Line edge roughness of high deprotection activation energy photoresist by using sub-millisecond post exposure bake

Abstract

The semiconductor industry is facing serious challenges in LWR control at the node of 16nm feature size. One of the reasons that causes LWR is the acid diffusion during post-exposure bake of chemically amplified resists. Laser spike annealing was introduced as a post-exposure bake (PEB) step in order to solve the image blurring problem by rapidly heating up a resist system to hundreds of degrees and completing the PEB in the millisecond time frame. However, lacking detailed knowledge of chemistry and kinetics for laser PEB (l-PEB) becomes an obstacle for resist design. The photoresist we synthesized with high deprotection activation energy and low diffusion activation energy has proved to help reduce LER for l-PEB. This photoresist was compared to another classical DUV model resist in order to analyze the benefits of its chemical structure and reaction kinetics. The interpretation of LER and activation energy will help us to identify better possible resist materials for l-PEB.