TY - JOUR
AU - Takemoto, Toyoki
AB - 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.
TI - An E-Beam Direct Write Process For Half Micron DRAMS
JO - Proceedings of SPIE
DO - 10.1117/12.945662
DA - 1988-06-14
UR - https://www.deepdyve.com/lp/spie/an-e-beam-direct-write-process-for-half-micron-drams-1qEJ0rkfBY
SP - 281
EP - 289
VL - 923
IS - 
DP - DeepDyve
ER -