A new class of deep UV Photoresist based on the principles of chemical amplification was developed. This photoresist consists of three basic elements: a copolymer, blocked tetrabromobisphenol-A as a dissolution inhibitor and a photosensitive onium salt as a photoacid generator. On irradiation followed by a post exposure bake, tert-butoxycarbonyloxy phenyl group is converted to phenol group. Thus the initially base insoluble resin is converted under UV irradiation to a base soluble resin which may be preferentially removed by dissolution. This new photoresist display high sensitivity, 10 mJ/cm2.