Electron beam nano-metrology system
First Claim
1. An electron beam, nanometer-level metrology tool for making precise measurements of relative positions of pattern features within an active pattern array of a workpiece, said tool comprising:
- an ambient temperature electron source;
movable stage means for mounting a workpiece having a surface with physical features to be measured, and for positioning said workpiece surface in a beam interrogation region;
beam control means including ambient temperature electrostatic focus means for converting electrons emitted by said electron source into an electron beam with a focal point in said beam interrogation region, said electron beam traversing a path to said beam interrogation region that is generally orthogonal to said workpiece; and
means for determining distance measurements between submicron-sized features on said workpiece surface where the distance measurements are very large compared with the size of the features from interactions of said beam and workpiece surface.
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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.
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Citations
11 Claims
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1. An electron beam, nanometer-level metrology tool for making precise measurements of relative positions of pattern features within an active pattern array of a workpiece, said tool comprising:
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an ambient temperature electron source;
movable stage means for mounting a workpiece having a surface with physical features to be measured, and for positioning said workpiece surface in a beam interrogation region;beam control means including ambient temperature electrostatic focus means for converting electrons emitted by said electron source into an electron beam with a focal point in said beam interrogation region, said electron beam traversing a path to said beam interrogation region that is generally orthogonal to said workpiece; and means for determining distance measurements between submicron-sized features on said workpiece surface where the distance measurements are very large compared with the size of the features from interactions of said beam and workpiece surface. - View Dependent Claims (2, 4, 5, 6, 7, 8, 9, 10, 11)
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3. The electron beam, nanometer-level metrology tool as recited in claim 13, wherein each said upper and lower electrostatic deflection means comprises:
plural deflection plates positioned about said path, said adjustable voltage means enabling a two-dimensional deflection of said beam, while retaining said substantially orthogonal relationship of said beam to said workpiece surface.
Specification