EUV pellicle development for mask defect control

The absence of a reliable non-removable pellicle is a significant obstacle in the development of EUV lithography. In this paper we present analytical and experimental results of a pellicle concept. The concept is based on the development of an EUV transmissive film supported with a wire-mesh. The form factor of the proposed solution is not different from a standard pellicle application, thus this would not require dramatic tool design changes. Results from developmental studies of two materials, silicon (Si) and ruthenium (Ru), are presented. As expected, Si shows oxidation on both surfaces of the thin film, while the less transmissive Ru has excellent resistance to oxidation. Spectral analysis at EUV wavelengths of pellicle coupons agrees very well with the theoretical analysis.