O-naphthoquinone diazide sulfonyl esters of 4-(4-hydroxyphenyl)cyclohexanone phenolic derivatives with associated radiation sensitive mixtures and articles

A radiation sensitive mixture comprising an alkali-soluble binder resin and at least one photoactive compound comprising a compound of formula (I): ##STR1## wherein each R is individually selected from hydrogen and a lower alkyl group having 1 to 4 carbon atoms; n is either 0, 1, or 2; and D is selected from the group consisting of hydrogen or o-naphthoquinone diazide sulfonyl group; with the proviso that at least two D's are o-naphthoquinone diazide sulfonyl groups, and wherein the amount of said binder resin is about 70 to 95% by weight and the amount of photoactive compound being from about 5 to about 30% be weight, based on the total solids content of said content of said raditional-sensitive mixture.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to selected phenolic derivatives of 
4-(4-hydroxyphenyl)cyclohexanone useful as backbones for certain 
photoactive compounds. Further, the present invention relates to such 
photoactive compounds formed by the esterification of these phenolic 
derivatives of 4-(4-hydroxyphenyl)cyclohexanone with sulfonyl halides of 
o-naphthoquinone diazides. Still further, the present invention also 
relates to radiation sensitive mixtures (e.g., those particularly useful 
as positive-working photoresists) containing the combination of these 
photoactive compounds with alkali-soluble binder resins dissolved in a 
solvent. And furthermore, the present invention also relates to substrates 
coated with these radiation sensitive mixtures as well as the process of 
coating, imaging and developing these radiation sensitive mixtures on 
these substrates. 
2. Description of the Related Art Including Information Disclosed under 37 
CFR .sctn..sctn. 1.97-1.98 
Photoresist compositions are used in microlithographic processes for making 
miniaturized electronic components such as in the fabrication of 
integrated circuits and printed wiring board circuitry. In these 
processes, a thin coating or film of a photoresist composition is 
generally first applied to a substrate material, such as silicon wafers 
used for making integrated circuits or aluminum or copper plates of 
printed wiring boards. 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 of radiation. This radiation exposure causes a 
chemical transformation in the exposed areas of the coated surface. 
Visible light, ultraviolet (UV) light, electron beam, ion 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 coated surface of the substrate. In some 
processes, it is desirable to bake the imaged resist coating before this 
developing step. This intermediate step is sometimes called post-exposure 
bake or PEB. 
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 a developing solution. 
Thus, treatment of an exposed negative-working resist with a developer 
solution causes removal of the nonexposed areas of the resist coating and 
the creation of a negative image in the photoresist coating, and thereby 
uncovering a desired portion of the underlying substrate surface on which 
the photoresist composition was deposited. On the other hand, when 
positive-working photoresist compositions are exposed image-wise to 
radiation, those areas of the resist composition exposed to the radiation 
become more soluble to the developer solution (e.g., the Wolff 
rearrangement reaction of the photoactive compound occurs) while those 
areas not exposed remain relatively insoluble to the developer solution. 
Thus, treatment of an exposed positive-working resist with the developer 
solution causes removal of the exposed areas of the resist coating and the 
creation of a positive image in the photoresist coating. Again, a desired 
portion of the underlying substrate surface is uncovered. 
Positive-working photoresist compositions are currently favored over 
negative-working resists because the former generally have better 
resolution capabilities and pattern transfer characteristics. 
After this development operation, the now partially unprotected substrate 
may be treated with a substrate etchant solution or plasma gases and the 
like. This etchant solution or plasma gases etch the portion of the 
substrate where the photoresist coating was removed during development. 
The areas of the substrate are protected where the photoresist coating 
still remains and, thus, an etched pattern is created in the substrate 
material which corresponds to the photomask used for the image-wise 
exposure of the radiation. Later, the remaining areas of the photoresist 
coating may be removed during a stripping operation, leaving a clean 
etched substrate surface. In some instances, it is desirable to heat treat 
the remaining resist layer after the development step and before the 
etching step to increase its adhesion to the underlying substrate and its 
resistance to etching solutions. 
End users of photoresists are demanding photoresist formulations which 
possess better lithographic properties for the fabrication of smaller 
microelectronic circuits. The lithographic properties which are critical 
to these end-users include the following: (1) resolution capabilities in 
both the micron and submicron ranges without incomplete development in the 
exposed areas (i.e., scumming); (2) higher thermal image deformation 
temperatures (e.g. above 120.degree. C.); (3) relatively fast photospeeds; 
(4) good adhesion to substrate; (5) good developer dissolution rates; (6) 
wide process latitude; (7) near to absolute vertical profiles (or good 
contrast) between exposed and unexposed photoresist areas after 
development; (8) good resistance to etching solutions and plasma etching 
techniques; (9) reduced tendency to form insoluble particulates; (10) mask 
linearity; and (11) low metal contamination. 
Generally, in the past efforts to improve one of these lithographic 
properties have caused significant decreases in one or more of the other 
lithographic properties of the photoresist. Accordingly, there is a need 
for improved photoresist formulations which possess all of these desired 
properties. The present invention is believed to be an answer to that 
need. 
For example, while photoactive compounds are essential to obtain the 
positive images of positive-working photoresists, such photoactive 
compounds are sometimes not soluble for extended time periods in 
photoresist formulations. They may also contribute to the degradation of 
photoresist formulations by chemical reaction. Still further, certain 
photoactive compounds may contribute to scumming, causing the degradation 
of the thermal profile, and contributing to the lowering of the thermal 
deformation temperature of the resist patterns. Selection of a suitable 
photoactive compound without those weaknesses is a difficult and not a 
totally predictable task. 
Separately, Japanese Patent Publication (Kokai) No. 3-291250, which was 
published on Dec. 20, 1991, teaches a phenolic compound defined by the 
structure of formula (PA-1): 
##STR2## 
This Kokai also teaches that positive photoresist compositions may be made 
which contain photoactive compounds made of the ester of compound (PA-1) 
with a quinonediazidesulfonate. The reference suggests that these 
photoresist compositions provide high gamma values without an increase in 
residues in development. 
Also, Japanese Patent Publication (Kokai) No. 4-012356, which was published 
on Jan. 16, 1992, teaches a positive-working photoresist composition 
containing a novolak resin, a quinonediazide compound, and a polyhydric 
phenolic compound having the structure of formula (PA-2): 
##STR3## 
wherein R.sup.1 is a bifunctional hydrocarbon, n is 0 or 1, R.sup.2 and 
R.sup.3 are selected from hydrogen, alkyl, aryl, or aralkyl group; R.sup.2 
and R.sup.3 are optionally combined to form a cyclic structure; R.sup.4, 
R.sup.5, R.sup.6, R.sup.7, R.sup.8, R.sup.9, and R.sup.11 are selected 
from hydrogen, halogen, hydroxyl, or an alkyl group. This Kokai suggests 
that these positive photoresist compositions possess high photosensitivity 
and are useful for high density integrated circuit fabrication. 
One polyhydric phenolic compound encompassed by the above formula (PA-2) is 
the following compound (PA-2a): 
##STR4## 
SUMMARY OF THE INVENTION 
Moreover, the present invention is directed to photoactive o-naphthoquinone 
diazide sulfonyl moieties of said phenolic derivatives of 
4-(4-hydroxyphenyl)cyclohexanone having formula (I): 
##STR5## 
wherein each R is individually selected from the group consisting of 
hydrogen and lower alkyl group having 1-4 carbon atoms and each n is 0, 1, 
or 2; and wherein each D is an o-naphthoquinone diazide sulfonyl moiety or 
a hydrogen atom, with the proviso at least two D's are o-naphthoquinone 
diazide sulfonyl moieties. 
Moreover, the present invention is directed to a radiation sensitive 
mixture useful as a positive photoresist comprising an admixture of at 
least one photoactive o-naphthoquinone diazide compound of formula (II) 
above and an alkali-soluble binder resin; the amount of said photoactive 
o-naphthoquinone diazide compound or compounds being about 5% to about 30% 
by weight and the amount of said binder resin being about 70% to 95% by 
weight, based on the total solids content of said radiation sensitive 
mixture. 
Still further, the present invention also encompasses the process of 
coating substrates with these radiation sensitive mixtures and then 
exposing and developing these coated substrates. 
Also further, the present invention encompasses said coated substrates 
(both before and after imaging) as novel articles of manufacture. 
DESCRIPTION OF PREFERRED EMBODIMENTS 
The selected phenolic derivatives of 4-(4-hydroxyphenyl)cyclohexanone are 
made by reacting 4-(4-hydroxyphenyl)cyclohexanone with phenol in the 
presence of an acid. The major product of this reaction is 
1,1,4-tris(trihydroxyphenol)cyclohexane. The lower alkyl-substituted 
homologs of this compound may be made with using various cresol 
precursors. 
The triphenolcyclohexane compounds of this invention may be converted into 
the photoactive compounds ('s) of formula (I) by their condensation 
with o-naphthoquinone diazide sulfonyl compounds. Any o-naphthoquinone 
diazide sulfonyl compound used in making photoresist sensitizers may be 
employed herein. The most preferred o-naphthoquinone diazide sulfonyl 
ester moieties are derived from 
3-diazo-3,4-dihydro-4-oxonaphthalene--sulfonic acid chloride (also known 
as 1,2-naphthoquinone-(2)-diazo-4-sulfonic acid chloride or Diazo M) or 
6-diazo-5,6-dihydro-5-oxonaphthalene-1-sulfonic acid chloride (also known 
as 1,2-napthaquinone-(2)-diazo-5-sulfonic acid chloride or Diazo L). These 
4- and 5-ester groups or moieties respectively have the following chemical 
formulae (A) and (B): 
##STR6## 
It is understood that the present invention covers the use of 
o-naphthoquinone diazide sulfonyl moieties singly or in mixtures in the 
condensation reaction with these triphenolcyclohexane compounds. Also, the 
present invention encompasses separate reactions of these 
triphenolcyclohexane compounds with different o-naphthoquinone diazide 
sulfonyl moieties followed by blending those reaction products together. 
This condensation reaction may be carried under any conventional ester 
condensation conditions. Preferably, these ester compounds of formula (I), 
above, are prepared by first dissolving the sulfonic acid halide 
precursor, preferably, the sulfonic acid chloride, in a suitable solvent. 
Suitable solvents include acetone, dioxane, gamma-butyrolactone, methylene 
chloride, tetrahydrofurfural alcohol and the like. The phenolic 
derivatives of 4-(4-hydrophenyl) cyclohexanone is then added to this 
solution. It is advantageous to carry out this reaction in the presence of 
an acid-scavenging base, such as alkali metal carbonates or bicarbonates, 
alkaline earth metal carbonates or bicarbonates, tertiary aliphatic amines 
or pyridine or pyridine derivatives. 
The esterification products of this reaction may be recovered from the 
reaction mixture by any conventional means, preferably by precipitation 
into acidified water, followed by filtration and drying. 
The preferred photoactive compounds (sometimes known as "sensitizers") are 
those made from the preferred phenolic derivatives of 
4-(4-hydroxyphenyl)cyclohexanone precursors mentioned above, namely, 
1,1,4-tris(4-hydroxyphenyl) cyclohexanone. This preferred photoactive 
compound has formula (II) as follows: 
##STR7## 
In these photoactive compounds, the D is most preferably 
3-diazo-3,4-dihydro-4-oxonaphthalene-1-sulfonyl; 
6-diazo-5,6-dihydro-5-oxonaphthalene-1-sulfonyl or hydrogen with the 
proviso that at least two of the D's are one or both of said sulfonyl 
moieties. 
At least one of the ester compounds of the present invention may be mixed 
with an alkali-soluble resin or resins to make radiation sensitive 
mixtures which are useful as positive-working photoresist compositions. 
The term "alkali-soluble resin" is used herein to mean a resin which will 
dissolve completely in an aqueous alkaline developing solution 
conventionally used with positive-working photoresist compositions. 
Suitable alkali-soluble resins include phenol-formaldehyde novolak resins, 
cresol-formaldehyde novolak resins, and polyvinyl phenol resins, 
preferably having a molecular weight of about 500 to about 40,000, and 
more preferably from about 800 to 20,000. These novolak resins are 
preferably prepared by the condensation reaction of phenol or cresols with 
formaldehyde and are characterized by being light-stable, water-insoluble, 
alkali-soluble and film-forming. The most preferred class of novolak 
resins is formed by the condensation reaction between a mixture of meta- 
and para-cresols with formaldehyde having a molecular weight of about 
1,000 to about 10,000. The preparation of examples of such suitable resins 
is disclosed in U.S. Pat. Nos. 4,377,631; 4,529,682; and 4,587,196, all 
which issued to Medhat Toukhy and are incorporated herein by references in 
their entireties or with U.S. patent application Ser. No. 07/713,891, 
which was filed by Charles Ebersole on Jun. 12, 1991. 
Other photoactive compounds may also be added to the radiation sensitive 
mixtures of the Present invention. These other photoactive compounds may 
include o-quinonediazide esters derived from polyhydric phenols, 
alkyl-polyhydroxyphenones, arylpolyhydroxyphenones, and the like which can 
contain up to six or more sites for esterification. The most preferred 
o-quinonediazide esters are derived from 
3-diazo-3,4-dihydro-4-oxonaphthalene--sulfonic acid chloride and 
6-diazo-5,6-dihydro-5-oxonaphthalene-1-sulfonic acid chloride. When other 
photoactive compounds are used in radiation sensitive mixtures besides the 
photoactive compounds of the present invention, the amount of photoactive 
compounds of the present invention should be at least about 5% by weight, 
preferably 10-100% by weight of the total photoactive compounds present. 
The proportion of the photoactive compound in the radiation sensitive 
mixture may preferably range from about 5 to about 30%, more preferably 
from about 8 to about 20% by weight of the nonvolatile (e.g., nonsolvent) 
content of the radiation sensitive mixture. The proportion of total binder 
resin of this present invention in the radiation sensitive mixture may 
preferably range from about 70 to about 95%, more preferably, from about 
80 to 92% of the nonvolatile (e.g. excluding solvents) solids content of 
the radiation sensitive mixture. 
These radiation sensitive mixtures may also contain conventional 
photoresist composition ingredients such as solvents, actinic and contrast 
dyes, anti-striation agents, plasticizers, speed enhancers, and the like. 
These additional ingredients may be added to the binder resin and 
photoactive compound before the solution is coated onto the substrate. 
The resins and sensitizers may be dissolved in a solvent or solvents to 
facilitate their application to the substrate. Examples of suitable 
solvents include methoxyacetoxy propane, ethyl cellosolve acetate, n-butyl 
acetate, ethyl lactate, ethyl 3-ethoxy propionate, 
methyl-3-methoxypropionate propylene glycol alkyl ether acetates, or 
mixtures thereof and the like. Cosolvents such as xylene or n-butylacetate 
may also be used. The preferred amount of solvent may be from about 50% to 
about 500%, or higher, by weight, more preferably, from about 100% to 
about 400% by weight, based on combined resin and sensitizer weight. 
Actinic dyes help provide increased resolution on highly reflective 
surfaces by inhibiting back scattering of light off the substrate. This 
back scattering causes the undesirable effect of optical notching, 
especially on a highly reflective substrate topography. Examples of 
actinic dyes include those that absorb light energy at approximately 
400-460 nm [e.g Fat Brown B (C.I. No. 12010); Fat Brown RR (C.I. No. 
11285); 2-hydroxy-1,4-naphthoquinone (C.I. No. 75480) and Quinoline Yellow 
A (C.I. No. 47000)] and those that absorb light energy at approximately 
300-340 nm [e.g. 2,5-diphenyloxazole (PPO-Chem. Abs. Reg. No. 92-71-7) and 
2-(4-biphenyl)-6-phenyl-benzoxazole (PBBO-Chem. Abs. Reg. No. 
17064-47-0)]. The amount of actinic dyes may be up to ten percent weight 
levels, based on the combined weight of resin and sensitizer. 
Contrast dyes enhance the visibility of the developed images and facilitate 
pattern alignment during manufacturing. Examples of contrast dye additives 
that may be used together with the radiation sensitive mixtures of the 
present invention include Solvent Red 24 (C.I. No. 26105), Basic Fuchsin 
(C.I. 42514), Oil Blue N (C.I. No. 61555) and Calco Red A (C.I. No. 26125) 
up to 10% weight levels, based on the combined weight of resin and 
sensitizer. 
Anti-striation agents or leveling agents level out the resist coating or 
film to a uniform thickness. In other words, the leveling agent is used to 
eliminate the formation of striations on the surface of the resist coating 
once the coating is spun onto the substrate surface. Anti-striation agents 
may be used up to 5% weight levels, based on the weight of solids in the 
resist formulation. One suitable class of anti-striation agents is 
nonionic silicon-modified polymers. A preferred one is TROYKYD 366 made by 
Troy Chemical Co., Newark, N.J. Another suitable class of anti-striation 
agents is fluoroaliphatic polymeric ester surfactants. A preferred one is 
FC-430 FLUORAD made by 3M of St. Paul, Minn. Nonionic surfactants may also 
be used for this purpose, including, for example nonylphenoxy 
poly(ethyleneoxy) ethanol; octylphenoxy (ethyleneoxy) ethanol; and dinonyl 
phenoxy poly(ethyleneoxy) ethanol; polyoxyethylene lauryl ether; 
polyoxyethylene oleyl ether; polyoxyethylene octylphenyl ether; 
polyoxyethylene nonylphenyl ether; polyoxyethylene glycol dilaurate; and 
polyoxyethylene glycol distearate. Also may be useful are orgnosiloxane 
polymers and acrylic acid-containing or methacrylate acid-containing 
polymers. 
Plasticizers improve the coating and adhesion properties of the photoresist 
composition and better allow for the application of a thin coating or film 
of photoresist which is smooth and of uniform thickness onto the 
substrate. Plasticizers which may be used include, for example, phosphoric 
acid tri-(B-chloroethyl)-ester; stearic acid; dicamphor; polypropylene; 
acetal resins; phenoxy resins; and alkyl resins up to ten percent weight 
levels, based on the combined weight of resin and sensitizer. 
Speed enhancers tend to increase the solubility of the photoresist coating 
in both the exposed and unexposed areas, and thus, they are used in 
applications where speed of development is the overriding consideration 
even though some degree of contrast may be sacrificed, i.e., in positive 
resists while the exposed areas of the photoresist coating will be 
dissolved more quickly by the developer, the speed enhancers will also 
cause a larger loss of photoresist coating from the unexposed areas. Speed 
enhancers that may be used include, for example, picric acid, nicotinic 
acid or nitrocinnamic acid, as well as poly(monohydric)phenolic compounds 
at weight levels of up to 20%, based on the combined weight of resin and 
sensitizer. 
The prepared radiation sensitive resist mixture, can be applied to a 
substrate by any conventional method used in the photoresist art, 
including dipping, spraying, whirling and spin coating. When spin coating, 
for example, the resist mixture can be adjusted as to the percentage of 
solids content in order to provide a coating of the desired thickness 
given the type of spinning equipment and spin speed utilized and the 
amount of time allowed for the spinning process. Suitable substrates 
include silicon, aluminum or polymeric resins, silicon dioxide, doped 
silicon dioxide, silicon resins, gallium arsenide, silicon nitride, 
tantalum, copper, polysilicon, ceramics and aluminum/copper mixtures. The 
coating surfaces of these substrates may or may not be primed with a 
conventional adhesion promoter (e.g. hexamethyldisilazane) before the 
photoresist coating is applied. 
The photoresist coatings produced by the above described procedure are 
particularly suitable for application to silicon wafers coated with a 
silicon dioxide or silicon nitride layer such as are utilized in the 
production of microprocessors and other miniaturized integrated circuit 
components. An aluminum or aluminum-coated substrates may be used as well. 
The substrate may also comprise various polymeric resins especially 
transparent polymers such as polyesters and polyolefins. 
After the resist solution is coated onto the substrate, the coated 
substrate is baked at approximately 70.degree. C. to 125.degree. C. until 
substantially all the solvent has evaporated and only a uniform radiation 
sensitive coating remains on the substrate. 
The coated substrate can then be exposed to radiation, especially 
ultraviolet radiation, in any desired exposure pattern, produced by use of 
suitable masks, negatives, stencils, templates, and the like. Conventional 
imaging process or apparatus currently used in processing 
photoresist-coated substrates may be employed with the present invention. 
While ultraviolet (UV) light is the preferred source of radiation, other 
sources of radiation such as visible light, electron or ion beam and X-ray 
radiant energy may be used instead. 
The exposed resist-coated substrates are preferably subjected to a post 
exposure bake at a temperature from about 100.degree. C. to about 
130.degree. C. from about 30-300 seconds to enhance image quality and 
resolution. 
The exposed resist-coated substrates are next developed in an aqueous 
alkaline solution. This solution is preferably agitated, for example, by 
nitrogen gas. Examples of aqueous alkaline developers include aqueous 
solutions of tetramethylammonium hydroxide, sodium hydroxide, potassium 
hydroxide, ethanolamine, choline, sodium phosphates, sodium carbonate, 
sodium metasilicate, and the like. The preferred developers for this 
invention are aqueous solutions of either alkali metal hydroxides, 
phosphates or silicates, or mixtures thereof, or tetramethylammonium 
hydroxide. 
Alternative development techniques such as spray development or puddle 
development, or combinations thereof, may also be used. 
The substrates are allowed to remain in the developer until all of the 
resist coating has dissolved from the exposed areas. Normally, development 
times from about 10 seconds to about 3 minutes are employed. 
After selective dissolution of the coated wafers in the developing 
solution, they are preferably subjected to a deionized water rinse to 
fully remove the developer or any remaining undesired portions of the 
coating and to stop further development. This rinsing operation (which is 
part of the development process) may be followed by blow drying with 
filtered air to remove excess water. A post-development heat treatment or 
bake may then be employed to increase the coating's adhesion and chemical 
resistance to etching solutions and other substances. The post-development 
heat treatment can comprise the baking of the coating and substrate below 
the coating's thermal deformation temperature. 
In industrial applications, particularly in the manufacture of 
microcircuitry units on silicon/silicon dioxide-type substrates, the 
developed substrates may then be treated with a buffered hydrofluoric acid 
etching solution or plasma gas etch. The resist compositions of the 
present invention are believed to be resistant to a wide variety of acid 
etching solutions or plasma gases and provide effective protection for the 
resist-coated areas of the substrate. 
Later, the remaining areas of the photoresist coating may be removed from 
the etched substrate surface by conventional photoresist stripping 
operations.

The present invention is further described in detail by means of the 
following Examples. All parts and percentages are by weight unless 
explicitly stated otherwise. 
EXAMPLE 1 
Preparation of 1,1,1-tris(4-hydroxyphenyl)cyclohexanone 
The reaction was conducted in a 500 mL three-neck round bottom flask fitted 
with a mechanical stirring apparatus, a thermometer, and a reflux 
condenser. 
The 4-(4-hydroxyphenyl)cyclohexanone (40.0 g, 0.2102 mole) and molten 
phenol (158.4 g, 1.68 mole) were added to the flask. The flask and 
contents were placed in a 45.degree.-50.degree. oil bath and stirring was 
begin. The methane sulfonic acid (96.10 g, 0.631 mole) was added to the 
reaction flask which caused the internal reaction temperature to rise to 
60.degree. C. The flask and contents were allowed to stir 3 hours in the 
heated oil bath and allowed to cool to room temperature. 
The contents of the flask were poured into 1,500 mL of 
50.degree.-60.degree. C. water with stirring and allowed to stir for 15 
minutes. The water layer was decanted and the gummy mass was treated once 
more with hot water in the above manner. The product mass was removed from 
the reaction flask. 
The solid was triturated under water and isolated by filtration. It was 
dissolved in 200 mL methanol and precipitated into 3,000 mL of deionized 
water and isolated by filtration. The product was dried to constant weight 
under high vacuum at 60.degree. C., weight 45 g (61.7%). 
EXAMPLE 2 
Esterification of the product of Example 1 with 1.8 Moles of 
6-Diazo-5.6-dihydro-5-oxonaphthalene-1-Sulfonic Acid Chloride (1.8 TPCH) 
The reaction was conducted in a one liter amber three-neck flask fitted 
with a mechanical stirring apparatus, pressure equalizing addition funnel, 
and a thermometer. 
The tris 1,1,4-(4-hydroxyphenyl)cyclohexane (10.93 g, 0.03 mole) and 
6-diazo-5,6-dihydro-5-oxonaphthalene-1-sulfonic acid chloride (14.51 g, 
0.0540 mole) and 350 mL of gamma-butyrolactone were added to the flask. 
The stirring was begun and after the substrate had dissolved, a solution 
of triethylamine (6.01 g, 0.0594 mole) and acetone (18 mL) was added over 
13 minutes. The reaction temperature rose to 22.degree. C. from 18.degree. 
C. during addition. The solution was allowed to stir one hour at room 
temperature after addition was completed. 
The reaction solution was poured into a stirred solution of 2,000 mL 
deionized water and 15 g acetic acid. The yellow precipitate was isolated 
by filtration and reslurried in 2L of deionized water. The solid was 
isolated by filtration and washed with 2L of deionized water. The yellow 
presscake was protected from light and dried at atmospheric pressure and 
ambient temperature and high vacuum at 40.degree. C., weight 21.6 g. 
The yellow solid was subjected to HPLC assay using phosphate buffer and 
acetonitrile according to the following program; elution with 50/50 
phosphate buffer acetonitrile for one minute. Change to 30/70 buffer 
acetonitrile in a linear manner over 25 minutes, and elution for 22 
minutes with the 30/70 mixture. The column is a 3 micron 5.times.150 mm 
Supelcosil C-18 system with a flow rate of 1 mL/min. Reported are the 
retention time and (area percent) for all peaks two area percent or 
greater: 12.3 (2.5); 17.8 (9.1); 22.6 (5.4); 23.1 (5.3) 28.5 (2.1); 32.2 
(14.5); 34.6 (25.3); 35.2 (3.9); 40.5 (2.3); 42.6 (2.0). 
EXAMPLE 3 
Esterification of the Product of Example 1 with 2.25 Moles of 
6-Diazo-5,6-dihydro-5-oxonaphthalene-1-Sulfonic Acid Chloride (2.25 TPCH) 
The reaction was performed in a one liter three-neck amber flask fitted 
with a pressure equalizing addition funnel, thermometer, and mechanical 
stirring apparatus. 
The tris 1,1,4-(4-hydroxyphenyl)cyclohexane (10.93 g, 0.03 mole) and 
6-diazo-5,6-dihydro-5-oxonaphthalene-1-sulfonic acid chloride (18.14 g, 
0.0675 moles) were added to the flask followed by 400 mL of 
gamma-butyrolactone and stirring was begin. After the solids had 
completely dissolved, a solution of triethylamine (7.51 g, 0.0742 mole) in 
acetone (22 mL) was added to the solution over 13 minutes. During 
addition, the temperature rose to 27.degree. C. from 20.degree. C. After 
addition was completed, the solution was allowed to stir for one hour at 
ambient temperature. 
The hazy mixture was poured into a stirred solution of 2,200 mL deionized 
water and 18 g acetic acid which produced a yellow precipitate. The 
precipitate was isolated by filtration and reslurried in 2 L of deionized 
water for about 30 minutes. The solid was isolated by filtration, and it 
was washed in portions with 2 L of deionized water. The yellow solid was 
protected from light and dried at atmospheric pressure at ambient 
temperature and high vacuum at 40.degree. C., weight 26.4 g. 
A sample of the solid was subjected to HPLC assay as described in the 
previous example and the retention time and (area percent) of the peaks 
greater than two area percent are reported; 17.8 (7.0); 22.56 (2.8); 23.0 
(2.7); 32.21 (20.6); 37.3 (34.6); 35.22 (6.2). 
EXAMPLE 4 
20% , 1.8 TPCH, 16% Speed Enhancer 
9.1 Grams of an STN novolak (having a dissolution time of 300 
seconds/micron in 0.262N aqueous developer of tetramethylammonium 
hydroxide (TMAH)) were dissolved in 36.61 g of methyl-3-methoxypropionate 
(MMP). 2.71 Grams of TPCH esterified at a ratio of 1.8 to 1 and 1.73 g 
of 1,3,3,5-tetrakis(4-hydroxyphenyl) pentane speed enhancer were dissolved 
in the novolak solution. 0.015 Grams of a leveling agent known 
commercially as FC-430 were added .to this resist. The resist solution was 
microfiltered through 0.2 um pore size filter to remove any particulate 
contamination. The final solids content of the resist is 27%. 
The STN novolak was prepared by condensing a mixture of substituted phenols 
with formaldehyde according to general procedure set forth in U.S. patent 
application Ser. No. 07/713,891 filed by Charles E. Ebersole on Jun. 19, 
1991. The phenolic composition of this novolak is 20% p-cresol (as 
dimers), 50% 2,3-dimethylphenol, 20% 2,3,5-trimethylphenol, 8% 
2,6-dimethylphenol, and 2% o-cresol. 
EXAMPLE 5 
18% , 1.8 TPCH, 16% Speed Enhancer 
9.3 Grams of the same novolak STN (having a dissolution time of 300 
seconds/micron in 0.262N aqueous developer of tetramethylammoniumhydroxide 
(TMAH)) were dissolved in 36.5 g of methyl-3-methoxypropionate (MMP). 2.43 
Grams of the TPCH esterified at a ratio of 1.8 to 1 and 1.77 g of 
1,3,3,5-tetrakis(4-hydroxyphenyl)-pentane speed enhancer were dissolved in 
the novolak solution. 0.015 Grams of the FC-430 leveling agent was added 
to this resist. The resist solution was microfiltered through 0.2 um pore 
size filter to remove any particulate contamination. The final solids 
content of the resist is 27%. 
EXAMPLE 6 
20% , 1.8 TPCH, 18% Speed Enhancer 
8.86 Grams of the same STN novolak were dissolved in 36.5 g of 
methyl-3-methoxypropionate (MMP). 2.7 Grams of the TPCH esterified at 
a ratio of 1.8 to 1 and 1.944 g of 1,3,3,5-tetrakis(4-hydroxyphenyl) 
pentane speed enhancer were dissolved in the novolak solution. 0.015 Grams 
of the FC-430 leveling agent were added to this resist. The resist 
solution was microfiltered through 0.2 um pore size filter to remove any 
particulate contamination. The final solids content of the resist is 27%. 
EXAMPLE 7 
20% , 2.25 TPCH, 16% Speed Enhancer 
8.3 Grams of the same STN novolak were dissolved in 36.5 g of 
methyl-3-methoxypropionate. 2.47 Grams of the TPCH esterified at a 
ratio of 2.25 to 1 and 1.58 g of 1,3,3,5-tetrakis(4-hydroxyphenyl) pentane 
speed enhancer were dissolved in the novolak solution. 0.0137 Grams of the 
FC-430 leveling agent were added to this resist. The resist solution was 
microfiltered through 0.2 um pore size filter to remove any particulate 
contamination. The final solids content of the resist is 27%. 
EXAMPLE 8 
16% , 2.25 TPCH, 16% Speed Enhancer 
9.53 Grams of the same STN novolak were dissolved in 36.5 g of 
methyl-3-methoxypropionate (MMP). 2.16 Grams of TPCH esterified at a 
ratio of 2.25 to 1 and 1.81 g of 1,3,3,5-tetrakis(4-hydroxyphenyl) pentane 
speed enhancer were dissolved in the novolak solution. 0.015 Grams of the 
FC-430 leveling agent were added to this resist. The resist solution was 
microfiltered through 0.2 um pore size filter to remove any particulate 
contamination. The final solids content of the resist is 27%. 
EXAMPLE 9 
18% , 2.25 TPCH, 20% Speed Enhancer 
8.856 Grams of the same STN novolak were dissolved in 36.5 g of 
methyl-3-methoxypropionate (MMP). 2.43 Grams of TPCH esterified at a 
ratio of 2.25 to 1 and 2.214 g of 1,3,3,5-tetrakis(4-hydroxyphenyl) 
pentane speed enhancer were dissolved in the novolak solution. 0.015 Grams 
of the FC-430 leveling agent were added to this resist. The resist 
solution was microfiltered through 0.2 um pore size filter to remove any 
particulate contamination. The final solids content of the resist is 27%. 
EXAMPLE 10 
20% , 1.8 TPCM, 20% Speed Enhancer 
8.64 Grams of the same STN novolak were dissolved in 36.4852 grams 
methyl-3-methoxypropionate (MMP). 2.7 Grams of the TPCH esterified at 
the ratio of 1.8 to 1 and 2.16 g of 1,3,3,5-tetrakis(4-hydroxyphenyl) 
pentane were dissolved in the novolak solution. 0.015 Grams of the FC-430 
leveling agent were added to this resist. The resist solution was 
microfiltered through 0.2 um pore size filter to remove any particulate 
contamination. The final solids content of the resist is 27%. 
COMATIVE EXAMPLE 1 
20% , 17% Speed Enhancer 
8.964 Grams of the same STN novolak were dissolved in 36.5 g of 
methyl-3-methoxypropionate (MMP). 0.54 Grams of a 3-TPM esterified at 
a ratio of 2.6 to 1, and 2.16 g of 4-TPM esterified at a ratio of 2.8 
to 1, and 1.836 g of 1,3,3,5-tetrakis(4-hydroxyphenyl)-pentane speed 
enhancer were dissolved in the novolak solution. 0.015 Grams of the FC-430 
leveling agent were added to this resist. The resist solution was 
microfiltered through 0.2 um pore size filter to remove any particulate 
contaminants. The final solids content of the resist is 27%. 
The 3-TPM is the product of esterifying about 2.6 moles of 
2,1-diazonaphthoquinone-5-sulfonyl chloride (DNQ) with one mole of 
bis-[3,5-dimethyl-4-hydroxyphenyl]-3-methoxy-4-hydroxyphenyl methane. The 
4-TPM is the product of esterifying about 2.24 moles of DNQ with one 
mole of bis-[3,5-dimethyl-4-hydroxyphenyl]-3,4-dihydroxyphenyl methane. 
COMATIVE EXAMPLE 2 
20% , 18.5% Speed Enhancer 
8.8 Grams of the same STN novolak were dissolved in 36.5 grams of 
methyl-3-methoxypropionate (MMP). 1.35 Grams of 3-TPM and 1.35 g of 
the 4-TPM ester, and 1.998 g of 
1,3,3,5-tetrakis(4-hydroxyphenyl)-pentane speed enhancer were dissolved in 
the novolak solution. 0.015 Grams of the FC-430 leveling agent were added 
to this resist. The resist solution was microfiltered through 0.2 um pore 
size filter to remove any particulate contaminants. The final solids 
content of the resist is 27%. 
COMATIVE EXAMPLE 3 
16% , 10% Speed Enhancer 
10.21 Grams of the same STN novolak were dissolved in 36.5 grams of 
methyl-3-methoxypropionate (MMP). 0.432 Grams of the 4-TPM and 1.728 g 
of the 3-TPM , and 1.134 g of 1,3,3,5-tetrakis(4-hydroxyphenyl)-pentane 
speed enhancer were dissolved in the novolak solution. 0.015 Grams of the 
FC-430 leveling agent were added to this resist. The resist solution was 
microfiltered through 0.2 um pore size filter to remove any particulate 
contaminants. The final solids content of the resist is 27%. 
COMATIVE EXAMPLE 4 
22% , 20% Speed Enhancer 
8.42 Grams of the same STN novolak were dissolved in 36.5 g of 
methyl-3-methoxypropionate (MMP). 0.594 Grams of the 4-TPM and 2.376 g 
of the 3-TPM , and 2.1 g of 1,3,3,5-tetrakis(4-hydroxyphenyl)-pentane 
speed enhancer were dissolved in the novolak solution. 0.015 Grams of the 
FC-430 leveling agent were added to this resist. The resist solution was 
microfiltered through 0.2 um pore size filter to remove any particulate 
contaminants. The final solids content of the resist is 27%. 
RESIST PROCESSING 
Resist samples were spin coated on 4" silicon wafers and soft baked at 
90.degree. C. for one minute. The spin speed of the spinner was adjusted 
for each sample to produce equal resist film thickness of 0.99 um. The 
resist coatings were exposed to i-line radiation of different energies 
using a Cannon 0.52NA i-line Stepper Model No. FPA-2000il. Post exposure 
bake was carried out at 120.degree. C. for one minute. An SVG track 
developer unit was used to develop the resist using 0.262N aqueous TMAH 
developer for 60 seconds followed by D.I. water rinse. 
RESIST CONTRAST TEST 
This preliminary test was used to characterize and compare resist 
performances. In this test, the resist was exposed to 50 different 
exposure energies ranging from 20 to 161 mJ/Cm.sup.2. After development, 
each area of different exposure is measured for remaining resist film 
thickness using prometrix optical measuring unit. The resist contrast is 
the slope of the line connecting all the points relating log dose and 
normalized remaining film thickness. The higher the slope, the higher the 
resist contrast. 
______________________________________ 
Results 
Resist Contrast Eo mJ/Cm.sup.2 
______________________________________ 
Example 4 5.8 144 
Example 5 6.1 146 
Example 6 6.7 120 
Example 7 Did not develop, too slow 
Example 8 4.6 165 
Example 9 5.4 165 
Example 10 4.3 128 
Comparative 
Examples 
1 3.7 86 
2 4.3 110 
3 1.73 101 
4 3.54 129 
______________________________________ 
LITHOGRAPHIC RESULTS 
The lithographic results for resist Examples 5, 6, and 10 are shown in 
Table 1. 
TABLE 1 
______________________________________ 
Ex- % % 
ample SE Gamma Eo Resolution 
DOF* .sup.E opt 
______________________________________ 
5 18 16 6.10 146 0.40 1.5 290 
6 20 18 6.70 120 0.37 2.1 270 
10 20 20 4.30 128 0.40 2.1 240 
C-1 20 17 3.7 86 0.36 1.8 190 
C-2 20 18.5 4.3 110 0.39 1.6 220 
C-3 16 10 1.73 101 0.55 0 130 
C-4 22 20 3.54 129 0.45 0.7 280 
______________________________________ 
*For 0.5 micron line/space features. 
The resists of the present invention exhibit high contrast performance, 
good resolution, and high defocus performance as shown above. In 
particular, the resists of the present invention showed particularly high 
gamma values. 
While the invention has been described above with reference to specific 
embodiments thereof, it is apparent that many changes, modifications, and 
variations can be made without departing from the inventive concept 
disclosed herein. Accordingly, it is intended to embrace all such changes, 
modifications, and variations that fall within the spirit and broad scope 
of the appended claims. All patent applications, patents, and other 
publications cited herein are incorporated by reference in their entirety.