Abstract: Disclosed is a process for manufacturing a gate oxide of a MOSFET. Since the performance of the gate oxide is deteriorated in photo resist removing, DI healing and high temperature annealing are introduced to recover the gate oxide. A process for manufacturing the gate oxide of the MOSFET on a wafer, includes the steps of: pre-cleaning the wafer, forming gate oxide layer, coating a photo resist, exposing the photo resist, developing the photo resist, implanting ions over the developed photo resist, removing the photo resist, post-cleaning the gate oxide for the purpose of good attachment of a gate polysilicon layer, DI healing the gate oxide, and annealing the gate oxide at a high temperature. As a result, the pass rates for Ebd and Qbd tests of the gate oxide increase.