Thickness dependence of the lithographic performance in 193nm photoresists

The lithographic performance of a 193nm resist was evaluated for 75nm line and space patterns with thicknesses ranging from 35 nm to 170 nm. Because of the high line edge roughness (LER) value and low depth of focus (DOF), the standard resist was not appropriate for sub-100nm thick films. The influence of the concentration of photo acid generator (PAG) on the lithographic performance-LER, depth of focus (DOF)- over the thickness range of 35nm to 110 nm will be investigated in this paper. With PAG loading percentage increased, the LER and DOF value were enhanced at sub-100nm thickness. Finally, It was demonstrated that the lithographic performance could be enhanced up to 50 nm thickness, changing the resist structure for less transparent type based on the high PAG loading resist.