Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
2002-06-25
2004-05-25
Huff, Mark F. (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S905000, C430S950000, C430S910000, C430S909000, C430S280100, C430S271100, C430S272100, C430S325000, C430S326000, C430S331000, C430S311000, C430S510000, C430S514000, C430S330000, C524S610000, C524S502000, C524S500000, C524S503000, C525S389000, C525S474000, C525S476000, C525S479000, C523S221000, C523S400000, C523S435000
Reexamination Certificate
active
06740469
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is concerned with new anti-reflective compositions for use in the manufacture of microelectronic devices. These compositions include polymeric metal alkoxides and are developable in aqueous photoresist developers.
2. Description of the Prior Art
Integrated circuit manufacturers are consistently seeking to maximize substrate wafer sizes and minimize device feature dimensions in order to improve yield, reduce unit case, and increase on-chip computing power. Device feature sizes on silicon or other chips are now submicron in size with the advent of advanced deep ultraviolet (DUV) microlithographic processes.
However, 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 use of an anti-reflective coating applied to the substrate beneath the photoresist layer. While anti-reflective coatings are effective at preventing or minimizing reflection, their use requires an additional break-through step in the process in order to remove the coatings. This necessarily results in an increased process cost.
One solution to this problem has been the use of wet developable anti-reflective coatings. These types of coating can be removed along with the exposed areas of the photoresist material. That is, after the photoresist layer is exposed to light through a patterned mask, the exposed areas of the photoresist are wet developable and are subsequently removed with an aqueous developer to leave behind the desired trench and hole pattern. Wet developable anti-reflective coatings are removed during this developing step, thus eliminating the need for an additional removal step. Unfortunately, wet developable anti-reflective coatings have not seen widespread use due to the fact that they must also exhibit good spin bowl compatibility and superior optical properties to be useful as an anti-reflective coating. Thus, there is a need for anti-reflective coating compositions which are developable in conventional photoresist developers while simultaneously exhibiting good coating and optical properties.
SUMMARY OF THE INVENTION
The present invention broadly comprises new microlithographic compositions that are useful in the manufacture of microelectronic devices.
In more detail, the compositions comprise a polymer dispersed or dissolved in a solvent system. Preferred polymers include recurring units having the formula
wherein X is a light-attenuating moiety, M is a metal, and each R is individually selected from the group consisting of hydrogen, alkyls (preferably C
1
-C
8
), aryls, alkoxys, and phenoxys. The most preferred R groups are —CH
3
and —OC
2
H
5
.
The polymer preferably further comprises recurring units having the formula
where each R
1
is individually selected from the group consisting of hydrogen, alkyls (preferably C
1
-C
8
), aryls, alkoxys, and phenoxys, and M
1
is a metal. The most preferred R
1
groups are —CH
3
and —OC
2
H
5
.
With either of the foregoing recurring units, the most preferred metals are Ti, Zr, Si, and/or Al. It is also preferred that the light-attenuating moiety include a functional group for coordinating with the metal atom of the polymeric metal alkoxide. Such functional groups include carbonyl, alcohol, and phenol groups. Furthermore, the moiety (i.e., X) is preferably present in the polymer at a level of from about 5-50% by weight, and more preferably from about 10-25% by weight, based upon the total weight of the polymer taken as 100% by weight. Suitable light-attenuating moieties include those selected from the group consisting of moieties of trimethylol ethoxylate, 4-hydroxybenzaldehyde, and 2-cyano-3-(4-hydroxyphenyl)-acrylic acid ethyl ester. Also, in order to avoid photosensitivity in the composition, none of X, R, and R
1
should include any ethylenically unsaturated groups.
In another embodiment, the polymer is formed by reacting a polymeric metal alkoxide with an organic compound. The polymeric metal alkoxide includes recurring units having the formula
where M is a metal, and each L is individually selected from the group consisting of diketo and alkoxide ligands. Preferred L groups have the formula
where each R is individually selected from the group consisting of hydrogen, alkyls (preferably C
1
-C
8
), aryls, alkoxys, and phenoxys, with —CH
3
and —OC
2
H
5
being the most preferred R groups. A moiety of ethyl acetoacetate is the most preferred L group. The preferred metal atoms are the same as those discussed previously.
In this embodiment, the polymeric metal alkoxide having the structure of Formula I above can first be formed by reacting a polymeric metal alkoxide (e.g., poly(dibutyltitanate)) with a diketo or alkoxide ligand (e.g., ethyl acetoacetate). Alternately, a starting monomer which already includes the diketo or alkoxide ligand as part of its structure can be formed into the desired polymer by hydrolyzing and then condensing the monomer. One example of this type of starting monomer is titanium diisopropoxide bis(ethylacetoacetate).
The organic compound which is reacted with the polymeric metal alkoxide having the structure of Formula I above should comprise a functional group suitable for coordinating with the metal atom of the polymeric metal alkoxide. Suitable functional groups include alcohols, phenols, thioalcohols, thiophenols, and carbonyls. The most preferred organic compounds are trimethylol ethoxylate, 4-hydroxybenzaldehyde, and 2-cyano-3-(4-hydroxyphenyl)-acrylic acid ethyl ester.
Regardless of the embodiment, the anti-reflective compositions are formed by simply dispersing or dissolving the polymers in a suitable solvent system, preferably at ambient conditions and for a sufficient amount of time to form a substantially homogeneous dispersion. The polymer should be present in the composition at a level of 2-50% by weight, more preferably from about 5-30% by weight, and more preferably from about 7-15% by weight, based upon the total weight of solids in the composition taken as 100% by weight. The viscosity of this polymer is preferably from about 2,000-5,000 cS, and more preferably from about 3,200-3,500 cS.
Preferred solvent systems include a solvent selected from the group consisting of propylene glycol methyl ether acetate (PGMEA), propylene glycol methyl ether (PGME), propylene glycol n-propyl ether (PnP), ethyl lactate, and mixtures thereof. Preferably, the solvent system has a boiling point of from about 50-250° C., and more preferably from about 100-175° C. The solvent system should be utilized at a level of from about 70-95% by weight, and preferably from about 80-90% by weight, based upon the total weight of the solids in the composition taken as 100% by weight.
Any additional ingredients are also preferably dispersed in the solvent system along with the polymer. One such preferred additional ingredient is a second polymer or polymer binder such as those selected from the group consisting of epoxy novolac resins (e.g., Epon 164®, available from Araldite), acrylates (e.g., poly(glycidyl methacrylate)), polymerized aminoplasts (e.g., Cymel® products available from Cytec Industries), glycourals (e.g., Powderlink® products available from Cytec Industries), vinyl ethers, and mixtures thereof. The weight average molecular weight of this additional polymer is preferably from about 1,000-50,000 Daltons, and more preferably from about 5,000-25,000 Daltons. In embodiments where an additional polymer is utilized, the composition should comprise from about 1-50% by weight of this additional polymer, and more preferably from about 5-25% by weight, based upon the total weight of the solids in the composition taken as 100% by w
Krishnamurthy Vandana
Neef Charles J.
Snook Juliet A. M.
Brewer Science Inc.
Hovey & Williams, LLP
Huff Mark F.
Lee Sin J.
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