Abstract: Diamond films are essential to next generation X-ray lithography mask. The affection of different
process parameter to nucleation density and nucleation quality were investigated by controlling substrate-temperature, changing growth-time
and CH₄ concentration etc., and some high-density nucleation samples were obtainted. Mean time, pregrowth process after nucleation of
diamond films was improved and dominant growth of major island was restrained effectively. The results show that the nucleation process
can be optimized as 14% of CH₄ concentration, 700℃ of substrate-temperature, 14min of nucleation. The optical properties and stress distribution
of free-standing diamond membranes can be improved greatly.

Key words: nucleation, diamond film, MPCVD, X-ray lithography .mask