Asymmetric Electrostatic Quadrupole Deflector for Improved Field Uniformity

摘要

An electron beam device for inspecting a target substrate or specimen thereon includes a beam separator with an asymmetric quadrupole electrostatic deflector for improving field uniformity for a single direction of deflection. The asymmetric quadrupole electrostatic deflector includes two orthogonal electrode plates spanning roughly 60 degrees and two electrode plates spanning roughly 120 degrees, the two latter plates defining a unidirectional deflection field. The device generates a primary electron beam and focuses the primary electron beam along an optical axis into the target substrate. Secondary electrons detected at the target substrate are focused into a secondary electron beam. The beam separator with asymmetric quadrupole electrostatic deflector deflects the secondary electron beam away from the axis of the primary electron beam in the direction of deflection and into a detector array.

主权项

1. An asymmetric quadrupole electrostatic deflector, comprising:
a first pair of plates including a first plate and a second plate, the first plate and the second plate each spanning a first radial angle; and a second pair of plates including a third plate and a fourth plate, the third plate and the fourth plate each adjacent to the first plate and the second plate and each spanning a second radial angle greater than the first radial angle.