Study On Surface Anti-contamination Capping Layer Of The EUV Optical Elements And Related Technologies

With the development of electronic information industry, integrated circuit technology plays a very important role in computer systems, automation and control, precision machinery, communications equipment, and many other areas of daily life. And the lithographic technology is the core of integrated circuit manufacture. In recent years, increasingly sophisticated 193 nm lithography systems and its objective lens immersion technology have been close to the limit of theoretical linewidth. To break through the 22 nm and below technology nodes, EUVL technology has shown excellent application prospects and its commercialization process tends to be stable. However, the surface deposited contamination of EUV optical components has become one of the key restricting factors of their business applications. To maintain longer using cycle, it is necessary to achieve in-depth study of the mechanism of surface contamination and propose appropriate solutions.According to the mechanisms of surface motion and reaction of organic molecules on EUV multilayers, establishes a theoretical model of the surface of carbon contamination. Complete a quantitative assessment about key factors which causing surface carbon deposition(including molecular reaction cross-sectional area σ, binding energy E, the proportion of carbon atoms η, secondary electron yield Y). Some contamination inhibiting methods are proposed to different radiation environment. Based on the theoretical model simulation results, Ti O2 is selected as capping layer material of EUV projection lens. By a optimization method of "hysteresis loop" of reactive magnetron sputtering, precisely determine the oxygen level. The film samples are prepared to meet the basic requirements of the EUVL mirrors. And taking into account the practical effect of surface contamination, a high performance EUV multilayer structure of insensitive to capping layer optical parameters is proposed. Simulation results show that, when the irreversible contamination appears on optical elements surface, the aperiodic structure has more stable EUV reflectivity than traditional periodic structure. This is especially suitable to prepare multilayer on large curvature surface type EUVL mirror in harsh exposure environment. Finally, expand the relate functions of the EUV capping layer. A complex functions EUV capping layer has been designed and prepared, which include the abilities of spectral purity and surface anti-contamination. The theoretical and experimental results show that this structure significantly reduces the reflectivity in non-working spectrum of the mirrors with no too much loss of EUV flux. Thus the operation cost of the extreme ultraviolet source system.The content of this paper provide theoretical and experimental basis for EUV capping layer and relate optical elements. The technology problems of commercial lithography systems are reasonable predicted and assessed. And make a solid foundation for its large-scale market promotion.