U.S. patent application number 09/876635 was filed with the patent office on 2001-10-25 for non-corrosive stripping and cleaning composition.
This patent application is currently assigned to Arch Specialty Chemicals, Inc.. Invention is credited to Hansen, Gale Lynne, Honda, Kenji, Molin, Richard Mark.
Application Number | 20010034313 09/876635 |
Document ID | / |
Family ID | 22469785 |
Filed Date | 2001-10-25 |
United States Patent
Application |
20010034313 |
Kind Code |
A1 |
Honda, Kenji ; et
al. |
October 25, 2001 |
Non-corrosive stripping and cleaning composition
Abstract
A non-corrosive photoresist stripping and cleaning composition,
comprising: (a) about 5% to about 50% of a solvent; (b) about 10%
to about 90% of an alkanolamine; (c) about 0.1 to 10% of a
carboxylic acid; and (d) about 1.0% to 40% of water.
Inventors: |
Honda, Kenji; (Warwick,
AZ) ; Molin, Richard Mark; (Phoenix, AZ) ;
Hansen, Gale Lynne; (Chandler, AZ) |
Correspondence
Address: |
PAUL D. GREELEY, ESQ.
OHLANDT, GREELEY, RUGGIERO & PERLE, L.L.P.
10th FLOOR
ONE LANDMARK SQUARE
STAMFORD
CT
06901-2682
US
|
Assignee: |
Arch Specialty Chemicals,
Inc.
|
Family ID: |
22469785 |
Appl. No.: |
09/876635 |
Filed: |
June 7, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09876635 |
Jun 7, 2001 |
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09135809 |
Aug 18, 1998 |
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6268323 |
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09135809 |
Aug 18, 1998 |
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08850991 |
May 5, 1997 |
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5798323 |
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Current U.S.
Class: |
510/176 ;
510/177; 510/178; 510/499 |
Current CPC
Class: |
C09D 9/00 20130101; C11D
7/264 20130101; C11D 7/261 20130101; C11D 7/5009 20130101; C11D
7/32 20130101; G03F 7/426 20130101; G03F 7/425 20130101; C11D
7/3263 20130101; C11D 7/34 20130101; C11D 7/5013 20130101; C11D
7/265 20130101; C11D 7/3281 20130101 |
Class at
Publication: |
510/176 ;
510/177; 510/178; 510/499 |
International
Class: |
C11D 001/00 |
Claims
What is claimed is:
1. A non-corrosive stripping and cleaning composition, which is
free of hydroxylamine and its derivatives, comprising: (a) about 5%
to 50% by weight of a solvent selected from the group consisting
of: N-methyl-2-pyrrolidinone, N-hydroxyethyl-2-pyrrolidinone,
1,3-dimethyl-2-imidazolidinone, dimethylsulfoxide,
N,N-dimethylacetamide, sulfolane, diacetone alcohol, ethylene
glycol, propylene glycol and admixtures thereof; (b) about 10% to
90% by weight of an alkanolamine selected from the group consisting
of: diethyleneglycolamine, monoethanolamine, diethanolamine,
triethanolamine, 2-(2-aminoethylamino)ethanol, and admixtures
thereof; (c) about 0.1% to 10% by weight of a carboxylic acid type
corrosion inhibitor; and (d) about 1% to 40% by weight of
water.
2. The non-corrosive stripping and cleaning composition of claim 1,
wherein said carboxylic acid corrosion inhibitor is selected from
the group consisting of: formic acid, acetic acid, propionic acid,
valeric acid, isovaleric acid, oxalic acid, malonic acid, succinic
acid, glutaric acid, maleic acid, furmaric acid, phthalic acid,
1,2,3-benzene-tricarboxy- lic acid, glycolic acid, lactic acid,
citric acid, salicylic acid, tartaric acid, gluconic acid, and
combinations thereof.
3. The non-corrosive stripping and cleaning composition of claim 1,
wherein said solvent is present in the range between about 8-40%,
said alkanolamine is present in the range between about 20-80%,
said corrosion inhibitor is present in the range between about 1 to
10%, and said water is present in the range between about
5-35%.
4. The non-corrosive stripping and cleaning composition of claim 1,
wherein said solvent is present in the range between about 10-35%,
said alkanolamine is present in the range between about 30-70%,
said corrosion inhibitor is present in the range between about 3 to
7%, and said water is present in the range between about
10-30%.
5. The non-corrosive stripping and cleaning composition of claim 1,
further comprising about 0.01% to 2% by weight of a surface-active
compound.
6. A non-corrosive stripping and cleaning composition, which is
free of hydroxylamine and its derivatives, comprising: (a) about
8-40% by weight N-methyl-2-pyrrolidinone; (b) about 20-80% by
weight monoethanolamine; (c) about 3 to 7% by weight lactic acid;
and (d) about 5-35% water.
Description
[0001] This is a Continuation-In-Part of U.S. patent application
Ser. No. 08/850,991, filed May 5, 1997.
[0002] The present invention relates to a non-corrosive photoresist
stripping and cleaning composition containing a combination of
certain percentages of (1) selected solvents; (2) selected
alkanolamine compounds; (3) selected corrosion inhibitors; and (4)
water.
BACKGROUND OF THE INVENTION
[0003] The photoresist stripper/plasma etch residue cleaner art is
replete with numerous references to compositions containing either
a polar solvent or an alkanolamine compound, or both. The presence
of an alkanolamine in photoreist stripper compositions has been
judged to be essential to effectively remove cross-linked resist
films. However, alkanolamine-type photoresist strippers sometimes
have a serious problem of corrosion, especially with aluminum
substrates.
[0004] It is believed that the corrosion is caused in part by the
ionization of water with the alkanolamine in post-stripping water
rinse, as residual stripper solution may be retained on the
substrate surface and/or substrate carrier after the stripping
step. In other words, the alkanolamine component of the stripper
composition does not corrode the substrate by itself, but can
trigger water to cause the corrosion.
[0005] To solve this problem, an intermediate rinse step with an
organic solvent (e.g., isopropyl alcohol) has been used between the
stripping step and the post-stripping rinse with water. However,
such intermediate rinses are not necessarily desirable because
overall stripping operation becomes more complicated and,
furthermore, an additional solvent waste is produced. Accordingly,
if alkanolamine-containing strippers are to be further employed,
there is a need to solve this corrosion problem without generation
of intermediate organic solvent wastes.
[0006] In addition, other mechanisms of metal corrosion are known.
For example, metal halides, such as aluminum chloride, tend to be
generated as plasma-etch by-products. Metal halides may cause
corrosion of substrates when contacted with water from a water
rinse following the cleaning process. Another corrosion mechanism
is observed especially with alloys such as Al--Cu--Si during
cleaning or in a post-clean rinse process. This type of corrosion
is usually observed locally and is referred to as pitting. Pitting
is thought to be caused by the galvanic type of the electrochemical
reaction between two metals which have different
electronegativities.
[0007] The present invention provides a solution for all the
above-described types of corrosion.
[0008] Furthermore, during anisotropic plasma etching processes for
via contacts, metal patterns, and passivation openings, "sidewall
residues" are frequently deposited on the resist sidewall. After
the oxygen plasma ashing of photoresist films, these residues
become metal oxides. Incomplete removal of these residues interfere
with the pattern definition and/or complete filling of via
holes.
[0009] Several different chemistries have been identified for
removing the post-etch residues, particularly the metal oxide type.
For example, alkaline aqueous developers such as those containing
tetramethylammonium hydroxide (TMAH) are known to attack aluminum.
Thus, an aluminum oxide residue can be etched away with TMAH.
However, other types of the post-etch residues associated with
multi-metal systems such as Al--Si--Cu cannot be so easily removed
with TMAH. TMAH also is ineffective on residues formed from
polysilicon plasma etch processes.
[0010] The metal oxide type sidewall residues can also be removed
with: (1) a mixture of hydrofluoric acid and ethylene glycol ether,
or (2) a mixture of nitric acid, acetic acid, and hydrofluoric
acid. These solutions require extreme process control to prevent
excessive attack of critical metal and oxide layers. In some device
structures, these solutions are not useful because of their
nonselective attack mechanisms.
[0011] Wai M. Lee described at Interconnects, Contact Metallization
and Multilevel Metallization Symposium (183rd Spring Meeting of The
Electrochemical Society) in Honolulu, Hi., May 16-21, 1993, that a
hydroxylamine-containing amine/water-based stripper composition can
remove some kinds of the sidewall residues. Although hydroxylamine
has a potential to enhance the stripperability and/or the metal
corrosion inhibition, it is not stable upon heating. Therefore, the
use of hydroxylamine is not recommended, especially when used in a
highly alkaline medium.
[0012] Accordingly, hydroxylamine is not suitable for use in
stripping of photoresist films or cleaning of the post-etch
residues at higher temperatures.
[0013] Illustrative of references suggesting photoresist stripping
or plasma-etch residue cleaning compositions containing a polar
solvent and/or an alkanolamine compound are the following:
[0014] U.S. Pat. No. 4,617,251, which issued to Sizensky et al. on
Oct. 14, 1986, teaches a positive photoresist stripping composition
containing: (A) selected amine compound (e.g.,
2-(2-aminoethoxy)ethanol, 2- (2-aminoethylamino)ethanol, and
mixtures thereof) and (B) selected polar solvents (e.g.,
N-methyl-2-pyrrolidinone, tetrahydrofurfuryl alcohol, isophorone,
dimethyl sulfoxide, dimethyl adipate, dimethyl glutarate,
sulfolane, gamma-butyrolactone, N,N-dimethylacetamide and mixtures
thereof). The reference further teaches that water as well as dyes
or colorants, wetting agents, surfactants and antifoamers may be
added into this composition.
[0015] U.S. Pat. No. 5,279,791, which issued to Lee on Jan. 18,
1994, teaches a stripping composition for removing resists from
substrates containing (A) hydroxylamine (e.g., NH.sub.2OH); (B) at
least one alkanolamine; and optionally (C) at least one polar
solvent.
[0016] European Patent Application No. 647884 assigned to J. T.
Baker Inc. discloses nonaqueous photoresist stripper composition
comprising (i) a stripping solvent (e.g. N-methyl-2-pyrrolidinone),
(ii) a nucleophilic amine (e.g., monoethanolamine), and (iii) a
reducing agent such as salicyl aldoxime, gallic acid, and gallic
acid esters.
[0017] European Patent Application No. 596515 assigned to J T
Baker, Inc. discloses an alkaline photoresist stripping composition
comprising a solvent, a nucleophilic amines (e.g.,
1-amino-2-propanol, 2-aminoethanol), and a non-nitrogen containing
weak acid
[0018] German Published Patent Application No. DE3828513, which
issued to Schulz on Mar. 1, 1990, teaches a positive and negative
photoresist stripper composition containing (A) an aprotic polar
solvent (e.g., 1,3-dimethyl-2-imidazolidinone or
1,3-dimethyl-tetrahydropyrimidinone); and (B) an organic base
(e.g., alkanolamine).
[0019] Japanese Published Patent Application No. 1-081949, which
issued to K. Matsumoto (Asahi Chemical) on Mar. 28, 1989, teaches a
positive-working photoresist stripper composition containing (A)
gamma-butyrolactone, N-methylformamide, N,N-dimethylformamide,
N,N-dimethylacetamide or N-methyl-2-pyrrolidinone; (B) an amino
alcohol (e.g., N-butyl-ethanolamine and N-ethyldiethanolamine); and
(C) water.
[0020] Japanese Published Patent Application No. 4-350660, which
issued to H. Goto et al. (Texas Instruments, Japan and Kanto
Chemical, Inc.) on Dec. 4, 1992, teaches a stripper for positive
photoresists comprising (A) 1,3-dimethyl-2-imidazolidinone, (B)
dimethylsulfoxide and (C) a water-soluble amine (e.g.,
monoethanolamine or 2-(2-aminoethoxy)ethanol wherein the amount of
the water-soluble amine is 7-30% by weight.
[0021] Japanese Published Patent Application No. 7-271057, which
was published on Oct. 20, 1997, and is assigned to Tokyo Ohka
Kogyo, teaches positive photoresist compositions that contain
N,N-diethylhydroxyamine. Preferred formulations also contained
either alkanolamines (e.g., monoethanolamine); water-miscible
organic solvents (e.g. N-methyl-2-pyrrolidinone); water; additives
(e.g., hydroxy aromatic compounds or triazole compounds); or
carboxylic group-containing organic compounds, or certain
combinations thereof. Salicyl alcohol is one of the preferred
hydroxy aromatic compounds.
[0022] Japanese Published Patent Application No. 7-271057 does
suggests the addition of carboxylic acid to an admixture of a
water-miscible polar solvent and an alkanolamine for the
application to photoresist stripping composition or plasma-etch
residue cleaning composition. However, that reference requires the
presence of a hydroxylamine compound, N,N-diethylhydroxylamine
(DEHA), to achieve its desired performance.
[0023] Likewise European Patent Application No. 596515 does
discloses an admixture of a solvent, an alkanolamine and a
non-nitrogen containing weak acid in its formulation. However, this
composition does not contain water which is essential in the
removal of some kinds of plasma etch residues.
[0024] The stripping and cleaning composition of the present
invention, on the other hand, is effective in removing a wide
variety of both organic polymeric materials and plasma-etch
residues. The inventor has found that some types of corrosion
inhibitors can prevent metal corrosion without any reduction in the
stripping rate of photoresist, or any reduction in the
effectiveness of removing plasma etch residues. The present
formulation provides a superior balance of various functional and
economic requirements, including excellent prevention of metal
contamination of substrate surfaces, and favorable material cost
for the desired corrosion inhibition effect.
SUMMARY OF THE INVENTION
[0025] The present invention is directed to a non-corrosive
stripping and cleaning composition which is free of hydroxylamine
and its derivatives, this composition comprises:
[0026] (a) about 5% to 50% of a solvent selected from the group
consisting of: N-methyl-2-pyrrolidinone,
N-hydroxyethyl-2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone,
dimethylsulfoxide, N,N-dimethylacetamide, sulfolane, diacetone
alcohol, ethylene glycol, propylene glycol and admixtures
thereof;
[0027] (b) about 10% to 90% of an alkanolamine selected from the
group consisting of: diethyleneglycolamine, monoethanolamine,
diethanolamine, triethanolamine, 2-(2-aminoethylamino)ethanol, and
admixtures thereof;
[0028] (c) about 0.1% to 10% of a carboxylic acid type corrosion
inhibitor, the carboxylic acid type corrosion inhibitor being
selected from the group consisting of: formic acid, acetic acid,
propionic acid, valeric acid, isovaleric acid, oxalic acid, malonic
acid, succinic acid, glutaric acid, maleic acid, furmaric acid,
phthalic acid, 1,2,3-benzene-tricarboxylic acid, glycolic acid,
lactic acid, citric acid, salicylic acid, tartaric acid, gluconic
acid, and combinations thereof; and
[0029] (d) about 1% to 40% of water.
[0030] All percentages above are by weight of the total weight of
the stripping and cleaning composition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0031] As defined herein, the term "non-corrosive" refers to
suppression of any chemical action that gradually wears away a
substrate. The term "stripping and cleaning composition" refers to
a composition that is able to both (1) remove or strip a
photoresist (or other similar organic polymeric material) film or
layer from a substrate, and (2) remove or clean various types of
plasma-etch residues (also sometimes called plasma sidewall
polymers) from a substrate.
[0032] As stated above, the non-corrosive stripping and cleaning
composition of the present invention has four components, namely,
one or more selected polar solvents, one or more selected
alkanolamine compounds, one or more selected corrosion inhibitors;
and water. These four components must be present in certain
percentages. Also, the present invention is preferably free of
hydroxylamine compounds and its derivatives such as
N,N-diethylhydroxylamine.
[0033] Solvents used in the stripping and cleaning composition of
the invention include N-methyl-2-pyrrolidinone (NMP),
N-hydroxyethyl-2-pyrrol- idinone (HEP),
1,3-dimethyl-2-imidazolidinone (DMI), dimethylsulfoxide (DMSO),
N,N-dimethylacetamide (DMAC), sulfolane, diacetone alcohol (DAAL),
ethylene glycol (EG), propylene glycol (PG) or combinations
thereof. NMP and HEP are the preferred solvents. These solvents are
effective in stripping various types of photoresist.
[0034] Especially desirable is an admixture of HEP and NMP wherein
the mixing ratio of HEP to NMP, by weight % is from about 10:90% to
90:10%, as HEP is a safer and more viscous solvent, while NMP is a
more powerful stripping solvent with low viscosity. In general, the
stripping power is increased by lowering the viscosity of a
stripper solution.
[0035] Alkanolamines are also included in the stripping and
cleaning composition, as mentioned above. Preferred alkanolamines
include diethyleneglycolamine (DEGA), monoethanolamine (MEA),
diethanolamine (DEA), triethanolamine (TEA),
2-(2-aminoethylamino)ethanol and admixtures thereof. MEA is
especially preferred.
[0036] Corrosion inhibitors useful in the present invention are
carboxylic acid compounds. Preferred carboxylic acid compounds are:
formic acid, acetic acid, propionic acid, valeric acid, isovaleric
acid, oxalic acid, malonic acid, succinic acid, glutaric acid,
maleic acid, furmaric acid, phthalic acid,
1,2,3-benzene-tricarboxylic acid, glycolic acid, lactic acid,
citric acid, salicylic acid, tartaric acid, gluconic acid, and
combinations thereof. More preferred carboxylic acid type corrosion
inhibitors are lactic acid, citric acid, succinic acid, salicyclic
acid, phthalic acid, tartaric acid, and gluconic acid. This family
of compounds has been found to effectively inhibit the corrosion
without any reduction of the stripping power especially in
combination with admixtures of all polar solvents, alkanolamines
and water as described above. These compounds provide a superior
balance of various functional and economic requirements, including
excellent prevention of metal contamination of substrate surfaces,
and favorable material cost for the desired corrosion inhibition
effect.
[0037] The fourth critical ingredient is water. Water increases the
cleaning power when the composition of the invention is used as a
cleaner of post-plasma etch residue.
[0038] Optional ingredients in the stripping and cleaning
composition of the invention include water-soluble surface-active
agents. Exemplary surface-active agents include poly(ethylene
oxide) condensates with fatty alcohols manufactured by Olin
Corporation of Norwalk, Conn. under the trade name of
"POLY-TERGENT.RTM. CS-1".
[0039] The preferred amounts of these ingredients are about 8-40%
polar solvent; about 20-80% amine compound; about 1 to 10%
corrosion inhibitor; 5-35% water; and, if used, 0.01-2%
surface-active compound; all based on the weight of the stripping
and cleaning composition. The more preferred amounts of these
ingredients are about 10-35% polar solvent; about 30-70% amine
compound; about 3 to 7% corrosion inhibitor; about 10-30% water;
and optionally about 0.05-1% surface-active compound; all based on
the weight of the total composition.
[0040] Various other ingredients known to those skill in the art
may optionally be included in the stripping and cleaning
composition, e.g., dyes or colorants, wetting agents, antifoamers
and so forth. Generally, the amount of each of these other optional
ingredients would be about 0.01-0.5% by weight, based on the total
composition.
[0041] The stripping and cleaning composition of the invention is
prepared by dissolving one or more selected corrosion inhibitors
with one or more selected solvents and one or more selected alkanol
compounds at room temperature. As indicated above, optional
ingredients may also be added.
[0042] One function of the described stripping and cleaning
composition is removal or stripping of organic polymeric material
from a substrate. This aspect of the invention is carried out by
contacting an organic polymeric material such as a photoresist film
with the described stripping and cleaning composition. The
above-described composition may also be used in removing
post-plasma etch by-products after plasma etching of a metallized
wafer. These plasma-etch by-products are, for example, oxides or
halides of aluminum, titanium, copper or related metals, such as,
AlCl.sub.3, AlF.sub.3, Al.sub.2O.sub.3, SiF.sub.4, SiO.sub.2 and
the like. This aspect of the invention is carried out by contacting
the plasma-etch residues with the described cleaner solution. The
actual conditions, i.e., temperature, time, and the like, may vary
over wide ranges and are generally dependent on the nature and
thickness of the organic polymeric material or plasma-etch residue
to be removed, as well as other factors familiar to those skilled
in the art. In general, however, temperatures ranging from about
45.degree. C. to 90.degree. C. for a period of about 5 minutes to
40 minutes are typical.
[0043] A variety of means can be employed in contacting the organic
polymeric material and/or plasma-etch residues with the stripping
and cleaning composition in the practice of the invention. For
example, the substrate containing the organic polymeric material
and/or plasma-etch residue can be immersed in a stripping and
cleaning bath or the stripping and cleaning composition can be
sprayed over the surface of the organic polymeric material, as well
as plasma-etch residues, as will be apparent to those skilled in
the art.
[0044] The stripping and cleaning composition of the invention is
effective in removing a wide variety of organic polymeric materials
and plasma-etch residues from substrates. Exemplary organic
polymeric materials include positive- and negative-working g-line,
i-line and deep UV resists, electron beam resists, X-ray resists,
ion beam resists, as well as organic dielectric materials such as
polyimide resins, and so forth. Specific examples of organic
polymeric materials which can be removed in the practice of the
invention include positive resists containing phenol-formaldehyde
resins or poly(p-vinylphenol), negative resists containing cyclized
polyisoprene, or poly(p-vinylphenol); and
polymethylmethacrylate-containing resists. In particular, the
stripping and cleaning composition has been found to be highly
effective in removing positive resists containing a novolak resin
and a diazonathoquinone type sensitizer, e.g., ortho naphthoquinone
diazide sulfonic acid ester. Resists of this type include HPR 204
Series POSITIVE RESIST, HPR 504 Series POSITIVE RESIST, OiR32
Series POSITIVE RESIST, and HPR 6500 Series POSITIVE RESIST, sold
by Olin Microelectronic Materials, of Norwalk, Conn. The organic
polymeric material residues can be removed from any of the
conventional substrates known to those skilled in the art, such as
silicon, silicon dioxide, silicon nitride, polysilicon, aluminum,
aluminum alloys, copper, copper alloys, polyimides, and so
forth.
[0045] The present invention is further described in detail by
means of the following examples. All parts and percentages are by
weight and all temperatures are degrees Celsius unless explicitly
stated otherwise.
EXAMPLE 1
[0046] A stripping/cleaning solution was prepared by mixing 30.0 g
of N-methyl-2-pyrrolidinone (NM), 55.0 g of monoethanolamine (MEA),
5.68 g of 88 wt. % of lactic acid (LA) solution in water, and 9.32
g of deionized water with stirring to produce a clear solution. The
ratio by weight of the components in the resulting solution was
NMP/MEA/H.sub.2O/LA=30.0/55.0/10.0/5.0. The pH of the solution was
11.8.
[0047] Silicon wafers which have a multi-layer of
Al--Cu--Si/SiO.sub.2/Si were prepared by plasma deposition method
and further top-coated with a positive photoresist (PR) at a film
thickness of 1.0 micron by spin coating method. Micropatterning was
applied to the PR layer photolithographically, followed by pattern
transfer onto the metal layer by plasma etching with the
prepatternized PR mask. Thus obtained wafers contained both
residues of PR and plasma etching by-products which were a mixture
of silicon and aluminum oxides and halides. The composition of the
resulting plasma-etch residues (PER) were characterized by x-ray
spectroscopy.
[0048] The wafers obtained were cut into 1 cm.times.1 cm pieces and
placed in a 200 ml beaker which contained 100 ml of the
above-mentioned stripping/cleaning solution in a
temperature-controlled bath at 70.degree. C. The pieces of wafer
were immersed in the solution with gentle agitation for 30 minutes.
The wafer pieces were transferred to another beaker that contained
deionized water at room temperature and gently stirred for 5
minutes. The wafer pieces were then removed from the water and
dried by blowing nitrogen gas onto the surface of the wafer
pieces.
[0049] The wafer pieces were inspected under a scanning electron
microscope (SEM) after gold sputtering. Top-down and cross-section
views of the wafer SEM pictures were obtained to visualize the
residue of PR and PER on the wafers. In addition, the exposed metal
layer surface was inspected under SEM to evaluate any corrosion of
the metal surface.
[0050] The SEM inspection results indicated that the present
formulation of NMP/MEA/H.sub.2O/LA=30/55/10/5 removed both residues
of PR and PER without metal corrosion even if the post-strip
intermediate rinse with an organic solvent such as isopropyl
alcohol (IPA) was not applied.
EXAMPLES 2-3
[0051] Examples 2-3 illustrate additional compositions tested with
admixtures of the same solvent, alkanolamine, water and lactic acid
at different concentrations. Detailed formulations are summarized
in Table 1 with the SEM inspection of each result.
CONTROL 1
[0052] In addition to Examples 1-3, a control formulation that
contained no corrosion inhibitor was prepared as follows:
NMP/MEA/H.sub.2O=35/55/10- . The strip test condition was the same
as described in Example 1.
[0053] The SEM inspection result showed that both residues of PR
and PER were completely removed as shown in Example 1. However, the
metal layer was severely corroded in comparison to the formulations
of Examples 1-3.
CONTROL 2
[0054] In addition to control 1, another control formulation that
did not contain water was prepared as follows: NMP/MEA/LA=35/60/5.
The strip test condition was the same as described in Example
1.
[0055] The SEM inspection showed that while PR residue was
completely removed, the formulation without water did not remove
the plasma-etch residues. Also, as shown in Table 1, no metal
corrosion was observed with this formulation.
[0056] Table 1 below shows the results of the different
formulations and their affect on stripping of the Photoresist (PR),
Plasma Etch Residues cleaning (PER) and Corrosion inhibition
(CIN).
1 TABLE 1 Formulation (Wt. %) Performance Example NMP MEA H.sub.2O
LA PR PER CIN 1 30 55 10 5 +++ +++ +++ 2 34 55 10 1 +++ +++ + 3 32
55 10 3 +++ +++ ++ Control 1 35 55 10 0 +++ +++ - Control 2 35 60 0
5 +++ - +++ +++ is highest score, and - is negative effect
[0057] The following conclusions may be drawn from the result shown
in Table 1:
[0058] (1) The addition of lactic acid to the mixture of solvent,
alkanolamine and water is essential to prevent the metal corrosion
without any drawback of the performance of the photoresist
stripping and plasma-etch residue cleaning;
[0059] (2) There is a concentration dependency of lactic acid on
the corrosion inhibition. In other words, there should be an
optimum concentration of lactic acid to make the best balance of
the corrosion inhibition vs. the residue removal; and
[0060] (3) The absence of water with the mixture of solvent,
alkanolamine and lactic acid results in the incomplete removal of
the plasma-etch residues.
[0061] While the invention has been described above with reference
to specific embodiments thereof, it is apparent that many changes,
modifications, and variations can be made without departing from
the inventive concept disclosed herein. Accordingly, it is intended
that the present invention embrace all such changes, modifications,
and variations that fall within the spirit and broad scope of the
appended claims.
* * * * *