Title: Controlling Photon and Plasma induced Processes at EUV optical surfaces (CP3E)  
Project Type: Approved Industrial Partnership Programme FOM
Number: I23
Project Leader: Prof. Dr. F. Bijkerk (f.bijkerk@utwente.nl)
Duration: 2009-2017
Base funding: FOM, ASML, Zeiss SMT
Partners: Carl Zeiss SMT AG, ASML Research


To understand and control collective plasma, photochemical and thin film processes, which occur in the application of multilayer reflective optics in Extreme UV photolithography.

Background, relevance and implementation

The development of deposition processes for multilayer mirrors with sub-nanometre layer accuracy has enabled high-resolution photolithography with 13.5 nm extreme ultraviolet (EUV) radiation. High throughput chip fabrication requires the use of high intensity EUV radiation, which may lead to several damage processes such as photo-induced growth of contaminants, plasma-induced etching and thermal diffusion inside the multilayer stack. The goal of CP3E is to understand and control the simultaneous occurrence of these processes, such that the required optics lifetime can be met. Methods to achieve this goal include new multilayer compositions and deposition methods, surface conditioning and the establishment of a dynamical equilibrium of plasma and photochemical processes. Within CP3E a group of UT researchers works in the EUV laboratory at the ASML campus in Veldhoven, using their high-flux EUV-exposure facilities in combination with surface analysis facilities designed by the UT team. Thin film growth and surface analysis will be carried out at the Twente base of the group, while Carl Zeiss contributes with state-of-the-art optics fabrication and characterisation. The main part of this research programme is closely connected to the industrial Zeiss-ASML EUVL development road map.