Design considerations and performance of 1-kHz KrF excimer lasers for DUV lithography

摘要

The operation of 1 kHz KrF lasers for DUV lithography applications requires a design which minimizes perturbations to the optical and electrical properties of the gas present, at one millisecond intervals in the lasing region and vicinity. The optimum design results from a compromise between electrical and fluid dynamic requirements, since these cannot be simultaneously fully satisfied. Other constraints on a commercially viable design are those rooted in issues such as manufacturability, safety, cost, compatibility with fluorine, and service lifetime of the resulting structure. CYMER has successfully engineered a laser which produces linear average power output scaling with pulse repetition rates to 1 kHz at a line- narrowed bandwidth of less than 0.8 pm. The stabilized pulse energy is 10 mJ with a FWHM of approximately 15 nS, producing an average power of 10W at 1 kHz pulse repetition rate. The 3$sigma value of pulse energy stability is 5 percent. In addition, the chamber exhibits low fluorine consumption and a lifetime in excess of 2 billion shots. Measured performance data are presented along with a general system layout and facilities requirements.