Methods and apparatus for testing semiconductor and integrated circuit structures

Abstract

A method of testing a semiconductor structure such as a finished or part-finished semiconductor wafer, a die on such a wafer, part of such a die, or even one functional element (e.g. a transistor or memory cell) of such a die. The method includes the steps of charging at least a part of the semiconductor structure; applying an electric field perpendicular to a surface of the structure while charging so as to determine charging potential and polarity (i.e. charging either positively or negatively); interrogating the structure including the charged part with a charged particle beam, such as an electron beam, so as to obtain voltage contrast data for the structure; and analyzing the data to determine the functionality of the element. Apparatus according to the invention for testing semiconductor structures, includes: a system for applying charge to at least part of the semiconductor structure, such as an electron beam, flood gun or mechanical probe; an electric field generator, typically an electrode spaced from the surface of the structure, which applies an electric field perpendicular to a surface of the structure so as to determine the potential and polarity of the charge applied to the element (i.e. positive or negative charge); a charged particle beam device such as an electron beam for interrogating the charged element; and a detector such as a secondary electron detector which obtains voltage contrast data from the structure on interrogation with the charged particle beam.