Photoresist qualification using scatterometry CD

As the semiconductor industry advances to smaller design rules, Photoresist performance is critical for the tight lithography process. Critical Dimension (CD), Side Wall Angle (SWA) and Photoresist height, which are critical for the final semiconductor patterning, depend on the Photoresist chemistry. Each Photoresist batch has to be qualified to verify that it can achieve the required quality specifications. Photoresist qualification is done by exposing Photoresist and monitoring outcome after developing. In this work, Archer 300LCM scatterometry-based Optical CD (OCD) was evaluated using Dow 193 Immersion Top Coat Free Photoresist and Anti Reflection Layers (ARL). As part of the sensitivity analysis, changes in Photoresist thickness, ARL thickness and Photoresist formulation were evaluated. Results were compared to CD-SEM measurements. The CD sensitivity was evaluated on two grating dense line and space features with nominal Middle CD (MCD) values of 37nm and 75nm. Sensitivity of the OCD for Photoresist parameters was demonstrated.