U.S. patent application number 10/008656 was filed with the patent office on 2002-05-23 for method for synthesizing polymeric azo dyes.
Invention is credited to Ding, Shuji, Gonzalez, Eleazar B., Khanna, Dinesh N., Shan, Jianhui.
Application Number | 20020061473 10/008656 |
Document ID | / |
Family ID | 23636201 |
Filed Date | 2002-05-23 |
United States Patent
Application |
20020061473 |
Kind Code |
A1 |
Shan, Jianhui ; et
al. |
May 23, 2002 |
Method for synthesizing polymeric azo dyes
Abstract
A method of coupling a diazonium salt with an organic polymer
comprising, on order, the steps of: providing a polymer in one
liquid phase; providing a diazonium salt in a separate liquid
phase; contacting the separate phases, and thereby reacting the
polymer and the diazonium salt.
Inventors: |
Shan, Jianhui; (High Bridge,
NJ) ; Ding, Shuji; (Branchburg, NJ) ;
Gonzalez, Eleazar B.; (Bloomfield, NJ) ; Khanna,
Dinesh N.; (Flemington, NJ) |
Correspondence
Address: |
Clariant Corporation
70 Meister Avenue
Somerville
NJ
08876
US
|
Family ID: |
23636201 |
Appl. No.: |
10/008656 |
Filed: |
November 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10008656 |
Nov 9, 2001 |
|
|
|
09413181 |
Oct 6, 1999 |
|
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Current U.S.
Class: |
430/326 ;
430/270.1; 430/330; 430/512 |
Current CPC
Class: |
G03F 7/021 20130101;
G03F 7/091 20130101; C09B 69/106 20130101 |
Class at
Publication: |
430/326 ;
430/270.1; 430/512; 430/330 |
International
Class: |
G03F 007/30; G03F
007/004 |
Claims
What is claimed is:
1. A process for producing an antireflective coating composition
suitable for use in photolithography, comprising, in the following
order: a) providing an azo coupled polymer produced by a method
comprising: i) dissolving an organic polymer having a weight
average molecular weight ranging from about 500 to 2,000,000 in a
solvent, thereby providing one liquid phase; ii) providing a
diazonium salt in another solvent, thereby providing a separate
liquid phase; and iii) contacting the diazonium salt liquid phase
and the organic polymer liquid phase, for a period of time that is
greater than or equal to the minimum reaction time required to
react said diazonium salt with said organic polymer; wherein said
method further comprises intimately mixing the separate phases
using an in-line mixing unit selected from: a static tubular
reactor and a dynamic mixer; and b) dissolving the azo coupled
polymer from step a) in a solvent, and thereby producing an
antireflective coating composition.
2. The process of claim 1, wherein said polymer has a weight
average molecular weight ranging from about 3000 to 1,000,000.
3. The process of claim 1, wherein said polymer has a weight
average molecular weight from about 5000 to 80,000.
4. The process of claim 1, wherein said synthetic organic polymer
contains at least one of the following moieties: 11where, R.sub.1
is selected from a substituted or unsubstituted aromatic group, a
substituted or unsubstituted heterocyclic group, or a group having
the structure: 12where, A.sub.1 and A.sub.2 are independently
selected from the group: halo, --CN, --COZ, --COOZ, --CONHZ,
--CONZ.sub.2, --SO.sub.2NHZ, --SO.sub.2NZ.sub.2, --SO.sub.2Z,
--SO.sub.2CF.sub.3, where Z is H, (C.sub.1-C.sub.10) alkyl,
(C.sub.1C.sub.10) hydroxyalkyl, (C.sub.1-C.sub.10) alkoxyl,
(C.sub.1-C.sub.10) fluoroalkyl, (C.sub.1-C.sub.10) epoxyalkyl,
(C.sub.1-C.sub.10) alkenyl, substituted or unsubstituted
carbocyclic, aromatic or heterocyclic group, or may be --COOM,
--SO.sub.3M, where M is alkali metal, ammonium, alkyl ammonium; or
A.sub.1 and A.sub.2 are combined to form a 3-10 membered
substituted or unsubstituted carbocyclic or heterocyclic ring
containing an .alpha.-carbonyl group said polymer optionally
further comprising one or more co-monomer moieties having a
structure: 13where, R.sub.6-R.sub.9 are independently either halo,
--O(CH.sub.2).sub.x--OH (where x=1-10),
O(CH.sub.2CH.sub.2).sub.y--OH, --(OCH.sub.2CH.sub.2).sub.Y--OH
(where y=0-10), --CN, Z, --OZ, --OCOZ, --COZ, --COOZ, --NHZ,
--NZ.sub.2--NHCOZ, --CONHZ, --CONZ.sub.2, SZ, --SO.sub.3Z,
--SO.sub.2NHZ, --SO.sub.2NZ.sub.2, --SO.sub.2Z, --SO.sub.2CF.sub.3,
where Z is H, (C.sub.1-C.sub.10) alkyl, (C.sub.1-C.sub.10)
hydroxyalkyl, (C.sub.1-C.sub.10) alkoxyl, (C.sub.1-C.sub.10)
fluoroalkyl, (C.sub.1-C.sub.10) epoxyalkyl, (C.sub.1-C.sub.10)
alkenyl, 3-10 membered substituted or unsubstituted carbocyclic or
heterocyclic group. , or R.sub.8 and R.sub.9 are combined to form a
3-10 membered carbocyclic or heterocyclic ring.
5. The process of claim 4, wherein said organic polymer
additionally comprises one or more moieties selected from (1):
14where, R.sub.1'-R.sub.3'and R.sub.4 are independently either
halo, nitro, --O(CH.sub.2).sub.x--OH, --O(CH.sub.2CH.sub.2).sub.xOH
(where x=1-10), --(OCH.sub.2CH.sub.2).sub.y--OH (where
y=0-10),--CN, Z, --OZ, --OCOZ, --COZ, --COOZ, --NHZ, --NZ.sub.2,
--NHCOZ, --CONHZ, --NZCOZ, --CONZ.sub.2, SZ, --SO.sub.3Z,
--SO.sub.2NHZ, --SO.sub.2NZ.sub.2, --SO.sub.2Z, --SO.sub.2CF.sub.3,
where Z is H, (C.sub.1-C.sub.10) alkyl, (C.sub.1-C.sub.10)
hydroxyalkyl, (C.sub.1-C.sub.10) alkoxyl, (C.sub.1-C.sub.10)
fluoroalkyl, (C.sub.1-C.sub.10) epoxyalkyl, (C.sub.1-C.sub.10)
alkenyl, 3-10 membered substituted or unsubstituted carbocyclic or
heterocyclic group; or --COOM, --SO.sub.3M, where M is alkali
metal, ammonium, alkyl ammonium, or R.sub.1' and R.sub.2' are
combined to form a 3-10 membered carbocyclic or heterocyclic ring;
m=0-4; or (2): 15where, R.sub.1"-R.sub.3" are independently either
--Z, --OZ, --OCOZ, --COZ, --COOZ, --NHZ, --NZ.sub.2, --NHCOZ,
--CONHZ, --NZCOZ, --CONZ.sub.2, --SZ, --SO.sub.3Z, --SO.sub.2NHZ,
--SO.sub.2NZ.sub.2, SO.sub.2NZ.sub.2, --SO.sub.2Z,
--SO.sub.2CF.sub.3, where Z is H, (C.sub.1-C.sub.10) alkyl,
(C.sub.1-C.sub.10) hydroxyalkyl, (C.sub.1-C.sub.10) alkoxyl,
(C.sub.1-C.sub.10) fluoroalkyl, (C.sub.1-C.sub.10) epoxyalkyl,
(C.sub.1-C.sub.10) alkenyl, a substituted or unsubstituted
carbocyclic or heterocyclic ring, or R.sub.1" and R.sub.2" are
combined to form a 3-10 membered carbocyclic or heterocyclic ring,
A.sub.1 and A.sub.2 are independently selected from the group:
halo, --CN, --Z, --OCOZ, --COZ, --COOZ, NHZ, --NZ.sub.2, --NHCOZ,
--CONHZ, --NZCOZ, --CONZ.sub.2, --SZ, SO.sub.3Z, --SO.sub.2NHZ,
--SO.sub.2NZ.sub.2, --SO.sub.2Z, --SO.sub.2CF.sub.3, where Z is H,
(C.sub.1-C.sub.10) alkyl, (C.sub.1-C.sub.10) hydroxyalkyl,
(C.sub.1-C.sub.10) alkoxyl, (C.sub.1-C.sub.10) fluoroalkyl,
(C.sub.1-C.sub.10) epoxyalkyl, (C.sub.1-C.sub.10) alkenyl, 3-10
membered substituted or unsubstituted carbocyclic or heterocyclic
ring; or --COOM, --SO.sub.3M, where M is alkali metal, ammonium,
alkyl ammonium; or A.sub.1 and A.sub.2 are combined to form a 3-10
membered substituted or unsubstituted carbocyclic or heterocyclic
ring containing an .alpha.-carbonyl group.
6. The process of claim 1, wherein said diazonium salt has the
general structure: ArN.sub.2.sup.+X.sup.-where, Ar is an aryl group
X is selected from the group consisting of Cl, Br, --NO.sub.3,
--HSO.sub.4, --OCOCH.sub.3, and --OH.
7. The process of claim 1, wherein said diazonium salt is derived
from an aryl amino acid or an amino substituted aromatic
compound.
8. The process of claim 1, wherein said organic polymer is a vinyl
polymer.
9. A process of forming an image on a substrate comprising, in the
following order, the steps of: a) providing an antireflective
coating composition prepared by the method of claim 1; b) either
before or after coating a photoresist composition onto a suitable
substrate, coating the antireflective coating composition from step
a) onto said suitable substrate; c) heating the coated substrate
from step b), and thereby substantially removing the photoresist
solvent; d) imagewise exposing the photoresist composition; e)
developing the imagewise exposed photoresist composition.
10. The process of claim 9, wherein the photoresist composition
comprises a novolak resin, a photosensitive compound and a
solvent.
11. The process of claim 9, wherein the photoresist composition
comprises a substituted polyhydroxystyrene, a photoactive component
and a solvent.
12. The process of claim 9, wherein said synthetic organic polymer
contains one or more moieties selected from (1a): 16where,
R.sub.1'-R.sub.3' and R.sub.4 are independently either halo, nitro,
--O(CH.sub.2).sub.x--OH, --O(CH.sub.2CH.sub.2).sub.x--OH (where
x=1-10),, --(OCH.sub.2CH.sub.2).sub.y--OH (where y=0-10), --CN, Z,
--OZ, --OCOZ, --COZ, --COOZ, --NHZ, --NZ.sub.2, --NHCOZ, --CONHZ,
--NZCOZ, --CONZ.sub.2, SZ, --SO.sub.3Z, --SO.sub.2NHZ,
--SO.sub.2NZ.sub.2, --SO.sub.2Z, --SO.sub.2CF.sub.3, where Z is H,
(C.sub.1-C.sub.10) alkyl, (C.sub.1-C.sub.10) hydroxyalkyl,
(C.sub.1-C.sub.10) alkoxyl, (C.sub.1-C.sub.10) fluoroalkyl,
(C.sub.1-C.sub.10) epoxyalkyl, (C.sub.1-C.sub.10) alkenyl, 3-10
membered substituted or unsubstituted carbocyclic or heterocyclic
group, or --COOM, --SO.sub.3M, where M is alkali metal, ammonium,
alkyl ammonium, or R.sub.1' and R.sub.2' are combined to form a
3-10 membered carbocyclic or heterocyclic ring; m=0-4; or (2a):
17where, R.sub.1"-R.sub.3" are independently either Z, --OZ,
--OCOZ, --COZ, --COOZ, --NHZ, --NZ.sub.2,--NHCOZ, --CONHZ, --NZCOZ,
--CONZ.sub.2, SZ, --SO.sub.3Z, --SO.sub.2NHZ, --SO.sub.2NZ.sub.2,
--SO.sub.2Z, --SO.sub.2CF.sub.3, where Z is H, (C.sub.1-C.sub.10)
alkyl, (C.sub.1-C.sub.10) hydroxyalkyl, (C.sub.1-C.sub.10) alkoxyl,
(C.sub.1-C.sub.10) fluoroalkyl, (C.sub.1-C.sub.10) epoxyalkyl,
(C.sub.1-C.sub.10) alkenyl, 3-10 membered substituted or
unsubstituted heterocyclic group, or R.sub.1" and R.sub.2" combined
to form a 3-10 membered carbocyclic or heterocyclic group; X.sub.1
and X.sub.2 are independently --CO--, --OC(O)--, --CONH--O--, aryl,
--(CH.sub.2CH.sub.2O).sub.y-- (where y=0-10), (C.sub.1-C.sub.10)
alkyl, cyclohexyl, --S--, --S (C.sub.1-C.sub.10) alkyl , --O
(C.sub.1-C.sub.10) alkyl, --NH--, --N (C.sub.1-C.sub.10) alkyl, or
(C.sub.1-C.sub.10) hydroxyalkyl, n is independently 0-2, A.sub.1'
and A.sub.2' are independently selected from the group: halo, --CN,
--COZ, --COOZ, --CONHZ, --CONZ.sub.2, --SO.sub.2NHZ,
--SO.sub.2NZ.sub.2, --SO.sub.2Z, --SO.sub.2CF.sub.3, where Z is H,
(C.sub.1-C.sub.10) alkyl, (C.sub.1-C.sub.10) hydroxyalkyl,
(C.sub.1-C.sub.10) alkoxyl, (C.sub.1-C.sub.10) fluoroalkyl,
(C.sub.1-C.sub.10) epoxyalkyl, (C.sub.1-C.sub.10) alkenyl, a
substituted or unsubstituted carbocyclic, aromatic or heterocyclic
group, or may be --COOM, --SO.sub.3M, where M is alkali metal,
ammonium, alkyl ammonium; or A.sub.1 and A.sub.2 are combined to
form a 3-10 membered substituted or unsubstituted carbocyclic or
heterocyclic ring containing an .alpha.-carbonyl group; said
polymer optionally having one or more co-monomer moieties of the
formula: 18where, R.sub.6-R.sub.9 are independently either halo,
--O(CH.sub.2).sub.x--OH, --O(CH.sub.2CH.sub.2).sub.x--OH (where
x=1-10), --(OCH.sub.2CH.sub.2).sub.y--OH (where y=0-10), --CN, Z,
--OZ, --OCOZ, --COZ, --COOZ, --NHZ, --NZ.sub.2, --NHCOZ, --NZCOZ,
--CONHZ,--CONZ.sub.2, --SZ, --SO.sub.3Z, --SO.sub.2NHZ,
--SO.sub.2NZ.sub.2, --SO.sub.2Z, --SO.sub.2CF.sub.3, where Z is H,
(C.sub.1-C.sub.10) alkyl, (C.sub.1-C.sub.10) hydroxyalkyl,
(C.sub.1-C.sub.10) alkoxyl, (C.sub.1-C.sub.10) fluoroalkyl,
(C.sub.1-C.sub.10) epoxyalkyl, (C.sub.1-C.sub.10) alkenyl, 3-10
membered substituted or unsubstituted carbocyclic or heterocyclic
group, or --COOM,--SO.sub.3M, where M is alkali metal, ammonium,
alkyl ammonium, or R.sub.8 and R.sub.9 are combined to form a 3-10
membered carbocyclic or heterocyclic ring.
Description
[0001] This application is a divisional of U.S. application Ser.
No. 09/413,181 filed Oct. 6, 1999.
FIELD OF THE INVENTION
[0002] The present invention is directed to a method for
synthesizing polymeric azo dyes from a diazonium salt and a
polymer. The resulting polymeric azo dye compounds are useful in
antireflective coating compositions used in conjunction with
photoresist materials in producing microelectronic devices.
BACKGROUND OF THE INVENTION
[0003] It has been observed that many chemical manufacturing
processes, which provide acceptable results on a small or lab
scale, prove to be impractical or not economical, when an attempt
is made to adopt such processes to large-scale production. This is
true when preparing products via fast reaction(s) of two or more
compounds, which are contained in two or more separate phases. This
type of fast reaction requires rapid interfacial mixing (in both
the macro and micro scope) so that the reactant carried in one
phase makes immediate intimate contact with the reactant(s)
contained in the other phase(s). This enables an efficient and
substantially complete chemical reaction(s) to take place between
the reactants from all phases before possible competitive side
reactions take place. An example of such a reaction is the
azo-coupling of a polymer with a diazonium salt. When the diazonium
salt is reacted with the polymer under basic conditions the result
is the addition of an azo chromophore to the polymer, for example
as set forth below: 1
[0004] The diazonium salt may be soluble in one solvent, such as
water, producing a first phase. The polymer may be soluble in
another solvent, such as an organic solvent, which produces a
second separate phase. Such an azo coupling is capable of taking
place in a very short period of time, provided that there is
intimate mixing and sufficient contact between the reactants.
[0005] For the purposes of this application, a diazonium salt is
preferably derived from the diazotization of a corresponding amine,
preferably an aromatic amine, followed by a diazotizing reagent,
such as a nitrite salt, in the presence of an acid, such as HCl,
H.sub.2SO.sub.4, etc. Most diazonium salts are relatively stable in
acidic conditions at a cold temperature, from about 0.degree. C. to
about 15.degree. C. However, if the polymer solvent blend with
which the diazonium salt is reacted is basic, this can have an
adverse impact because the diazonium salt tends to decompose or
undergo side reactions, under such basic conditions, to form a
number of possible undesirable side products, for example as set
forth below: 2
[0006] Therefore, if the coupling reaction proceeds too slowly, the
diazonium salt has sufficient time to undergo such side reactions
or decomposition and the desired end product is not obtained.
[0007] When a chromophore, such as a diazonium salt is added to a
polymer the standard practice would be to use a reaction vessel
equipped with an agitator. In the lab when small vessels are
employed, this set up works well at high agitation speeds. As the
size of the vessel increases this set up loses its effectiveness,
resulting in progressively lower yields of the desired product. In
experimental settings with one-kilogram or smaller scale equipment,
some options may still be available to improve the overall mixing
in the vessel, such as the addition of more than one agitator or
additional agitation blades. However, in scaling up for large-scale
commercial production, these options may be too costly. Running the
reaction on a commercial scale without sufficient agitation results
in a very poor yield of the desired product and the generation of
undesired side products that are difficult and costly to remove.
Therefore, a need exists for a commercial-scale chemical process,
which favors the azo coupling of the polymer while at the same time
substantially reducing the competing reaction(s), such as the
decomposition of the diazonium salt.
[0008] U.S. Pat. No. 5,886,102 teaches that in the production of
antireflective coating compositions the "grafting of chromophore
units onto a preformed resin often provides a resin mixture of
polymers with varying percentages of chromophore. Such differing
quantities of chromophore units can compromise resolution of an
image patterned into an overcoated photoresist layer as the
chromophore differences may result in essentially random
reflections of exposure radiation." This reference goes on to
explain that "[g]rafting chromophore units onto at least some types
of preformed polymers may be quite difficult, or simply not
possible, particularly in larger scale productions. For example, it
can be particularly difficult to drive the reaction to completion
resulting in undesired products which must be removed from desired
materials."
[0009] An article in Chemical Engineering and Processing teaches
the synthesis of an azo dye via azo coupling of a diazonium salt
and a monomer. Specifically, the monomer, 1-naphthol, is reacted
with a diazotized sulphanilic acid solution using a static in-line
mixer. The static mixer is described as having no moving parts,
instead it consists of fixed elements that progressively reduce
radial gradients of concentration and temperature by combining,
stretching, splitting and recombining two separate but miscible
streams.
[0010] It should be noted that phase transfer catalysts are
available for the reaction of two or more reactants contained in
two or more separate phases. Such catalysts can be used in cases
where the purity of the final product is not a major concern.
However, in applications where even relatively low levels of
impurities pose a problem, a phase transfer catalyst is not an
option because it may be too costly and very difficult, if not
impossible, to separate such impurities from the desired final
product. This is especially true in applications where impurities
are required to be from less than 1 part per million to as low as
less than 20 parts per billion.
SUMMARY OF THE INVENTION
[0011] A method for coupling a diazonium salt with a polymer is
provided, which method comprises, in the following order, the steps
of: dissolving an organic polymer having a weight average molecular
weight ranging from about 500 to 2,000,000 in a solvent, and
thereby providing one liquid phase; providing a diazonium salt in
another solvent, and thereby providing a separate liquid phase;
contacting the diazonium salt with the organic polymer, preferably
by intimately mixing the separate phases, for a time at least equal
to the minimum reaction time required to react the diazonium salt
with the polymer ("minimum contact time"), and thereby reacting the
diazonium salt and the organic polymer for a period of time at
least equal to such minimum reaction time. Preferably the mole
ratio of organic polymer to diazonium salt is from 90:10 to 10:90,
more preferably from about 75:25 to 25:75, and most preferably from
60:40 to 40:60.
[0012] An in-line mixing unit capable of intimate mixing is
preferably provided, which (mixing unit) has a sufficient length to
provide a contact time that is greater than or equal to the minimum
reaction time. The inline mixing unit is preferably selected from a
static tubular reactor or a dynamic mixer. The organic polymer and
diazonium salt are preferably reacted in the in-line mixing unit,
which initially provides rapid interphase macro- and micro-mixing,
thus enabling an efficient and substantially complete chemical
reaction to take place, without any substantial side reactions or
decomposition of the diazonium salt.
[0013] A process for producing an antireflective coating
composition is also provided, which process comprises, in the
following order, the steps of: dissolving an organic polymer having
a weight average molecular weight ranging from about 500 to
2,000,000 in a solvent, and thereby providing one liquid phase;
providing a diazonium salt in another solvent and thereby providing
a separate liquid phase; contacting the diazonium salt in contact
with the organic polymer, preferably by intimately mixing the
separate phases, for a time at least equal to the minimum reaction
time required to react the diazonium salt with the polymer
("minimum contact time"), and thereby reacting the diazonium salt
and the organic polymer for a period of time at least equal to such
minimum reaction time. The organic polymer-diazonium salt reaction
product is then dissolved in a suitable solvent, thereby providing
an antireflective coating composition.
[0014] A process is also provided for forming an image on a
substrate, which process comprises, in the following order:
dissolving an organic polymer, having a weight average molecular
weight ranging from about 500 to 2,000,000 in a solvent, and
thereby providing one liquid phase; providing a diazonium salt in
another solvent, and thereby providing a separate liquid phase;
contacting the diazonium salt with the organic polymer, preferably
by intimately mixing the separate phases, for a time at least equal
to the minimum reaction time required to react the diazonium salt
with the organic polymer ("minimum contact time"), and thereby
reacting the diazonium salt and the organic polymer for a period of
time at least equal to such minimum reaction time. The organic
polymer-diazonium salt reaction product is then dissolved in a
solvent, thereby providing an antireflective coating composition.
The process further comprises, in the following order; either
before or after coating a photoresist composition onto a suitable
substrate, coating the antireflective coating composition onto such
a suitable substrate; heating the coated substrate, and thereby
substantially removing the photoresist solvent; imagewise exposing
the photoresist composition; and developing the imagewise exposed
photoresist composition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 A schematic view of an apparatus for synthesis of
polymeric azo dyes produced according to the process of the present
invention, using a tubular in-line static mixer.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] A method is provided for coupling a diazonium salt with an
organic polymer comprising, in the following order, the steps of:
dissolving an organic polymer in a solvent to thereby provide one
liquid phase; providing a diazonium salt in another solvent, and
thereby providing a separate liquid phase that is either miscible
or partially miscible or immiscible with the first liquid phase;
contacting the diazonium salt with the organic polymer, such as by
providing an in-line tubular mixing/reaction unit 110, as shown in
FIG. 1, which has a sufficient length to provide a contact time
that is greater than or equal to the minimum reaction time required
for the reaction of the diazonium salt with the organic polymer,
and thereby reacting the organic polymer and the diazonium salt,
for a period of time at least equal to such minimum reaction time,
in the in-line mixing unit.
[0017] Minimum reaction time is defined as the minimum amount of
time necessary to react two or more reactants to obtain the desired
product in a yield that is commercially acceptable. Commercially
acceptable yields can range from a single digit percentage to a
100% yield, though only in very few cases would a yield as low as
10% to 25% be acceptable. A small number of cases exist where a
yield of 25% to 50% is acceptable. A majority of the commercially
viable cases have a yield of 50% or greater, with preference given
to yields of 80% and greater, with greater preference given to
yields of 90% or greater.
[0018] The azo coupling reaction is often very rapid, with a
minimum reaction time of as little as ten microseconds, in the
presence of good intimate mixing of the reactants. These reactions
have a minimum reaction time, in the presence of such good mixing,
from ten microseconds to 120 minutes, many from ten milliseconds to
60 minutes, while most are from 0.1 seconds to 10 minutes. It is
believed that in such rapid reactions, such as these azo coupling
reactions, a yield up to a given percentage (e.g. 50-70%) probably
takes place very rapidly, but the last 30-50% yield of the reaction
product may take much longer. Therefore, in many cases it may be
beneficial to run the reaction longer than the minimum reaction
time, when it is desired to maximize the yield of the final
product.
[0019] Contact time is defined as the amount of time that two or
more reactants are actually in intimate contact with one another,
such that a reaction between the two or more reactants can
efficiently take place. To assure that a complete reaction takes
place and to maximize the yield, contact times are generally
greater than the required minimum reaction time. Contact times of
as little as 0.1 seconds are desired. Azo coupling reactions
generally require contact times ranging from 0.1 seconds to 6
hours, however contact times in excess of two hours are rare. Most
azo coupling reactions utilize contact times from 1 second to 120
minutes, while many require only from 2 seconds to 20 minutes.
Process parameters such as flow rate can also have an effect on
contact time, as do the length and diameter of the in-line
mixing/reaction unit.
[0020] As shown in FIG. 1, this azo coupling reaction may be
carried out by simultaneously pumping the diazonium salt solution
from vessel 10 and the polymer solution from vessel 20 through an
in-line tubular mixing/reaction unit 110, such as an in-line static
mixer (available from Cole-Parmer Instrument Co.). Two gear pumps
70 and 80 are utilized to deliver the polymer solution and the
diazonium salt solution from their respective vessels 10 and 20 to
the in-line mixing unit 110. Gear pumps have been found to achieve
smooth and substantially pulseless flow. The diazonium salt
solution and the organic polymer solution are added in a molar
ratio of from 100 to 1 to 1 to 100, preferably from about 5 to 1 to
1 to 5, of diazonium salt to organic polymer. The flow rates are
measured gravimetrically by two balances 30 and 40 or flow rates
can be monitored by flowmeters 50 and 60. The resulting azo-coupled
product is carried by tubing 120 and precipitated into water in a
precipitation vessel 140 and is collected as a solid. Optionally,
precipitation vessel 140 has a means of agitation 130, such as an
agitation blade or magnetic stirrer. The resulting precipitate is
then sent to a filter 150.
[0021] Polymers are divided into two broad classes: inorganic
polymers and organic polymers. For the purposes of this
application, the polymer is an organic polymer. The organic polymer
in this reaction is selected from polymers, which contain at least
one of the following moieties: 3
[0022] where,
[0023] R.sub.1 is either: 1) a substituted or unsubstituted
aromatic ring, such as phenyl, naphthyl or anthracyl, 2) a
substituted or unsubstituted heterocyclic ring containing
heteroatoms such as oxygen, nitrogen, sulfur or combinations
thereof, such as pyrrolidinyl, furanyl, pyranyl or piperidinyl, or
3) a group having the structure: 4
[0024] where,
[0025] A.sub.1 and A.sub.2 are independently selected from the
groups: halo, --CN, --COZ,--COOZ, --CONHZ,--CONZ.sub.2,
--SO.sub.2NHZ, --SO.sub.2NZ.sub.2, --SO.sub.2Z, --SO.sub.2CF.sub.3,
where Z is H, (C.sub.1-C.sub.10) alkyl, (C.sub.1-C.sub.10)
hydroxyalkyl, (C.sub.1-C.sub.10) alkoxyl, (C.sub.1-C.sub.10)
fluoroalkyl, (C.sub.1-C.sub.10) epoxyalkyl, (C.sub.1-C.sub.10)
alkenyl, or a substituted or unsubstituted carbocyclic, aromatic or
heterocyclic group such as but not limited to pyrrolidinyl,
furanyl, pyranyl, phenyl, cyclohexyl, piperidinyl, or A.sub.1 and
A.sub.2 may be --COOM, --SO.sub.3M, where M is alkali metal,
ammonium, or alkyl ammonium; or
[0026] A.sub.1 and A.sub.2 may be combined to form a substituted or
unsubstituted carbocyclic or heterocyclic ring containing an
.alpha.-carbonyl group such as 2-cyclohexanoyl, 2-cyclopentanoyl,
2-(.alpha.-butyrolactoyl); and preferably also comprising a
co-monomer moiety having the structure: 5
[0027] where,
[0028] R.sub.6-R.sub.9 are independently either halo,
--O(CH.sub.2).sub.x, H, --O(CH.sub.2CH.sub.2).sub.xOH (where x
=1-10), --(OCH.sub.2CH.sub.2).s- ub.yOH (where y=0-10), --CN, --Z,
--OZ, --OCOZ, --COZ,--COOZ, --NHZ, --NZ.sub.2, --NHCOZ, --CONHZ,
--NZCOZ, --CONZ.sub.2, --SZ, --SO.sub.3Z,--SO.sub.2NHZ,
--SO.sub.2NZ.sub.2, --SO.sub.2Z, --SO.sub.2CF.sub.3, where Z is H,
(C.sub.1-C.sub.10) alkyl, (C.sub.1-C.sub.10) hydroxyalkyl,
(C.sub.1-C.sub.10) alkoxyl, (C.sub.1C.sub.10) fluoroalkyl,
(C.sub.1-C.sub.10) epoxyalkyl, (C.sub.1-C.sub.10) alkenyl, or may
be --COOM, --SO.sub.3M, where M is alkali metal, ammonium, alkyl
ammonium, or R.sub.8 and R.sub.9 are combined to form a carbocyclic
or heterocyclic group such as but not limited to a maleic anhydride
or maleimide moiety. Preferably the polymer contains one or more
moieties selected from: 6
[0029] where,
[0030] R.sub.1'-R.sub.3' and R.sub.4 are independently either halo,
nitro, --O(CH.sub.2).sub.xOH, --O(CH.sub.2CH.sub.2).sub.xOH (where
x=1-10), --(OCH.sub.2CH.sub.2).sub.y--OH (where y=0-10), --CN, Z,
--OZ, --OCOZ, --COZ, --COOZ, --NHZ, --NZ.sub.2, --NHCOZ, --CONHZ,
--NZCOZ, --CONZ.sub.2, --SZ, --SO.sub.3Z, --SO.sub.2NHZ,
--SO.sub.2NZ.sub.2, --SO.sub.2Z, --SO.sub.2CF.sub.3, where Z is H,
(C.sub.1-C.sub.10) alkyl, (C.sub.1-C.sub.10) hydroxyalkyl,
(C.sub.1-C.sub.10) alkoxyl, (C.sub.1-C.sub.10) fluoroalkyl,
(C.sub.1-C.sub.10)epoxyalkyl, (C.sub.1-C.sub.10) alkenyl,
substituted or unsubstituted carbocyclic or heterocyclic group such
as but not limited to pyrrolidinyl, furanyl, pyranyl, piperidinyl,
or may be COOM, --SO.sub.3M, where M is alkali metal, ammonium,
alkyl ammonium, or R.sub.1' and R.sub.2' are combined to form a
carbocyclic or heterocyclic group such as but not limited to a
maleic anhydride or maleimide moiety; and m=0-4; or: 7
[0031] where,
[0032] R.sub.1"-R.sub.3" are independently either --Z, --OZ,
--OCOZ, --COZ, --COOZ, --NHZ,--NZ.sub.2, --NHCOZ, --CONHZ, --NZCOZ,
--CONZ.sub.2, --SZ, --SO.sub.3Z, --SO.sub.2NHZ, --SO.sub.2NZ.sub.2,
--SO.sub.2Z, --SO.sub.2CF.sub.3, where, Z is H, (C.sub.1-C.sub.10)
alkyl, (C.sub.1-C.sub.10) hydroxyalkyl, (C.sub.1-C.sub.10) alkoxyl,
(C.sub.1-C.sub.10) fluoroalkyl, (C.sub.1-C.sub.10) epoxyalkyl,
(C.sub.1-C.sub.10) alkenyl, a substituted or unsubstituted
carbocyclic or heterocyclic group such as but not limited to
pyrrolidinyl, furanyl, pyranyl, piperidinyl, or R.sub.1" and
R.sub.2" are combined to form a 3-10 membered carbocyclic or
heterocyclic group such as a maleic anhydride or a maleimide
moiety;
[0033] A.sub.1 and A.sub.2 are independently selected from the
group: halo, --CN, --COZ, --COOZ, --CONHZ, --CONZ.sub.2,
--SO.sub.2NHZ, --SO.sub.2NZ.sub.2, --SO.sub.2Z, --SO.sub.2CF.sub.3,
where Z is H, (C.sub.1-C.sub.10) alkyl, (C.sub.1-C.sub.10)
hydroxyalkyl, (C.sub.1-C.sub.10) alkoxyl, (C.sub.1-C.sub.10)
fluoroalkyl, (C.sub.1-C.sub.10) epoxyalkyl, (C.sub.1-.sub.10)
alkenyl, 3-10 membered substituted or unsubstituted carbocyclic or
heterocyclic group such as but not limited to pyrrolidinyl,
furanyl, pyranyl, piperidinyl, or may be --COOM, --SO.sub.3M, where
M is alkali metal, ammonium, alkyl ammonium;
[0034] A.sub.1 and A.sub.2 may be combined to form a 3-10 membered
substituted or unsubstituted carbocyclic or heterocyclic ring
containing an .alpha.-carbonyl group such as 2-cyclohexanoyl,
2-cyclopentanoyl, or 2-(.alpha.-butyrolactoyl);
[0035] and preferably also having one or more comonomer moieties of
the previously defined formula: 8
[0036] For the purposes of this application the symbols: 9
[0037] each signify either a direct bond to an organic group or an
organic chain comprising either the same or different organic
groups, such as methylene, ethylene, etc. This is illustrated by
the following formula wherein R.sub.1", R.sub.2", A.sub.1' and
A.sub.2' are previously defined. X.sub.1 and X.sub.2 are
independently --CO--, --OC(O)--, --CONH--O--, aryl,
--(CH.sub.2CH.sub.2O).sub.y-- (where y=0-10), (C.sub.1-C.sub.10)
alkyl, cyclohexyl, --S--, --S--(C.sub.1-C.sub.10) alkyl ,
--O--(C.sub.1-C.sub.10) alkyl, --NH--, --N--(C.sub.1-C.sub.10)
alkyl, or (C.sub.1-C.sub.10) hydroxyalkyl. n is independently 0-2.
10
[0038] Organic polymers within the scope of the present invention
include vinyl polymers such as disclosed in copending U.S.
application Ser. No. 08/841,750 filed on Apr. 30, 1997, which
include: 1) poly (vinylphenols), 2) substituted poly
(vinylphenols), 3) poly (vinylphenol) copolymers, or 4) acrylate
polymers, including methacrylates. These include poly
p-hydroxystyrene-co-methyl methacrylate; poly p-hydroxystyrene; or
poly 2-(methacryloyloxy)ethyl acetoacetate-co-methyl
methacrylate.
[0039] Polymers having a weight average molecular weight of greater
than or equal to 500 are preferred. Greater preference is given to
polymers having a weight average molecular weight greater than or
equal to 5000. Polymers, which fall into the following range are
preferred, polymers where the weight average molecular weight
ranges from about 500 to 2,000,000; more preferably from about
3,000 to 1,000,000; and most preferably from about 5,000 to 80,000.
These polymers are dissolved in an organic solvent, mixed organic
solvents or organic solvents mixed with water.
[0040] The cation of the diazonium salt has the general
structure:
ArN.sub.2 .sup.+
[0041] where, Ar is an aryl group. The aryl group is selected from:
1) a substituted or unsubstituted aromatic ring, such as phenyl,
naphthyl or anthracyl, or 2) a substituted or unsubstituted
heterocyclic ring containing heteroatoms, such as oxygen, nitrogen,
sulfur or combinations thereof, such as pyridinyl, or a thiophene
moiety. The diazonium salt anion can be any negatively charged ion.
Examples of such anions include --Cl, --Br, --NO.sub.3,--HSO.sub.4,
--OCOCH.sub.3, and --OH. Examples of such diazonium salts include
those derived from aryl carboxylic acids, such as
4-NH.sub.2C.sub.6H.sub.4CO.sub.2H, or from other substituted aryl
compounds, such as 4-aminoacetanilide
[0042] The in-line mixing/reaction unit 110 is selected from a
tubular reactor that provides static mixing or may be a dynamic
mixer. Such dynamic mixers include a rotor stator and an in-line
centrifugal pump, while tubular reactors include in-line static
mixers and packed tubular reactors. A tubular reactor is a reaction
vessel in the shape of a tube, where a tube is defined as a hollow
cylinder or pipe long in proportion to its inner diameter. Any
reaction vessel which is appreciably longer than its diameter can
be said to be tubular, it can also be defined in terms of the ratio
of length divided by inner diameter or:
[0043] Ratio=L (length)/D (inner diameter)
[0044] so that vessels having a L/D ratio in excess of 10 are
considered tubular. While these can include vessels having
extremely high numbers most will fall in the L/D ratio of 10 to
1,000, preferably having a ratio from 25 to 500.
[0045] The static tubular mixing unit has a void volume, which is
determined by a defined length and inner diameter. The length of
the tubular mixer is defined as the distance from a point where the
two or more feed streams come into the mixer and begin to contact
each other to a point where the product stream leaves the mixer
into the precipitation container and the reaction stops. The
contact time for the process of this invention is determined by
dividing the void volume of the mixer by the total flow rate of the
diazonium salt solution and the organic polymer solution. The
length and the inner diameter of the mixer are adjusted so that the
contact time is greater than or equal to the required minimum
reaction time. Flow rate is defined as the volume of fluid that
passes through any given path in a defined unit of time.
[0046] The static tubular mixing unit contains fixed mixing
elements, which create turbulent energy dissipation, thereby
promoting good macro-and micro-mixing. No moving mechanical parts
are contained in the static tubular fixed element mixer. The fixed
mixing elements progressively reduce radial gradients of
concentration and temperature by combining, splitting, stretching
and recombining two or more separate streams. This results in
intimate mixing while at the same time introducing little to no
shear into the reaction mixture. In large-scale production where an
in-line mixing unit is not used, shear is transmitted through the
agitator blade in the mixing vessel and often results in extra heat
being introduced into the reaction mixture, which can result in the
decomposition of the diazonium salt and substantially decrease the
amount of desired end product. With the use of the in-line mixing
unit, minimal mixing energy is introduced at the point of mixing so
that the introduction of shear is minimized.
[0047] A packed column or reactor also falls into this general
class of static mixers. The packed reactor is a tubular reaction
vessel, which contains a packing material. The packing material is
defined as an inert material that is frequently used in a
distillation column to baffle the downward flow of countercurrent
liquid. It may be, for example, glass fibers or beads, metal tubes
called Raschig rings, metal chains, or specially shaped devices of
various kinds (saddles, helices, rings, etc.).
[0048] A rotor stator mixer is a dynamic mixer, where a rotor turns
inside a close fitting stator, as is well known in the art. Rotor
speeds vary, but most rotors run at speeds of from 2000 rpm to 5000
rpm. The centrifugal force causes flow into the inside of the
rotor, where the liquid flows radically outwards through the rotor
and the slits in the stator and is subject to a very mild shearing
action. When a dynamic mixer is used as the in-line mixing unit 110
the contact time can be extended by using longer tubing 120, which
is counted in the length (L) determination for the reactor, until
the reactants reach the water in precipitation vessel 140. Unlike a
larger mixing vessel, the in-line dynamic mixer deals with a much
smaller volume into which the reactants are introduced, which
allows intimate contact to be maximized, while at the same time
stratification of the reactant phases and the introduction of shear
are minimized. The smaller volume of reactants being processed, at
any given moment, by the in-line dynamic mixer also means that the
reactants are under the influence of the pump or rotor stator for
far less time than the conventional agitator blade in a reaction
vessel. The small amount of shear that may be introduced has a
chance to dissipate in the tubing 120 before the reaction mixture
reaches vessel 140. In vessel 140 the azo coupling reaction mixture
is quenched as it is mixed with water and the resulting product is
precipitated.
[0049] In some applications, such as in the electronics industry,
metal impurities can pose a serious problem. Many times undesirable
metal ions can be introduced by simply mixing the reactants in a
metal container, by using uncoated metal transfer tubes or metal
agitator blades. In practicing the present process, one can
minimize or eliminate this problem simply by avoiding contacting
the reactants or the final product with metal. This can be
accomplished by, e.g. providing: 1) glass-lined or Teflon.RTM.
PTFE-coated vessels and agitator blades, 2) A plastic or
Teflon.RTM.-coated static in-line mixer and inserts, and 3) a
Teflon.RTM.-coated dynamic mixer.
[0050] The azo coupled polymer prepared by the method of the
present invention is light absorbing and is useful in instances
where light absorption is advantageous, particularly in
antireflective coating compositions, or as light absorbing
additives, for photosensitive compositions such as photoresists.
Antireflective coatings are used in image processing by forming
either a thin layer between a reflective substrate and a
photoresist coating, or as a coating on top of a photoresist. Such
compositions are especially useful in the fabrication of
semiconductors and other microelectronic devices by
photolithographic techniques. The polymer may also be used as an
additive in photoresists to prevent or substantially reduce the
reflection of light from the substrate.
[0051] Photoresist compositions are used in microlithography
processes for making miniaturized electronic components such as in
the fabrication of computer chips and integrated circuits.
Generally, in these processes, a thin coating of film of a
photoresist composition is first applied to a substrate material,
such as silicon wafers used for making integrated circuits. The
coated substrate is then baked to evaporate any solvent in the
photoresist composition and to fix the coating onto the substrate.
The baked coated surface of the substrate is next subjected to an
image-wise exposure to radiation.
[0052] This radiation exposure causes a chemical transformation in
the exposed areas of the coated surface. Visible light, ultraviolet
(UV) light, electron beam and X-ray radiant energy are radiation
types commonly used today in microlithographic processes. After
this image-wise exposure, the coated substrate is treated with a
developer solution to dissolve and remove either the
radiation-exposed or the unexposed areas of the photoresist.
[0053] The trend towards the miniaturization of microelectronic
devices has lead to the use of sophisticated multilevel systems to
overcome difficulties associated with such miniaturization. The use
of highly absorbing antireflective coatings in photolithography is
a simple approach to diminish the problems that result from back
reflection of light from highly reflective substrates. Two
deleterious effects of back reflectivity are thin film interference
and reflective notching. Thin film interference results in changes
in critical line-width dimensions caused by variations in the total
light intensity in the resist film as the thickness of the resist
changes. Variations of line-width are proportional to the swing
ratio (S) and therefore must be minimized for better linewidth
control. Swing ratio is defined by:
S=4(R.sub.21R.sub.22).sup.1/2e.sup.-.alpha.D
[0054] where,
[0055] R.sub.21 is the reflectivity at the resist/air or resist/top
coat interface,
[0056] R.sub.22 is the reflectivity at the resist/substrate
interface,
[0057] .alpha. is the resist optical absorption coefficient,
[0058] and D is the film thickness.
[0059] Bottom antireflective coatings function by absorbing the
radiation used for exposing the photoresist, thus reducing R.sub.22
and thereby reducing the swing ratio. Reflective notching becomes
severe as the photoresist is patterned over substrates containing
varying topographical features, which scatter light through the
photoresist film, leading to linewidth variations, and in the
extreme case, forming regions with complete resist loss. Similarly,
top antireflective coatings reduce the swing ratio by reducing
R.sub.21, where the coating has the optimal values for refractive
index and absorption characteristics, such as absorbing wavelength
and intensity.
[0060] The azo coupled polymer prepared by the instant method is
useful in an antireflective coating composition, which comprises
the azo coupled polymer and a suitable solvent or mixtures of
solvents. Other components may, optionally, be added to enhance the
performance of the coating, e.g. crosslinking agents, thermal acid
generators, monomeric dyes, lower alcohols, surface leveling
agents, adhesion promoters, antifoaming agents, etc. Monomeric dyes
may also be added to the antireflective coating, examples of which
are Sudan Orange, 2,4-dinitronaphthol, curcumin, coumarins and
others.
[0061] The absorption of the antireflective coating can be
optimized for a certain wavelength or ranges of wavelengths by the
suitable choice of substituents on the dye functionality. Using
substituents that are electron-withdrawing or electron-donating
generally shifts the absorption wavelength to longer or shorter
wavelengths, respectively. In addition, the solubility of the
antireflective polymer in a particularly preferred solvent can be
adjusted by the appropriate choice of substituents on the
monomers.
[0062] The polymer is present in the antireflective coating
composition in an amount from about 1% to about 40% by total weight
of the solution. The exact weight used is partially dependent on
the molecular weight of the polymer and the film thickness of the
coating desired. Solvents, used as mixtures or alone, that might be
used include PGME (Propylene Glycol Methyl Ether), PGMEA (Propylene
Glycol Methyl Ether Acetate), EL (Ethyl Lactate), cyclopentanone,
cyclohexanone, water, (C.sub.1-C.sub.4) alkyl alcohols, ketones,
esters and gamma-butyrolactone, but PGME, PGMEA and EL or mixtures
thereof are preferred. Solvents with a lower degree of toxicity,
good coating and solubility properties are generally preferred.
Examples of lower alcohols, ketones or esters are ethanol,
isopropyl alcohol, butyl acetate, methyl amyl ketone, and
acetone.
[0063] Since the antireflective film is coated on top of the
substrate (either before or after coating with a photoresist
composition) and is then normally subjected to dry etching, it is
important that the film is of sufficiently low metal ion level and
purity that the properties of the microelectronic device are not
adversely effected. Treatments such as passing a solution of the
polymer through an ion exchange column, filtration, and extraction
processes can be used to reduce the concentration of metal ions and
to reduce particles.
[0064] The antireflective coating composition is coated on the
substrate using techniques well known to those skilled in the art,
such as dipping, spincoating or spraying. The film thickness of the
antireflective coating ranges from about 0.1 .mu.m (micrometer) to
about 1 .mu.m (micrometer). The coating is further heated, such as
on a hot plate or convection oven, to remove residual solvent and
induce crosslinking, if desired, and insolubilizing the
antireflective coatings to prevent intermixing between the
antireflective coating and the photoresist.
[0065] Photoresists coated under or, preferably, over the
antireflective film can be any of the types used in the
semiconductor industry. It is preferred that the refractive index
of the photoactive compound in the photoresist matches or is very
close to that of the antireflective coating so that the
reflectivity at the interface of the photoresist layer and the
antireflective film can be substantially minimized or
eliminated.
[0066] There are two types of photoresist compositions,
negative-working and positive-working. When negative-working
photoresist compositions are exposed image-wise to radiation, the
areas of the resist composition exposed to the radiation become
less soluble to a developer solution (e.g. a cross-linking reaction
occurs) while the unexposed areas of the photoresist coating remain
relatively soluble to such a solution. Thus, treatment of an
exposed negative-working resist with a developer causes removal of
the non-exposed areas of the photoresist coating and the creation
of a negative image in the coating, thereby uncovering a desired
portion of the underlying substrate surface on which the
photoresist composition was deposited.
[0067] On the other hand, when positive-working photoresist
compositions are exposed image-wise to radiation, those areas of
the photoresist composition exposed to the radiation become more
soluble to the developer solution (e.g. a rearrangement reaction
occurs) while those areas not exposed remain relatively insoluble
to the developer solution. Thus, treatment of an exposed
positive-working photoresist with the developer causes removal of
the exposed areas of the coating and the creation of a positive
image in the photoresist coating. Again, a desired portion of the
underlying surface is uncovered.
[0068] Positive-working photoresist compositions are currently
favored over negative- working resists because the former generally
have better resolution capabilities and pattern transfer
characteristics. Photoresist resolution is defined as the smallest
feature which the resist composition can transfer from the
photomask to the substrate with a high degree of image edge acuity
after exposure and development. In many manufacturing applications
today, resist resolution on the order of less than one micron is
necessary. In addition, it is almost always desirable that the
developed photoresist wall profiles are to be near vertical
relative to the substrate. Such demarcations between developed and
undeveloped areas of the resist coating translate into accurate
pattern transfer of the mask image onto the substrate. This becomes
even more critical as the push toward miniaturization reduces the
critical dimensions on the devices.
[0069] Positive-working photoresists comprising novolak resins or
vinyl phenols as the film forming resin, and acid-generators or
quinone-diazide compounds as the photoactive component are well
known in the art. Novolak resins are typically produced by
condensing formaldehyde and one or more multi-substituted phenols,
in the presence of an acid catalyst, such as oxalic acid.
Photoactive quinone diazide compounds are generally obtained by
reacting multihydroxyphenolic compounds with naphthoquinone diazide
acids or their derivatives.
[0070] Photoresists utilizing a vinyl phenol polymer as the film
forming resin normally comprise polyhydroxystyrene or substituted
polyhydroxystyrene derivatives, a photoactive component, and
optionally a solubility inhibitor. The following references
exemplify the types of photoresists used and are incorporated
herein by reference, U.S. Pat. Nos. 4,491,628, 5,069,997 and
5,350,660.
[0071] When used as a bottom antireflective coating composition,
the composition is used to form a film on the substrate and then
heated, such as on a hotplate or convection oven at a sufficiently
high temperature for a sufficient length of time to substantially
remove the coating solvent, and crosslink the polymer if necessary,
to a sufficient extent so that the film is not soluble in the
coating solution of the photoresist or in the aqueous alkaline
developer. An edge bead remover may be applied to clean the edges
of the substrate using solvents and processes well known in the
art. The preferred range for heating is from about 70.degree. C. to
about 250.degree. C. If the temperature is below 70.degree. C. then
insufficient loss of solvent or insufficient amount of crosslinking
takes place, and at temperatures above 250.degree. C. the polymer
may become chemically unstable. A film of photoresist is then
coated on top of the antireflective coating and baked to
substantially remove the photoresist solvent. The photoresist is
imagewise exposed and developed in an aqueous developer to remove
the treated resist. An optional heating step (post exposure bake)
can be incorporated into the process prior to development and after
exposure. The process of coating and imaging photoresists is well
known to those skilled in the art and is optimized for the specific
type of resist used. The patterned substrate can then be etched,
such as by dry etching in a suitable etch chamber, to remove the
exposed portions of the antireflective film, with the remaining
photoresist acting as an etch mask.
[0072] An intermediate layer may be placed between the
antireflective coating and the photoresist to prevent intermixing,
and is envisioned as lying within the scope of this invention. The
intermediate layer is an inert polymer cast from a solvent, where
examples of the polymer are polysulfones and polyimides.
EXAMPLES
Comparative Example 1
[0073] To a 1-L cooling-jacketed round-bottomed flask, were added,
in sequence, 4-aminoacetanilide (AAA, 0.46 mole, 70.0 g), water
(230 ml), and hydrochloride acid (37%, 77 ml) under stirring. The
suspension was cooled to 0-5.degree. C. Pre-chilled (about
15.degree. C.) isobutyl nitrite (IBN, 0.46 mole, 50.1 g) was added
to the flask. As AAA reacted, the newly formed diazonium salt
dissolved in water to give a brownish solution.
[0074] In a 5-L round-bottomed flask, equipped with a mechanical
stirrer and a temperature controller, poly
p-hydroxystyrene-co-methyl methacrylate (PHS-MMA, 55-45 mole ratio,
0.36 mole, 79.2 g) was dissolved in tetrahydrofuran (THF, 1.2 L)
and water (0.4 L), and cooled to 0-5.degree. C. The pH of the
PHS-MMA solution was adjusted to 12-13 by adding
tetramethylammonium hydroxide (TMAH, 25%). The azo coupling
reaction was carried out by adding the diazonium salt over a period
of 1.5 hours to the PHS-MMA solution at a pH of 12-13. After the
addition of the diazonium salt was completed, the reaction mixture
was stirred for an additional hour. The azo-coupled product was
precipitated into 6 L of water and collected as a reddish solid.
The UV-Visible spectrum of the polymer in ethyl lactate showed
.lambda.max at 359 nm. A Gel Permeation Chromatograph (GPC) showed
the polymer had a weight average molecular weight (Mw) of
18,000-22,000. Table 1 summarizes the extinction coefficient (E) of
the azo coupled polymer product produced using both high and low
agitation speeds. The data indicate that the extinction coefficient
of the product was significantly affected by agitation speed.
1 TABLE 1 Agitation Rate E Yield Run # (RPM) (L/g.cm) (%) 1 100 25
62 2 300 55 95
Comparative Example 2
[0075] To a 5-L cooling-jacketed round-bottomed flask, were added
in sequence AAA (4.67 mole, 700.0 g), water (2.3 L), and
hydrochloride acid (37%, 0.7 L) under stirring. The suspension was
cooled to 0-5.degree. C. Pre-chilled IBN (4.87 mole, 502.0 g) was
added to the flask over a period of 60 minutes. As AAA reacted, the
newly formed diazonium salt dissolved in water to give a brownish
solution.
[0076] In a 30-L reactor, equipped with an agitator and a
temperature controller, PHS-MMA (55-45 mole ratio, 3.62 moles,
795.4 g) was dissolved in tetrahydrofuran (THF, 12.0 L) and water
(4.0 L) and cooled to 0-5.degree. C. The pH of the PHS-MMA solution
was adjusted to 12-13 by adding TMAH (25%). The azo coupling
reaction was carried out by adding the diazonium salt over a period
of 3 hours to the PHS-MMA solution at a pH of 12-13. After the
addition of the diazonium salt was completed, the reaction mixture
was stirred for an additional hour. The azo-coupled product was
precipitated into 60 L of water and collected as a reddish solid.
The UV-Visible spectrum of the polymer in ethyl lactate showed
.lambda.max at 359 nm. The GPC showed that the polymer had a Mw of
18,500-22,000 Table 2 shows that the agitation speed had
significant impact on the extinction coefficient (E) of the azo
coupled polymer product.
2 TABLE 2 Agitation Rate E Yield Run # (RPM) (L/g.cm) (%) 1 100 16
63 2 300 22 68
Example 3
[0077] To a 5-L cooling-jacketed round-bottomed flask were added,
in sequence, 4-nitroaniline (2.5 mole, 345 g), water (2.0 L), and
hydrochloride acid (37%, 0.5 L) under stirring. The mixture was
cooled to 0-10.degree. C. and pre-chilled IBN (15.degree. C.-2.6
mole, 268 g) was added to the flask. The diazotization reaction
took place immediately. After the addition of the IBN was
completed, the reaction mixture was stirred for an additional hour.
The diazonium salt solution that was formed was then ready for the
continuous azo coupling reaction.
[0078] To a 20-L glass reactor were added PHS-MMA (55:45 mole ratio
- 2.5 mole, 300 g), THF (6.0 L), water (2.0 L), methanol (3.0 L),
and tetramethylammonium hydroxide (TMAH, 25%, 2.5 L) and the mixed
solution was cooled to 0-10.degree. C. The azo coupling reaction
was carried out by simultaneously pumping the diazonium salt
solution and the PHS solution through a 1/4".times.60"in-line
static mixer (available from Cole-Parmer Instrument Co.). Two gear
pumps (70 and 80 in FIG. 1) were utilized in order to achieve
smooth and substantially pulseless flow. The diazonium salt and the
PHS solution were added at a molar ratio of 1 to 1 of diazonium
salt to PHS. The flow rates were measured gravimetrically by two
balances (30 and 40 in FIG. 1). The contact time of the two feed
streams was about 20 seconds. It took about 70 minutes to pump all
the diazonium salt and the PHS-MMA solution through the in-line
mixer. The azo-coupled product was precipitated directly into 30 L
of water and was collected as a reddish solid with a 90% yield. In
this particular case the minimum reaction time was defined as the
time it took to achieve a desired product yield of 50% or greater,
and as the yield exceeded this value the contact time (estimated
here to be 20 seconds) was longer than the minimum reaction time,
which was defined as the time it would take to obtain a yield of at
least 50%. In this reaction, the optimum minimum reaction time was
defined as the time to produce a yield of 80% or more of the
desired product. The UV-Visible spectrum of the product in ethyl
lactate showed .lambda.max at 390 nm and extinction coefficients
(E) of 42 L/g.cm. The GPC showed that the polymer had a Mw of
11,200.
Example 4
[0079] To a 5 L cooling-jacketed round-bottomed flask, equipped
with a mechanical stirrer and a temperature controller, were added,
in sequence, 4-aminoacetanilide (AAA, 2.5 mole, 375.0 g), water
(1.5 L), and hydrochloride acid (37%, 0.5 L) under stirring. The
suspension was cooled to 0-5.degree. C. Pre-chilled IBN (15.degree.
C. -2.55 mole, 262.6 g) was added to the flask. As AAA reacted, the
newly formed diazonium salt dissolved in water to give a brownish
solution.
[0080] In a 20 L reactor PHS-MMA (55-45 mole ratio, 2.3 mole, 506
g) was dissolved in a mixture of THF (4.9 L), water (1.3 L),
methanol (2.5 L), and TMAH (25%, 1.9 L) at 5.degree. C. The
diazonium salt solution and the polymer solution were pumped
through a 1/4".times.6 in-line static mixer connected with a
centrifugal pump at a flow rate ratio of 1 to 4.2 of diazonium salt
solution to PHS-MMA solution. The flow rates were monitored
gravimetrically. The contact time of the reactants was estimated to
be about 2 seconds. It took about 50 minutes to pump all of the
diazonium salt and the PHS-MMA solution through the in-line mixer
and the centrifugal pump. The azo-coupled product was precipitated
into 25 L of water and was collected as a reddish solid, with a 95%
yield. In this particular case the minimum reaction time was
defined as the time it took to achieve a desired product yield of
50% or greater, and as the yield exceeded this value the contact
time was longer than the minimum reaction time, defined as the time
it took to obtain a yield of at least 50% yield. In this reaction,
the optimum minimum reaction time, was defined as the time to
produce a yield of 80% or more, of the desired product. The
UV-Visible spectrum of the polymer in ethyl lactate showed
.lambda.max at 359 nm and (E) of 50 L/g.cm. The GPC showed that the
polymer had a Mw of 18,500.
Example 5
[0081] 2-(Methacryloyloxy)ethyl acetoacetate (MEAA, 2.5 mole, 535.0
g) and THF (4.0 L) were added into a 10 L round-bottomed flask. The
solution was degassed by bubbling nitrogen through the solution for
about 1 hour. Methyl methacrylate (MMA, 2.5 mole, 250.0 g) and a
solution of 2,2'-azobisisobutyronotrile (AIBN, 41.0 g) in THF were
then injected into the first solution. The mixture was further
degassed with nitrogen for 30 minutes. The nitrogen outlet needle
was then removed and the mixture in the sealed vessel was stirred
overnight at 65.degree. C. This solution was then precipitated into
25 L of 2-propanol. The polymer product (MEAA-MMA, 50-50 mole
ratio) was collected as a yellow solid at a 96% yield. The GPC
showed that the polymer had a Mw of 32,800.
Examples 6-11
[0082] Table 3 shows the polymers synthesized using the synthesis
procedure described in Example 3 and gives the Mw for each polymer
so synthesized, the peak absorbance (.lambda.max) in EL and the
extinction coefficient (E) for these polymers.
3TABLE 3 Diazo./ Polymer E.lambda. Diazonium Mole GPC .lambda.max
(L/g .multidot. Yield Ex Salt Polymer Ratio Mw (NM) cm) (%) 6 4-
PHS- 1.2/1.0 9,362 335 45 86 NH.sub.2C.sub.6H.sub.4CO.sub.2 MMA H
(50/50) 7 4 MEAA- 1.0/1.0 51,500 359 52 91
NH.sub.2C.sub.6H.sub.4CO.sub.2 MMA H (50/50) 8 4- MEAA- 1.0/1.0
27,400 359 52 92 NH.sub.2C.sub.6H.sub.4CO.sub.2 MMA Et (70/30) 9
AAA PHS 0.7/1.0 5,200 358 55 94 (100) 10 AAA PHS- 1.0/1.0 17,500
359 51 95 MMA (50/50) 11 AAA MEAA- 1.0/1.0 29,600 389 46 90 MMA
(60/40)
Examples 12-14
[0083] To a solution of 10.0 grams of the polymeric azo dye
synthesized according to the procedure of Examples 8-10 and 156.0
grams of ethyl lactate were added 1.92 grams of Powderlink.RTM.
1174 crosslinking agent and 0.50 grams of Powerlink.RTM. MTSI
thermal acid generator (both are available from CYTEC industries,
Inc.). The formulation obtained was spin-coated at 3000 rpm onto a
4-inch non-HMDS (hexamethyldisilazane) treated silicon wafer and
baked on a hot plate at 200.degree. C. for 60 seconds. The coated
wafer was then immersed in ethyl lactate for 60 seconds and then
spin-dried. The film thickness before and after immersion for the
wafer was measured by a NANOSPEC.RTM.-AFT. The extent of interlayer
mixing between the azo dye coating and the solvent was determined
by the changes of the azo dye film thickness as listed in Table 4
below. It is clear that the solubility of the azo dye coating of
the present invention in typical photoresist casting solvents is
negligible.
4TABLE 4 Example Dye synthesized in T.sub.1 (.ANG.) T.sub.2 (.ANG.)
12 Example 8 1108 1099 13 Example 9 1856 1838 14 Example 10 1723
1721 where, T.sub.1= polymer film thickness in Angstroms, before
solvent immersion T.sub.2= polymer film thickness in Angstroms,
after solvent immersion
Example 15
[0084] Dye solutions formulated according to the procedure of
Examples 12-14 were each spin-coated onto a 4-inch non-HMDS treated
silicon wafer and each baked on a hot plate at 200.degree. C. for
60 seconds to give a film thickness of about 1950 .ANG.. The wafers
were then each coated with AZ.RTM. 7805 i-line photoresist
(available from Clariant Corporation, 70 Meister Ave., Somerville,
N.J. 08876) and each baked at 90.degree. C. for 90 seconds to give
a photoresist film thickness of 0.50 .mu.m. A 4-inch HMDS treated
silicon wafer was coated with AZ.RTM. 7805 photoresist at 0.50
.mu.m film thickness and baked at 90.degree. C. for 60 seconds and
was used as the reference. These wafers were then each imagewise
exposed with a NIKON.RTM. 0.54 NA i-line stepper. The exposed
wafers were then each baked at 110.degree. C. for 60 seconds and
each puddle developed with AZ.RTM. 300 MIF TMAH Developer
(available from Clariant Corporation, 70 Meister Ave., Somerville,
N.J. 08876) for 35 seconds. The resist patterns generated on each
of these wafers were using a Hitachi.RTM. S-4000 field emission
scanning electron microscope. Table 5 shows the comparison of
lithographic performance of AZ.RTM. 7805 photoresist with and
without the bottom antireflective coating of the present invention.
The bottom antireflective coating of the present invention clearly
improves the resolution and effectively eliminate standing waves
caused by wafer substrate reflection, without sacrificing
resolution.
5TABLE 5 DTP Standing Bottom Coating Solution (mj/cm.sup.2)
Resolution (.mu.m) Wave None 195 0.38 Severe Example 12 210 0.30
Eliminated Example 13 205 0.30 Eliminated Example 14 210 0.30
Eliminated where, DTP is dose to print in millijoules per square
centimeter (mj/cm.sup.2)
Example 16
[0085] Azo dye solutions formulated according to the procedure of
Examples 12-14 were each spin-coated onto a 4-inch non-HMDS treated
silicon wafer and baked on a hot plate at 180.degree. C. for 60
seconds to give a film thickness of about 1950 .ANG.. The wafers
were each then coated with AZ .RTM. 7908 photoresist (available
from Clariant Corporation, 70 Meister Ave., Somerville, N.J. 08876)
and each baked at 90.degree. C. for 90 seconds to give a resist
thickness from 0.75 .mu.m to 1.10 .mu.m. These wafers were then
each imagewise exposed using a NIKON.RTM. 0.54 NA i-line stepper,
then each baked at 110.degree. C. for 60 seconds and each puddle
developed with AZ.RTM. 300 MIF TMAH Developer for 35 seconds. The
minimum dose required to clear the film (Dose to Clear --DTC) was
plotted as a function of resist thickness, the sinusoidal curve
thus obtained is called the swing curve. The swing curve ratio
(swing ratio) of a photoresist is closely related to the line width
variation of the photoresist pattern over a highly reflective
substrate or topography commonly encountered in semiconductor
device manufacturing. The lower the swing ratio, the better the
line width control over their reflective substrate or topography.
The swing ratio was calculated using the equation:
Swing Ratio=(Emax-Emin)/(Emax+Emin)
[0086] where, Emax and Emin correspond to the dose-to-clear of a
resist thickness at the maximum and minimum on a swing curve. Swing
curves were generated by plotting the dose required to clear a
resist film after development as a function of the resist
thickness. 1 % Swing Reduction = ( Swing Ratio on silicon - Swing
Ratio on polymer ) Swing Ratio on silicon
[0087] where, Swing Ratio on silicon and Swing Ratio on polymer
correspond to the swing ratio of photoresist coated on silicon
wafer and on polymer bottom antireflective coating
respectively.
[0088] The %Swing Ratio Reduction of AZ.RTM. 7908 photoresist over
the antireflective coatings of the present invention are listed in
Table 6. It is clear that the polymer coatings of the present
invention can effectively reduce the swing ratio of the
photoresist.
6 TABLE 6 Bottom Coating Solution % Swing Ratio Reduction None 0
Example 12 92 Example 13 90 Example 14 90
[0089] Unless otherwise specified, all parts and percents are by
weight; all molecular weights (Mw) are weight average molecular
weights; all temperatures are in degrees Centigrade; alkyl is
C.sub.1-C.sub.10 alkyl; aryl or aromatic group signifies a group
containing 1-3 aromatic rings and includes unsubstituted or alkyl,
alkoxyl, hydroxyl, hydroxyalkyl, fluoroalkyl, carboxylic acid and
ester, or halo substituted aryl groups such as but not limited to
phenyl, tolyl, bisphenyl, trisphenyl, phenylene, biphenylene,
naphthyl or anthracyl; halo or halogen means chloro-,fluoro-, or
bromo-; fluoroalkyl groups may be linear or branched and include by
trifluoromethyl, 1,1,2-trifluoriethyl, pentafluoroethyl,
perfluoropropyl, perfluorobutyl and 1,1,2,3,3-pentafluorobutyl;
alkoxy can include methoxy, ethoxy, n-propyoxy, isopropoxy,
n-butoxy- isobutoxy, tert-butoxy, pentyloxy, hexyloxy, heptyloxy,
octyloxy, nonyloxy, decanyloxy, 4-methylhexyloxy, 2-propyheptyloxy,
2-ethyloctyloxy, 4-methylhexyloxy, 2-propylheptyloxy,
2-ethyloctyloxy, phenoxy, tolyoxy, xylyloxy, phenylmethoxy, etc.;
carboxylic acid or carboxylic ester is a C.sub.1-C.sub.10alkyl
carboxylic acid or ester.
* * * * *