A method for preparing a wafer includes forming a film layer on a substrate of the wafer; coating the film layer with a photoresist layer; exposing a first portion of the photoresist layer to a beam of light; and patterning a second portion of the photoresist layer after performing exposing the first portion of the photoresist layer. A cross-link reaction is caused on the first portion of the photoresist layer and the first portion of the photoresist layer is converted to a reacted first portion of the photoresist layer. The reacted first portion of the photoresist layer is near an edge of the wafer. The second portion of the photoresist layer is different from the reacted first portion of the photoresist layer. The second portion of the photoresist layer is converted to a patterned second portion of the photoresist layer.