Provided is a photoresist that includes a polymer having a backbone that is breakable and a photo acid generator that is free of bonding from the polymer. Further, provided is a method of fabricating a semiconductor device. The method includes providing a device substrate. A material layer is formed over the substrate. A photoresist material is formed over the material layer. The photoresist material has a polymer that includes a backbone. The photoresist material is patterned to form a patterned photoresist layer. A fabrication process is then performed to the material layer, wherein the patterned photoresist layer serves as a mask in the fabrication process. Thereafter, the patterned photoresist layer is treated in a manner that breaks the backbone of the polymer. The patterned photoresist layer is then removed.