Method for measuring submicron images

Abstract

A method for determining the quality of features of a photoresist pattern, especially for vias and contacts, formed on a semiconductor wafer. A photoresist mask layer having a pattern of openings therein is deposited onto the wafer, and a test region (kerf) of the wafer is marked through the openings in the mask layer. In a preferred embodiment, the mask layer is a photoresist layer, although in alternative embodiments the mask layer could be provided as an insulator mask layer or a metal mask layer. The marking transfers an image of the bottom of the mask layer into the substrate by etching, such as by rastering a focused ion beam over the openings in the mask layer in the presence of an etchant gas. This provides an etched mark in the wafer defined by the passage of the focused ion beam through the mask opening. In alternative embodiments, the marking could be performed by staining or dyeing. Following the marking step, the mask layer is removed from the test region to facilitate an inspection of the wafer for the presence of the marking while leaving the mask layer in place over remaining portions of the wafer.

Dependencies are inferred from the claim text.