US Patent 7851370 Patterning method

A patterning method is provided. In the patterning method, a film is formed on a substrate and a pre-layer information is measured. Next, an etching process is performed to etch the film. The etching process includes a main etching step, an etching endpoint detection step, an extension etching step and an over etching step. An extension etching time for performing the extension etching step is set within 10 seconds based on a predetermined correlation between an extension etching time and the pre-layer information, so as to achieve a required film profile.