Implementation of pattern-specific illumination pupil optimization on Step & Scan systems

Step&Scan systems are pushed towards low k 1 applications. Contrast enhancement techniques are crucial for successful implementation of these applications in a production environment. A NA - sigma - illumination mode optimizer and a contrast-based optimization algorithm are implemented in LithoCruiser in order to optimize illumination setting and illumination pupil for a specific repetitive pattern. Calculated illumination pupils have been realized using Diffractive Optical Elements (DOE), which are supported by ASML's AERIAL II illuminator. The qualification of the illumination pupil is done using inline metrology on the ASML Step & Scan system. This paper describes the process of pattern specific illumination optimization for a given mask. Multiple examples will be used to demonstrate the advantage of using non-standard illumination pupils.