Thermal deformation variations with field positions on the wafer and resist types (CAR and MOR)

Abstract

The ongoing shrinkage in minimum pitch has necessitated an even stricter and more restrictive error budget. Paradoxically, as the pitch decreases, image performances (e.g., NILS, image contrast) deteriorate, which necessitates compensation through dose adjustments, consequently resulting in thermal issues in the resist. Therefore, to meet the stringent requirements for the feature size, it is necessary to consider physical material properties such as deformation effects in dose optimization and overlay control. In this study, the systematic simulation on wafer heating have been explored to understand the deformation mechanism induced by EUV exposure. We found the thermal deformation as a significant factor leading to image fading and overlay errors. Furthermore, we discovered that deformation varied depending on the location in field-To-field, die-To-die, and within-slit. Particularly, the concentrated mechanical load at the edge domain intensified thermal stress. Additionally, through thermal-mechanical analysis based on the resist type, we explored the correlation between deformation and material properties. Our investigation revealed that the primary contributing factor is the dose energy rather than material properties. © 2023 SPIE. All rights reserved.