U.S. patent application number 10/998489 was filed with the patent office on 2005-05-12 for photoresist processing aid and method.
This patent application is currently assigned to Rohm and Haas Electronic Materials, L.L.C.. Invention is credited to Anzures, Edgardo, Barr, Robert K., Lundy, Daniel E., O'Connor, Corey.
Application Number | 20050100833 10/998489 |
Document ID | / |
Family ID | 30772815 |
Filed Date | 2005-05-12 |
United States Patent
Application |
20050100833 |
Kind Code |
A1 |
Anzures, Edgardo ; et
al. |
May 12, 2005 |
Photoresist processing aid and method
Abstract
A composition and method to reduce photolithographic residue and
scum formation on a substrate or in a solution, and to reduce or
prevent foam formation. The composition contains a diphenyl oxide
compound in combination with an antifoam agent. The composition may
be added to developer solutions and stripper solutions used in
manufacturing printed wiring boards.
Inventors: |
Anzures, Edgardo;
(Westborough, MA) ; Lundy, Daniel E.; (Winchendon,
MA) ; Barr, Robert K.; (Shrewsbury, MA) ;
O'Connor, Corey; (Worcester, MA) |
Correspondence
Address: |
John J. Piskorski
EDWARDS & ANGELL, LLP
P.O. Box 55874
Boston
MA
02205
US
|
Assignee: |
Rohm and Haas Electronic Materials,
L.L.C.
Marlborough
MA
|
Family ID: |
30772815 |
Appl. No.: |
10/998489 |
Filed: |
November 29, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10998489 |
Nov 29, 2004 |
|
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10408414 |
Apr 7, 2003 |
|
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60371986 |
Apr 12, 2002 |
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Current U.S.
Class: |
430/464 ;
430/256 |
Current CPC
Class: |
G03F 7/425 20130101;
G03F 7/322 20130101 |
Class at
Publication: |
430/464 ;
430/256 |
International
Class: |
G03C 005/18 |
Claims
1-11. (canceled)
12. A composition consisting of a diphenyl oxide in a sufficient
amount to reduce or inhibit formation of photolithographic residue
on a substrate or in a solution and an antifoam agent.
13. The composition of claim 12, wherein the antifoam agent
comprises silicones, hydrocarbons, acetylenics, vinyl polymers,
polyalkoxylates or mixtures thereof.
14. The composition of claim 12, wherein the diphenyl oxide
comprise from about 20% to about 95% by weight of the composition
and the antifoam agent comprises from about 5% to about 80% by
weight of the composition.
15. A method of reducing residue formation and foaming comprising
contacting a substrate or a solution comprising photoresist with a
sufficient amount of a photolithographic residue reducing-antifoam
agent composition to inhibit the formation of photolithographic
residue on the substrate or the solution and to inhibit or reduce
foaming, the composition comprises a diphenyl oxide and an antifoam
agent.
16. The method of claim 15, wherein the antifoam agents comprises
silicones, hydrocarbons, acetylenics, vinyl polymers,
polyalkoxylates or mixtures thereof.
17. The method of claim 15, wherein the photoresist cleaning
composition further comprises an auxiliary surfactant.
18. The method of claim 15, wherein the photoresist cleaning
composition further comprises a solvent.
19. The method of claim 15, wherein the composition further
comprises a developer or stripper component.
20. The method of claim 19, wherein the developer or stripper
component develops or strips photoresist from the substrate.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention is directed to a composition and
method for reducing residue and scum formation originating from
photolithographic compositions as well as reducing foam formation.
More specifically, the present invention is directed to a
composition and method for reducing residue and scum formation
originating from photolithographic compositions and for reducing
foaming with a diphenyl oxide compound in combination with an
antifoam agent.
[0002] Residue and scum from photolithographic compositions such as
photoresists, surfactants, alkaline compounds and antifoam agents
from developer and stripping compositions present difficult
cleaning problems for the electronics industry. Such residue and
scum can build-up on various products and apparatus. Photoresist
materials are employed in the manufacturing of semiconductor
devices, and electronic components such as integrated circuits,
photomasks for the manufacture of integrated circuits, printed
wiring boards and the like as well as planographic printing plates.
In photolithographic processing, a step in the process of making
electronic devices and components, a substrate surface is coated
with a photoresist, i.e., a coating composition that is sensitive
to actinic radiation, e.g., ultraviolet light, X-rays, electron
beams and the like, to give a layer that is sensitive to actinic
radiation which is irradiated pattern-wise with the actinic
radiation. The irradiated photoresist is then developed with a
developer solution to form a patterned photoresist layer that
serves to selectively protect the substrate surface from etching,
plating or diffusion of dopants.
[0003] Photoresists may be positive-working, or negative-working.
Such photoresists may be liquid, or dry film. A photoresist
composition of the positive-working type has such a
photosensitivity that solubility of the composition in the
developer solution is increased by exposure to light so that the
patterned photoresist layer is formed on the areas unexposed to
ultraviolet light where the composition is left undissolved. A
negative-working photoresist composition exhibits behavior of a
sensitivity and solubility that is the reverse of the
positive-working photoresist.
[0004] Along with recent progress in the technology of
semiconductor devices with a requirement for finer and finer
high-fidelity patterning of a line width of 1 micron or even finer
to comply with the trend of increased density of integration in
semiconductor devices, photolithographic processes of patterning
using a positive-working photoresist also envisages a difficult
problem. When patterning is desired of an extremely fine contact
hole in a fine pattern, alkaline developer solution is admixed with
a surface active agent with an object to increase the wettability
of the substrate surface with the aqueous developer solution. One
of the problems in the addition of a surface active agent to the
developer solution is that film residues and scums sometimes occur
on the exposed areas where the photoresist layer desirably is
dissolved away completely and cleanly. Although the film residues
and scums can be removed by gently treating the surface with oxygen
plasma or sputtering, no complete solution of the problem can be
obtained by such methods because such treatments must be performed
under well controlled troublesome conditions and is not efficient
in respect of smooth removal of the scums, or gives no uniform
effect of treatment in finely patterned areas having contact holes
of about 1 micron or smaller in diameter.
[0005] U.S. Pat. No. 4,820,621 to Tanaka et al. has addressed the
problem of residue and scum formation by modifying a developer
solution with the addition of a non-ionic surface active agent that
is a polyoxyethylene alkyl-substituted phenyl ether. The ether is
included in the developer solution in an amount of from 50 to 5000
ppm (parts per million). The developer solution is employed in
patterning using a positive-working photoresist composition
composed of an alkali-soluble novolac resin and a naphthoquinone
diazide compound. The '621 patent alleges that patterning the
positive photoresist with the developer containing the
polyoxyethylene alkyl-substituted phenyl ether prevents formation
of residues and scums after development.
[0006] Similar residue and scum formation also occur when
negative-working photoresists are employed. For example, in
manufacturing printed circuit boards UV curable negative-working
photoresists may be used. Exposed portions of the photoresist
become insoluble in alkaline developer solution and form a
protective barrier to other processing chemicals such as etching
and plating solutions. Unexposed portions of the photoresist are to
rinse freely from the circuit board with an alkaline solution such
as a 1% sodium carbonate, monohydrate in water. Development occurs
because polymers in the photoresist contain acid functionality.
Such acid functionality within the polymers are neutralized in
alkaline solution forming a water soluble organic salt. As the
dissolved photoresist builds up in solution (developer loading),
insoluble organic materials begin to form in the developing tank
eventually forming a water insoluble residue or scum. Presence of
anti-foam additives (conventionally added to developing solutions
to minimize foaming) greatly increases the tendency for residue and
scum to form. As the level of scum builds, chances increase for an
inadvertent redeposit of these water insoluble residues onto the
developed circuit board. Such redeposited residues cause a
retardation of the etching solution (etching chemistries have
difficulty penetrating any organic residues). Where etch is
retarded, circuit shorts form causing a defective circuit board. In
addition to increasing the potential for defective circuit boards,
the residue also makes cleaning equipment difficult, thus
increasing maintenance time.
[0007] In addition to the problem of built-up residue and scum
formation from primary photoresists, there also is a residue and
scum build-up problem from secondary photoresists. Such secondary
photoresists may be employed in soldermasks. Residue and scum are
deposited on a substrate as a result of component separation in the
soldermask. Such component separation may be exacerbated when an
improperly balanced soldermask developer solution, i.e., improper
developing conditions and/or soldermask developer solution
chemistry, contact the soldermask. Built-up residue and scum from
secondary photoresists often appear as a bright green coating on a
substrate such as a developer apparatus.
[0008] Conventional cleaners used to remove residue and scum may
vary in composition. Typically, such conventional cleaners include
as active ingredients a strong base such as sodium hydroxide, and
chelating agents such as ethylene diamine tetraacetate (EDTA).
Surfactants, solvents and emulsifying agents may also be included
in the cleaners. Conventional cleaners are employed at temperature
ranges from about 45.degree. C. to about 55.degree. C. Such
conventional cleaners are primarily used because of the low cost of
their ingredients. However, workers in the field using such
conventional cleaners have discovered that the residue problem is
often made worse. Often the equipment has to be manually cleaned to
remove the residue from the photoresist as well as the conventional
cleaners. Such manual cleaning is both a labor and time intensive
operation that can cause a significant loss of production time.
Further, as mentioned above, such cleaners are not effective enough
for removing residue from new generation photoresists that have
many hydrophobic aromatic materials. Accordingly, it is
advantageous to reduce or prevent the build-up of such residue and
scum to prevent or at least reduce the amount of cleaning. U.S.
Pat. No. 5,922,522 to Barr et al.; U.S. Pat. No. 6,063,550 to Lundy
et al.; and U.S. Pat. No. 6,248,506 B1 to Lundy et al. disclose
surfactant and surfactant mixtures included in developer solutions
that prevent or inhibit the formation of residues and scum on
circuit boards and circuit board manufacturing equipment. Such
surfactants are composed of a hydrophobic group, an alkoxylated
hydrophilic group and a nonionic or anionic capping group. Examples
of suitable hydrophobic groups include nonylphenol, octylphenol and
tristyrylphenol. Examples of suitable alkoxylated hydrophilic
groups include ethylene oxide, propylene oxide and ethylene
oxide/propylene oxide groups. Examples of suitable capping groups
include hydroxyl, carboxyl, sulfonyl, phosphonyl, or mixtures
thereof. Such residue and scum reducing compounds are included in
developer solutions in amounts of from about 0.05% to about 1.0% by
weight.
[0009] Although the developer solutions disclosed in U.S. Pat. No.
5,922,522; U.S. Pat. No. 6,063,550; and U.S. Pat. No. 6,248,506 B1
provide an effective means of reducing the amount of build-up of
residue and scum on substrates containing photoresist, such as
circuit boards, and equipment used in the manufacture of electronic
components, there is still a need for a composition and method for
further reducing the amount of residue and scum formation to reduce
cleaning or to prevent cleaning. Additionally, there is also a need
for a cleaning composition and method for further reducing foam
formation in both developer and stripper solutions. While the
above-mentioned patents address residue and scum formation in
developer solutions, the patents do not address the problem of
residue formation or foam formation in stripper solutions. Thus,
there is a need for a composition that prevents residue formation
and foaming in both developer and stripper solutions. Developers
may be acid or basic solutions that remove un-cross-linked
photoresist from a substrate after exposure of the photoresist to
actinic radiation. Strippers are acidic or basic solutions that
remove all photoresist from a substrate.
[0010] Photoresist that is removed by developer and stripper
solutions can cause undesirable amounts of foaming. If the foaming
is excessive, it can overflow from apparatus, and cause the
solution levels to go down below a minimum threshold level that may
result in equipment shutdown. Foaming can also obscure the field of
view of workers making it difficult to determine photoresist break
points, and to monitor panels in developing chambers. It is also
more difficult to clean equipment that contains significant amounts
of foam. Washing with water only aggravates the foaming problem In
many cases, antifoaming agents are utilized in developing and
stripping baths.
[0011] Many commercially available antifoams, however, can increase
the amount of undesirable residue in developer and stripping
solutions. The solutions can contain fairly high levels of organic
material because the developed or stripped photoresist are
emulsified and/or solubilized in the solution. An analysis of the
residue from such photolithographic compositions reveals that it is
a complex mixture of photoresist, antifoam, developer or stripper
components. These residues can float on a developer or stripper
solution surface and/or adhere to equipment parts. As mentioned
above, presence of these residues can cause sub-optimum performance
of the process equipment and surface contamination of the circuit
boards. Both of these factors can result in printed wiring board
defects. As a result, the key requirements for an antifoam in a
developer or stripper are to control foaming in addition to
minimizing the formation of residues from photolithographic
compositions.
[0012] Accordingly, it is advantageous to have an antifoam product
that effectively lessens the amount of foam while also reducing
undesirable residues in photoresist developers. It is useful if the
same antifoam product minimizes the foaming in photoresist
strippers. Many antifoams are not suitable for both developers and
strippers. Thus, there is a need for a composition that reduces or
inhibits residue and scum deposited by photolithographic
compositions, and reduces or inhibits foaming.
SUMMARY OF THE INVENTION
[0013] The present invention is directed to a residue
reducing-antifoam composition containing a photolithographic
composition residue cleaning component for reducing the amount of
photolithographic residue on a substrate or in a solution and an
antifoam agent, the residue reducing-antifoam composition contains
a diphenyl oxide with at least one hydrophilic group in a
sufficient amount to inhibit or reduce formation of
photolithographic residues. The residue-reducing-antifoam
composition of the present invention may be added to developer and
stripper solutions to reduce or inhibit residue and scum formation
caused by photolithographic compositions, and to reduce or inhibit
foaming during developing and stripping processes.
[0014] Advantageously, the components of the composition do not
aggravate residue and scum formation as many conventional cleaners.
Antifoam agents employed in the cleaning composition reduce or
inhibit foam formation during developing and stripping processes.
Formation of residue and scum is difficult to prevent and once
formed is difficult to emulsify and remove from a substrate or a
solution. Continuous or prolonged use of equipment employed in
developing and stripping photoresist, or that contacts photoresist
during the manufacture of photolithographic devices such as printed
wiring boards results in the build-up of undesirable residue and
scum on the equipment. The residue and scum may block or clog lines
or movable parts on the equipment resulting in production shutdown.
Additionally, the residue build-up on printed wiring boards causes
defects in the boards such as electrical shorts. Cleaning done with
conventional cleaners is not always effective because residue and
scum contain chemicals that are difficult to re-emulsify with
conventional cleaners. Also, conventional cleaners may further
contaminate the equipment and manufactured articles. Thus,
prevention or at least reduction of residue and scum formation is
highly desirable along with no or minimal cleaning. Advantageously,
the compositions of the present invention are compatible with
photolithographic equipment and do not aggravate residue and scum
formation, but inhibit or reduce the formation of residue and
scum.
[0015] Another problem is foaming. When photoresist is removed from
a substrate with either a developer solution or a stripper
solution, foaming may occur. As mentioned above, excessive foaming
during photoresist removal may cause developer or stripper solution
levels to go below their effective minimum threshold levels. Such a
condition results in developer or stripper equipment shutdown.
Foaming also may obscure a workers field of view during
manufacturing of printed wiring boards making it difficult to
determine photoresist break points, and to monitor printed wiring
board panels in developing or stripping chambers. Additionally,
cleaning equipment that contains large amounts of foam is
difficult. Antifoam agents employed in the present invention
prevent or reduce foam formation during developing and stripping
procedures.
[0016] The combination of the diphenyl oxide and an antifoam agent
reduce or inhibit residue and scum formation as well as reduce or
inhibit foam formation during developing and stripping processes.
Another advantage of the cleaning composition is that antifoam
agents that are utilized are compatible with both developer and
stripper solutions. Generally, antifoam agents are not suitable for
use in both developer and stripper solutions. Strippers generally
have higher electrolyte content and are at higher pH ranges than
developers. Such conditions are not suitable for many antifoam
agents. Thus the cleaning composition of the present invention
solves at least two important problems in developing and
stripping.
[0017] Accordingly, a primary objective of the present invention is
to provide for an improved residue reducing-antifoam composition
containing a diphenyl oxide with at least one hydrophilic group and
an antifoam agent.
[0018] Another objective of the present invention is to provide for
an improved residue reducing-antifoam composition that reduces or
inhibits the formation of residue and scum from photolithographic
compositions on a substrate and a solution.
[0019] A further objective of the present invention is to provide
for a residue reducing-antifoam composition that reduces or
inhibits foaming during developing and stripping procedures.
[0020] An additional objective of the present invention is to
provide for an improved method of reducing residue and scum
formation as well as foaming during developing and stripping
procedures.
[0021] Other advantages may be ascertained by a person of skill in
the art reading the following description of the invention and the
appended claims.
DETAILED DESCRIPTION OF THE INVENTION
[0022] A residue reducing-antifoam composition of the present
invention contains a diphenyl oxide with at least one hydrophilic
group and an antifoam agent. The diphenyl oxide with at least one
hydrophilic group is included in the composition in a sufficient
amount such that residue formation from photolithographic
compositions is reduced or inhibited from forming on a substrate or
in a solution. Photolithographic residue includes primarily residue
from photoresist but also includes scum and residue from developer
and stripper compositions such as for some antifoams, surfactants
and alkaline compounds used in developer and stripper
solutions.
[0023] Diphenyl oxides within the scope of the present invention
have the following formula: 1
[0024] where M is --COO.sup.-, --SO.sub.3.sup.-, --SO.sub.4.sup.2-,
--PO.sub.4.sup.3-, --PO.sub.4(R').sub.2, X is hydrogen or a counter
ion, R.sub.1 and R.sub.2 are the same or different and include, but
are not limited to, hydrogen, an aliphatic, cycloaliphatic, or
aromatic, R' is a hydrocarbon, n and q are 0 or 1 with the proviso
that at least one of the two phenyl rings of the diphenyl oxide has
n=1. When n=0, q also equals 0.
[0025] Examples of suitable aliphatic groups include, but are not
limited to, linear or branched alkyl groups of from 1 to 25 carbon
atoms, preferably from 5 to 10 carbon atoms. Illustrative aliphatic
groups are methyl, ethyl, propyl, isopropyl, butyl, isobutyl,
pentadecyl, hexadecyl, octadecyl and the like. Examples of suitable
cycloaliphatic groups include, but are not limited to,
cycloaliphatic groups having from 5 to 10 carbon atoms, preferably
from 5 to 6 carbon atoms. Examples of hydrophobic aromatic groups
include, but are not limited to, aromatic groups having from 5 to
14 carbons, preferably from 5 to 6 carbons.
[0026] Counter ion X includes, but is not limited to, sodium,
potassium, calcium, magnesium, ammonium or an amine. X ammonium ion
radicals are of the formula (R").sub.3NH.sup.+ wherein each R" is
independently hydrogen, a C.sub.1-C.sub.4 alkyl or a
C.sub.1-C.sub.4 hydroxyalkyl radical. Illustrative C.sub.1-C.sub.4
alkyl and hydroxyalkyl radicals include methyl, ethyl, propyl,
isopropyl, butyl, hydroxymethyl and hydroxyethyl. Typical ammonium
ion radicals include ammonium (+H.sub.4), methylammonium
(CH.sub.3N.sup.+H.sub.3), ethylammonium
(C.sub.2H.sub.5N.sup.+H.sub.3), dimethylammonium
((CH.sub.3).sub.2NH.sub.2.sup.+), methylethyalammonium
(CH.sub.3N.sup.+H.sub.2C.sub.2H.sub.5), trimethylammonium
((CH.sub.3).sub.3N.sup.+H.sub.2), dimethylbutylammonium
((CH.sub.3).sub.2N.sup.+HC.sub.4H.sub.9), hydroxyethylammonium
(HOCH.sub.2CH.sub.2N.sup.+H.sub.3) and methylhydroxyethylammonium
(CH.sub.3N.sup.+H.sub.2CH.sub.2CH.sub.2OH). Preferably, X is
hydrogen, sodium, calcium, potassium or ammonium.
[0027] Preferably, M is --SO.sub.3.sup.-, --PO.sub.4.sup.3-, or
--PO.sub.4(R').sub.2 where R' is as defined above, and R.sub.1 and
R.sub.2 are the same or different and are hydrogen or a 1 to 20
carbon aliphatic group, or a 5 to 6 hydrophobic aromatic group with
the proviso that when one of R.sub.1 or R.sub.2 is hydrogen the
other is the aliphatic or aromatic group. More preferably, M is
--PO.sub.4.sup.3- or PO.sub.4(R').sub.2 and R.sub.1 and R.sub.2 are
the same or different and are hydrogen or a 1 to 20 carbon
aliphatic group with the proviso that when one of R.sub.1 or
R.sub.2 is hydrogen the other is the aliphatic group. Most
preferably, M is --PO.sub.4.sup.3- and R.sub.1 and R.sub.2 are the
same or different and are hydrogen or a 1 to 20 carbon aliphatic
group with the proviso that when one of R.sub.1 or R.sub.2 is
hydrogen the other is the aliphatic group.
[0028] Diphenyl oxides with at least one hydrophobic group may be
prepared by any suitable method know in the art. Alkylated diphenyl
oxides may be sulfonated with any suitable sulfonating agent, such
as sulfur trioxide, mixtures of sulfur dioxide and sulfur trioxide,
chlorosulfonic acid, and the like by conventional procedures. The
resulting sulfonic acid can be neutralized with an alkali metal
hydroxide or carbonate, such as sodium carbonate or potassium
hydroxide, or by the use of any other suitable base conventionally
employed in the preparation of ammonium or alkali metal salts or
aryl sulfonic acids. Methods for preparing diphenyl oxide compounds
with at least one hydrophobic group are disclosed in U.S. Pat. No.
3,248,335 and U.S. Pat. No. 4,687,593 the entire disclosures of
which are hereby incorporated herein by reference. The disclosures
of both patents provide sufficient information to a person of skill
in the art to make any of the diphenyl oxide compounds of the
present invention.
[0029] Diphenyl oxides within the scope of the present invention
also may be obtained commercially. Commercially available solutions
containing alkylated diphenyl oxide sulfonate surfactants are
DOWFAX.RTM. C10L, DOWFAX.RTM. 8390 and DOWFAX.RTM. 8390A.
("DOWFAX.RTM. is a registered trademark of The Dow chemical Company
for its brand of these anionic surfactants.). The alkyl group
R.sub.1 and R.sub.2 is predominantly a hexadecyl (C.sub.16) group
in the 8390 and 8390A composition. DOWFAX.RTM. 8390A contains about
25% of the acid form of the surfactant, that is, in which X is
hydrogen. DOWFAX.RTM. 8390 contains about 35% of sodium salts of
the surfactant, that is, in which X is sodium. DOWFAX.RTM. 8390A
solution is fully or partially neutralized with ammonium
hydroxide.
[0030] Antifoam agents used in combination with the diphenyl oxides
include, but are not limited to, silicones including, but not
limited to, polysiloxanes, petroleum hydrocarbons, acetylenics,
vinyl polymers and polyalkoxylates. Such antifoam agents are highly
suitable for reducing or inhibiting foam formation when combined
with one or more diphenyl oxides when developing or stripping
photoresist residue from a substrate.
[0031] Examples of suitable silicones include, but are not limited
to, siloxanes such as polydimethyl siloxane (TP305 manufactured by
OSI Specialties), polyalkylene oxide methyl siloxane and a mixture
of polyglycol and siloxane. Also included are polysiloxane mixed
with polyglycols.
[0032] The major class of compounds found to provide highly
suitable cosurfactants with silicone compounds are water-soluble
polyethylene glycols having a molecular weight of 150 to 1000,
polypropylene glycol of the formula HO(CH.sub.3CHCH.sub.2O).sub.pH
wherein p is a number from 2 to 18, mixtures of polyethylene glycol
and polypropylene glycol (Synalox.RTM.) and mono and di
C.sub.1-C.sub.6 alkyl ethers and esters of ethylene glycol and
propylene glycol having the structural formulas R.sub.3(Y).sub.rOH,
R.sub.4 (Y).sub.rOH, R.sub.3(Y).sub.rOR.sub.3 and
R.sub.4(Y).sub.rOR.sub.4 wherein R.sub.3 is C.sub.1-C.sub.6 alkyl
group, R.sub.4 is C.sub.2-C.sub.4 acyl group, Y is
(OCH.sub.2CH.sub.2) or (OCH.sub.2(CH.sub.3)CH) and r is a number
from 1 to 4, diethylene glycol, triethylene glycol, an alkyl
lactate, wherein the alkyl group has 1 to 6 carbon atoms, 1
methoxy-2-propanol, 1 methoxy-3-propanol, and 1 methoxy 2-, 3- or
4-butanol.
[0033] Examples of suitable petroleum hydrocarbons include, but are
not limited to, alkanes and alkenes that have a flash point not
lower than about 65.degree. C., preferably not lower than about
90.degree. C. (Tag closed cup test), an initial boiling point not
lower than about 130.degree. C., and a solidification point not
above about 20.degree. C. In general, the preferred alkanes that
meet these criteria will be aliphatic hydrocarbons having the
generic formula C.sub.mH.sub.2m+2, in which m is from about 10 to
about 18 (i.e., the aliphatic series decane through octadecane).
Although single compounds are suitable for use in this invention,
most commercially available solvents that meet the boiling point
and distillation point criteria will be mixtures of aliphatic
hydrocarbons. Examples of suitable commercially available materials
are Paraffin F.RTM. (Exxon), Isopar.RTM. (Exxon), Varsol.RTM.
(Exxon), Norpar.RTM. (Exxon), 95% dodecane, and kerosene,
especially deodorized kerosene. Byks.RTM. which is a petroleum
hydrocarbon obtainable by Byk-Chemie also may be employed.
[0034] Kerosene is a mixture of petroleum hydrocarbons comprising
principally alkanes having from 10 to 16 carbon atoms per molecule.
It constitutes the fifth fraction in the distillation of petroleum,
being collected after the petroleum ethers and before the oils.
Although kerosene is comprised mainly of alkanes, a typical
kerosene also includes alkyl derivatives of benzene and
naphthalene. Kerosene particularly suitable for use in this
invention is deodorized and decolorized by washing with sulfuric
acid followed by treatment with sodium plumbite solution and
sulfur.
[0035] The use of alkanes containing substantial molecular species
with carbon chain lengths over about 18 is undesirable because of a
tendency to distribute poorly in aqueous medium. In general, any
alkane/alkene mixture should be freely pourable at 20.degree. C. In
general, suitable alkanes will have a density at 20.degree. C. less
than about 0.8.
[0036] Examples of suitable acetylenics include, but are not
limited to, compounds having the general formula
R.sub.5--C.ident.C--R.sub.6 (II) where R.sub.5 and R.sub.6 are the
same or different and are alkyl or aryl. Examples include, but are
not limited to, R.sub.5 and R.sub.6 are C.sub.1-C.sub.10 alkyl.
Commercially available acetylenics include SURFYNOLS.RTM.
obtainable from Air Products.
[0037] Examples of suitable vinyl polymers include, but are not
limited to, materials having C.dbd.C moieties and other useful
copolymerizable monomer components for use in the present invention
can be selected from a variety of unsaturated materials as
illustrated in the following list. The material may be selected
from the group consisting of acrylonitrile, methacrylonitrile,
methyl acrylate, methyl methacrylate, vinyl acetate, vinyl methyl
ketone, isopropenyl methyl ketone, acrylic acid, methacrylic acid,
acrylamide, methacrylamide, n-amyl methacrylate, styrene,
m-chlorostyrene, o-chlorostyrene, p-chlorostyrene, n-decyl
methacrylate, N,N-diallylmelamine, N,N-di-n-butylacrylamide,
di-n-butyl itaconate, di-n-butyl maleate, diethylaminoethyl
methacrylate, diethyleneglycol monovinyl ether, diethyl fumarate,
diethyl itaconate, diethyl vinylphosphonate, vinylphosphonic acid,
diisobutyl maleate, diisopropyl itaconate, diisopropyl maleate,
dimethyl fumarate, dimethyl itaconate, dimethyl maleate, di-n-nonyl
fumarate, di-n-nonyl maleate, dioctyl fumarate, di-n-octyl
itaconate, di-n-propyl itaconate, n-dodecyl vinyl ether, ethyl acid
fumarate, ethyl acid maleate, ethyl acrylate, ethyl cinnamate,
N-ethylmethacrylamide, ethyl methacrylate, ethyl vinyl ether,
5-ethyl-2-vinylpyridine, 5-ethyl-2-vinylpyridine 1-oxide, glycidyl
acrylate, glycidyl methacrylate, n-hexyl methacrylate,
2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, isobutyl
methacrylate, isobutyl vinyl ether, isoprene, isopropyl
methacrylate, isopropyl vinyl ether, itaconic acid, lauryl
methacrylate, methacrylamide, methacrylic acid, methacrylonitrile,
N-methylolacrylamide, N-methylolmethacrylamide,
N-alkoxymethylacrylamide, N-alkoxymethylmethaerylamide,
N-butoxymethylmethacrylamide, N-vinyl-caprolactam, methyl acrylate,
N-methylmethacrylamide, m-methylstyrene, o-methylstyrene,
p-methylstyrene, 2-methyl-5-vinylpyridine, n-propyl methacrylate,
sodium p-styrene sulfonate, stearyl methacrylate, styrene,
p-styrene sulfonic acid, p-styrenesulfonamide, vinyl bromide,
9-vinylcarbazole, vinyl chloride, vinylidene chloride,
1-vinylnaphthalene, 2-vinylnaphthalene, 2-vinylpyridine,
4-vinylpyridine, 2-vinylpyridine N-oxide, 4-vinylpyrimidine, and
N-vinylpyrrolidone. Mixtures of these materials may also be
employed.
[0038] Polyalkoxylates such as the Pluronics.RTM. and
Tetronics.RTM. from BASF may be employed as antifoams in the
present invention. Examples of suitable polyalkoxylates include,
but are not limited to, nonionic surfactants such as block
copolymers of polyoxypropylene-polyoxyethylene or ethylene oxide
and propylene oxide adducts of fatty alcohols such as
poly(oxyalkylated) alcohols which are represented by the
formula:
R.sub.7--(PO).sub.x-(EO).sub.yHPO).sub.z--H (III)
[0039] wherein
[0040] R.sub.7 is a linear, alkyl hydrocarbon having an average of
from about 7 to about 10 carbon atoms;
[0041] PO stands for propylene oxide groups 2
[0042] and
[0043] EO stands for ethylene oxide groups
(CH.sub.2--CH.sub.2--O);
[0044] x is an integer having a value from 1 to 6;
[0045] y is an integer having a value from 4 to 15; and
[0046] z is an integer having a value from 4 to 25.
[0047] In addition to the diphenyl oxides described above, the
cleaning composition may optionally contain auxiliary surfactants
and a solvent to assist in removing photoresist residue. Examples
of such auxiliary surfactants include, but are not limited to,
quaternary ammonium salts, water soluble or water dispersable
polymers other than the polymers described above, or surfactants
having the following general formula: 3
[0048] where R.sup.1 is a (C.sub.1 to C.sub.6) alky or (C.sub.6 to
C.sub.14) aryl group, G is a carboxyl, sulfonyl, or phosphonyl,
M.sub.1 is a charge-balancing cation such as sodium, potassium, or
ammonium, and u is an integer of from 1 to 200, preferably an
integer of from 2 to 200. When u is an integer of 2 or greater, G
may be the same or different. An example of such surfactants is
Newkalgen.RTM. TX-C (obtainable from Takemoto Oil and Fat Co.)
which is a phenolic sulfonyl salt. Other suitable auxiliary
surfactants include, but are not limited to, amine alkoxylates,
fatty alcohol alkoxylates, fatty sorbitan esters and their
alkoxylates, amphoteric surfactants, and the like.
[0049] Residue reducing-antifoam compositions of the present
invention reduce or inhibit residue and scum formation from
photolithographic compositions as well as reducing or inhibiting
foaming during developing and stripping processes in the
manufacture of printed wiring boards. Diphenyl oxides of the
present invention may be employed in amounts of from about 20% by
weight to about 95% by weight of the cleaning composition.
Preferably, diphenyl oxides are employed at concentration ranges of
from about 50% by weight to about 85% by weight of the cleaning
composition. Antifoam agents are employed from about 5% by weight
to about 80% by weight of the cleaning composition. Preferably,
antifoam agents are employed from about 10% by weight to about 50%
by weight of the cleaning composition. Auxiliary surfactants may be
employed in amounts of up to about 75% by weight of the
composition. Optionally, the balance of the cleaning composition
may be solvent. Water is a preferred solvent, however organic
solvents such as alcohols and ketones and the like also may be
employed. Any suitable organic solvent may be employed. A preferred
residue reducing-antifoam composition of the present invention
consists essentially of a diphenyl oxide, an auxiliary surfactant,
an antifoam agent and a solvent. A most preferred residue
reducing-antifoam composition consists of a diphenyl oxide and an
antifoam agent.
[0050] Surprisingly, the compositions of the present invention
prevent residue and scum formation from photolithographic
compositions from both positive-working (both liquid and dry film)
and negative-working photoresist (both liquid and dry film).
Built-up residue and scum on a substrate or in solutions are
difficult to remove with conventional cleaners because of the types
of chemicals used in photoresists, in particular the new generation
of photoresists which contain many compounds of a hydrophobic
aromatic character. Thus, the compositions of the present invention
prevent or reduce the amount of cleaning after processing printed
wiring boards.
[0051] Additionally, the compositions of the present invention
prevent residue and scum formation deposited by secondary
photoresists. Such photoresist may be employed in soldermasks.
Residue and scum are deposited on a substate as a result of
component separation in the soldermask. Such component separation
may be exacerbated when an improperly balanced soldermask developer
solution, i.e. improper developing conditions and/or soldermask
developer solution chemistry, contact the soldermask. Residue and
scum build-up on such substrates as printed wiring boards and
soldermask developer apparatus. Built-up residue and scum may
appear as a bright green coating on developer apparatus surfaces.
The bright green coating comes from an oily layer of water
insoluble material from the secondary photoresist in which pigment
from the photoresist concentrates. Generally, there is a higher
level of hydrophobic aromatic compounds in secondary photoresist
formulations than primary photoresist formulations.
[0052] Residues and scum from photoresist include, but are not
limited to, such chemical materials as hydrophobic aromatic
materials such as photoinitiators, thermoinitiators, dyes, acrylic,
and methacrylic monomers. Photoinitiators such as photoacid
generators, photobase generators or free-radical generators once
built-up as residue or scum on a substrate are more difficult to
remove than many of the other components that compose the residue
and scum. Such materials do not readily re-emulsify once they
build-up on a substrate such as photolithographic manufacturing
apparatus.
[0053] Photoresists vary in composition. Generally, a photoresist
composition may compose from about 20% to about 90% by weight of a
binder polymer, about 15% to about 50% by weight of
.alpha.,.beta.-ethylenically unsaturated compounds (cross-linkers)
such as monomers and short-chain oligomers and from about 0.1% to
about 25% by weight of a photoinitiator or photoinitiator chemical
system. Liquid photoresists may contain a larger concentration of
binder in relation to monomers or short-chain oligomers whereas dry
film may contain larger concentrations of monomers or short-chain
oligomers. Such concentrations are known in the art. Other
components employed in a photoresist that may contribute to residue
and scum build-up are discussed below. Built-up residue and scum
from liquid photoresist appears as crystalline material on a
substrate. Such built-up residue and scum may be removed with
cleaning compositions containing a cleaning compound of formula I
in a concentration range of from about 0.1% by weight to about 35%
by weight, preferably from about 0.2% by weight to about 0.8% by
weight of the cleaning composition or cleaning bath. Built-up
residue from dry film as well as secondary photoresists may be
removed from a substrate at concentrations of a compound of formula
I of from greater than 1.0% by weight to about 35% by weight of the
cleaning composition or bath. Preferably, a compound of formula I
may be employed at a concentration of from about 2% to about 8% by
weight of the cleaning composition to remove built-up residue and
scum generated from dry film or secondary photoresists.
[0054] Examples of components that compose a photoresist that may
cause undesirable built-up residue or scum on a substrate include,
but are not limited to, polymeric binders such as those containing
as polymerized units one or more ethylenically or acetylenically
unsaturated monomers. Examples of monomers include, but are not
limited to: (meth)acrylic acid, (meth)acrylamides, alkyl
(meth)acrylates, alkenyl (meth)acrylates, aromatic (meth)acrylates,
vinyl aromatic monomers, nitrogen-containing compounds and their
thio-analogs, substituted ethylene monomers, cyclic olefins,
substituted cyclic olefins, and the like. Preferred monomers
include (meth)acrylic acid, alkyl (meth)acrylates and vinyl
aromatic monomers. Such polymeric binders may be homopolymers or
copolymers and preferably copolymers.
[0055] Cross-linkers that may cause residue or scum build-up
include di-, tri-, tetra-, or higher multi-functional ethylenically
unsaturated monomers. Examples of such cross-linkers include, but
are not limited to: trivinylbenzene, divinyltoluene,
divinylpyridine, divinylnaphthalene and divinylxylene; and such as
ethyleneglycol diacrylate, trimethylolpropane triacrylate
("TMPTA"), diethyleneglycol divinyl ether, trivinylcyclohexane,
allyl methacrylate ("ALMA"), ethyleneglycol dimethacrylate
("EGDMA"), diethyleneglycol dimethacrylate ("DEGDMA"),
propyleneglycol dimethacrylate, propyleneglycol diacrylate,
trimethylolpropane trimethacrylate ("TMPTMA"), divinyl benzene
("DVB"), glycidyl methacrylate, 2,2-dimethylpropane 1,3 diacrylate,
1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate,
1,4-butanediol diacrylate, diethylene glycol diacrylate, diethylene
glycol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol
dimethacrylate, tripropylene glycol diacrylate, triethylene glycol
dimethacrylate, tetraethylene glycol diacrylate, polyethylene
glycol 200 diacrylate, tetraethylene glycol dimethacrylate,
polyethylene glycol dimethacrylate, ethoxylated bisphenol A
diacrylate, ethoxylated bisphenol A dimethacrylate, polyethylene
glycol 600 dimethacrylate, poly(butanediol) diacrylate,
pentaerythritol triacrylate, trimethylolpropane triethoxy
triacrylate, glyceryl propoxy triacrylate, pentaerythritol
tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol
monohydroxypentaacrylate, ethoxylated diacrylates, ethoxylated
triacrylates such as ethoxylated TMPTA and ethoxylated TMPTMA,
ethoxylated tetraacrylates, divinyl silane, trivinyl silane,
dimethyl divinyl silane, divinyl methyl silane, methyl trivinyl
silane, diphenyl divinyl silane, divinyl phenyl silane, trivinyl
phenyl silane, divinyl methyl phenyl silane, tetravinyl silane,
dimethyl vinyl disiloxane, poly(methyl vinyl siloxane), poly(vinyl
hydro siloxane), poly (phenyl vinyl siloxane), glycosyl ureas
including di-, tri- and tetra-glycosyl ureas, epoxies and mixtures
thereof. Such cross-linking agents are generally commercially
available.
[0056] Photoimageable compositions contain one or more photoactive
components. The photoactive components may be photoacid generators,
photobase generators or free-radical generators. Such photoactive
components are a major source of scum formations.
[0057] Example of photoacid generators include halogenated
triazines, onium salts, sulfonated esters, halogenated sulfonyloxy
dicarboximides, diazodisulfones, .alpha.-cyanooxyaminesulfonates,
imidesulfonates, ketodiazosulfones, sulfonyldiazoesters,
1,2-di(arylsulfonyl)hydrazines and the like.
[0058] Free-radical generators include, but are not limited to,
n-phenylglycine, aromatic ketones such as benzophenone,
N,N'-tetramethyl-4,4'-diaminobenzophenone [Michler's ketone],
N,N'-tetraethyl-4,4'-diaminobenzophenone,
4-methoxy-4'-dimethylaminobenzo- phenone,
3,3'-dimethyl-4-methoxybenzophenone, p,p'-bis(dimethylamino)benzo-
phenone, p,p'-bis(diethylamino)-benzophenone, anthraquinone,
2-ethylanthraquinone, naphthaquinone and phenanthraquinone,
benzoins such as benzoin, benzoinmethylether, benzoinethylether,
benzoinisopropylether, benzoin-n-butylether, benzoin-phenylether,
methylbenzoin and ethybenzoin, benzyl derivatives such as dibenzyl,
benzyldiphenyldisulfide and benzyldimethylketal, acridine
derivatives such as 9-phenylacridine and
1,7-bis(9-acridinyl)heptane, thioxanthones such as
2-chlorothioxanthone, 2-methylthioxanthone,
2,4-diethylthioxanthone, 2,4-dimethylthioxanthone and
2-isopropylthioxanthone, acetophenones such as
1,1-dichloroacetophenone, p-t-butyldichloro-acetophenone,
2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, and
2,2-dichloro-4-phenoxyacetophenone, 2,4,5-triarylimidazole dimers
such as 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer,
2-(o-chlorophenyl)-4,5-di- (m-methoxyphenyl imidazole dimer,
2-(o-fluorophenyl)-4,5-diphenylimidazole dimer,
2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer,
2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer,
2,4-di(p-methoxyphenyl)-- 5-phenylimidazole dimer,
2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer and
2-(p-methylmercaptophenyl)-4,5-diphenylimidazole dimer, and the
like. Though, not a free-radical generator, triphenylphosphine may
be included in the photoactive chemical system as a catalyst.
[0059] Optional additives that may be used in photoimageable
compositions and that cause residue and scum include, but are not
limited to: anti-striation agents, plasticizers, speed enhancers,
fillers, dyes, film forming agents, non-polymerizable organic acids
and the like. Suitable plasticizers include esters such as
dibenzoate esters. Non-polymerizable organic acids may also be
added to photoresist compositions. Such organic acids are
substantially non-polymerizable with the polymeric binders,
optional cross-linking agents or both. A wide variety of organic
acids may suitably be added to photoresist compositions. Suitable
organic acids include, but are not limited to, alkanecarboxylic
acids and arylcarboxylic acids, sulfonic acids such as
alkanesulfonic acids and arylsulfonic acids, phosphonic acids such
as alkylphosphonic acids and arylphosphonic acids, and the like.
Exemplary carboxylic acids include, but are not limited to,
(C.sub.1-C.sub.12)alkylcarboxylic acids,
(C.sub.1-C.sub.12)alkyldicarboxylic acids,
(C.sub.1-C.sub.12)alkyltricarb- oxylic acids, substituted
(C.sub.1-C.sub.12)alkylcarboxylic acids, substituted
(C.sub.1-C.sub.12)alkyldicarboxylic acids, substituted
(C.sub.1-C.sub.12)alkyltricarboxylic acids, amine carboxylic acids
such as ethylenediamine tetraacetic acid, arylcarboxylic acids such
as arylmonocarboxylic acids, aryldicarboxylic acids and
aryltricarboxylic acids, and substituted arylcarboxylic acids.
Preferred organic acids include formic acid, acetic acid, propionic
acid, oxalic acid, malonic acid, succinic acid, glutaric acid,
adipic acid, glycolic acid, lactic acid, tartaric acid, citric acid
or malic acid, ethylenediamine tetraacetic acid, phthalic acid,
benzene tricarboxylic acid, salicilic acid, cyclohexanecarboxylic
acid, 1,4-cyclohexanedicarboxylic acid and sebacic acid.
[0060] A wide variety of photoresist strip enhancers also may be
used in photoresists. Such strip enhancers may contribute to
residue and scum build-up. Examples of photoresist strip enhancers
are compounds containing one or more trihalomethyl-substituents in
an alpha position relative to a group capable of stabilizing a
negative charge.
[0061] Advantageously, the cleaning composition and method of the
present invention provides for a method of inhibiting residue
formation and foaming. The cleaning composition is highly effective
for removing built-up organic residue and organic scum of
photoresist from a substrate such as equipment used in
manufacturing printed wiring boards. The cleaning composition and
method may remove up to 98% by weight of undesirable built-up
organic residue and scum from a substrate. The cleaning composition
and method of the present invention eliminates the use of cleaners
that may further aggravate contamination of equipment and printed
wiring boards. The present invention provides for a more efficient
manufacturing process since less time is involved in cleaning
equipment, and less waste is generated thus providing for a more
environmentally friendly cleaning composition and method.
Additionally, the cleaning compositions of the present invention
may clean built-up residue and scum from a substrate at lower
temperatures then conventional cleaners. Accordingly, the cleaning
composition and method of the present invention is more energy
efficient.
[0062] The following Example is intended to further illustrate the
present invention and are not intended to limit the scope of the
invention.
EXAMPLE
[0063] Test Photoresist: The test photoresist used in the
evaluations was composed of about 50% acrylic polymer, about 37% of
acrylic monomers, about 10% of photoinitiators, and the remainder
of the composition included dyes, stabilizers and flow control
agents in conventional amounts.
[0064] Residue Testing in Developer Solution: 200 ml of an aqueous
solution of 1 wt. % alkali carbonate was placed in a modified
gas-washing bottle. Optionally, antifoam was put into the solution.
23 mil*ft.sup.2/gal of uncured test photoresist was dissolved in
this solution. The mixture was aerated with dry air at 1000 cc/min
for 5 hrs. through a submerged glass frit. The solution temperature
during aeration was 30.degree. C. (86.degree. F.). It was allowed
to stand overnight at ambient temperature. The solution was then
filtered through a 3 micron filter and the retained residue was
dried and weighed.
1TABLE 1 Amount of Residue Generated in a Photoresist-Loaded
Developer Solution Recommended Amount of Residue Percent Residue
Antifoam Conc. (ppm) (mg) Change No Antifoam (control) 0 28.4 0.0
Commercial Antifoam A 500 75.4 +165.5 (polyalkylene oxide polyol)
Commercial Antifoam B 250 >19.4* X (mineral oil) Commercial
Antifoam C 125 29.5 +3.9 (polysiloxane) DOWFAX C10L/Byk-028 = 8/2
1775 21.2 -25.3 ppm = wt. antifoam in grams/vol. developer in
milliliters *Note: For Commercial Antifoam B (mineral oil), the
residue was very sticky and could not be easily removed from the
test container. As a result the actual amount of the residue should
be considerably higher.
[0065] Foam Testing in Developer Solution: 30 ml of aqueous
solutions of 1 wt. % alkali carbonate was placed in a 250 mL
graduated cylinder. Optionally, antifoam was put into the solution.
23 mil*ft.sup.2/gal of uncured test photoresist was dissolved in
this solution. The mixture was aerated with dry air at 1000 cc/min
through a submerged glass frit. The foam height at 1, 2, 4, and 10
minutes was measured using the volume markings on the graduated
cylinder. The experiment was carried out at ambient temperature.
Less than or equal to 100 mL of foam was considered acceptable.
2TABLE 2 Amount of Foam Generated in a Photoresist-Loaded Developer
Solution Avg. Recommended Percent Antifoam Conc. Foam (ppm) 1 min.
2 min. 4 min. 10 min. Change No Antifoam (control) 0 166 171 166
163 0.0 Commercial Antifoam A 500 230 205 195 200 +24.6
(polyalkylene oxide polyol) Commercial Antifoam B 250 48 50 52 60
-68.4 (mineral oil) Commercial Antifoam C 125 88 92 97 112 -41.6
(polysiloxane) DOWFAX C10L/Byk-028 = 8/2 1775 74 78 78 82 -53.2 ppm
= wt. antifoam in grams/vol. developer in milliliters
[0066] Foam Testing in Stripper Solution: 30 ml of aqueous
solutions of 3 wt. % sodium hydroxide was placed in a 250 mL
graduated cylinder. Optionally, antifoam was put into the solution.
23 mil*ft.sup.2/gal of cured test photoresist (65 mJ/cm.sup.2,
copper step 9 on a Stouffer 21 step wedge) was added to the
solution and stirred for 2 hrs. at 54.degree. C. (130.degree. F.).
The undissolved solids were filtered from the solution. The mixture
was aerated with dry air at 1000 cc/min through a submerged glass
frit. The foam height at 1, 2, 4, and 10 minutes was measured using
the volume markings on the graduated cylinder. The experiment was
carried out at 54.degree. C. (130.degree. F.). Less than or equal
to 100 mL of foam was considered acceptable.
3TABLE 3 Amount of Foam Generated in a Photoresist-Loaded Stripper
Solution Avg. Recommended Percent Antifoam Conc. Foam (ppm) 1 min.
2 min. 4 min. 10 min. Change No Antifoam (control) 0 237 230 207
207 0.0 Commercial Antifoam A 500 125 130 136 124 -41.5
(polyalkylene oxide polyol) Commercial Antifoam B 250 71 77 95 104
-60.6 (mineral oil) Commercial Antifoam C 125 179 181 187 190 -16.3
(polysiloxane) DOWFAX C10L/Byk-028 = 8/2 1775 91 94 96 99 -56.9 ppm
= wt. antifoam in grams/vol. stripper in milliliters
[0067] The DOWFAX C10L/Byk-028 mixture achieves the best overall
properties in the developer and stripper as shown in Table 4.
4TABLE 4 Summary of Antifoam Properties in Photoresist-Loaded
Developer and Stripper Solutions Recommended Percent Residue Avg.
Percent Avg. Percent Antifoam Conc. Change in Foam Change in Foam
Change in (ppm) Developer Developer Stripper Commercial Antifoam A
500 +165.5 +24.6 -41.5 (polyalkylene oxide polyol) Commercial
Antifoam B 250 Very sticky -68.4 -60.6 (mineral oil) Commercial
Antifoam C 125 +3.9 -41.6 -16.3 (polysiloxane) DOWFAX C10L/Byk-028
= 8/2 1775 -25.3 -53.2 -56.9 ppm = wt. antifoam in grams/vol.
developer or stripper in milliliters
[0068] Antifoam A did not perform well in the developer and
stripper. Antifoam B worked well to control foam in the developer
and stripper, but it resulted in very sticky residues in the
developer. Antifoam C suppressed foam well in the developer, but it
contributed to residues in the developer and only marginally
lessened the foam in the stripper.
[0069] Equipment Parts Compatibility Testing: An aqueous solution
of 1 wt. % alkali carbonate was placed in a container. Optionally,
2660 ppm of the novel antifoam (DOWFAX CIOL/Byk-028=8/2 by weight)
was put into the solution to exaggerate the presence of the
antifoam in the system. 23 mil*ft.sup.2/gal of uncured test resist
was dissolved in this solution. Common materials used in the
construction of photoresist processing equipment were soaked in
this solution at 30.degree. C. (86.degree. F.) for 3 days.
[0070] Compatibility of the parts with the cleaning composition was
determined via the following tests:
[0071] Percent Weight Change: to determine whether the part was
swelling or dissolving (>5% considered a failure)
[0072] Visual and Tactile Examination: to determine whether the
physical properties (e.g. appearance, hardness, elongation, etc.)
of the part were changing compared to a control part that was not
soaked
5TABLE 5 Percent Weight Change After Soaking % Weight Change %
Weight Change with No Additive with DOWFAX (control) C10L/Byk-028 =
8/2 Polyvinylchloride 0 0 Polyethylene 0 0 Polypropylene 0 0 Teflon
0 0 Tygon +0.1 +0.1 Silicone Rubber +0.3 +0.4 Nitrile Rubber +1.3
-1.0 Buna-N Rubber +1.1 +1.4 Viton +0.7 +0.8 EPDM Rubber 0 0
Neoprene Rubber +0.7 +1.2 (30A) Neoprene Rubber +0.3 +0.7 (80A)
Precision Brass 0, blackened 0, blackened Extruded Brass 0,
blackened 0, blackened Cast Brass 0, blackened 0, blackened 304
Stainless Steel 0 0 316 Stainless Steel 0 0 Titanium 0 0
[0073] Visual and Tactile Examination: Other than the swelling (see
weight change measurements), there were no other obvious changes
observed from visual and tactile examinations of the parts with the
exception of the brass parts in which the control and the
experimental sample both showed blackening of the parts.
[0074] In summary, the main advantages of the residue-reducing
antifoam were:
[0075] Effective control of foam in the developer and stripper
[0076] Minimization of residue formation in the developer
[0077] Compatibility with common equipment parts
* * * * *