Patent ID: 11927549
Assignee: KLA CORPORATION
Field: Measurement (Instruments)
Classification: CPC G  H | IPC G  H

Claim 10:
11. A method of stray field mitigation applied to a multi-column inspection system including an array of electron beam columns, each electron beam column comprising an electron beam source configured to emit electrons toward a stage, the method comprising:
directing the electrons from each electron source through a first permanent magnet array to condense the electrons into an array of electron beams, wherein the first permanent magnet array is arranged at a first end of the array of electron beam columns; and
directing the array of electron beams through a plurality of shielding plates extending across the array of electron beam columns downstream of the first permanent magnet array;
wherein the plurality of shielding plates each comprise a plurality of apertures and have a thickness between 1 μm and 1 mm, and the array of electron beams pass through the plurality of apertures; and
whereby the plurality of shielding plates reduce stray magnetic field in a radial direction of the array of electron beams.