An effective approach for reducing surface roughness of PMMA by thermal radiation induced local reflow

(a) A radiation source irradiates the sample directly and a temperature gradient is formed in PMMA and silicon wafer. The top part of the PMMA undergoes a phase change into liquid state, which is called local reflow. The key to the success in removing the surface roughness is to create such a local reflow of PMMA in the region whose depth is in the same magnitude order as the roughness dimension. (b) The ones after four TRILR processes inspected by AFM of the whole profile. Each TRILR process needs 25 s. (c) The surface roughness of each step after four TRILR processes, and (d) the tendency of roughness reduction percentage for each step.132