Deconstructing the resist to probe innate material roughness

Abstract

We have developed an AFM-based technique to measure intrinsic material roughness after base development. This method involves performing an interrupted development of the resist film and measuring the resulting film roughness after a certain fixed film loss. Employing this technique, we have deconstructed the resist into component materials and established that the PAG is a major material contributor of film roughness and that PAG segregation in the resist is likely responsible for nano-scale dissolution inhomogeneities. Small differences in PAG concentration as a result of standing waves in the resist can lead to large changes in surface roughness due to PAG or PAG-photoproduct segregation and the resultant non-linear change in nano-scale dissolution rates. The temperature dependence of the PAG segregation suggests that increased mobility of the PAG occurs due to a lowering of the film T_g during the deprotection process.