Influence of Shape PEC on Resist Profile
Electrons are scattered when exposed to the resist, resulting in pattern deviation from the design. Dose proximity effect correction (PEC) modulates the exposure, taking into account long range electron scattering effects. When the critical size is in the range of the process blur, short and mid-range effects are critical for correct pattern realization.
In addition to long-range corrected dose PEC, Shape PEC compensates for short and mid-range energy loss and provides a uniform dose at all layout edges by iteratively shifting pattern edges. The undersize/overdose (ODUS) shape PEC performs over exposure to give an enhanced intensity image slope at the pattern edge, thus improving the sidewall angles of the resist edge and the process window of small feature fabrication. The functionality of ODUS can be demonstrated by our software LAB. LAB simulates the whole E-Beam lithography process from exposed pattern to intensity image and resist profile.