Patent ID: 6296991
Filing Date: 2001-10-02
Classification: G03F

Abstract:
A bi-focus exposure process for exposing a wafer, comprising:providing a mask on the wafer, wherein the mask comprises:a transparent substrate having a phase shift of about 0 degrees;a plurality of first hole features having a transmission of about 100% and having a phase shift of about 0 degrees on the substrate;a plurality of second hole features having a transmission of about 100% and having a phase shift of about 180 degrees on the substrate, wherein the second hole features and the first hole features are alternatively located on the substrate; anda patterned material layer, having a transmission between 0 and 100% and having a phase shift of about 90 degrees, substantially and adjacently surrounds each of the first and the second hole features on the substrate;exposing the wafer through the mask at a first defocus to print the patterns of the first hole features on the wafer; andexposing the wafer through the mask at a second defocus to print the patterns of the second hole features on the wafer.