A study of aerial image NILS and exposure energy as improvement factors for LER

Line edge roughness (LER) played more critical- role with the semiconductor manufacturing keep shrinking down to new technology nodes. From our previous study, the larger exposure area gives positive impact to LER performance, as more photons can be captured by photoresist, reducing the randomness of photoacid distribution and make line edge smoother. In this paper, we further investigate the litho process impact factors for LER, including Normalized Image Log-Slope (NILS) and exposure energy. Simulation model was setup on top of experiment data, and further expand to different critical dimension (CD) and pitch conditions.