Electron beam nano-metrology system

Abstract

An electron beam nanometer-level metrology tool includes an ambient temperature electron source and a movable stage for mounting a workpiece. The stage is adapted to position the workpiece's surface in a beam interrogation region. Electrostatic focus lenses convert electrons emitted by the electron source into a beam with a focal point that is positioned in the beam interrogation region. The lenses cause the electron beam to traverse a path that is generally orthogonal to the workpiece surface. Along the beam path are positioned upper and lower electrostatic deflection plates which are connected to an adjustable voltage source that applies ganged, opposite-sense d/c potentials thereto. Those potentials enable a scanning of the beam across the beam interrogation region while the beam remains substantially orthogonal to the workpiece surface, thereby enabling more accurate measurements of surface features. Within the metrology tool, all beam control surfaces are electrostatic so as to minimize power dissipation and temperature differentials.