SHIELDING STRATEGY FOR MITIGATION OF STRAY FIELD FOR PERMANENT MAGNET ARRAY

• Main Authors: Maurino, Joseph, Zhang, Qian, Plettner, Tomas, Lo, Wayne Chiwoei
• Format: Patent
• Language: English
• Published: 09.03.2023
• Subjects: BASIC ELECTRIC ELEMENTS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; INDUCTANCES; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MAGNETS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS; MEASURING; PHYSICS; PRINTED CIRCUITS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES; TESTING; TRANSFORMERS

The present disclosure provides an inspection system and a method of stray field mitigation. The system includes an array of electron beam columns, a first permanent magnet array, and a plurality of shielding plates. The array of electron beam columns each includes an electron source configured to emit electrons toward a stage. The first permanent magnet array is configured to condense the electrons from each electron source into an array of electron beams. The first permanent magnet array is arranged at a first end of the array of electron beam columns. The plurality of shielding plates extend across the array electron beam columns downstream of the first permanent magnet array in a direction of electron emission. The array of electron beams pass through a plurality of apertures in each of the plurality of shielding plates, which reduces stray magnetic field in a radial direction of the array of electron beams.