Direct-Drive Oscillation of KrF Excimer Laser Using Pulsed Power Generator Based on LTD

The excimer laser is a laser characterized by high output and high gain oscillation in the ultraviolet region. Utilizing these features, excimer lasers are currently in practical use as light sources for semiconductor lithography. We are aiming to improve the oscillation efficiency and to extend the lifetime of excimer lasers. In this article, we have evaluated the oscillation efficiency by directly driving the krypton fluoride (KrF) excimer laser using a pulsed power generator based on a linear transformer driver (LTD), which is one of the new pulsed power generation methods. As a result, we have demonstrated, for the first time, the direct pumping of KrF excimer laser using LTDs. However, although it is confirmed that the oscillation efficiency was improved by about 15% on the low-input level, it is observed that the laser output is significantly reduced on the high-input level, compared with the traditional method. It is concluded that the circuit and the pumping waveform need further optimization.