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Proceedings Paper

An E-Beam Direct Write Process For Half Micron DRAMS
Author(s): Noboru Nomura; Kenji Kawakita; Toshihiko Sakashita; Kenji Harafuji; Toyoki Takemoto
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Paper Abstract

Direct write electron beam (EB) lithography is expected to write a very fine wafer pattern below half micron for the development of the comming generation ULSIs. But direct write EB lithography has two main peculiar problems for obtaining such a very fine resist pattern on an uneven topography of a processed wafer. One is a pattern dimension deviation from the designed value due to resist topography and proximity effects. The other problem is pattern registration deviation due to charge-up in the EB-resist. In order to investigate the proximity effect. we evaluated the deposited energy density profile by a double gaussian Exposure Intensity Distribution ( EID ) function. The theoretical and experimental results showed that in a 2.2 micron thick trilayer planerizing resist system. both 0.5 micron isolated line and isolated space were simultaneously resolved in half micron thick top layer resist. To compensate the charge-up problem, we treated the bottom-layer by a brand-new ion shower material modification process. A 40 KV proton shower irradiation decreased the resistance of the bottom layer. The charge of the electron beam was dissipated through the bottom layer resist. The resultant half micron rule 16 M-bit DRAM patterns were compared with the optically exposed tri-level resist patterns. The optically exposed patterns also had an optical proximity effect and half micron patterns were not resolved even adopting the contrast enhancement lithographic ( CEL ) technology. On the other hand, we successfully obtained 16M-bit DRAM patterns on the uneven topography of the processed wafer using EB direct write.

Paper Details

Date Published: 14 June 1988
PDF: 9 pages
Proc. SPIE 0923, Electron-Beam, X-Ray, and Ion Beam Technology: Submicrometer Lithographies VII, (14 June 1988); doi: 10.1117/12.945662
Show Author Affiliations
Noboru Nomura, Matsushita Electric Ind. Co (Japan)
Kenji Kawakita, Matsushita Electric Ind. Co (Japan)
Toshihiko Sakashita, Matsushita Electric Ind. Co (Japan)
Kenji Harafuji, Matsushita Electric Ind. Co (Japan)
Toyoki Takemoto, Matsushita Electric Ind. Co (Japan)

Published in SPIE Proceedings Vol. 0923:
Electron-Beam, X-Ray, and Ion Beam Technology: Submicrometer Lithographies VII
Arnold W. Yanof, Editor(s)

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