A method for implanting a dopant in a substrate is provided. A patterned photoresist mask is formed over the substrate, wherein the patterned photoresist mask has patterned photoresist mask features. A protective layer is deposited on the patterned photoresist mask by performing a cyclical deposition, wherein each cycle, comprises a depositing phase for depositing a deposition layer over surfaces of the patterned mask of photoresist material and a profile shaping phase for providing vertical sidewalls. A dopant is implanted into the substrate using an ion beam. The protective layer and photoresist mask are removed.