Process for making hard pellicles

Disclosed is a process for making thin hard pellicle for photomasks used in projection photolithography. The process can be used for making thin hard pellicles comprising a pellicle layer having a thickness in the range of about 5 to 120 mum and a mount frame attached to the peripheral area of a surface of the pellicle layer. The pellicle layer can consist essentially of a material selected from silica, fluorine doped silica, aluminum doped silica, methylated silica, fluorinated and methylated silica, fluorinated aluminum doped silica, CaF2, MgF2, BaF2 and SiC. The mount frame is preferred to have substantially the same CTE of the pellicle layer to minimize stress caused by temperature change. The mount frame is preferred to be porous to the purging gas. The process for making the hard pellicle involves deposition of an intermediate layer comprising a hydrogenated amorphous silicon layer on a flat substrate, deposition of the pellicle layer on the intermediate layer, mounting the frame to the pellicle layer and the separation of the pellicle from the substrate by heat treatment.