Patent ID: 7736841
Filing Date: 2010-06-15
Classification: G03F

Abstract:
1. A method of exposing a resist layer with regions of photosensitivity to an image in a lithographic process using a high numerical aperture imaging tool comprising: providing an imaging tool having a high numerical aperture for projecting radiation forming an aerial image; providing a substrate having a layer reflective to the imaging tool radiation and a resist layer with a region of photosensitivity over the reflective layer, the resist layer having a thickness; projecting radiation containing an aerial image from the imaging tool onto the resist layer, a portion of the radiation containing the aerial image passing through the resist layer; and reflecting a portion of the radiation containing the aerial image that passes through the resist layer off the reflective layer back to the resist layer, the reflected radiation forming an interference pattern in the resist layer of the projected aerial image through the resist layer thickness, wherein the location of the resist layer region of photosensitivity with respect to the reflective layer is selected to include from within the interference pattern higher contrast portions of the interference pattern in the direction of the resist thickness, and to exclude lower contrast portions of the interference pattern in the resist thickness direction from said resist layer region of photosensitivity, to improve contrast of the aerial image in said resist layer region of photosensitivity.