High Speed Electron Beam Cell Projection Exposure System

Yoshihiko OKAMOTO  Norio SAITOU  Haruo YODA  Yoshio SAKITANI  

IEICE TRANSACTIONS on Electronics   Vol.E77-C   No.3   pp.445-452
Publication Date: 1994/03/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Quarter Micron Si Device and Process Technologies)
Category: Process Technology
cell projection,  electron beam,  lithography,  mask process,  exposure data,  

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An electron beam cell projection system has been developed that can effectively expose the fine, demagnified resultant pattern of repeated and non-repeated patterns such as the 256 Mb DRAM on a semiconductor wafer. Particular attention was given to the beam shaping and deflecting optics, which has two stage deflectors for the cell projection beam selection as well as the beam sizing, and three stage deflectors for objective deflection. The cell mask with a rectangular aperture and multiple figure apertures is fabricated by modified Si wafer processes. A new exposure control data for the cell projection is proposed. This data is fitted for the combination of pattern data for the cell mask projection and pattern data for the variable rectangular shape beam within the divided units of the objective deflection. On this exposure system, selective exposure of the desired pattern becomes possible on the semiconductor wafer while a mounting stage of the wafer is being moved, even if the pattern exposure of the repeated and non-repeated patterns is to be carried out. The total overhead time for selecting a subset of multiple figures and a rectangular aperture of the cell mask is less than 5 seconds/wafer. The estimated throughput of this system is approximately 20 wafers/hour.