Feasibility study of 6 kHz ArF excimer laser for 193 nm immersion lithography

Abstract

A feasibility study of next generation 6 kHz ArF laser for lithography is presented. High repetition rate operation of excimer lasers faces two technical challenges: 1) the occurrence of acoustic waves caused by the discharge in the laser chamber and 2) the huge energy consumption of the large gas flow fans. This paper describes our approach to dampen the acoustic waves. A computer simulation of acoustic wave generation inside the discharge chamber was done. The simulation correlates well with Schlieren photography measurements that visualized the acoustic waves. Based on these results, a chamber for 6 kHz repetition rate was newly designed. Measured spectral data (FHWM and E95) proved that the acoustic wave perturbation was remarkably reduced. A very efficient design method for high repetition rate laser chamber has therefore been established.

High power injection lock 6 kHz 60 W laser for ArF dry/wet lithography

“…We improve acoustic intensity at discharge area. We demonstrated numerical simulation analysis at discharge area before 6) . We found out optimized solution blow 6kHz (figure 8).…”

A single-filament schlieren method for flowing characteristic measurements in the pulsed gas lasers

“…ArF excimer lasers with narrow linewidth [1] and high repetition rate [2,3] have been greatly developed and widely applied in photolithography [4,5], a critical technology used in the manufacturing of microelectronic devices. High average power is achieved by increasing the repetition rate up to several kilohertz [2,6].…”

Evolution of shock wave in TEA gas laser

“…3 In the past two decades, the flow field developing process after discharge in the chamber and its influence to the next discharge have attracted the attentions of scientists and Engineers for the increasing high-repetitive-rate and stable-discharge demands of repetitively pulsed gas laser application, especially the EUV Lithography application. 4,5,10 The schlieren 6,10 , shadowgraph 11 , and interferometry 5,7 were all applied, and the images of three kinds of shock waves (the longitudinal shock waves in the gas flow direction, the transversal shock waves between the electrodes and the transversal shock waves between optics) were obtained 7,11 . However, most of these works were qualitative or semi-quantitative 5,7,10,11 .…”

“…4,5,10 The schlieren 6,10 , shadowgraph 11 , and interferometry 5,7 were all applied, and the images of three kinds of shock waves (the longitudinal shock waves in the gas flow direction, the transversal shock waves between the electrodes and the transversal shock waves between optics) were obtained 7,11 . However, most of these works were qualitative or semi-quantitative 5,7,10,11 . Furthermore, the shortest exposure time of traditional CCD or COMS camera limited the transient observation of the whole chamber, which restricted the application of imaging technique in the flow field temporal analysis.…”