REPETITIVE ONE-10TH MICRON PATTERN FABRICATION USING AN EB BLOCK EXPOSURE SYSTEM

Beam calibration techniques of an EB block exposure system (NOWEL 3) a re developed to determine deflection and correction data to deflect be ams through each mask pattern. After the calibration, the current dens ities in a deflection area differ less than 1.6% from the mean value. The exposure positioning errors are below 0.03 mu m in magnitude. The calibration results are used to expose a repetitive pattern of DRAM st orage capacitors. The block mask has doughnut-type structures held by 2 mu m-wide bridges. Rectangular 0.45 x 0.85 mu m(2) resist patterns w ith clear edges are resolved at 0.11 mu m intervals. Repetitive patter ns in a logic LSIC are also exposed with the block exposure. We extrac t mask patterns from the cache memory and shift register regions. The number of exposure spots is decreased to about 1/5 of that used in con ventional rectangular shaped beam methods. The stitching errors betwee n the mask patterns are measured from the exposure results, which are less than 0.04 mu m.