U.S. patent application number 09/790160 was filed with the patent office on 2002-08-22 for developer/rinse formulation to prevent image collapse in resist.
This patent application is currently assigned to International Business Machines Corporation. Invention is credited to Messick, Scott A., Moreau, Wayne M., Robinson, Christopher F..
Application Number | 20020115022 09/790160 |
Document ID | / |
Family ID | 25149812 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020115022 |
Kind Code |
A1 |
Messick, Scott A. ; et
al. |
August 22, 2002 |
Developer/rinse formulation to prevent image collapse in resist
Abstract
An apparatus and method are provided for developing photoresist
patterns on electronic component substrates such as semiconductor
wafers. The method and apparatus use a specially defined developer
composition in sequence with a specially defined rinse composition
to develop an exposed photoresist pattern and then to rinse the
developed pattern. Both the developer composition and rinse
composition contain an anionic surfactant and, when the solutions
are used in sequence, have been found to provide a resist pattern
which avoids pattern collapse even when small features such as line
widths less than 150 nm with aspect ratios of greater than about 3
are formed. It is preferred to use a puddle developing and puddle
rinsing process to develop and rinse the exposed wafer. Preferred
anionic surfactants are ammonium perfluoroalkyl sulfonate and
ammonium perfluoroalkyl carboxylate.
Inventors: |
Messick, Scott A.; (Pleasant
Valley, NY) ; Moreau, Wayne M.; (Wappingers Falls,
NY) ; Robinson, Christopher F.; (Hyde Park,
NY) |
Correspondence
Address: |
DELIO & PETERSON, LLC
121 WHITNEY AVENUE
NEW HAVEN
CT
06510
US
|
Assignee: |
International Business Machines
Corporation
Armonk
NY
|
Family ID: |
25149812 |
Appl. No.: |
09/790160 |
Filed: |
February 21, 2001 |
Current U.S.
Class: |
430/311 ;
396/571; 396/604; 396/611; 430/325; 430/330; 430/331 |
Current CPC
Class: |
G03F 7/322 20130101;
G03F 7/32 20130101; G03F 7/40 20130101 |
Class at
Publication: |
430/311 ;
430/325; 430/330; 430/331; 396/604; 396/611; 396/571 |
International
Class: |
G03F 007/20; G03F
007/32; G03F 007/40 |
Claims
What is claimed is:
1. A method for developing a photoresist pattern on an electronic
component substrate for avoiding collapse of the developed pattern
comprising the steps of: coating a photoresist film on an
electronic component substrate; exposing the photoresist film to a
predetermined pattern; supplying a developer composition to the
exposed photoresist film to develop the photoresist pattern, the
developer composition containing an anionic surfactant in a
sufficient amount to avoid collapse of the pattern; developing the
photoresist film to form the predetermined photoresist pattern and
maintaining the substrate wet; supplying a rinse water solution on
the wet developed substrate, the rinse water solution comprising
deionized water and an anionic surfactant in an amount sufficient
to avoid collapse of the pattern; rinsing the developed substrate;
and drying the developed substrate to form an electronic component
substrate having a predetermined photoresist pattern thereon.
2. The method of claim 1 wherein the anionic surfactant is a
fluorine-containing surface active agent represented by the general
formulaR.sub.fCOOM,orR'.sub.fSO.sub.3M,in which R.sub.f and
R'.sub.f each denote a monovalent hydrocarbon group having from 2
to 20 carbon atoms, of which at least a part of the hydrogen atoms
are replaced with fluorine atoms, and M denotes a hydrogen atom H,
ammonium NH.sub.4 or quaternary ammonium NR.sub.4, each R being,
independently from the others, a hydrogen atom or a alkyl group
having from 1 to 3 carbon atoms.
3. The method of claim 1 wherein a puddling method is used to apply
the developer composition and rinse solution.
4. The method of claim 1 wherein a spray method is used to apply
the developer composition and rinse solution.
5. The method of claim 1 wherein the electronic component is a
semiconductor wafer.
6. An apparatus for developing a photoresist pattern on an
electronic component substrate for avoiding collapse of the
developed pattern comprising: coating means for coating a
photoresist film on an electronic component substrate; exposing
means for exposing the photoresist film to a predetermined pattern;
supplying means for supplying a developer composition on the
exposed photoresist film, the developer composition containing an
anionic surfactant in a sufficient amount to avoid collapse of the
pattern; developing means for developing the photoresist film to
form the predetermined photoresist pattern and maintaining the
substrate wet; supplying means for supplying a rinse composition on
the wet developed substrate, the rinse composition comprising water
and an anionic surfactant in an amount sufficient to avoid collapse
of the pattern; rinsing means for rinsing the developed electronic
component substrate; and drying means for drying the developed
substrate to form an electronic component substrate having a
predetermined photoresist pattern thereon.
7. The apparatus of claim 6 wherein the anionic surfactant in the
developer composition is a fluorine-containing surface active agent
represented by the general
formulaR.sub.fCOOM,orR'.sub.fSO.sub.3M,in which R.sub.f and
R'.sub.f each denote a monovalent hydrocarbon group having from 2
to 20 carbon atoms, of which at least a part of the hydrogen atoms
are replaced with fluorine atoms, and M denotes a hydrogen atom H,
ammonium NH.sub.4 or quaternary ammonium NR.sub.4, each R being,
independently from the others, a hydrogen atom or a alkyl group
having from 1 to 3 carbon atoms.
8. The apparatus of claim 6 wherein the supplying means for both
the developer composition and rinse composition is a puddler.
9. The apparatus of claim 6 wherein the supplying means for both
the developer composition and rinse composition is a spray
device.
10. An electronic component made using the method of claim 1.
11. An electronic component made using the method of claim 2.
12. An electronic component made using the method of claim 3.
13. An electronic component made using the method of claim 4.
14. An electronic component made using the method of claim 5.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates generally to the fabrication of
electronic components such as integrated circuit semiconductors
and, in particular, to a method for avoiding resist pattern
collapse in the microlithography steps of integrated circuit
fabrication wherein a resist pattern is formed on the wafer surface
for subsequent etch removal or material addition steps.
[0003] 2. Description of Related Art
[0004] The fabrication of electrical circuits on electronic
component substrates such as thin film integrated circuits and
semiconductor devices such as wafers requires circuit pattern
definition using a microlithographic process. Lithographic
processes define substrate regions for subsequent etching removal
or material addition and the trend for integration is to continue
decreasing feature size which includes the line width of the
electrical circuit.
[0005] Photolithography is the production of a three-dimensional
relief image based on the patterned exposure to light and
subsequent development of a light-sensitive photoresist on the
wafer surface. Microlithography is used to print ultra small
patterns in the semiconductor industry but the basic steps to form
a resist image is essentially the same as in conventional optical
lithography.
[0006] Broadly stated, a radiation-sensitive photoresist is applied
to a substrate such as a wafer and then an image exposure is
transmitted to the photoresist, usually through a mask. Depending
on the type of photoresist used, exposure will either increase or
decrease the solubility of the exposed areas with a suitable
solvent called a developer. A positive photoresist material will
become more soluble in exposed regions whereas a negative
photoresist will become less soluble in exposed regions. After
exposure, regions of the substrate are dissolved by the developer
and no longer covered by the patterned photoresist film and the
circuit pattern may now be formed either by etching or by
depositing a material in the open patterned areas.
[0007] Basic steps involved in photoresist processing for
microlithography comprise first cleaning the substrate and priming
the substrate for adhesion of the photoresist. The wafer substrate
is then coated with a photoresist typically by spin coating the
resist over the wafer surface. The spin coating procedure typically
has three stages wherein the photoresist is dispensed onto the
wafer surface, the wafer is accelerated to a final rotational speed
and then the wafer is spun at a constant speed to spread and dry
the resist film. After the spinning stage, the coating acquires a
relatively uniform symmetrical flow profile typically about 0.1 to
10 micrometers thick. Spin coating is typically performed at a
speed from 3,000 to 7,000 rpm for twenty to sixty seconds producing
coatings with uniformities to .+-.100 .ANG. over a wafer with a 150
mm diameter. After spin coating, the wafers are typically soft
baked to remove solvents from the resist.
[0008] The photoresist is then exposed to form the desired pattern
in the resist. A post-exposure bake is then typically used and then
the resist developed with a developer to remove unwanted parts of
the resist and forming the desired resist pattern. The development
may be done by immersing the wafer into the developer or spraying a
developer solution onto the resist surface. A puddle technique may
also be used in which the developer solution is puddled or dripped
onto the surface of the wafer and then the wafer is spun (similarly
to apply the resist material) to simultaneously spread the
developer over the wafer surface. The above development techniques
are described in U.S. Pat. No. 6,159,662 to Chen et al., which
patent is hereby incorporated by reference.
[0009] To stop the development process, the developer then is
rinsed from the substrate surface with a rinse solution and this is
also typically performed by immersion, spraying or puddling as
described above.
[0010] A post-development baking step is typically performed to
remove residual solvents, improve adhesion and increase the etch
resistance of the resist. The wafer can then be treated by etching
or the addition of materials depending on the results desired.
[0011] Unfortunately, as the demands of industry require smaller
feature sizes, the line width defined by the resist is likewise
smaller. However, the resist pattern height cannot be significantly
reduced because the pattern must have a certain height or thickness
in order to remain functional. The ratio of the height of the
resist to the width of the standing line defined by the resist is
called the aspect ratio and when lined patterns with a high aspect
ratio are formed, a serious problem occurs since the resist pattern
has a tendency to fall down or collapse.
[0012] An article by Tanaka et al. in Japan J. Appl. Phys. vol. 32
(1993) pps. 6059-6064 entitled "Mechanism of Resist Pattern
Collapse During Development Process" discusses the problem of fine
resist pattern collapse. In one form of collapse, the tips of the
pattern come in contact with each other and the pattern collapse
results in a bending, breaking, tearing or peeling of the resist
pattern which results in the patterned wafer being unsuitable for
further processing.
[0013] Image collapse is a serious problem especially as the
features on the wafer become smaller, for example, for aspect
ratios greater than about 3 and lines less than 150 nm in width. As
a person skilled in the art would appreciate, as the aspect ratio
is increased and the line width decreases, the problem becomes more
pronounced and in lines having an aspect ratio of 6 and 100 nm line
width the collapse problem is very severe.
[0014] Industry has tried a number of solutions to solve the
collapse problem. In the Tanaka article, supra, it was concluded
that the source of resist pattern collapse was the surface tension
of the rinse liquid and a low-surface-tension rinse liquid was
proposed such as a mixture of tert-butylalcohol and water in a
mixture ratio of 50:50 volume percent. Use of a supercritical
resist dryer to prevent pattern collapse is proposed in an article
by Namatsu et al. entitled "Supercritical Resist Dryer" reported in
the J. Vac. Sci. Technol. B 18(2), March/April 2000. U.S. Pat. No.
4,784,937 to Tanaka et al. shows the use of an aqueous developing
solution for a positive-working photoresist composition containing
an organic base such as tetramethyl ammonium hydroxide and an
anionic or non-ionic fluorine-containing surface active agent to
improve the dissolving selectivity between the exposed areas and
unexposed areas of the photoresist layer. U.S. Pat. No. 5,474,877
to Suzuki shows a method for developing a photoresist pattern using
a rinsing liquid close to its boiling point to decrease the surface
tension of the rinsing liquid so that the collapse of the
photoresist pattern is avoided. The above articles and patents are
hereby incorporated by reference.
[0015] Bearing in mind the problems and deficiencies of the prior
art, it is therefore an object of the present invention to provide
a method for developing a photoresist pattern on an electronic
component substrate such as a semiconductor wafer to avoid pattern
collapse of the developed photoresist.
[0016] In another object of the present invention an apparatus is
provided for developing photoresist patterns on electronic
component substrates such as semiconductor wafers to avoid pattern
collapse of the developed photoresist.
[0017] It is further object of the invention to provide electronic
component substrates including semiconductor wafers which have been
developed using the method and apparatus of the invention.
[0018] It is yet another object of the present invention to provide
electronic components such as semiconductor wafers made using
electronic component substrates developed using the method and
apparatus of the invention.
[0019] Still other objects and advantages of the invention will in
part be obvious and will in part be apparent from the
specification.
SUMMARY OF THE INVENTION
[0020] The above and other objects and advantages, which will be
apparent to one of skill in the art, are achieved in the present
invention which is directed to, in a first aspect, a method for
developing a photoresist pattern on an electronic component
substrate such as a semiconductor wafer for avoiding collapse of
the developed pattern comprising the steps of:
[0021] coating a photoresist film on an electronic component
substrate;
[0022] exposing the photoresist film to a predetermined
pattern;
[0023] supplying a developer composition to the exposed photoresist
film to develop the photoresist pattern, the developer composition
containing an anionic surfactant in a sufficient amount to avoid
collapse of the pattern;
[0024] developing the photoresist film to form the predetermined
photoresist pattern and maintaining the substrate wet;
[0025] supplying a rinse water solution on the wet developed
substrate, the rinse water solution comprising deionized water and
an anionic surfactant in an amount sufficient to avoid collapse of
the pattern;
[0026] rinsing the developed substrate; and
[0027] drying the developed substrate to form an electronic
component substrate having a predetermined photoresist pattern
thereon.
[0028] In another aspect of the present invention, an apparatus is
provided for developing a photoresist pattern on an electronic
component substrate such as a semiconductor wafer for avoiding
collapse of the developed pattern comprising:
[0029] coating means for coating a photoresist film on an
electronic component substrate;
[0030] exposing means for exposing the photoresist film to a
predetermined pattern;
[0031] supplying means for supplying a developer composition on the
exposed photoresist film, the developer composition containing an
anionic surfactant in a sufficient amount to avoid collapse of the
pattern;
[0032] developing means for developing the photoresist film to form
the predetermined photoresist pattern and maintaining the substrate
wet;
[0033] supplying means for supplying a rinse composition on the wet
developed substrate, the rinse composition comprising water and an
anionic surfactant in an amount sufficient to avoid collapse of the
pattern;
[0034] rinsing means for rinsing the developed electronic component
substrate; and
[0035] drying means for drying the developed substrate to form an
electronic component substrate having a predetermined photoresist
pattern thereon.
[0036] In another aspect of the present invention, the method and
apparatus of the invention is employed to develop a photoresist on
electronic component substrates to avoid pattern collapse of the
developed substrate.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0037] The present invention is applicable to developing
photoresist patterns on a variety of electronic component
substrates such as printed circuit boards, integrated circuits,
microelectromechanical devices and magnetic discs components and is
particularly applicable to developing photoresist patterns on
semiconductor wafers having small feature sizes characterized by
line widths less than 150 nm and high aspect ratios greater than
about 3. For convenience, the following description will be
directed to the use of a positive photoresist on a semiconductor
wafer and it will be appreciated by those skilled in the art that
other type photoresists and other type electronic component
substrates may be used in the method and apparatus of the
invention. A negative type resist can also be used.
[0038] The present invention may be broadly stated as comprising a
method and apparatus for developing photoresist patterns on
semiconductor wafers wherein both the developer composition and the
rinse composition are used sequentially and both contain an anionic
surfactant. The use of an anionic surfactant in both the developer
composition and rinse composition has been found to minimize and/or
avoid the problem of pattern collapse in the developed wafer
substrate.
[0039] Any photoresist may be used in the method and apparatus of
the invention and as noted above the following description is
directed to a positive photoresist such as KRS (Ketal resist
system) as described in U.S. Pat. No. 6,043,003. Likewise, any
method for exposing the photoresist film to a predetermined pattern
may be used such as ultraviolet, electron beam, x-rays and ion
beams.
[0040] After the photoresist film has been formed on a
semiconductor wafer surface it is preferred to soft-bake the film
to remove solvents and this is typically done at a temperature of
about 90.degree. C. to 150.degree. C. for 30 to 120 seconds on a
hot plate. Any suitable time and temperature and baking equipment
may be used however depending on the photoresist used.
[0041] The photoresist is then exposed and this may be performed
using any of the standard and conventional techniques in the art
such as projection or direct write. It is preferred after the
exposure to bake the exposed photoresist film for about 1 to 2
minutes at 70 to 150.degree. C. to amplify the latent image.
[0042] There are essentially four methods that are used to develop
a photoresist image on a semiconductor wafer and these include
quiescence, immersion, spray and puddle development. In each
method, the development time and temperature must be carefully
controlled as will be appreciated by those skilled in the art. U.S.
Pat. No. 6,159,662, supra, discusses the development process.
[0043] The quiescense method adds developer to the exposed wafer
surface, and, after a period of time sufficient to develop the
pattern, a rinse composition is added to the wafer surface. After
rinsing the wafer is dried.
[0044] The immersion process basically comprises dipping the
exposed semiconductor wafer into a bath of the developer
composition for a certain period of time and then removing the
wafer from the bath. After the wafer has been removed from the
immersion bath, it is immersed in a rinse composition bath. A
displacement rinse method may be used using the same tank for both
the development immersion and rinsing. Instead of immersing the
developed wafer, the immersed wafer could be rinsed by
spraying.
[0045] In the spray development method, the exposed wafer is
sprayed with the developer composition for a certain period of time
to develop the pattern typically for about 1-2 minutes. The
developed wafer would then be sprayed with the rinse composition to
rinse the developer from the wafer surface. The rinse composition
would typically be sprayed for about 1-2 minutes and then dried
using conventional techniques such as air drying.
[0046] In a preferred embodiment, because of its demonstrated
effectiveness, a puddle development process is used in which the
developer composition is puddled onto the exposed semiconductor
wafer while the wafer is at rest and then the wafer spun slowly at,
for example, 100 rpm to distribute the developer composition over
the wafer surface. Then developer is left on the wafer surface for
sufficient developing time to develop the pattern, e.g., 1-2
minutes. The rinse composition is then puddled onto the still wet
wafer surface typically while the wafer is at rest and spun
similarly to the developer composition to rinse the wafer. After
the rinsing procedure, the rinsed wafer is dried, typically by spin
drying.
[0047] With regard to the developer composition, any suitable
commercial developer composition may be used in the invention with
the proviso that the developer composition contain an anionic
surfactant as defined hereinbelow. Developer compositions are
typically basic and may contain potassium hydroxide, sodium
hydroxide, sodium silicate and the like as the principal component
but it is highly preferred that the basic component be a basic
organic compound which is free from metal ions such as tetramethyl
ammonium hydroxide.
[0048] As described in U.S. Pat. No. 4,784,937, supra, the basic
organic compound free from metal ions is the principal ingredient
of the developer composition used in the inventive method and may
be any of known compounds conventionally used in the developing
solution of this type. Exemplary of such basic organic compounds
are aliphatic and aromatic amine compounds such as alkylene
diamines, e.g., 1,3-diaminopropane, and aryl amines, e.g.,
4,4'-diaminodiphenyl amine, as well as bis(dialkylamino) imines,
heterocyclic bases having a ring structure formed of 3 to 5 carbon
atoms and 1 or 2 hetero atoms selected from nitrogen, oxygen and
sulfur atoms as the ring members, e.g., pyrrole, pyrrolidine,
pyrrolidone, pyridine, morpholine, pyrazine, piperidine, oxazole
and thiazole, lower alkyl quaternary ammonium bases and others.
[0049] Particularly preferable among the above are the tetraalkyl
ammonium hydroxides where the alkyl group is C1-C4 or a substituted
C1-C4. Exemplary are tetramethyl ammonium hydroxide (TMAH) and
trimethyl 2-hydroxyethyl ammonium hydroxide, i.e., choline. Other
ammonium hydroxides include tetraethylammonium hydroxide,
tetrapropylammonium hydroxide, tetrabutylammonium hydroxide,
methyltriethylammonium hydroxide, trimethylethylammonium hydroxide,
dimethyldiethylammonium hydroxide, triethyl(2-hydroxyethyl)ammonium
hydroxide, dimethyldi(2-hydroxyethyl)ammonium hydroxide,
diethyldi(2-hydroxyethyl)am- monium hydroxide,
methyltri(2-hydroxyethyl)ammonium hydroxide,
ethyltri(2-hydroxyethyl)ammonium hydroxide, and
tetra(2-hydroxyethyl)ammo- nium hydroxide. The above named organic
bases free from metal ions can be used singly or as a combination
of two kinds or more accordingly to need.
[0050] The inventive developing solution is typically prepared in
the pH range of about 11.0 to 13.5 by dissolving the above
mentioned base compound in deionized water.
[0051] The optional additives used in conventional developer
compositions may also be used in the developer compositions of the
invention and include stabilizers and dissolving aids, and
monohydric alcohols, which serve to remove residues of the
photoresist which may otherwise be left on the exposed areas after
development. These optional additives can be added to the inventive
developing solution either singly or as a combination of two kinds
or more according to need.
[0052] It is an important feature of the invention that an anionic
surfactant be used in both the developer composition and rinse
water composition of the present invention.
[0053] Anionic surfactants are characterized by having a large
non-polar hydrocarbon end that is oil soluble and a polar end that
is water-soluble. For sodium lauryl sulfate, for example, the
C.sub.11H.sub.22CH.sub.2 group is the non-polar end and the
OSO.sub.3.sup.-Na.sup.+ is the polar end.
[0054] The anionic class of detergents includes ordinary alkali
metal soaps such as the sodium, potassium, ammonium and alkyl
ammonium salts of higher fatty acids containing from about 8 to
about 24 carbon atoms and preferably from about 10 to about 20
carbon atoms.
[0055] This class of detergents also includes water-soluble salts,
particularly non-metal ammonium salts of organic sulfuric reaction
products having in their molecular structure an alkyl radical
containing from about 8 to about 22 carbon atoms and a sulfonic
acid or sulfuric acid or sulfuric acid ester radical. (Included in
the term alkyl is the alkyl portion of higher acyl radicals.)
Examples of this group of synthetic detergents which form a part of
the preferred detergent compositions of the present invention are
the ammonium alkyl sulfates, especially those obtained by sulfating
the higher alcohols (C.sub.8-C.sub.19 carbon atoms); ammonium alkyl
benzene sulfonates, in which the alkyl group contains from about 9
to about 15 carbon atoms, in straight chain or branched chain
configuration.
[0056] Anionic phosphate surfactants are also useful in the present
invention. These are surface active materials in which the anionic
solubilizing group connecting hydrophobic moieties is an oxy acid
of phosphorus. The more common solubilizing groups are --SO.sub.4H,
--SO.sub.3H, and --CO.sub.2H. Alkyl phosphates esters such as
(R--O).sub.2PO.sub.2H and ROPO.sub.3H.sub.2 in which R represents
an alkyl chain containing from about 8 to about 30 carbon atoms are
useful.
[0057] A preferred anionic surfactant is a fluorine-containing
surface active agent represented by the general formula
R.sub.fCOOM,
[0058] or
R'.sub.fSO.sub.3M,
[0059] in which R.sub.f and R'.sub.f each denote a monovalent
hydrocarbon group having from 2 to 20 carbon atoms, of which at
least a part of the hydrogen atoms are replaced with fluorine
atoms, and M denotes a hydrogen atom H, ammonium NH.sub.4 or
quaternary ammonium NR.sub.4, each R being, independently from the
others, a hydrogen atom or a alkyl group having from 1 to 3 carbon
atoms. More particularly, the fluorine-containing carboxylic and
sulfonic acids and salts of the above mentioned types having an
activity as a surface active agent include straight-chain or
branched-chain perfluorocarboxylic acids of the formula
C.sub.nF.sub.2n+1COOH, perfluoroalkane sulfonic acids of the
formula C.sub.nF.sub.2n+1SO.sub.3H, partially fluorinated
carboxylic acids of the formula
C.sub.nF.sub.2n+1C.sub.mH.sub.2mCOOH, partially fluorinated
unsaturated carboxylic acids of the formula
C.sub.nF.sub.2n+1C.dbd.CHC.su- b.mH.sub.2mCOOH, partially
fluorinated alkane sulfonic acids of the formula
C.sub.nF.sub.2n+1C.sub.mH.sub.2m SO.sub.3H and partially
fluorinated alkene sulfonic acids of the formula
C.sub.nF.sub.2n+1CH.dbd.- CHC.sub.mH.sub.2m SO.sub.3H, in which n
and m are each a positive integer of 1 to 10 and 1 to 15,
respectively, as well as ammonium salts and tetraalkyl ammonium
salts thereof.
[0060] Particular compounds belonging to these classes include
perfluorocaprylic acid C.sub.7F.sub.15COOH, perfluorooctane
sulfonic acid C.sub.8F.sub.17SO.sub.3H, ammonium perfluorocaprate
C.sub.9F.sub.19COONH.sub.4, tetramethyl ammonium perfluorocaprylate
C.sub.7F.sub.15COON(CH.sub.3).sub.4,C.sub.5F.sub.11(CH.sub.2).sub.3COOH,
CF.sub.3(CF.sub.2).sub.3CF(CF.sub.3) (CH.sub.2).sub.10COONH.sub.4,
CF.sub.3(CF.sub.2).sub.6CH.dbd.CH(CH.sub.2).sub.2COOHN.sub.4 and
the like though not limited thereto. These compounds can be used
either singly or a combination of two kinds or more according to
need.
[0061] The developer composition will typically contain a base in
an amount of about 10 to 40 g/l to provide a pH of about 12 to 13.
A 0.21 N or a 0.26 N solution are typically used. An anionic
surfactant is present in the developer composition in an amount
sufficient to provide the desired anti-collapse properties of the
compositions used in the method and apparatus of the invention and
generally is in an amount of about 100 to 10,000 ppm or more,
preferably 500 to 5,000 ppm.
[0062] The developer composition may be used at a wide variety of
temperatures up to 35.degree. C. or higher, and is typically about
19 to 25.degree. C., preferably 21.degree. C.
[0063] The rinse composition preferably comprises deionized water
and the above described anionic surfactant in an amount of about
100 to 10,000 ppm or more, preferably 500 to 5,000 ppm to provide
the desired anti-collapse properties for the method and apparatus
of the invention.
[0064] The rinse composition may be used at a wide variety of
temperatures up to 35.degree. C. or higher, and is typically about
19 to 25.degree. C., preferably 21.degree. C.
EXAMPLE
[0065] A semiconductor wafer was coated with a KRS positive resist
by spin coating using a puddling procedure. The resist coated wafer
was exposed to provide line and space widths of about 100 nm with
an aspect ratio of about 6. The exposed wafer was developed by
puddling a deionized water solution of 0.263 N TMAH and 1% by
weight FC-93 (25% active) on the wafer surface while the wafer was
at rest. FC-93 is an ammonium perfluoroalkyl sulfonate surfactant
sold by 3M Chemicals. After developing and while the wafer was
still wet, the still wet wafer was rinsed with a rinse composition
containing deionized water and FC-93 anionic surfactant at a level
of 1 weight %. The rinse composition was applied to the wafer at
rest and the wafer was rinsed by spinning and then air dried. The
results show that the resist pattern did not collapse and was
satisfactory from a commercial standpoint. A control sample (no
surfactant added to developer and rinse) collapsed at an aspect
ratio of 3.5.
[0066] The above example was repeated using FC-143 which is an
anionic surfactant comprising an ammonium perfluoroalkyl
carboxylate surfactant and is also sold by 3M Chemicals. The
developed resist pattern did not collapse and was commercially
acceptable.
[0067] The above example was repeated using as the anionic
surfactant ammonium lauryl sulfate in amount of about 0.5% by
weight. In this case, an aspect ratio of 4 was achieved as the
upper limit.
[0068] While the present invention has been particularly described,
in conjunction with a specific preferred embodiment, it is evident
that many alternatives, modifications and variations will be
apparent to those skilled in the art in light of the foregoing
description. It is therefore contemplated that the appended claims
will embrace any such alternatives, modifications and variations as
falling within the true scope and spirit of the present
invention.
[0069] Thus, having described the invention,
* * * * *