Fabrication of metal embedded photo-mask for sub-micrometer scaled photolithography and patterning sapphire substrate

This paper describes the fabrication processes of a new type of metal-embedded photo-mask, which will be used in standard photolithography and for fabricating patterned sapphire substrates. This new metal-embedded photo-mask is prepared by metal contact printing lithography and therefore can easily achieve smaller feature size around or below 1 μm. Besides its easiness in fabricating and obtaining smaller line-width, this new metal-embedded photo-mask differs from a conventional Cr/glass photo-mask in that the metallic patterns are embedded and therefore are not in contact with photo-resist during UV exposure. This unique feature can minimize the damage to photo-mask in use and prolong its lifetime. In this work, this metal-embedded photo-mask is experimentally prepared and applied to photolithographic patterning of PR microstructures on sapphire substrates, which are important in LED industries.