acidic methanol.
[0097] The reaction solution is then transferred to a round bottom
flask and most the tetrahydrofuran is removed at elevated
temperature under vacuum. The concentrated polymer solution is then
poured into a beaker of deionized water to precipitate the polymer.
The polymer is then dried under vacuum at 50.degree. C.
overnight.
EXAMPLE 2
Additional Block Copolymer Preparation
[0098] By procedures similar to those of Example 1, the following
block copolymers are prepared:
##STR00007## ##STR00008##
EXAMPLE 3
Photoresist Preparation and Processing
[0099] A photoresist composition is prepared by admixing the
following materials in the specified amounts: [0100] 1. Resin
component: Terpolymer of (2-methyl-2-adamantyl
methacrylate/beta-hydroxy-gamma-butyrolactone
methacrylate/cyano-norbornyl methacrylate in an amount of 6.79
weight % based on total weight of the photoresist composition;
[0101] 2. Photoacid generator compound: T-butyl phenyl
tetramethylene sulfonium perfluorobutanesulfonate in an amount of
0.284 weight % based on total weight of the photoresist
composition; [0102] 3. Base additive: N-Alkyl Caprolactam in an
amount of 0.017 weight % based on total weight of the photoresist
composition; [0103] 4. Surfactant: R08 (fluorine-containing
surfactant, available from Dainippon Ink & Chemicals, Inc.) in
an amount of 0.0071 weight % based on total weight of the
photoresist composition [0104] 5. Block copolymer: Polymer of
Example 1 prepared as described in Example 1 above and in an amount
of 0.213 weight % based on total weight of the photoresist
composition. [0105] 6. Solvent component: propylene glycol
monomethyl ether acetate to provide about a 90 percent fluid
composition.
[0106] This photoresist composition containing is spin-coated onto
silicon wafers, dried on vacuum hotplate to remove soft-plate and
then exposed in an immersion lithography process with aqueous
immersion fluid directly contacting the dried photoresist layers.
In that immersion system, the photoresist layers is exposed to
patterned 193 nm radiation at a dose of 24.1 mJ/cm.sup.2 for the
control photoresist layers and 23.4 mJ/cm.sup.2.
[0107] The photoresist layers is then post-exposed baked (such as
at about 120.degree. C.) and developed with 0.26N alkaline aqueous
developer solution.
[0108] To evaluate leaching of resist components after the
post-exposure bake and before development, the immersion fluid is
evaluated for the photoacid in the resist and its photo-degradation
byproducts by LC/mass spectroscopy (60 second leaching time
tested).
* * * * *