US20020045125A1

US20020045125A1 - Non-aromatic chromophores for use in polymer anti-reflective coatings

Info

Publication number: US20020045125A1
Application number: US09/961,751
Authority: US
Inventors: Xie Shao; Robert Cox; Shreeram Deshpande; Tony Flaim; Rama Puligadda
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-11-30
Filing date: 2001-09-24
Publication date: 2002-04-18
Also published as: CN1402840A; WO2001040865A1; AU7602600A; JP2003515793A; US20040067441A1; EP1266264A1; KR20030009326A; JP4831909B2; US7132216B2

Abstract

An improved light attenuating compound for use in the production of microdevices is provided. Broadly, the light attenuating compound is non-aromatic and can be directly incorporated (either physically or chemically) into photolithographic compositions such as bottom anti-reflective coatings (BARC) and contact or via hole fill materials. The preferred non-aromatic compounds of the invention are conjugated aliphatic and alicyclic compounds which greatly enhance the plasma etch rate of the composition. Furthermore, the light attenuating compounds are useful for absorbing light at shorter wavelengths. In one embodiment, the inventive compounds can be polymerized so as to serve as both the polymer binder of the composition as well as the light absorbing constituent.

Description

RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No. 09/450,966 filed Nov. 30, 1999, incorporated by reference herein.[0001]

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is broadly concerned with light attenuating compounds for incorporation into photolithographic compositions (e.g., anti-reflective coatings and contact or via hole fill compositions) utilized in the manufacturing of microdevices. More particularly, the light attenuating compounds are non-aromatic and are especially useful for absorbing light at shorter wavelengths (e.g., 248 nm). The compounds can be physically incorporated into the particular composition, or alternately, can be chemically bonded to a polymer binder already present in the composition. The compounds of the invention comprise conjugated aliphatic and alicyclic moieties which meet the necessary light absorbency requirements for the composition while enhancing the plasma etch rate of the composition when compared to prior art aromatic dyes.

2. Description of the Prior Art

A frequent problem encountered by photoresists during the manufacturing of semiconductor devices is that activating radiation is reflected back into the photoresist by the substrate on which it is supported. Such reflectivity tends to cause blurred patterns which degrade the resolution of the photoresist. Degradation of the image in the processed photoresist is particularly problematic when the substrate is non-planar and/or highly reflective. One approach to address this problem is the incorporation of an anti-reflective dye either into the photoresist layer, into a contact or via hole fill composition, into a bottom anti-reflective coating (BARC), or as a separate layer adjacent the photoresist layer.

Prior art BARC compositions usually contain aromatic anti-reflective dyes which attenuate light that would otherwise reflect from the substrate during photoresist exposure. For example, anthracene and naphthalene derivatives are typically the preferred dyes for use at 248 nm exposing wavelengths. Dyes comprising a benzene ring with at least one conjugated substituent are widely used in BARC's which operate at 365 nm, while dyes comprising a benzene ring without conjugated substituents have ample absorptivity to satisfy most 193 nm applications.

Aromatic dyes have been preferred for BARC applications because of their high light absorbency per unit mass as well as their wide availability, easy preparation, and high chemical stability. While aromatic dyes are useful for achieving high film optical density, they limit the plasma etch rate of the BARC compositions by virtue of their chemical stability. Aromatic dyes require considerably more energy for decomposition than do the polymer binders (which are typically non-aromatic) used in the BARC compositions. As a result, the composite etch rate is highly dependent on the aromatic character of the dyes.

U.S. Pat. No. 4,719,166 to Blevins et al. discloses the use of certain butadienyl dyes in a photoresist layer, an anti-reflective layer, or a planarizing layer for do protecting photoresist elements against reflection of activating radiation from the substrate. However, the dyes of the '166 patent are not attached to the backbone of a polymer binder, thus permitting them to readily solubilize in the photoresist, often leading to pattern degradation. Furthermore, current technology continues to require increasingly complex circuitry be imprinted on chips of decreasing size. These smaller chips require shorter wavelengths (e.g., 248 nm) be used during photoresist exposure. The dyes of the '166 patent are useful for absorbing light only at 365 nm exposure wavelengths, making them unsuitable for use in the manufacturing of most current microdevices.

There is a need for a compound which can effectively attenuate light at shorter wavelengths and which does not inhibit the etch rate of the particular BARC or contact or via hole fill composition in which it is utilized.

SUMMARY OF THE INVENTION

The present invention fills this need by providing light attenuating compounds for BARC compositions, contact or via hole fill compositions, and other microdevice manufacturing compositions which do not inhibit the etch rate of the composition. Furthermore, the inventive compounds are useful for absorbing light at shorter wavelengths.

In more detail, the light attenuating compounds are non-aromatic and can be formulated to absorb light at the desired wavelength. Advantageously, the compounds are also useful for absorbing light at wavelengths of less than about 300 nm, and preferably less than about 250 nm (e.g., for 248 nm applications).

As used herein, non-aromatic refers to compounds or moieties of compounds which either:

(1) do not include a benzene ring; or

(2)

(a) have non-planar carbon skeletons; and

(b) do not contain (4n+2) π electrons, where n=0, 1, 2, 3, etc. (i.e., do not obey Hückel's Rule as described in Solomons, T. W.

Graham, Fundamentals of Organic Chemistry, 3rd ed., John Wiley & Sons, Inc. (1990)).

The light attenuating compounds of the invention comprise moieties having general structural formulas (set forth in detail below). Preferably, these compounds include one or more reactive groups selected from the group consisting of COOH, OH, CONH ₂, CONHR, CH₂X groups, and mixtures thereof, where R is selected from the group consisting of hydrogen, alkyls (preferably C₁-C₄branched and unbranched), and heteroalkyls, and X is a halogen.

The light attenuating compounds can be incorporated into the particular photolithographic composition either physically (i.e., as a mixture) or by chemically attaching the light attenuating compound to the polymer binder or resin present in the composition (either to a functional group on the binder or directly to the backbone of the binder). In situations where the light attenuating compound is attached to the polymer binder, a linkage unit can be used as an intermediate for securing the light attenuating compound to the binder. That is, the light attenuating compound can be attached to a linkage unit which in turn is attached to the polymer binder (either to a functional group on the binder or to the binder backbone). Examples of suitable linkage units are those which comprise a moiety selected from the group consisting of alkyls (preferably C ₁-C₄branched and unbranched), acyclic heteroalkyls, non-aromatic cyclic alkyls (preferably C₃-C₆) and non-aromatic cyclic heteroalkyls.

In another embodiment, the light attenuating compounds can be polymerized alone so as to directly form the polymer binder utilized in the particular photolithographic composition while simultaneously acting as a light absorber. Thus, in these applications an additional polymer binder would not be necessary.

In applications where a polymer binder other than the light attenuating compound is present in the composition, the binder should be dissolved in a solvent system (either single or multiple solvents). The particular polymer binders and solvent systems utilized are readily ascertainable by those skilled in the art. Examples of suitable polymer binders include polyesters, polyacrylates, polyheterocyclics, polyetherketones, polyhydroxystyrene, polycarbonates, polyepichlorohydrin, polyvinyl alcohol, oligomeric resins (such as crown ethers, cyclodextrins, epoxy resins), and mixtures of the foregoing. Examples of preferred solvents for use in the solvent system include alcohols, ethers, glycol ethers, amides, esters, ketones, water, propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA), ethyl lactate, and PCBTF (p-chlorobenzotrifluoride).

Incorporating light attenuating compounds into photolithographic compositions in accordance with the invention will not increase the etch rate of the composition as is the case with prior art compositions comprising aromatic dyes. Thus, when practicing the instant invention, the etch rate of the photolithographic composition will be at least about 4000 Å/minute, where a mixture of HBr and O ₂is the etchant gas.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the inventive light attenuating compounds broadly include non-aromatic dyes, and particularly non-aromatic dyes which absorb light at shorter wavelengths, in preferred embodiments the compounds include one or more of the following moieties.

Generally speaking, the light attenuating compounds should include at least one double bond in conjugation with at least one electron-withdrawing group (EWG). One such structure is shown below in Formula I.

where:

each R ₁is non-aromatic and may individually be hydrogen, or an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl;

in structure A, where EWG and R ₂do not form a cyclic unit:

EWG is a non-aromatic electron-withdrawing group such as a carbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group; and

R ₂is non-aromatic and may be hydrogen, an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, or an electron-withdrawing group such as a carbonyl, imino, cyano, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group;

in structure B, where EWG and R ₂form a cyclic electron-withdrawing unit, the cyclic unit preferably comprises a C═O, C═S, or a C═N at a first carbon atom, and: a C═O or a C═N attached to a carbon atom at least two carbon atoms away from the first carbon atom; or an O, S, or N as a member of the ring at least two positions away from the first carbon atom; and

(1) and (2) refer to the respective double-bonded carbon atoms.

Examples of particularly preferred structures B of Formula I where EWG and R ₂form a cyclic electron-withdrawing unit include the following:

where R ₁is non-aromatic and may individually be hydrogen, or an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl.

In another embodiment, the light attenuating compounds include at least one EWG across a double bond from an electron donating group (EDG) as shown in Formula II.

Formula II:

where:

R ₁is non-aromatic and may individually be hydrogen, or an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₁-C₆) alkyl or heteroalkyl;

EDG is an electron-donating group such as H ₃CO—, —OH, or R_xR_yN—, where each of R_xand R_yis non-aromatic and may individually be hydrogen, or an acyclic (preferably C₁-C₂) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl;

in structure A, where EWG and R ₂do not form a cyclic unit:

(1) and (2) refer to the respective double-bonded carbon atoms.

Examples of particularly preferred structures B of Formula II where EWG and R ₂form a cyclic electron-withdrawing unit include the following:

In another embodiment, the light attenuating compounds include two conjugated double bonds in series with at least one EWG (see Formula III) or with two EWG's (see Formula IV). The structures shown in Formulas III and IV are particularly useful at 248 nm or 365 nm wavelength applications, depending upon the selection of R and EWG.

Formula III:

where:

in structure A, where EWG and R ₂do not form a cyclic unit:

(1)-(4) refer to the respective double-bonded carbon atoms.

Examples of particularly preferred structures B of Formula III where EWG and R ₂form a cyclic electron-withdrawing unit include the following:

Formula IV:

where:

(1)-(4) refer to the respective double-bonded carbon atoms.

In another embodiment the light attenuating compounds include an EWG coupled with an EDG across a conjugated double bond system. An example of this structure is shown in Formula V.

Formula V:

where:

EDG is an electron-donating group such as H ₃CO—, —OH, or R_xR_y,N—, where each of R_xand R_yis non-aromatic and may individually be hydrogen, or an acyclic (preferably C₁-C₂) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl;

in structure A, where EWG and R ₂do not form a cyclic unit:

EWG is a non-aromatic electron-withdrawing group (other than cyano groups) such as a carbonyl, imino, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group, and R ₂is non-aromatic and may be hydrogen, an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, or an electron-withdrawing group such as a carbonyl, imino, cyano, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group; or

EWG is a cyano group, and R ₂is non-aromatic and may be hydrogen, or an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl;

(1)-(4) refer to the respective double-bonded carbon atoms.

Examples of particularly preferred structures B of Formula V where EWG and R ₂form a cyclic electron-withdrawing unit include the following:

Of course, those skilled in the art will appreciate that light attenuating compounds in accordance with the invention can include mixtures of the foregoing Formulas I-V in the particular photolithographic composition.

In another embodiment, the foregoing structures can be dimerized to form new compositions which are preferably incorporated into photolithographic compositions to absorb light, thus minimizing or eliminating the reflectance from the substrate. These dimerized structures are shown in Formulas VI-VIII.

Formulas VI:

where:

each R ₁is non-aromatic and may individually be hydrogen, or an X's acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl;

each R ₃may individually be R₁or

where each R ₁is non-aromatic and may individually be hydrogen, or an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, and where the (*) represents the double-bonded carbon atom (1) or (4);

each EWG is a non-aromatic electron-withdrawing group such as a carbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group;

each R ₂is non-aromatic and may individually be hydrogen, an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, or an electron- withdrawing group such as a carbonyl, imino, cyano, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group;

R ₄is a divalent, non-aromatic-containing bridging group such as —(CH₂)_n—, dimethylenecyclohexyl (—CH₂-C₆H₄-CH₂-), —CH₂CH₂—O—CH₂CH₂—, or other acyclic (preferably C₁-C₄, branched or unbranched) or cyclic (preferably C₅-C₆) alkyls or heteroalkyls; and

(1)-(4) refer to the respective double-bonded carbon atoms.

Formulas VII:

where:

each R ₃may individually be EDG, or

where each R ₁is non-aromatic and may individually be hydrogen, or an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl; EDG is an electron-donating group such as H₃CO—, —OH, or R_xR_yN—, where each of R_xand R_yis non-aromatic and may individually be hydrogen, or an acyclic (preferably C₁-C₂) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl; and where the (*) represents the double-bonded carbon atom (1) or (4);

R ₄is a divalent, non-aromatic-containing bridging group such as —(CH₂)_n—, dimethylenecyclohexyl (—CH₂-C₆H₄-CH₂—), —CH₂CH₂—O—CH₂CH₂—, or other acyclic (preferably C₁-C₄, branched or unbranched) or cyclic (preferably C₅-C₆) alkyls or heteroalkyls;

each EWG is a non-aromatic electron-withdrawing group such as a carbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group; and

(1)-(4) refer to the respective double-bonded carbon atoms.

Formula VIII:

where:

where each R ₃may individually be an EWG,

in structure A of Formula VIII, in situations where R ₃is an EWG or structure C (i.e., EWG and R₂do not form a cycic unit):

each EWG is a non-aromatic electron-withdrawing group (other than cyano groups) such as a carbonyl, imino, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group, and each R ₂is non-aromatic and may individually be hydrogen, an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, or an electron-withdrawing group such as a carbonyl, imino, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group; or

EWG is a cyano group, and each R ₂is non-aromatic and may individually be hydrogen, or an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl;

in structure B of Formula VIII, and in structure A of Formula VIII where R ₃is structure D (i.e., in situations where EWG and R₂form a cyclic electron-withdrawing unit), the cyclic unit preferably comprises a C═O, C═S, or a C═N at a first carbon atom, and: a C═O or a C═N attached to a carbon atom at least two carbon atoms away from the first carbon atom; or an O, S, or N as a member of the ring at least two positions away from the first carbon atom; and

each EDG is an electron-donating group such as —O—, —S—, or

—R ₅N—, where R₅is hydrogen or an acyclic (preferably C₁-C₂) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl;

R ₄is a divalent, non-aromatic-containing bridging group such as —(CH₂)_n—, dimethylenecyclohexyl (—CH₂-C₆H₄-CH₂—), —CH₂CH₂—O—CH₂CH₂—, or other acyclic (preferably C₁-C₄, branched or unbranched) or cyclic (preferably C₅-C₆) alkyls or heteroalkyls; and

(1)-(4) refer to the respective double-bonded carbon atoms.

Examples of particularly preferred structures A of Formula VIII where R ₃is structure D (i.e., so that EWG and R₂form a cyclic electron-withdrawing unit) include the following:

where each R ₁is non-aromatic and may individually be hydrogen, an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, and each R₂is non-aromatic and may individually be hydrogen, an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, or an electron-withdrawing group such as a carbonyl, imino, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group.

Examples of particularly preferred structures B of Formula VIII where EWG and R ₂form a cyclic electron-withdrawing unit include the following:

where R ₁is non-aromatic and may individually be hydrogen, acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, and each R₂is non-aromatic and may individually be hydrogen, an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, or an electron-withdrawing group such as a carbonyl, imino, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group.

In another embodiment, a light attenuating compound is attached to a polymer binder (either directly to the backbone or via a linkage unit) via an EWG. A specific example of one such structure is shown in Formula IX.

Formula IX

where EWG is a non-aromatic electron-withdrawing group such as a carbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group, and each R ₁may individually be hydrogen or an alkyl group (and preferably a methyl group).

One preferred structure of Formula IX wherein the EWG (a carboxyl group) is directly attached to a polymer backbone as shown below.

In another embodiment, two R ₁substituents on a moiety of the light attenuating compound form a cyclic structure such as those shown in Formulas X and XI.

where:

R ₂is non-aromatic and may individually be hydrogen, an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, or an electron-withdrawing group such as a carbonyl, imino, cyano, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group; and EWG is a non-aromatic electron-withdrawing group such as a carbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group.

where:

R ₂is non-aromatic and may individually be hydrogen, an acyclic (preferably C₁-C₄branched or unbranched) or cyclic (preferably C₅-C₆) alkyl or heteroalkyl, or an electron-withdrawing group such as a carbonyl, imino, cyano, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group; and EWG is a non-aromatic electron- withdrawing group such as a carbonyl, cyano, imino, carboxylic acid, carboxylic ester, carboxamido, carboximido, or sulfonyl group.

In yet another embodiment, the disclosed Formulas can be joined to one another to form a polymeric structure for use in a photolithographic composition without the need for an additional polymer binder. That is, the polymerized structures would act as the polymer binder as well as the light absorbing compound. The structures of Formulas I-XI can by polymerized in a linear fashion by creating non-conjugated, non-aromatic linkages between two of the functional groups as shown in the table below.



Formula	Linkages Between:

I	R₁-R₁; R₁-R₂; R₁-EWG; and R₂-EWG
II	R₁-EDG; R₁-EWG; R₁-R₂; EDG-EWG; R₂-EDG; and R₂-EWG
III	R₁-R₁; R₁-R₂; R₁-EWG; and R₂-EWG
IV	R₁-R₁; R₁-EWG; and EWG-EWG
V	R₁-EDG; R₁-EWG; R₁-R₂; EDG-EWG; R₂-EWG; and R₂-EWG
VI	R₁′-R₂″ and R₁′-R₁″
VII	R₁′-R₂″; R₁′-R₁″; R₁′-EDG″; R₂′-EDG″; and EDG′-EDG″
VIII	R₁′-R₂″; R₁′-R₁″; R₁-EWG″; R₂′-EWG″; and EWG′-EWG″

Linkage units could be utilized between the structures to form the above-described linkages. Suitable linkage units include a moiety selected from the group consisting of alkyls, acyclic heteroalkyls, non-aromatic cyclic alkyls, and non-aromatic cyclic heteroalkyls.

As indicated previously, the light attenuating compound can be attached to the polymer binder backbone or to a functional group or linkage unit which is, in turn, attached to the polymer backbone. Structures E and F below illustrate these attachments. In structure E, a 365 nm dienyl dye having an amino electron-donating group is bonded to a polymer binder via a hydroxypropyl linking group. The dye is attached by a carboxylic ester electron-withdrawing group. In structure F, the amino electron-donating group is functionalized with two hydroxyethyl substituents which are reacted with a diisocyanate to form a polyurethane backbone.

When used in reference to Formulas I-XI, the term “compounds” is intended to refer to the actual compound represented in the particular Formula, as well as all functional olefinic and/or diolefinic moieties thereof. For example, the “compound of structure A of Formula I,” refers to the structure A shown in Formula I above as well as the structure:

where “M” is a compound to which R′ is bonded. Thus, “compound of structure A of Formula I” would include those moieties where any of the constituents (i.e., any of the R groups or the EWG) are bonded to another compound.

Also, as used herein, “cyclic” is intended to refer to any group, compound, or moiety which includes a cyclic group as part of its structure. Thus, cyclic would include groups such as methylenecyclohexyl (—CH ₂-C₆H₅) and ethylenecyclohexyl.

The following table sets forth preferred compounds which fall into the classes described above with respect to Formulas I-XIII.



Class	Preferred Substituents

Acyclic Alkyls	methyl, ethyl, propyl, and isopropyl
Cyclic Alkyls	cyclopentyl and cyclohexyl
Acyclic Heteroalkyls	methoxyethyl, ethoxyethyl, methoxypropyl,
	chloroethyl, and 1,1,1-trifluoroethyl
Cyclic Heteroalkyls	tetrahydrofurfuryl, methylenecyclohexyl
	(—CH₂—C₆H₅), and ethylenecyclohexyl
EWG's Having	—CO—CH₃, —CO—CH₂CH₃, and
Carbonyl Groups	—CO—CH₂(CH₃)₂
EWG's Having	—CO—O—CH₃, —CO—O—CH₂CH₃, and
Carboxyl Groups	—CO—O—CH₂—CH(OH)—CH₂—O—
EWG's Having	—CO—NH—CH₂—CH₂—OH and
Carboxamido Groups	—CO—NH—CH₂—CH₂—O—
EWG's Having	—SO₂—CH₃and —SO₂—CH₂CH₃
Sulfonyl Groups
EDG's Having an	H₃C—O—, H₃CCH₂—O—, —CH₂CH₂—O—,
Alkoxy Group	and R₁-O—, wherein R₁is non-aromatic and may
	individually be hydrogen, or an acyclic
	(preferably C₁-C₄branched or unbranched) or
	cyclic (preferably C₅-C₆) alkyl or heteroalkyl
EDG's Having an	(H₃C)₂N—, (H₃CCH₂)₂N—,
R_XR_YN Group	(—O—CH₂CH₂)₂N—, and

EXAMPLE

The following example sets forth preferred methods in accordance with the invention. It is to be understood, however, that this example is provided by way of illustration and nothing therein should be taken as a limitation upon the overall scope of the invention. [0126]
Poly(glycidyl methacrylate) was reacted with 2,4-hexadienoic acid (a non-aromatic, deep ultraviolet chromophore) at 100-1 10° C. for 24 hours with a benzyltriethylammonium chloride catalyst to form a solution of the dye-attached binder shown in Scheme A. [0127]
The resulting polymer binder was combined in solution (with 1-methoxy-2-propanol and ethyl lactate as the solvents) with a glycouril-formaldehyde cross-linking agent and an acid catalyst (p-toluenesulfonic acid) to form a BARC composition. The concentrations of the various compounds utilized in the composition were as follows: [0128]

Compounds Parts by Weight^a

Polymer Solution 14.52

Cross-Linking Agent 0.66

p-toluenesulfonic acid 0.06

1-methoxy-2-propanol 42.38

ethyl lactate 42.38
The composition was spin coated onto a silicon wafer at 1500 rpm for 60 seconds followed by a hotplate bake at 175° C. for 60 seconds to form a BARC layer with a film optical density at 248 nm of 4.83/micron. The coating was then plasma etched in a commercial wafer etching tool using a mixture of HBr and O[0129] ₂as the etchant gas. The etch rate of the coating was 5815 Å/minute.
For comparison purposes, the etch rate of a BARC composition (DUV-42 for use in 248 nm photolithographic processes, available from Brewer Science, Inc., Rolla, Mo.) was determined. The binder in DUV-42 is a copolymer of glycidyl methacrylate and 2-hydroxypropyl methacrylate in which the glycidyl groups have been reacted with 9-anthracenecarboxylic acid (9-ACA) to form a dye-attached binder with high light absorbency at 248 nm. The DUV-42 was applied to a silicon wafer and processed following the procedures set forth above with respect to the inventive composition. The etch rate of the DUV-42 was 3218 Å/minute. Thus, the composition utilizing a light attenuating compound according to the invention etched 1.8 times faster than the prior art product. The comparatively low plasma etch rate of the DUV-42 was a result of the high aromatic ring content of the 9-ACA. [0130]

Claims

We claim:

1. In a curable composition for use during microlithographic processes, said composition comprising a polymer binder dissolved in a solvent system, the improvement which comprises a non-aromatic, light attenuating compound which absorbs light at wavelengths of less than about 300 nm in said composition.

2. The composition of claim 1, wherein said light attenuating compound is bonded to the polymer binder.

3. The composition of claim 1, wherein the polymer binder comprises a backbone, and said light attenuating compound is bonded to said backbone.

4. The composition of claim 1, wherein said light attenuating compound is bonded to a linkage unit and said linkage unit is bonded to the polymer binder.

5. The composition of claim 4, wherein said linkage unit comprises a moiety selected from the group consisting of cyclic alkyls, acyclic alkyls, acyclic heteroalkyls, and cyclic heteroalkyls.

6. The composition of claim 1, wherein said light attenuating compound includes a moiety selected from the group consisting of COOH, OH, CONH₂, CONHR′, CH₂X, and mixtures thereof, wherein R′ is selected from the group consisting of hydrogen, alkyls, and heteroalkyls, and wherein X is a halogen.

7. The composition of claim 1, wherein after curing, said composition has an etch rate of at least about 4000 Å/minute when utilizing an etchant gas comprising a mixture of HBr and O₂.

8. The composition of claim 1, wherein said light attenuating compound comprises an olefinic moiety including carbon atoms C₁and C₂double-bonded to one another, and an EWG bonded to carbon atom C₁.

9. The composition of claim 8, wherein the EWG includes a moiety selected from the group consisting of carbonyl, carboxyl, carboxamido, sulfonyl, and non-aromatic heterocyclic groups.

10. The composition of claim 8, said light attenuating compound comprising a diolefin, including carbon atoms C₃and C₄double-bonded to one another, and wherein C₃is bonded to C₂so as to form conjugated double bonds.

11. The composition of claim 10, further including an EDG bonded to C₄.

12. The composition of claim 11, wherein the EDG includes a moiety selected from the group consisting of H₃CO, OH, and R₁—O—, wherein R₁is non-aromatic and is selected from the group consisting of hydrogen, acyclic and cyclic alkyls, and heteroalkyls.

13. The composition of claim 10, further including a second EWG, said second EWG being bonded to C₄.

14. The composition of claim 13, wherein the second EWG includes a moiety selected from the group consisting of carbonyl, carboxyl, carboxamido, sulfonyl, and non-aromatic heterocyclic groups.