Thermally Developable, Positive Tone, Oxygen RIE Barrier Resist for Bilayer Lithography

Itô, Hiroshi; Ueda, Mitsuru; Renaldo, A. F.

doi:10.1149/1.2096595

Cited by 24 publications

(15 citation statements)

References 10 publications

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“…We have synthesized poly(4-trimethylsilylphthalaldehyde) (PSPA) by anioic initiation in THE at -78°C. Cationically prepared PSPA is of broad molecular weight distribution and much less stable thermally [11,14]. As illustrated in Scheme III, radiochemically generated trifluoromethanesulfonic (triflic) acid depolymerizes PSPA to the monomer upon postbake, which also facilitates evaporation of the monomer and increases the sensitivity, providing positive images without subsequent development steps (thermal development).…”

Section: Introductionmentioning

confidence: 99%

Chemical amplification based on acid-catalyzed depolymerization.

Itô

England

Ueda

1990

J. Photopol. Sci. Technol.

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The chemical amplification concept proposed in 1982 to support high resolution short wavelength lithographic technologies that demand highly sensitive advanced resist systems is based on acid-catalyzed crosslinking, deprotection, and depolymerization reactions. Each approach has shown a tremendous progress. In this paper is reviewed the depolymerization concept for the design of sensitive positive resist systems formulated with triarylsulfonium salt acid generators.Three modes of the initiation of acid-catalyzed depolymerization are discussed; (1) attack of acids onto backbone oxygens as exemplified by depolymerization of polyphthalaldehyde (PPA), (2) scission of pendant ester groups followed by depolymerization with poly(a-acetoxystyrene ) (PACOST) as an example, and (3) unzipping from the polymer ends as demonstrated by depolymerization of cationically obtained polyp-hydroxy-a-methylstyrene) (pPHOMS). The positive resist systems based on depolymerization of PPA derivatives include a thermally-developable OZ reactive ion etch (RIE) barrier resist for use in the bilayer scheme and the use of PPA as a polymeric dissolution inhibitor for novolac resins. The deesterification of PACOST results in formation of poly(phenylacetylene) (PPA) and simultaneous depolymerization to provide positive images upon development with xylenes, which is briefly discussed. Cationically prepared pPHOMS exhibits 80 % thickness loss at ca. 1 mJ/cm2 upon postbake at 130°C whereas anionic pPHOMS and cationic meta-PHOST are very stable toward acidolysis, indicating that the depolymerization propagates from the termination side of the chain.

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Section: Introductionmentioning

confidence: 99%

Chemical amplification based on acid-catalyzed depolymerization.

Itô

England

Ueda

1990

J. Photopol. Sci. Technol.

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“…Thus, we demonstrated in 1980 three modes of photochemically induced acid‐catalyzed imaging; (1) positive self‐development through acid‐catalyzed depolymerization of polyphthalaldehyde, (2) dual‐tone imaging based on a polarity change through acid‐catalyzed deprotection, and (3) negative imaging by crosslinking through cationic polymerization 3. We termed this gain mechanism “chemical amplification.” While I continued to work on the polyphthalaldehyde system, moving from self‐development to thermal development,8 and then to a thermally developable bilayer resist based on poly(trimethylsilylphthalaldehyde),9 Fréchet and Willson incorporated the side‐ehain deprotection chemistry into the polymer backbone for depolymerization 10–12. Although we did not pursue the crosslinking through cationic ring‐opening polymerization any further, this system was picked up by our colleagues at the IBM T. J. Watson Research Center,13 and SU‐8 has become the thick resist of choice for microelectromechanical systems (MEMS) applications.…”

Section: Inventionmentioning

confidence: 99%

Chemical amplification resists: Inception, implementation in device manufacture, and new developments

Itô

2003

J. Polym. Sci. A Polym. Chem.

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109

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ABSTRACT:The chemical amplification concept aimed at dramatically boosting the resist sensitivity was invented at IBM Research in San Jose, CA, in 1980. The sensitivity enhancement is achieved by generating acid by irradiation, which induces a cascade of chemical transformations in a resist film. A chemically amplified resist based on acid-catalyzed deprotection was quickly employed in the mid-80s in manufacture of 1 megabit (Mbit) dynamic random access memory (DRAM) devices by deep ultraviolet (UV) (ϳ250 nm) lithography in IBM. The unexpectedly high-resolution capability of chemical amplification resists promoted their acceptance in the resist community and the microelectronics industry. All the advanced lithographic technologies (current workhorse 248 nm, maturing 193 nm, and emerging 157 nm, extreme UV, and projection electron beam) depend on chemical amplification resists.This article describes the invention, implementation in device manufacturing, current status, and future perspective of chemical amplification resists.

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“…Polyaldehyde-based materials are sensitive self-developing resists, but can suffer from two major drawbacks: (a) they liberate a volatile aldehyde during the exposure ste p that could be injurious to the optics of the exposure tool, and (b) they exhibit poor plasma etching resistance. Examples of systems that have been designed to avoid these problems are poly(4-chlorophthalaldehydc) (174,175) and poly(4-trimethylsilylphthalaldehyde) (174,176). Alter natively, poly(phthalaldehyde) may be used as a dissolution inhibitor fo r a novolac, which is itself more resistant to plasma etching (177).…”

Section: Depolymerization Chemistrymentioning

confidence: 99%