Permanent magnet based high performance multi-axis immersion electron lens array with low axial leakage field

摘要

An apparatus includes a magnetic adjustment lens positioned at the electron beam path between the electron source and sample, the magnetic adjustment lens excited by an electric coil, and a permanent magnet lens positioned below the magnetic adjustment lens to focus the electron beam onto the sample surface, the permanent magnet lens excited by one or more permanent ring magnets enclosed except on a bottom surface by a magnetic field conductor. The magnetic adjustment lens may be excited to eliminate magnetic field leakage of the permanent magnet lens.

主权项

1. An apparatus, comprising:
a magnetic adjustment lens, which is excited by an electric coil, positioned along an electron beam path between an electron source and a sample to be scanned by an electron beam in the electron beam path; a permanent magnet lens positioned directly below the magnetic adjustment lens to focus the electron beam onto the sample to be scanned, the permanent magnet lens excited by one or more permanent ring magnet enclosed except on a bottom surface of the permanent ring magnet by a permanent magnet lens magnetic field conductor; and the magnetic adjustment lens adapted to emit a high magnetic leakage field relative to a magnetic leakage field produced by the permanent magnet lens above the permanent magnet lens, the magnetic adjustment lens positioned relative to the permanent magnet lens such that the high magnetic leakage field is emitted when the electric coil is excited and interferes to substantially eliminate the magnetic leakage field produced by the permanent magnet lens above the permanent magnet lens.