LWR reduction and flow of chemically amplified resist patterns during sub-millisecond heating

Chemically amplified resists are critical for sub-30 nm photolithography. As feature sizes decrease, challenges continue to arise in controlling the aerial image during exposure, acid diffusion during post exposure bakes, and swelling during development. Ultimately these processes limit the line width roughness (LWR). While there exists substantial research to modify resists and exposure protocols, post-development treatment of resist patterns to improve the LWR has received only modest attention. In this work, we use a scanned laser spike annealing system to anneal fully developed resist patterns at temperatures of 300-420°C for sub-millisecond time frames. When heated above its glass transition temperature for a controlled time, patterned resist flows to minimize the surface energy resulting in reduced roughness. While LWR and critical dimension (CD) of the resist is very sensitive to the hardbake temperature, SEM and AFM analysis show a >30% reduction in LWR with <1 nm change in CD at 26W (385°C) hardbake power compared to that of features without hardbake. Quantitative determination of surface roughness, resist trench profiles, LWR, and CD is presented and discussed.