U.S. patent application number 10/847679 was filed with the patent office on 2004-10-21 for solvents and photoresists compositions for short wavelength imaging.
This patent application is currently assigned to Shipley Company, L.L.C.. Invention is credited to Szmanda, Charles R., Zampini, Anthony.
Application Number | 20040209188 10/847679 |
Document ID | / |
Family ID | 27256093 |
Filed Date | 2004-10-21 |
United States Patent
Application |
20040209188 |
Kind Code |
A1 |
Szmanda, Charles R. ; et
al. |
October 21, 2004 |
Solvents and photoresists compositions for short wavelength
imaging
Abstract
New photoresists are provides that are suitable for short
wavelength imaging, particularly sub-170 nm such as 157 nm. Resists
of the invention comprise a fluorine-containing polymer, a
photoactive component, and a solvent component. Preferred solvents
for use on the resists of the invention can maintain the resist
components in solution and include one or more preferably two or
more (i.e. blends) of solvents. In particularly preferred solvent
blends of the invention, each blend member evaporates at
substantially equal rates, whereby the resist composition maintains
a substantially constant concentration of each blend member.
Inventors: |
Szmanda, Charles R.;
(Westborough, MA) ; Zampini, Anthony;
(Westborough, MA) |
Correspondence
Address: |
Peter F. Corless
EDWARDS & ANGELL, LLP
P.O. Box 55874
Boston
MA
02205
US
|
Assignee: |
Shipley Company, L.L.C.
Marlborough
MA
|
Family ID: |
27256093 |
Appl. No.: |
10/847679 |
Filed: |
May 17, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10847679 |
May 17, 2004 |
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10101202 |
Mar 19, 2002 |
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60278170 |
Mar 22, 2001 |
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Current U.S.
Class: |
430/270.1 |
Current CPC
Class: |
G03F 7/0395 20130101;
C23C 18/2006 20130101; G03F 7/0048 20130101; H05K 3/0055 20130101;
C08J 7/02 20130101; C23C 18/24 20130101; G03F 7/0392 20130101; H05K
3/381 20130101; G03F 7/0397 20130101; G03F 7/0046 20130101; Y10S
430/113 20130101 |
Class at
Publication: |
430/270.1 |
International
Class: |
G03C 001/76 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2001 |
GB |
0105718.1 |
Claims
1. A photoresist composition comprising a fluorinated resin, a
photoactive component, and a solvent component, the solvent
component comprising a mixture of least two distinct solvents,
wherein one of the distinct solvents does not contain a ketone
moiety, and with the exclusion of a solvent component consisting of
methyl ethyl ketone and chlorobenzene.
2. A photoresist composition of claim 1 wherein the solvent
component comprises a heptanone.
3. A photoresist composition of claim 1 wherein the solvent
component comprises cyclohexanone.
4. A photoresist composition of claim 1 wherein the solvent
component comprises ethyl lactate.
5. A photoresist composition of claim 1 wherein the solvent
component comprises propylene glycol methyl ether acetate.
6-7. (cancelled)
8. A photoresist composition of claim 1 wherein the photoresist
comprises at least three distinct solvents.
9-59. (cancelled)
60. A method for forming a photoresist relief image; comprising:
applying a coating layer of a photoresist composition of claim 1 to
a substrate; exposing the photoresist coating layer to activating
radiation and developing the exposed resist layer.
61. The method of claim 60 wherein the photoresist coating layer is
exposed to radiation having a wavelength of less than about 200
nm.
62. The method of claim 60 wherein the photoresist coating layer is
exposed to radiation having a wavelength of less than about 170
nm.
63. The method of claim 60 wherein the photoresist coating layer is
exposed to radiation having a wavelength of about 157 nm.
64. An article of manufacture comprising a substrate having a
coating layer thereon of a photoresist composition of claim 1.
65-66. (cancelled)
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to new photoresists that are
suitable for short wavelength imaging, including sub-200 nm,
particularly sub-170 run such as 157 nm. Resists of the invention
comprise a fluorine-containing polymer, a photoactive component,
typically one or more photoacid generators, and a solvent
component. Preferred solvents for use on the resists of the
invention can maintain the resist components in solution and
include a blend of two or more fluid materials (blend members). In
particularly preferred solvent blends of the invention, each blend
member evaporates at substantially equal rates, whereby the resist
composition maintains a substantially constant concentration of
each blend member.
[0003] 2. Background
[0004] Photoresists are photosensitive films used for transfer of
images 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.
[0005] A photoresist can be either positive-acting or
negative-acting. For most negative-acting photoresists, those
coating layer portions that are exposed to activating radiation
polymerize or crosslink in a reaction between a photoactive
compound and polymerizable reagents of the photoresist composition.
Consequently, the exposed coating portions are rendered less
soluble in a developer solution than unexposed portions. For a
positive-acting photoresist, exposed portions are rendered more
soluble in a developer solution while areas not exposed remain
comparatively less developer soluble. Photoresist compositions are
described in Deforest, Photoresist Materials and Processes, McGraw
Hill Book Company, New York, ch. 2, 1975 and by Moreau,
Semiconductor Lithography, Principles, Practices and Materials,
Plenum Press, New York, ch. 2 and 4.
[0006] 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-half micron and sub-quarter micron
features.
[0007] Consequently, interest has increased in photoresists that
can be photoimaged with short wavelength radiation, including
exposure radiation of about 250 nm or less, or even about 200 nm or
less, such as wavelengths of about 193 nm. Use of such short
exposure wavelengths can enable formation of smaller features.
Accordingly, a photoresist that yields well-resolved images upon
248 nm or 193 run exposure could enable formation of extremely
small (e.g. sub-0.25 .mu.m) features that respond to constant
industry demands for smaller dimension circuit patterns, e.g. to
provide greater circuit density and enhanced device
performance.
[0008] Quite recently, F.sub.2 excimer laser imaging, i.e.
radiation having a wavelength of about 157 nm, has been considered
as a route to manufacture of even smaller features. See, generally,
Kunz et al., SPIE Proceedings (Advances in Resist Technology), vol.
3678, pages 13-23 (1999).
SUMMARY OF THE INVENTION
[0009] Novel photoresist compositions are provided that comprise a
fluorine-containing polymer, a photoactive component particularly a
photoacid generator compound, and solvent. Resists of the invention
are particularly suitable for imaging at extremely short
wavelengths, such as sub-170 nm, particularly about 157 nm.
[0010] In one aspect, preferred solvents for use in resists of the
invention include heptanone, particularly 2-hetaptanone
(methyl-n-amyl-ketone) and 3-heptanone; ethyl-n-amyl-ketone;
ethylene glycol ethyl ether; propylene glycol methyl ether acetate;
amyl acetate; methyl iso-amyl ketone; methyl ethyl ketone; ethylene
glycol methyl ether acetate; methylamyl acetate; ethylene glycol
methyl ether acetate; ethyl-n-butyl ketone; iso-butyl isobutyrate;
2-methyl-1-pentanol (hexanol); ethylene glycol propyl ether;
propylene glycol t-butyl ether; methylcaproate; ethyl caproate
(ethyl hexanoate); cumene (isopropylbenzene); xylenes; ahisole;
cyclohexanone; ethylene glycol ethyl ether acetate; 1-tridecanol;
cyclohexanol; mesitylene; hexyl acetate (2-methyl-1-pentyl
acetate); diethylene glycol dimethyl ether (diglyme); diisobutyl
ketone; di-n-propyl carbonate; diacetonealcohol; ethylene glycol
butyl ether; and propylene glycol butyl ether.
[0011] In another aspect, preferred solvents for use in resists of
the invention are halogenated materials, particularly fluorinated
materials. Such halogenated solvents can be particularly effective
in solubilizing a fluorinated resin of a resist of the invention.
Exemplary halogenated solvents for use in resists of the invention
include halogenated aromatic solvents such as chlorobenzene,
fluorobenzene, trifluoromethylbenzeone,
bis-(trifluoromethyl)benzene, and the like; perfluoroalkyl
solvents; and fluoroethers such as HFE-700, FC-43, and FC-3248 (all
available from the 3M Corporation) and other fluoroether solvents
and other fluorinated solvents available from 3M Corporation; and
the like.
[0012] Resists formulations are also preferred that comprise a
blend of solvents, wherein one of the blend members is a heptanone,
preferably 2-heptanone. Other blend members may suitably be e.g.
ethyl lactate, propylene glycol methyl ether acetate (PGMEA),
diacetone alcohol, hexyl acetate, ethyl hexanoate,
gamma-butyrolactone (GBL), diglyme, propylene glycol dimethyl
ether, and propylene glycol methyl ether.
[0013] Other solvent blends for use with resists of the invention
include blends that comprise other ketones or other carbonyl
functionalities (e.g., ester). It has been found that solvents that
contain a carbonyl group can solvate a fluoropolymer more
effectively than other non-carbonyl solvents. In particular,
cyclohexanone, various dialkyl-ketone such as diisobutyl ketone and
ethoxy ethyl propionate are preferred solvents for are use in a
resist formulation of the invention, including as a blend member
with one or more other solvents such as ethyl lactate, propylene
glycol methyl ether acetate (PGMEA), diacetone alcohol, hexyl
acetate, ethyl hexanoate, gamma-butyrolactone (GBL), diglyme,
propylene glycol dimethyl ether, and propylene glycol methyl ether.
In general, a ketone solvent such as a heptanone or dissobutyl
ketone, is more preferred than an ester-containing solvent such as
ethyl ethoxy propionate.
[0014] Solvent blends of resist formulations of the invention may
suitably comprise two or three or more different solvents in a
single blend, more typically two or three distinct solvents.
Preferably a carbonyl solvent, such as a heptanone, diissobutyl
ketone, is present in a solvating effective amount, i.e. an amount
wherein the carbonyl solvent itself is effective in dissolving the
resist components.
[0015] A preferred component of a resist solvent blend of the
invention is a halogenated solvent such as those discussed above.
Enhanced solubilization can be realized in many cases with the
halogenated solvent present as even a minor component of the
solvent blend, e.g. where one or more halogenated solvents comprise
about 50 volume percent or less of the total solvent of a resist
composition, or where one or more halogenated solvents comprise
about 40, 30, 25, 20, 15, 10, 5, 3 or even 2 volume percent or less
of the total solvent of a resist composition. A solvent blend of a
resist composition of the invention also may contain greater
amounts of one or more halogenated solvents, e.g. where one or more
halogenated solvents comprise about 55, 60, 70, 80, 90 or 95 volume
percent or more of the total solvent of a resist composition. One
or more halogenated solvents are preferably used in a solvent blend
that comprises other solvents that contain carbonyl and/or hydroxy
moieties, e.g. a heptanone, cyclohexanone, ethyl lactate, and the
like.
[0016] Another preferred component of a resist solvent blend of the
invention is water. It is believed water may stabilize a solvent
blend and a resist composition, e.g. render a photoacid generator
compound more resistant to degradation during storage. Water
present as residual solvent after a soft-bake step also may
facilitate a deprotection reaction of photoacid-labile groups
present in a resist composition. Preferably, water will be present
in relatively small amounts in a resist composition, e.g. where
water constitutes no more than about 10, 8, 6, 5, 4, 3, 2, 1, 0.5
or 0.25 volume percent of the total solvent of a resist
composition. Generally preferred is where water is present in no
more than about 3, 2, 1, 0.5 or 0.25 volume percent of the total
solvent component of a resist composition. Water preferably will be
employed in a solvent blend that comprises other solvents that
contain carbonyl and/or hydroxy moieties, e.g. a heptanone,
cyclohexanone, ethyl lactate, and the like.
[0017] Particularly preferred solvent blends of the invention will
vaporize from a resist formulation at substantially constant rates,
whereby blend members remain at substantially equal concentrations
in the resist composition. In particular, preferred are solvent
blends which can form azeotropes at about room temperature, thereby
evaporating from a resist liquid formulation at a constant rate,
maintaining a substantially constant ratio of solvent blend members
in the resist composition. By maintaining a substantially constant
ratio of blend members throughout coating and soft-bake treatment,
lithographic properties of the resist can be improved as may be
related to enhanced film-forming characteristics of the resist,
e.g. avoidance of undesired crystallization or other precipitation
of resist components, irregular film layer formation, undesired
segregation of polymer chains, and the like.
[0018] In addition to a fluorine-polymer and photoactive component,
resists of the invention may suitably comprise one or more other
components, such as a basic additive, a dissolution inhibitor
compound which preferably is a polymeric and/or fluorinated
composition, surfactant or leveling agent; and a plasticizer.
Preferred resists of the invention also may comprise a blend of two
or more resin components, preferably where each blend member is a
fluorine-containing resin, and/or a blend of two br more photoacid
generator compounds.
[0019] The invention also includes methods for forming relief
images, including methods for forming a highly resolved relief
image such as a pattern of lines (dense or isolated) where each
line has vertical or essentially vertical sidewalls and a line
width of about 0.40 microns or less, or even about 0.25, 0.20,
0.15, or 0.10 microns or less. In such methods, preferably a
coating layer of a resist of the invention is imaged with
short-wavelength radiation, particularly sub-200 nm radiation,
especially 157 nm radiation, and higher energy radiation having a
wavelength of less than 100 nm, and otherwise high energy radiation
such as EUV, electron beam, ion beam or x-ray. The invention
further comprises articles of manufacture comprising substrates
such as a microelectronic wafer having coated thereon the
photoresists and relief images of the invention. Other aspects of
the invention are disclosed infra.
DETAILED DESCRIPTION OF THE INVENTION
[0020] As discussed above, novel photoresist compositions are
provided that comprise a fluorine-containing polymer, a photoactive
component particularly a photoacid generator compound, and
solvent.
[0021] The solvent component may suitably contain a single solvent,
or contain multiple distinct fluids (solvent blend).
[0022] As discussed above, particularly preferred solvents for use
in resists of the invention are fluids that contain ketone or other
carbonyl (e.g. ester) functionality, such as a heptanone, e.g.
2-hetaptanone (methyl-n-amyl-ketone) and 3-heptanone, with
2-heptanone being generally preferred; methyl iso-amyl ketone; a
variety of dialkyl ketones, such as
C.sub.1-12alkyl(C.dbd.O)C.sub.1-12alkyl, more preferably
C.sub.2-6alkylC(.dbd.O)C.sub.2-6alkyl such as ethyl-n-butyl ketone
and diisobutylketone; and alicyclic ketone compounds such as
cylohexanone.
[0023] As used herein, the term "ketone" is used in accordance with
its recognized meaning, i.e. a functionality of the structure
--C.dbd.O)--, typically with adjacent saturated carbons, and not
inclusive of groups with hetero atoms adjacent to the --C(.dbd.O)--
structure such as esters, amides, carboxy and the like. The term
"carbonyl" as used herein includes the moiety --C(.dbd.O)-- with
adjacent carbons as well as hetero atoms, i.e. the term "carbonyl"
is inclusive of ketones, esters, amides, carboxy (--COOH), and the
like.
[0024] Resists formulations are preferred that comprise a blend of
solvents, wherein one of the blend members is a heptanone,
preferably 2-heptanone. Other blend members may suitably be e.g.
ethyl lactate, propylene glycol methyl ether acetate (PGMEA),
diacetone alcohol, hexyl acetate, ethyl hexanoate,
gamma-butyrolactone (GBL), diglyme, propylene glycol dimethyl
ether, and propylene glycol methyl ether.
[0025] Other solvent blends for use with resists of the invention
include blends that comprise other ketones or carbonyl
functionalities (e.g., ester). It has been found that solvents that
contain a carbonyl group can solvate a fluoropolymer more
effectively than other non-keto solvents. In particular,
cyclohexanone, barious dialkyl-ketone such as diisobutyl ketone and
ethoxy ethyl propionate are preferred solvents for are use in a
resist formulation of the invention, including as a blend member
with one or more other solvents such as ethyl lactate, propylene
glycol methyl ether acetate (PGMEA), diacetone alcohol, hexyl
acetate, ethyl hexanoate, gamma-butyrolactone (GBL), diglyme,
propylene glycol dimethyl ether, and propylene glycol methyl
ether.
[0026] Solvent blends of resist formulations of the invention may
suitably comprise two, three, four or more different solvents in a
single blend, more typically two or three distinct solvents in a
single resist composition. Preferably a carbonyl solvent, such as a
heptanone, dissobutyl ketone, is present in a solvating effective
amount, i.e. an amount wherein the carbonyl solvent itself is
effective in dissolving the resist components. A solvating
effective of a carbonyl solvent typically is where the carbonyl
solvent constitutes at least about 20, 30, 40, 50, 60, or 70 volume
percent of a solvent blend, for a resist composition formulated at
85 to 90 weight percent solvent based on total weight of the
composition.
[0027] As discussed above, halogenated solvents, particularly
fluorinated solvents such as organic fluoroether solvents e.g.
having 1 to about 8 or 10 carbons are preferred solvent blend
members. Additionally, as discussed above, water is a preferred
solvent blend member, preferably present in relatively small
amounts of the total solvent component of a resist composition,
e.g. less than about 10, 9, 8, 7, 6, 5, 4, 3, 2, or 0.5 volume
percent of all solvent of a resist composition.
[0028] As discussed above, particularly preferred solvent blends of
the invention will vaporize from a resist formulation at
substantially constant rates, whereby blend members remain at
substantially equal concentrations in the resist compositions. In
particular, preferred are solvent blends which can form azeotropes
at about room temperature (ca. 25.degree. C.), thereby evaporating
from a resist liquid formulation at a constant rate, maintaining a
substantially constant ratio of solvent blend members in the resist
composition.
[0029] A room temperature solvent azeotrope for use in a resist
composition of the invention can be readily identified by simple
testing. For instance, a solvent of two members can be admixed at
different portions, e.g. a first blend sample having 5 parts by
volume of the first blend member to 20 parts of the second blend
member; a second blend member having 5 parts by volume of the first
blend member to 15 parts of the second blend member; a third blend
sample having 5 parts of the first blend member to 10 parts of the
second blend member; a fourth blend sample having 5 parts of the
first blend member to 5 parts of the second blend member; a fifth
blend sample having 10 parts of the first blend member to 5 parts
of the second blend partner; a sixth blend sample having 15 parts
of the first blend member to 5 parts of the second blend partner;
and a seventh blend sample having 20 parts of the first blend
member to 5 parts of the second blend partner.
[0030] Each of those blend samples is contained in an open top
vessel and subjected to increasingly reduced pressure until the
blend boils at room temperature. Immediately upon reaching boiling
a sample is condensed and isolated. Additional samples are
condensed and collected during the course of the low pressure
boiling of the blend, e.g. after 50 volume percent of the blend
sample has been vaporized, another sample of the blend is condensed
and isolated.
[0031] A solvent blend will be considered a room temperature
azeotrope where the composition of the condensed and isolated
sample approximates the composition of the solvent blend, e.g.
where the solvent blend members of the isolated sample are present
in volume amounts within about 30, 20, 10 or even 5 percent of the
composition of the thermally treated solvent blend. For preferred
azeotropes, a condensed sample isolated after approximately 50
volume of the original blend sample has been vaporized approximates
the composition of the solvent blend, e.g. where the solvent blend
members of the isolated sample are present in volume amounts within
about 30, 20, 10 or even 5 percent of the composition of the
thermally treated solvent blend. Amounts of each blend member of an
isolated sample may be suitably determined by any of a number of
methods such as gas chromatography.
[0032] Specifically preferred solvent blends of resist compositions
of the invention include:
[0033] 1) a solvent blend comprising a heptanone preferably
2-heptanone and ethyl lactate, where the heptanone and ethyl
lactate together preferably constitute at least 60, 70, 80, 90 or
95 volume percent of all solvent of a resist composition, and
preferably where the heptanone is in a greater volume amount than
the ethyl lactate, preferably where the heptanone: ethyl lactate
volume-to-volume ratio is 2:1 or greater;
[0034] 2) a solvent blend comprising a heptanone preferably
2-heptanone and propylene glycol methyl ether acetate, where the
heptanone and propylene glycol methyl ether acetate together
preferably constitute at least 60, 70, 80, 90 or 95 volume percent
of all solvent of a resist composition, and preferably where the
heptanone is in a greater volume amount than the propylene glycol
methyl ether acetate, preferably where the heptanone: propylene
glycol methyl ether acetate volume-to-volume ratio is 2:1 or
greater;
[0035] 3) a solvent blend comprising cyclohexanone and ethyl
lactate, where the cyclohexanone and ethyl lactate together
preferably constitute at least 60, 70, 80, 90 or 95 volume percent
of all solvent of a resist composition, and preferably where the
cyclohexanone is in a greater volume amount than the ethyl lactate,
preferably where the cyclohexanone: ethyl lactate volume-to-volume
ratio is 2:1 or greater;
[0036] 4) a solvent blend comprising a cyclohexanone and propylene
glycol methyl ether acetate, where the cyclohexanone and propylene
glycol methyl ether acetate together preferably constitute at least
60, 70, 80, 90 or 95 volume percent of all solvent of a resist
composition, and preferably where the cyclohexanone is in a greater
volume amount than the propylene glycol methyl ether acetate,
preferably where the cyclohexanone:propylene glycol methyl ether
acetate volume-to-volume ratio is 2:1 or greater;
[0037] 5) a solvent blend that comprises both 2-heptanone and
3-heptanone, where the 2-heptanone and 3-heptanone preferably
constitute at least about 40, 50, 60, 70, 80, 90 or 95 volume
percent of all solvent of a resist composition;
[0038] 6) a solvent blend that comprises a heptanone, preferably
2-heptanone, cyclohexanone, and at least one additional solvent,
e.g. a ketone, carbonyl or non-carbonyl solvent such as ethyl
lactate or propylene glycol methyl ether acetate;
[0039] 7) a solvent blend that comprises water, and one or more
additional solvents such as one or more of a carbonyl and/or
non-carbonyl solvent such as a heptanone, cyclohexanone, ethyl
lactate, propylene glycol methyl ether acetate, and the like;
preferably, water is present in minor amounts, e.g. no more than
about 5 volume %, more preferably no more than about 4, 3, 2, 1,
0.5 or 0.25 volume percent of the total solvent component of a
resist composition; and
[0040] 8) a solvent blend that comprises a halogenated solvent,
particularly a fluorinated solvent such as an HFE solvent
(hydrofluoroether available from 3M), and one or more additional
solvents such as one or more of a carbonyl and/or non-carbonyl
solvent such as a heptanone, cyclohexanone, ethyl lactate,
propylene glycol methyl ether acetate, and the like.
[0041] Less preferred, and hence excluded from preferred aspects of
the invention, as solvent blends, particularly binary solvent
blends (i.e. a resist having a total of two distinct solvents) that
contain a ketone such as methyl ethyl ketone and a benzene solvent
such as a halobenzene particularly chloro benzene. Also excluded
from certain preferred aspects of the invention are photoresists
that contain PGMEA (propylene glycol methyl ether acetate),
particularly PGMEA as a sole solvent (no blend partners).
[0042] Solvents used in resist compositions of the invention
preferably are employed at a high purity, e.g. greater than 98
percent or 99 percent purity as may be determined by gas
chromatography. Solvents used in resists of the invention also may
be suitably filtered immediately prior to use.
[0043] As discussed above, resists of the invention suitably
comprise a fluorine-containing resin, a photoactive component which
preferably comprises one or more photoacid generator compounds, and
optionally one or more other additives such as a base additive, one
or more dissolution inhibitor compounds, a surfactant, and/or a
plasticizer.
[0044] Resins
[0045] The fluorine-containing resin component of a resist of the
invention suitably contains a repeat unit derived from at least one
ethylenically unsaturated compound. Preferably the unsaturated
group is an alicyclic group such as norbornene, cyclohexene,
adamantene and the like. The alicylic unsaturated compound
preferably has one or more substituents of fluorine, perfluoralkyl
particularly C.sub.1-12perfluoralkyl, or perfluoroalkoxy
particularly C.sub.1-12perfluoralkoxy. Preferably, such a fluorine
substituent is separated from the unsaturated carbons by at least
one saturated carbon in order to not unduly inhibit the
polymerization reaction. Also preferred are fluorinated olefinic
compounds such as tetrafluorethylene (TFE) compounds and
hexafluoroisopropanol compounds and derivatives thereof. Exemplary
preferred unsaturated compounds for synthesis of
fluorine-containing polymers of the invention include the following
of Formulae (A) through (J): 1
[0046] wherein in those Formulae (A) through (J), each R is
independently hydrogen or a non-hydrogen substituent such as a
halogen particularly fluoro optionally substituted alkyl such as
C.sub.1-12 alkyl, haloalkyl particularly C.sub.1-12fluoroalkyl
preferably C.sub.1-12perfluoroalkyl., optionally substituted alkoxy
such as C.sub.1-12 alkoxy, haloalkoxy particularly
C.sub.1-12fluoroalkyl, a carboxyl group, C.sub.1-14alkylcarboxyl,
or a photoacid-labile group such as an photoacid-labile ester or
acetal;
[0047] m is an integer of 1 to the maximum permitted by the valence
of the monomer, and m is typically 1, 2, 3, 4 or 5; and n is 0, 1
or 2. Some of the compounds (A) through (J) are generally described
in WO 00/17712, incorporated herein by reference.
[0048] Generally preferred monomers of the above formulae, include
those of the following Formulae (K) and (L): 2
[0049] wherein in those Formulae (K) and (L), X is
(--CH.sub.2--).sub.p where p is zero, 1 or 2, preferably 1 or 2, or
--OCH.sub.2-- or CH.sub.2O--; --OCH.sub.2--; --CH.sub.2OCH.sub.2--;
or --CH.sub.2O--; LG is hydrogen or a component of a
photoacid-labile moiety, such as a quaternary carbon e.g. t-butyl
or other quaternary carbon of an optionally substituted
C.sub.4-18alkyl; and n is zero or 1.
[0050] Generally preferred pendant groups from a monomer (such as
groups R in (A) through (F)) incorporated into a resin of a resist
of the invention include groups of the following structure: 3
[0051] wherein X is as defined for Formulae (K) and (L) above;
[0052] Y is hydrogen, a chemical bond linking the oxygen and group
Z, (--CH.sub.2--).sub.p where p is 1 or 2, --CH.sub.2O--, or CHRO--
where R is C.sub.1-16alkyl, preferably C.sub.1-4alkyl; and
[0053] Z is alkyl preferably having 1 to about 20 carbon s and
including tri(C.sub.1-16) alkylmethyl;
di(C.sub.1-16)alkylcarboxylicarylmethyl; benzyl; fenchyl;
tri(C.sub.1-16alkyl)carbocyclicaryl; C.sub.1-16alkylcarbonyloxy; a
formyl group; an acetate group such as having 2 to about 20 carbon
atoms; tetrahydropyranyl; or tetrahydrofuranyl;
[0054] and preferably X is --OCH.sub.2--; preferably Y is a bond or
--CH.sub.2O--; and preferably Z is t-butyl, methyl or fenchyl.
[0055] Additional monomers that may be polymerized to provide a
fluorine-containing resin of a resist of the invention include
those of the following Formulae (M) through O), where starting
materials (i.e. (N') and (O')) are shown as well as the polymerized
group (i.e. (M"), (N") and (O")): 45
[0056] in those structures for M, M", N',N", O, O' and O", R and m
are the same as defined above for monomers of Formulae (A) through
(J); X is (--CH.sub.2--).sub.p where p is zero or 1; --OCH.sub.2--;
--CH.sub.2OCH.sub.2--; or --CH.sub.2O--;
[0057] Y is a bond, hydrogen, --CH.sub.2O--, or --CHRO-- where R is
C.sub.1-16alkyl, preferably C.sub.1-4alkyl; and preferably X is
--OCH.sub.2--; and preferably Y is a bond or --CH.sub.2O--.
[0058] Specifically preferred units of a fluorine polymer of a
resist of the invention include the units of the following Formulae
1 through 9: 67
[0059] wherein in those structures 1 through 9, LG is hydrogen,
C.sub.1-12 alkyl or a component of a photoacid-labile moiety, such
as a quaternary carbon (e.g. t-butyl); and
[0060] Y and Z are the same as defined above, i.e. Y is hydrogen, a
chemical bond linking the oxygen and group Z, (--CH.sub.2--).sub.p
where p is 1 or 2, --CH.sub.2O--, or CHRO-- where R is
C.sub.1-16alkyl, preferably C.sub.1-4alkyl; and
[0061] Z is alkyl preferably having 1 to about 20 carbon s and
including tri(C.sub.1-16)alkylmethyl;
di(C.sub.1-6)alkylcarboxylicarylmethyl; benzyl; fenchyl;
tri(C.sub.1-16alkyl)carbocyclicaryl; C.sub.1-16alkylcarbonyloxy; a
formyl group; an acetate group such as having 2 to about 20 carbon
atoms; tertrahydropyranyl; or tetrahydrofuranyl;
[0062] and preferably X is OCH.sub.2--; preferably Y is a bond or
--CH.sub.2O--; and preferably Z is t-butyl, methyl or fenchyl. In
the above structures, the lines extended from the norbornyl ring
indicate the polymer backbone or linkage thereto.
[0063] Particularly preferred fluorine-containing polymers for use
in resists of the invention include resins that comprise repeat
units selected from the following group of monomers of Formulae
(P), (O), (R) and (S): 8
[0064] wherein in those Formulae (P), (O), (R) and (S), R is
hydrogen or optionally substituted alkyl, such as C.sub.1-12alkyl,
particularly methyl, ethyl, propyl, butyl including t-butyl, and
the like; and X is as defined above X is (--CH.sub.2--).sub.p where
p is zero, 1 or 2, preferably 1 or 2, or --OCH.sub.2-- or
--CH.sub.2O--.
[0065] Preferred polymers for use in resists of the invention
include those that contain units of 1) (P) and (O) in combination;
2) (P), (Q') and (R) in combination; and 3) (P) and/or (Q'), (R)
and (S) in combination.
[0066] Particularly preferred polymers for use in resists of the
invention include:
[0067] (1) resins consisting of units of (P) and (Q) where (P):(Q')
are present in a respective molar ratio of approximately: 50:50;
60:40; 70:30; 80:20; 90:10; 40:60; 30:70; 20:80; or 10:90;
[0068] (2) resins consisting of units of (P), (Q) and (R), where
(P) is present at about 10 to 60 mole percent based on total units
of the polymer, preferably 20 to 50 or 30 to 40 mole percent based
on total units of the polymer; (Q) is present at about 1 to 50 mole
percent based on total units of the polymer, preferably 5 to 50 or
10 to 40 mole percent based on total units of the polymer; and (R)
is present at about 20 to 60 mole percent based on total units of
the polymer, preferably 20 to 60 or 30 to 50 or 60 mole percent
based on total units of the polymer; and
[0069] (3) resins consisting of units of (P) and/or (Q), (R) and
(S), where (P) and (Q) are each independently present at about 0 to
60 mole percent based on total units of the polymer, preferably 10
to 50 or 20 to 40 mole percent based on total units of the polymer,
provided that at least one of (P) and (Q) are present in the
polymer; (R) is present at about 50 to 60 mole percent based on
total units of the polymer, preferably 10 to 60 or 10 to 30, 40 or
50 mole percent based on total units of the polymer; and (S) is
present at about 10 to 60 mole percent based on total units of the
polymer, preferably 10 or 20 to 50 or 60 mole percent based on
total units of the polymer.
[0070] The fluorine-containing polymer of a resist of the invention
suitably does not contain aromatic units such as phenyl, naphthyl,
or pyridyl.
[0071] As discussed above, a fluorine-containing polymer may be
present with one or more other resins in a resist composition.
Those additional resin(s) may or may not contain fluorine and
typically do not contain aromatic units.
[0072] The resin component of a resist composition of the invention
should be present in an amount sufficient to providing acceptable
film-forming characteristics. See the example which follows for
preferred amounts of a resin component.
[0073] Photoactive Component
[0074] A variety of photoactive components may be employed in
resists of the invention. Photoacid generators (PAGs) are generally
preferred. Particularly preferred PAGs for use in resists of the
invention include include onium salt compounds including iodonium
and sulfonium compounds; and non-ionic PAGs such as imidosulfonate
compounds, N-sulfonyloxyimide compounds; diazosulfonyl compounds
and other sulfone PAGS including
.alpha.,.alpha.-methylenedisulfones and disulfonehydrazines,
nitrobenzyl compounds, halogenated particularly fluorinated
non-ionic PAGS. Preferred PAGs do not have aromatic
substitution.
[0075] More specifically, preferred iodonium PAGs include those of
the following Formula I: 9
[0076] wherein in Formula I, R.sup.1 and R.sup.2 are each
independently optionally substituted alkyl such as C.sub.1-20alkyl
including alicyclics such as cyclohexyl, adamantly, isobornyl,
norbornyl, fencyl, dodecanyl, and the like; optionally substituted
carbocyclic aryl such as phenyl, naphthyl and the like; and
optionally substituted heteroaromatic or heteroalicyclic such as
groups having 1 to 3 separate or fused rings and 1-3 hetero atoms
(N, O or S) as ring members; and
[0077] X is a counter anion such as a carboxylate or sulfonate
counter anion, preferably a a sulfonate (--SO.sub.3.sup.-) or
carboxylate (--COO.sup.-) substituted with one or more moieties
such as optionally substituted alkyl preferably C.sub.1-20alkyl,
particularly C.sub.1-10alkyl substituted with one or more
electron-withdrawing groups e.g. F or other halo, nitro, cyano,
etc., with perfluoruoalkyl, particularly C.sub.1-10perfluoroalkyl
being preferred; optionally substituted carbocylic aryl such as
phenyl or naphthyl; optionally substituted heteroaromatic or
heteroalicyclic such as groups having 1 to 3 separate or fused
rings and 1-3 hetero atoms (N, O or S) as ring members.
[0078] Preferred imidosulfonate PAGs include compounds of the
following Formula II: 10
[0079] wherein in Formula II, R is suitably by optionally
substituted alkyl preferably C.sub.1-20alkyl, particularly
C.sub.1-10alkyl substituted with one or more electron-withdrawing
groups e.g. F or other halo, nitro, cyano, etc., with
perfluoruoalkyl, particularly C.sub.1-10perfluoroalkyl being
preferred; optionally substituted carbocyclic aryl such as phenyl
or naphthyl; optionally substituted heteroaromatic or
heteroalicyclic such as groups having 1 to 3 separate or fused
rings and 1-3 hetero atoms (N, O or S) as ring members;
[0080] R.sup.1, R.sup.2, R.sup.3 and R.sup.4 each independently
being hydrogen or a group as defined for R, or where R.sup.2 and
R.sup.3 are taken together and/or R.sup.1 and R.sup.4 are taken
together to form a ring, preferably an alicyclic ring, e.g. having
from 4 to about 8 ring members; and
[0081] n is 1, 2, 3 or 4, preferably 1 or 2.
[0082] Preferred PAGs of Formula II include those with a fused
alicyclic ring structure, such as PAGs of the following Formula
IIa: 11
[0083] wherein in Formula IIa, R, R.sup.1, R.sup.2, R.sup.3 and
R.sup.4 are each the same as defined in Formula II above, with one
(and preferably all) of R.sup.1, R.sup.2, R.sup.3 and R.sup.4
suitably being hydrogen is the same as defined in Formula II above;
and X is methylene (--CH.sub.2--), O or S. Particularly preferred
PAGs of Formula IIa include those where X is methylene and R is
fluorinated C.sub.1-12alkyl, particularly perfluoroC.sub.1-12allyl
such as --CF.sub.3.
[0084] Sulfonium PAGS also will be suitable for use in resists of
the invention, although perhaps less preferred than the iodonium
salts and imidosulfonate compounds. For instance, preferred
sulfonium PAGs include compounds of the following Formula III:
12
[0085] wherein R.sup.1, R.sup.2 and R.sup.3 are each independently
selected from the same group as defined for R.sup.1 and R.sup.2 in
Formula I above; and X is the same as defined for Formula I
above.
[0086] Also preferred are ring sulfonium PAGs such as those of the
following Formula IV: 13
[0087] wherein R.sup.1 and X are the same as defined in Formula III
above; the dotted lines designate a ring structure that includes
the depicted sulfur cation as a ring member, the ring suitably
having 5 to about 8 ring members, and one, two or more endocyclic
multiple bonds, and one or more optional ring substituents.
Preferably the dotted lines form a non-aromatic ring, such as
thienyl, or a completely saturated ring (no endocyclic double
bonds).
[0088] In the above Formulae I, II and IV, preferred counter anions
X are perfluoroalkyl and perfluoroalkoxy groups such as
C.sub.1-15perfluoroalky- l and C.sub.1-15perfluoroalkoxy, e.g.
triflate, perfluorobutanesulfonate, perfluorohexanesulfonate,
perfluoroctanesulfonate, and perfluoroethoxyethylsulfonate.
[0089] A variety of other PAGs may be used in resists of the
invention, including non-ionic PAGs such as substituted disulfone
compounds; sulfonate compounds including N-oxyimino sulfonate
compounds, .alpha.-cyano N-oxyimino sulfonate compounds; sidulfone
hydrazine compounds; diazomethanedisulfone compounds; nitrobenzyl
compounds; substituted acylsulfonoium compounds; and oxime
sulfonate compounds including bis-N-oxyimidosulfonate
compounds.
[0090] More particularly, preferred disulfone PAGs for use in
resists of the invention include compounds of the following Formula
V: 14
[0091] wherein R.sup.1 and R.sup.2 are the same as defined for
Formula I above.
[0092] Preferred oxime sulfonate PAGs for use in resists of the
invention include those of the following Formula VI:
R.sup.1R.sup.2C.dbd.NOS(O).sub.2Y VI
[0093] wherein R.sup.1 and R.sup.2 may be the same as defined above
for Formula I, and/or where at least one of R.sup.1 and R.sup.2 is
an electron-withdrawing moiety such as cyano, nitro, haloalkyl
particularly C.sub.1-12haloalkyl especially
C.sub.1-12perfluoroalkyl such as --CF.sub.3, --CF.sub.2CF.sub.3 and
other perfluoroalkyl, alkanoyl, and the like;
[0094] Y is a non-hydrogen substituent and is suitably the same as
defined for R in Formula II above.
[0095] Preferred diazosulfone PAGS for use in resists of the
invention include those of the following Formula VII: 15
[0096] wherein R.sup.1 and R.sup.2 are the same as defined in
Formula I above.
[0097] Preferred .alpha.,.alpha.-methylenedisulfone PAGs for use in
resists of the invention include those of the following Formula
VIII: 16
[0098] wherein R.sup.1 and R.sup.2 are the same or different and
are other than hydrogen and are suitably the same as defined above
in Formula I;
[0099] R.sup.3 and R.sup.4 are the same or different and may be
hydrogen or a non-hydrogen substituent such as defined for R' in
Formula I above, and preferably at least one of R.sup.3 and R.sup.4
is other than hydrogen, more preferably both R.sup.3 and R.sup.4
are other than hydrogen.
[0100] As mentioned above, disulfonehydrazine PAGS (i.e. hydrazine
moiety interposed between the two sulfone moieties) also are
suitable, preferably where the hydrazine moiety (e.g.
--N(R.sup.3)--N(R.sup.4)-- of Formula IX below) interposed between
the two sulfone moieties is mono- or di-substituted with
non-hydrogen substituents. Preferred disulfonehydrazine PAGS for
use in resits of the invention include compounds of the following
Formula IX: 17
[0101] wherein R.sup.1 and R.sup.2 are the same or different and
are other than hydrogen, and suitably are the same as defined in
Formula I;
[0102] R.sup.3 and R.sup.4 are the same or different and may be
hydrogen or a non-hydrogen substituent such as defined for R.sup.1
in Formula I above, and preferably at least one of R.sup.3 and
R.sup.4 is other than hydrogen, more preferably both R.sup.3 and
R.sup.4 are other than hydrogen.
[0103] Further suitable PAGs for use in resists of the invention
include disulfonylamine (i.e. --SO.sub.2--N--SO.sub.2--) salts,
such as compounds of the following Formula X: 18
[0104] wherein R.sup.1 and R.sup.2 are the same or different and
are other than hydrogen, and suitably are the same as defined in
Formula I; and X is a counter ion.
[0105] One or more PAGS should be employed in a resist in an amount
sufficient to provide a developable image upon exposure to
activating radiation, such as 157 nm radiation. Suitably one or
more PAGs are employed in an amount of 1 to 15 weight percent based
on total solids of the resist (all components except solvent), more
typcially about 2 to 12 weight percent of total solids.
[0106] PAGs for use in resists of the invention can be made by
generally known procedures. For instance, see U.S. Pat. Nos.
4,442,197 and 4,642,912 and European Application 0708368A1 for
synthesis of iodonium PAGs. See WO 94/10608 for synthesis of
N-sulfonyloxyimide PAGs. Diazosulfone PAGs can be made, e.g., by
procedures disclosed in European Patent Application 0708368A1 and
U.S. Pat. No. 5,558,976. See also WO 00/10056.
[0107] Basic Additive
[0108] As discussed above, resists of the invention may suitably
comprise a basic additive. The basic additive can be used in
relatively small amount (e.g. 0.1 to 1, 2 or about 3 weight percent
of the photoactive component) and can significantly enhance
lithographic performance, particularly resolution of a developed
resist relief image. In particular, addition of an appropriate
basic compound to a resist of the invention can effectively
suppress undesired photoacid diffusion into masked areas following
an exposure step.
[0109] Preferred basic additives are amine compounds, including
primary, secondary, tertiary and quaternary amines. Amines that are
not highly nucleophilic are generally preferred to avoid undesired
reaction of the base additive with other resist composition
components such as the PAG and/or solvent.
[0110] More particularly, secondary and tertiary amines are
generally preferred, particularly secondary and tertiary amines
that have sterically large substituents, such as optionally
substituted alkyl having at least 3 or 4 carbons e.g. optionally
substituted C.sub.3-20alkyl; optionally substituted alkyl having at
least 3 or 4 carbons e.g. optionally substituted C.sub.3-20alkyl
including alicyclic groups such as optionally substituted
cyclohexyl, adamantly, isobornyl, etc.; optionally substituted
alkenyl having at least 3 or 4 carbons e.g. optionally substituted
C.sub.3-20alkenyl; optionally substituted alkynyl having at least 3
or 4 carbons e.g. C.sub.3-20alkynyl; optionally substituted
carbocyclic ayl such as phenyl; optionally substituted heteroaryl
or heroalicyclic such as heteroaryl or heteroalicyclic groups
having 1 to 3 separate or fused rings with 1 to 3 hetero atoms
(particularly N, O or S) per ring.
[0111] Specifically preferred basic additives for use in resist
compositions of the invention include DBU
(1,8-diazobicyclo[5.4.0]undec-7- -ene); DBN
(1,5-diazabicyclo[4.3.0]non-5-ene; N,N-bis-(2-hydroxyethyl)pipe-
razine; N,N-bis-(2-hydroxyethyl)-2,5-diazobicyclo[2.2.1]heptane;
N-triisopropanolamine; dibutyl amine preferably branched isomers
thereof such as diisobutylamine and ditertbutylamine; tributyl
amine and again branched isomers thereof such as ditertbuylamine
and tritertbutylamine; and the like. Optionally substituted
piperidine and other optionally piperazine compounds also will be
suitable, particularly hydroxy-substituted or
C.sub.1-12alcohol-substituted piperidines and piperazines, such as
N-ethanol piperidine and N-diethanol piperazine. Other basic
compounds also are suitable, particularly having one or more
nitrogen ring members and 5 to about 8 total ring members.
[0112] Other preferred base additives include hydroxy-alkyl
secondary and teriarty amines, e.g. secondary and tertiary amines
having at least one N-substituent of C.sub.2-20alkyl having one,
two three or more hydroxy moieties, typically one or two hydroxy
moieties; alicyclic amines where at least one secondary or tertiary
nitrogen is at the junction or bridgehead of a bicyclic or
multicyclic compound. Pyridyl compounds also will be suitable such
as di-butyl pyridine and polymers thereof such as
poly(vinylpyridine). In general, polymeric basic additives will be
suitable, e.g. substituted amines having a molecular weight of up
to about 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200,
1300, 1400 or 1500.
[0113] In a particular resist system, the basic additive should be
substantially non-interfering with the photoactive component, i.e.
not reactive with a PAG during typical storage of a resist. In
particular, a base additive is preferably selected to avoid
undesired degradation of the photoacid generator during storage of
a resist composition, e.g. 2, 3, 4, 5 or 6 months at room
temperature (ca. 25.degree. C.) or reduced temperature such as
refrigerated conditions (e.g., ca. 5, 10, 15 or 18.degree. C.).
More specifically, for resists that contain a dicarboxylate imide
PAG (such as depicted in Formulae II and IIA above), or an iodonim
compound such as those PAGs of Formula I above, preferably
secondary or tertiary amines are employed, particularly hindered
secondary or tertiary amines, such as moncyclic, bicylic and
tricylic amines where nitrogen is a ring member e.g. DBU, DBN,
alkylated pyridines e.g. pyridine substituted with one or more
C.sub.1-8 alkyl groups, optionally substitute quinolines,
optionally substituted piperidines; optionally substituted
pyrazines, and the like. In addition to alicyclic base additives
with nitrogen ring members, also preferred for use in combination
with imidosulfonate and iodonium PAGs are non-cyclic secondary and
tertiary amines having one or more alkyl substituents with at least
about 4 carbon atoms. Hindered secondary and tertiary amines
substituted with one or more alkyl groups, such as C.sub.1-20alkyl
groups, also are preferred for use with an iodonium PAG.
[0114] Carboxylate additives (e.g. a carboxylate salt such as a
ammonium carboxylate salt) are much less preferred for use with a
dicarboxylate imide. Carboxylate additives are also less preferred
with an iodonium PAG.
[0115] The basic additive is suitably employed in a resist
composition is an amount of 0.01 to 5 weight percent based on total
solids of the resist (all components except solvent), more
preferably about 0.05 to 2 weight percent of total solids.
[0116] Dissolution Inhibitor Compounds
[0117] Preferred dissolution inhibitor compounds of resists of the
invention are polymeric and/or comprise fluorine substitution. As
discussed above, preferred dissolution inhibitor compounds include
those that contain a photoacid-labile group, e.g. a
photoacid-labile ester or acetal moiety. Lower molecular weight
materials also are generally preferred, e.g. polymers or oligomers
having an Mw of less than 5,000, more preferably less than about
4,000, 3,000, 2,000, 1,000 or 500. Fluorinated polymers or
oligomers are particularly preferred dissolution inhibitor
compounds.
[0118] The dissolution inhibitor also need not be polymeric (i.e.
contain repeat units). For example, a variety of non-polymeric
compositions are suitable dissolution inhibitors for resists of the
invention, particularly where those materials are fluorinated. For
instance, suitable are fluorinated compounds having one or more
separate or fused rings, including fluorinated steroidal compounds,
e.g. a fluorinated cholates and lithocholates such as cholic acid,
deoxycholic acid, lithocholic acid, t-butyl deoxycholate, t-butyl
lithocholate, and the like. Fluoirnated steroidal compounds may be
suitably preferred by fluorination of a known steroid, where a
carbonyl group is modified to a difluromethylene. Such
non-polymeric compounds also may have one photoacid-labile groups,
e.g. a photoacid-labile ester or acetal moiety.
[0119] One or more dissolution inhibitor compounds may be suitably
present in a resist composition in an amount of from about 0.001 to
5 or more weight percent based on total solids (all components
except solvent), more preferably 0.001 to 1 weight percent of total
solids of a resist.
[0120] Surfactants and Levelers
[0121] Surfactant and leveling agents employed in resists of the
invention include e.g. silicon-containing compounds and ionic salts
such as an ammonium compound. Silicon-containing compounds are
generally preferred surfactant agents. Exemplary preferred
surfactants and levelers include Silwet 7604 (siloxane copolymer
available from Union Carbide); FC-430 (an imidosulfoante, available
from 3M); RO.sup.8 (mixture containing a fluoroalcohol); Modaflow
(an acrylate material). Surfactants and levelers may be suitably
employed in amounts as disclosed above for dissolution inhibitor
compounds.
[0122] Plasticizer Compounds
[0123] As discussed above, resists of the invention also may
contain one or more plasticizer materials, which can inhibit or
prevent undesired crazing or cracking of a deposited resist layer
as well as enhance adhesion of the resist layer to an underlying
material. Preferred plasticizers include e.g. materials having one
or more hetero atoms (particularly S or O), and preferably
materials having a molecular weight of about 20 to 1000, more
typically about 20 to about 50, 60, 70, 80, 90, 100, 150, 200, 250,
300, 400 or 500, e.g. adipates, sebacates and phthalates such as
bis(2-butoxyethyl)adipate; bis(2-butoxyethyl)sebacate;
bis-(2-butoxyethyl)phthalate; 2-butoxyethyl oleate; diisodecyl
adipate; diisodecyl glutarate; and poly(ethylene glycols) such as
poly(ethyleneglycol)acrylate, poly(ethylene
glycol)bis(2-ethylhexanoate), poly(ethylene glycol)dibenzoate,
poly(ethylene glycol)dioleate, poly(ethylene glycol)monooleate,
tri(ethylene glycol)bis(2-ethylhexanoate- ), and the like.
[0124] One or more plasticizer compounds may be suitably present in
a resist composition in an amount of from about 0.5 to 10 or more
weight percent based on total solids (all components except
solvent), more preferably 0.5 to 3 weight percent of total solids
of a resist.
[0125] As discussed, various moieties of PAGs, base additives and
resin units, and other components of resists of the invention may
be optionally substituted, typically 1, 2, or 3 positions by one or
more suitable groups such as e.g. halogen particularly F, Cl or
Br); C.sub.1-8 alkyl; C.sub.1-8 alkoxy; C.sub.2-8 alkenyl;
C.sub.2-s alkynyl; hydroxyl; alkanoyl such as a C.sub.1-6 alkanoyl
e.g. acyl; carobcyclic aryl such as phenyl; and the like, although
multiple carbon-carbon bonds and aromatic groups will be less
preferred due to excessive absorbance of exposure radiation.
[0126] Preferred substitution groups will generally include or
consist of at least one halogen atom, preferably fluorine such as
fluorinated C.sub.1-12alkyl, perfluoroC.sub.1-12alkyl, and
perfluoroC.sub.1-12alkylen- e, fluorinated C.sub.3-8cycloalkyl, and
fluorinated ethers (including C.sub.1-12 alkoxy) and esters
(including C.sub.1-12 esters) including fluorinated cyclic ethers
and fluorinated cyclic esters.
[0127] As used herein, the term alkyl, alkenyl and alkynyl unless
otherwise modified refers to both cyclic groups, although of course
cyclic groups will comprise at least three carbon ring members.
Alkoxy groups of resist components suitably have 1 to about 16
carbons and 1, 2, 3 or 4 alkoxy linkages. Suitable alkanoyl groups
have 1 to about 16 carbons and one or more carbonyl groups,
typically 1, 2 or 3 carbonyl groups. Carbocyclic aryl as used
herein refers to non-hetero aromatic groups that have 1 to 3
separate or fused rings and 6 to about 18 carbon ring members and
may include phenyl, naphthyl, biphenyl, acenaphthyl, phenanthracyl
and the like. Phenyl and naphthyl are often preferred. Suitable
heteroaromatic or heteroaryl groups will have 1 to 3 rings, 3 to 8
ring members in each ring and from 1 to about 3 hetero atoms (N, O
or S). Specifically suitable heteroaromatic or heteroaryl groups
include e.g. courmarinyl, quinolinyl, pyridyl, pyrimdinyl, furyl,
pyrrolyl, thienyl, thiazolyl, oxazolyl, imidazolyl, indolyl,
benzofuranyl and benzothiazole.
[0128] The resists of the invention can be readily prepared by
those skilled in the art. For example, a photoresist composition of
the invention can be prepared by dissolving the components of the
photoresist in a suitable solvent as disclosed herein, e.g. a blend
of 2-hetpanone and ethyl lactate, which is a preferred solvent.
Typically, the solids content of the composition varies between
about 5 and 35 percent by weight of the total weight of the
photoresist composition, more typically 5 to about 12 or 15 weight
of the total weight of the photoresist composition. The resin
binder and photoactive components should be present in amounts
sufficient to provide a film coating layer and formation of good
quality latent and relief images. See the example which follows for
exemplary preferred amounts of resist components.
[0129] The compositions of the invention are used in accordance
with generally known procedures. The liquid coating compositions of
the invention are 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.
[0130] The resist compositions of 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.
[0131] Following coating of the photoresist onto a surface, it is
dried by heating to remove the solvent until preferably the
photoresist coating is tack free. Thereafter, it is imaged through
a mask in conventional manner. The exposure is sufficient to
effectively activate the photoactive component of the photoresist
system to produce a patterned image in the resist coating layer
and, more specifically, the exposure energy typically ranges from
about 1 to 100 mJ/cm.sup.2, dependent upon the exposure tool and
the components of the photoresist composition.
[0132] As discussed above, coating layers of the resist
compositions of the invention are preferably photoactivated by a
short exposure wavelength, particularly a sub-300 and sub-200 nm ad
sub-170 nm exposure wavelength, particularly 157 nm is a
particularly preferred exposure wavelength. However, the resist
compositions of the invention also may be suitably imaged at higher
wavelengths. For example, a resin of the invention can be
formulated with an appropriate PAG and a sensitizer if needed and
imaged at higher wavelengths such as about 193 nm or 248 nm.
[0133] 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. The
exposed resist film is rendered positive working by employing a
polar developer, preferably 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.
Plasma development also may be employed. In general, development is
in accordance with procedures recognized in the art.
[0134] 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.
[0135] All documents mentioned herein are incorporated herein by
reference. The following non-limiting example is illustrative of
the invention.
EXAMPLE 1
Preparation of a Resist of the Invention
[0136] A resist of the invention is prepared by admixing the
following components where amounts are expressed as weight percent
of solids (all components except solvent) and the resist is
formulated as a 90 percent fluid formulation:
1 Component Amount Resist balance solids PAG 5 Basic Additive 0.5
Dissolution inhibitor 10 Surfactant 0.2 Plasticizer 0.6 Solvent to
10 weight percent solids
[0137] In the resist, the resin is a fluorine-containing terpolymer
consisting of norbornene; t-butylacrylate and tetrefluorethylene
(TFE) units prepared by free radical polymerization of the
monomers; the PAG is a compound of the Formula IIa above where X is
methylene and R is --CF.sub.3; the basic additive is DBU; the
dissolution inhibitor is fluorinated cholic acid; the surfactant is
Silwet 7604; the plasticizer is poly(ethylene glycol)dioleate; and
the solvent is a 70:30 v/v blend of 2-heptanone and ethyl
lactate.
[0138] The formulated resist composition is spin coated onto HMDS
vapor primed 4 inch silicon wafers and softbaked via a vacuum
hotplate at 90.degree. C. for 60 seconds. The resist coating layer
is exposed through a photomask at 157 nm, and then the exposed
coating layers are post-exposure baked at 110.degree. C. The coated
wafers are then treated with 0.26N aqueous tetramethylammonium
hydroxide solution to develop the imaged resist layer and provide a
relief image.
[0139] The foregoing description of the invention is merely
illustrative thereof, and it is understood that variations and
modifications can be effected without departing from the spirit or
scope of the invention as set forth in the following claims.
* * * * *