Laser-produced plasma-based extreme-ultraviolet light source technology for high-volume manufacturing extreme-ultraviolet lithography

Since 2002, we have been developing a CO2-Sn-laser plasma produced (LPP) extreme-ultraviolet (EUV) light source, the most promising solution as the 13.5-nm high-power (> 200 W) light source for high-volume manufacturing (HVM) EUV lithography. Because of its high efficiency, power scalability, and spatial freedom around plasma, we believe that the CO2-Sn-LPP scheme is the most feasible candidate as the light source for EUVL. By now, our group has proposed several unique original technologies, such as CO2 laser-driven Sn plasma generation, double-laser pulse shooting for higher Sn ionization rate and higher CE, Sn debris mitigation with a magnetic field, and a hybrid CO2 laser system that is a combination of a short-pulse oscillator and commercial cw-CO2 amplifiers. The theoretical and experimental data have clearly demonstrated the advantage of combining a laser beam at a wavelength of the CO2 laser system with Sn plasma to achieve high CE from driver laser pulse energy to EUV in-band energy. We have the engineering data from our test tools, which include 20-W average clean power, CE = 2.5%, and 7 h of operating time; the maximum of 3.8% CE with a 20-mu m droplet, 93% Sn ionization rate, and 98% Sn debris mitigation by a magnetic field. Based on these data, we are developing our first light source for HVM: "GL200E." The latest data and the overview of EUV light source for the HVM EUVL are reviewed in this paper. (c) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.JMM.11.2.021111]