Precision control methods in the fabrication of mask via femtosecond laser irradiation

Femtosecond laser mask fabrication and repair is a research focus in micro- and nano-manufacturing field, precision control is the key to obtain high quality mask. Precision control methods for the femtosecond laser fabrication of mask were proposed. On the basis of the theoretical researches on the damage characteristics of femtosecond laser pulse on the chromium film and the fused silica, a femtosecond pulsed laser system with the output pulse width of 25 fs, the maximum power of 1 W, the central wavelength of 800 nm and the repetition rate of 1 kHz was adopted in experiments. The relationships among the feature size of micro-structure, laser energy density, and scan speed were studied, and a mask with the critical dimension of 290 nm was fabricated with the optimized processing parameters. Furthermore, the effects of energy density and scan times on the edge and bottom morphologies of micro-structures were discussed, and some important principles for selecting the processing parameters were proposed to realize precision control and optimization of mask quality.