Microstructure defect detection

Abstract

Methods of inspecting a microstructure comprise: applying charged particles to the wafer to negatively charge up the wafer over a region having contact or via holes, scanning a charged-particle beam over the region while detecting secondary particles so as to produce a detector signal, determining from the detector signal an apparent dimension of a contact hole, and comparing the apparent dimension of the contact hole with reference information to identify a defect. The reference information can be a conventional voltage-contrast image or can be design data indicating expected physical size of the contact hole and expected electrical connectivity of material within or beneath the contact hole. The wafer can be charged up by directing a flood of electrons toward a surface of the wafer and/or by controlling potential of an energy filter so as to direct secondary electrons back to the wafer while directing a charged-particle beam at the wafer. Other methods of inspecting a microstructure comprise charging up a microstructure, interrogating the microstructure with a charged-particle beam to obtain apparent dimensional information for a feature of the microstructure, and comparing the apparent dimensional information with reference information about the microstructure to identify a defect. Apparatus for inspecting semiconductor wafers and other microstructures are also disclosed, as are computer program products comprising a computer usable media having computer-readable program code embodied therein for controlling a charged-particle-beam system for inspecting a microstructure.