Patent ID: 7279689

Claim:
A method comprising: directing a beam of charged particles to irradiate contact openings in a sample along a beam axis that deviates substantially in angle from a normal to a surface of the sample, the sample having a first layer that is at least partially conductive and a second layer formed over the first layer, the contact openings having been formed in the second layer using an etch process; measuring, in response to incidence of the beam on the sample, a specimen current flowing through the sample; analyzing the specimen current so as to assess whether a contaminant residue is present within the contact openings, and, if so, irradiating the sample with the beam of charged particles along the normal to the surface so as to remove the residue, wherein some of the contact openings are characterized by a tilt relative to the normal to the surface, and wherein directing the beam comprises angling the beam so as to compensate for the tilt.