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16 May 1994 Characterization of the quarter-micron i-line lithography using a top surface imaging process
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The practical limits of i-line top surface imaging process using a novolak based photoresist were investigated dependent on exposure techniques such as conventional and off-axis illumination. Ultimately, quarter micron small geometry was clearly delineated and depth of focus (DOF) latitude of 1.5micrometers and 2.7micrometers was achieved respectively for 0.25micrometers and 0.30micrometers lines and spaces pattern by annular illumination of 0.50NA. To compensate proximity effect caused by pattern density, sub-resolution auxiliary pattern was firstly optimized for off- axis illumination of quadrapole and annular. As a result, critical dimension (CD) difference between dense and isolated pattern in 0.30micrometers reduced to half-level compared to that of non-auxiliary pattern. It was found that desilylation phenomenon was critically affected by the kind of photopolymer reacted with silicon source and molecular weight of silylation agent. Novolak based polymer maintained superior silylation durability to polyvinyl phenolic (PVP) resin. New silylation process concept which is dual silylation method was developed to utilize PVP's merits in the silylation process against desilylation. Dry development lithography of i-line was feasible to practical application of prototype 256 mega bit DRAM which demands 0.30micrometers patterning with a reproducibility.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Seung-Chan Moon, Hyeong-Soo Kim, Chang-Moon Lim, Tai-Kyung Won, and Soo-Han Choi "Characterization of the quarter-micron i-line lithography using a top surface imaging process", Proc. SPIE 2195, Advances in Resist Technology and Processing XI, (16 May 1994);

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