Dong-Chul Seo

Poly(t-butyl-3α-(5-norbornene-2-carbonyloxy)-7α, 12α-dihydroxy-5β-cholan-24-oate- co-maleic anhydride) for a 193-nm photoresist

Abstract A copolymer of t -butyl-3α-(5-norbornene-2-carbonyloxy)-7α,12α-dihydroxy-5β-cholan-24-oate and maleic anhydride was synthesized as a matrix polymer for ArF excimer laser lithography. The polymer has an excellent transmittance at 193xa0nm and possesses good thermal stability up to 255°C. The resist formulated with the polymer showed better dry-etching resistance than the conventional KrF excimer laser resist for chlorine and oxygen mixed gas. A 0.15xa0μm line and space patterns were obtained at a dose of 18xa0mJxa0cm −2 using an ArF excimer laser stepper.

Chemically Amplified Resists based on the Norbornene Copolymers with Steroid Derivatives

In order to develop a new series of chemically amplified photoresists for 193-nm lithography, norbornene substituted with a steroid derivative was copolymerized with maleic anhydride by free radical polymerization. The resulting polymers have excellent transmittance at 193 nm and possess good thermal stability up to 260 degrees C. The resist formulated with the polymers showed better dry-etching resistance than the conventional poly(hydroxystyrene) resist for Cl2/O2 plasma. With the standard developer, the resists from 0.15-0.20 micrometers patterns at doses of 5-18 mJ/cm2 using an ArF excimer laser stepper.

New approach for 193-nm resist using modified cycloolefin resin

We have investigated new photoresist materials based on modified cycloolefin-maleic anhydride resin for 193nm lithography. Compared to COMA resin, the new resin offers several good properties such as UV transmittance, taper in pattern profile, PED stability and storage stability. The resist using the new resin showed good lithographic performances on ArF exposure tool. So, we obtained good hole patterns below 90nm with condition of exposure: PAS 5500/900 full field scanner, resist thickness: 320nm, development: 2.38% TMAH, for 40sec., Illumination: 0.61NA, conventional SOB: 110 degree(s)C/90sec, PEB:130 degree(s)C/90sec, on BARC. In this paper we will report on the properties of new polymer and will show the contact hole pattern that demonstrate progress in these areas.

Novel approach for high resolution using cycloolefin-alt-maleic acid derivatives polymer for ArF lithography

Polyacrylate derivative was first developed as raw material for ArF resist and it was selected the first candidate in spite of some defects. Cycloolefin-maleic anhydride polymer[COMA] and other polymers were therefore given opportunity. The resist based on COMA shows a good dry-etch resistance compared with that based on acrylate polymer. However, the pattern profile of the resist formulated by using COMA has some defects such as taper and low resolution because of transmittance issue of the polymer. In order to solve the issue, we have developed a new polymer [It was named ROMA Resin]. The new polymer has good physical properties such as UV transmittance, stability during storage and moderate glass transition temperature. We also found that the pattern profile of the resist formulated by using the polymer shows good results in terms of pattern profile, CD SEM slimming and PED stability.

Materials design and lithographic performance of maleic anhydride/cycloolefin copolymer for ArF resist

Photoresist using maleic anhydride/cycloolefin copolymer is a leading candidate for the 193 nm photolithography. Until recently, the efforts to improve 193 nm photoresist have been focused on resolution and dry-etch resistance. Therefore, we have synthesized some kinds of matrix resins and additives containing alicyclic group and acid labile group. The matrix resin is alternating copolymer obtained by free radical polymerization of maleic anhydride and cycloolefinic derivatives. And, the additives have a low molecular weight containing alicyclic group and acid labile group. The additives not only serve as dissolution inhibitors but also improve the pattern profile and dry-etch resistance. In this paper, we will describe the approaches to the resist materials, which are involved in our photoacid generator concept.