The present application provides a method for process a substrate. The method includes steps of providing a substrate having a sacrificial layer and an insulative layer, forming a polysilicon hardmask on the insulative layer, etching the insulative and sacrificial layers through multiple openings in the polysilicon hardmask to thus form multiple channels, depositing a metal film and a passivation film on the polysilicon hardmask and in the channels, performing a first removal process to remove portions of the passivation film and the metal film above the polysilicon hardmask, performing a second removal process to remove portions of the polysilicon hardmask exposed through the passivation film and the metal film, and performing a third removal process to remove the polysilicon hardmask and portions of the passivation film and the metal film surrounding the polysilicon is hardmask.