Phase shift mask blank, phase shift mask, and method of manufacture

摘要

In a phase shift mask blank comprising a transparent substrate and a phase shift film thereon, after the phase shift film is formed on the substrate, it is surface treated with ozone water having an ozone concentration of at least 1 ppm. The resulting phase shift film is of quality in that it experiences minimized changes of phase difference and transmittance upon immersion in chemical liquid during subsequent mask cleaning step or the like.