Nanosecond Pulsed Discharge Characteristics in an ArF Excimer Gas Mixture

High-pressure discharge-pumped ArF excimer lasers play a critical role in advanced semiconductor lithography systems. This study investigates nanosecond pulsed discharge in a Ne/Ar/F₂/Xe mixture, with particular focus on main discharge homogeneity and preionization discharge homogeneity. The experimental configuration features flat-profile electrodes (23 cm × 1 cm) with a linear array of 9 UV pre-ionization pins for controlled seed electron generation. Discharge spatiotemporal evolution images were captured using a 500 ps-gated ICCD camera, while the time-resolved 193-nm emission intensity from spontaneous decay of ArF* molecules was measured via the ICCD camera equipped with a 193 nm narrow-band filter. It is found that the discharge initially develops as a uniform glow, and then transitions to a structured pattern with alternating regions of strong and weak emission, accompanied by cathode spot formation. Analysis reveals that glow intensity distribution is strongly influenced by pre-ionization characteristics, where variations in pin discharge conditions lead to localized electric field distortions. By varying the inductance of the pre-ionization circuit, the intensity dispersion of the pre-ionization pins was optimized, thereby improving the axial uniformity of the discharge. These insights advance the understanding of discharge dynamics in excimer lasers and provide guidance for optimizing uniformity and 193 nm output in industrial applications.