Method for forming dual damascene structure

摘要

A method for forming dual damascene metallic structure that utilizes the formation of a protective photoresist layer at the bottom of a vertical window to prevent damages to a device region in the substrate when subsequent etching operation is carried out to form a horizontal trench pattern. The protective photoresist layer at the bottom of the vertical window is formed by irradiating the photoresist layer with a dose of radiation having energy level insufficient to chemically dissociate the photoactive molecules of the photoresist layer near the bottom of the vertical window.