Post exposure bake effect in 193 nm chemically amplified resist

Abstract

Lithography simulation can help the selection of process tools, techniques, and materials. It can also improve process control and precision. ArF excimer laser with 193 nm wavelength is believed to be the main lithography source for similar to 100 nm devices. The characterization of 193 nm chemically amplified resist is necessary in order to extract the parameters needed by the simulation model. Good measurement of resist refractive index is needed for accurate simulation. We investigated the post exposure bake effects in 193 nm chemically amplified resist. We measured the thickness and transmittance of the resist by changing the post exposure bake conditions. The optical constants of the resist were obtained from these measurements by using the multiple thin him interference calculation. After post exposure bake, the thickness and the refractive index changed significantly. These changes were dependent on the exposure energy and the post exposure bake conditions. We found that the refractive index is directly related to the de-protection of the resist. De-protection parameters needed for 193 nm lithography are extracted from this relationship.