Novel Anionic Photoacid Generators (PAGs) and Photoresists for sub 50 nm Patterning by EUVL and EBL
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0961-O11-04
Novel Anionic Photoacid Generators (PAGs) and Photoresists for sub 50 nm Patterning by EUVL and EBL Mingxing Wang1, Cheng-Tsung Lee2, Clifford L. Henderson2, Wang Yueh3, Jeanette M. Roberts3, and Kenneth E. Gonsalves1 1 Department of Chemistry, UNC-Charlotte, Charlotte, NC, 28223 2 Georgia Institute of Technology, Atlanta, GA, 30332 3 Intel Corp., Hillsboro, OR, 97124 A new series of anionic photoacid generators (PAGs), and corresponding polymers were prepared. The thermostability of PAG bound polymers was superior to PAG blend polymers. PAG incorporated into the polymer main chain may improve acid diffusion compared with the PAG blend polymers, which was demonstrated by Extreme Ultraviolet lithography (EUVL) results:
the fluorine PAG bound polymer resist gave 45 nm (1:1), 35 nm (1:2), 30 nm (1:3) and
20 nm (1:4) Line/Space as well as 50 nm (1:1) elbow patterned, showed better resolution than the blend sample. Keywords: Anionic photoacid generator (PAG); polymer resist; EUV lithography; outgassing
1. Introduction Extreme ultraviolet (EUV) lithography at 13.5 nm wavelength has emerged as a leading candidate to meet the resolution requirements of the microelectronic industry roadmap[1]. Although critical dimensions below 50 nm have been achieved, extensive research still needs to be conducted in the development of EUV technology to meet the 32 nm and the lower 22 nm technology node[2]. In addition to developing the exposure tools themselves, significant challenges remain in developing photoresist materials with all of the required imaging properties. Conventional chemically amplified photoresist formulations are complex mixtures of a protected polymer matrix and a small molecule photoacid generator (PAG). The inherent incompatibility can lead to PAG phase separation, nonuniform initial PAG and photoacid distribution, as well as acid migration during the post-exposure baking (PEB) processes[3]. To alleviate these problems, the potential use of a polymer bound PAG blended with a chemically amplified resist, for controlling acid diffusion and outgassing have been reported[4]. Several systems with ionic or non-ionic PAG incorporated in the main chain have been studied[5-9]. The incorporation of ionic PAG units into the main chain of the hydroxystyrene and adamantyl methacrylate based polymers showed improved EUV lithographic performance, such as faster photospeed and higher stability, lower outgassing, and lower line edge roughness (LER) than corresponding blend resists[8,9]. In this paper, we report a series of novel bound (vinyl functionalized PAG) and blend anionic PAGs and corresponding photoresists incorporating PAG in the main chain (Figures 1 and 2), and an investigation of their thermostability, acid generating efficiency, outgassing and EUVL properties.
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