Theoretical modeling of the simultaneous exposure and development (SED) process of a positive photoresist.
The simultaneous exposure and development (SED) process for a positive photoresist, when exposed to a uniform incident flux and to a real image with a nonuniform transverse intensity distribution, is mathematically simulated. The calculation is done for photoresist on optically matched and unmatched substrates while varying the incident radiation intensity, the initial resist thickness, and developer concentration. The results of the calculation and several experiments with SED produced gratings suggest that SED will yieldhigher contrast than the usual expose-and-then-develop (E-D) process. Furthermore, the standing wave effect in the photoresist films coated on reflective substrates is minimized and decreases with depth into the films when the SED process is used.
Tsang
W T
WT