The Development of Excimer Laser Technology – History and Future Prospects

Abstract

With focus on commercial aspects the paper reviews the historical development and various technological achievements in the field of excimer lasers since their discovery in 1970. The first commercial excimer laser model in the world, the EMG 500 from Lambda Physik was operating at maximum repetition rates of only 20 Hz, whereas today multi kHz excimer lasers as the NovaLine industrial lasers are available. In 2000, Lambda Physik introduced the most powerful commercial excimer laser, the Lambda Steel with 300 W output power having extremely high stability.In the more than 30 years of excimer lasers their properties have been studied in a multitude of research laboratories at universities, institutes, national laboratories, and industry. In the attempts to reach parameters in the UV never seen before, energies ranging from mJ to kJ, pulse durations from sub μs down to fs, spectral bandwidths from fractions of 1 nm down to less then 0.1 pm, and beam divergence from 10 mrad down to 10 μrad could be demonstrated at the various excimer lasers wavelengts. Over the years various technological achievements like the NovaTube laser chamber technology, the NovaPowerSwitch pulsed power modules and the HaloSafe fluorine and chlorine generators could be made which make the use of excimer lasers simple and user friendly. Recently, the development of DuraTube technology gave a strong push towards the development of high power 157 nm laser technology for microlithography and laser based micro-machining of “difficult” materials as fused silica or teflon.The paper describes important steps and quantum leaps in developing and improving excimer lasers. Since a large part of excimer laser development was driven by application requirements some applications developed over the years are touched as well – including early photochemistry and dye laser pumping in F. P. Schäfers laboratories. Finally, currently ongoing and for the future expected technological developments are discussed which will strengthen the position of excimer lasers as user friendly work horses in many industrial and research areas.