Influence of Shape PEC on Resist Profile

Motivation:

The interaction of electrons with a photoresist leads to scattering of the electrons inside the material. This phenomenon widens exposed structures and thus reduces patterning precision and quality. Proximity effect corrections (PEC) account for long-range interactions diminishing the scattering issues. However, in cases where the critical dimension is of the order of beam blur together with thick resist or dense patterns, PEC is insufficient to enhance the patterning of a device.

Solution:

In addition to long-range corrected dose PEC, Shape PEC compensates for short and mid-range energy loss, providing a uniform dose at all layout edges by iteratively shifting pattern edges. The overdose/undersize (ODUS) shape PEC performs overexposure to give an enhanced intensity image slope at the pattern edge, thus improving the sidewall angles of the resist edge and the process window. LAB simulates the functionality of Shape PEC - ODUS by modelling the E-Beam lithography process from exposure to intensity image and resist profile.