A thermal lithography technique was proposed for fabricating nanoscale patterns. Due to heat of illuminating laser, the phase of a resist material can be altered from amorphous to crystalline states. The contrast of dissolution rate between these two states can conduct a formation of nanopatterns through development. Using thermal lithography, a minimum pattern width of 140 nm with a height of 80 nm, far beyond the diffraction limit of 312 nm, for Ge-Sb-Sn-O inorganic resist can be obtained with a numerical aperture of 0.65 at the wavelength of 405 nm. Thermal lithography technique will be applied to the mastering process because it is convenient, low-cost and time-saving.