Advances in excimer laser technology for sub-0.25-μm lithography

There are several lasers that can provide high-power radiation at deep-UV wavelengths. The only laser that has been successfully used in semiconductor manufacturing as a source for lithography is the excimer laser Excimer lasers provide direct deep-UV light, are scalable in energy and power, and are capable of operating with narrow spectral widths. Also, by providing three wavelengths at 248, 193, and 157 nm, excimer lasers span three generations. They have large beams and a low degree of coherence. Their physics and chemistry are well understood. Thanks to major technical developments, these lasers have kept up with the ever-tightening specifications of the lithography industry. We will discuss what these specifications are and the advances that have been made in laser technology to meet these. We will also identify any possible future limitation in this technology. The success behind the microelectronics explosion is attributed to many factors. The excimer laser is one of them.