Development of capillary Z-pinch discharge light source for EUV lithography

摘要

Extreme ultraviolet (EUV) lithography is under discussion to be the successor of the optical lithography to reduce the size of line width in semiconductor devices below 50 nm. The use of EUV radiation around 13.5 nm in comparison to the UV radiation allows to reduce the structure sizes and offers as well sufficient large depths of focus. The usable spectral band is defined by the fact that there is a consensus to use molybdenum-silicon multilayer mirrors, which show highest reflectivity around 13.5 nm [1]. For industrially realizing the EUVL, serious efforts have been made to achieve the challenges and overcome the critical issues such as high power, high efficiency, compactness, high frequency operation, stable and debris-free EUV source. The gas-filled discharge plasma sources have the competitive advantages in above-mentioned points. Therefore, the discharge produce plasma produced by capillary Z pinch, plasma focus, hollow cathode triggered pinch und so on have attracted much attention in last several years and until now the research is being progressed. Each approach has individual technical aspects that influence the efficiency and the technical chances of realization. The comparisons of these are well defined by NeiTet al [2,3]. Common to all approaches is that optimized conversion efficiency is of major importance because this minimizes the demand on driving power for required EUV power. A debris-free EUV source with collectable radiation power of about 115 W with repetition rates exceeding 7 kHz is required to achieve an economical wafer throughput. We investigated the xenon-filled capillary Z-pinch as a potential source for the EUV lithography and employed an EUV pholodiodc to detect the EUV photon output and a high-speed camera to observe the capillary plasma dynamics, respectively. A grazing incidence spectrograph will be used to examine the spectral emission form the plasma and the scaling of this EUV light source for lithography.