High-resolution microlithography applications of deep-UV excimer lasers

The recent trend in microelectronics towards patterning critical feature sizes of 0.25 micrometer and below has motivated the development of microlithography at the deep ultra-violet (DUV) laser wavelengths of 248 and 193 nm. In recent years the performance, reliability, and cost of ownership of excimer light sources have improved. Some key technologies needed for excimer lasers in microlithography include materials issues, gas lifetime, higher repetition rates and improved pulse-to-pulse energy repeatability. An experimental demonstration of a new method to generate nearly nondiffracting Bessel beams using a Fabry-Perot interferometer is described. It is experimentally demonstrated that the DOF can be increased by a factor of 2 and simultaneously the transverse resolution improved by a factor of about 1.6, when using this technique to image contact holes.