US Patent No. 9,905,322

MULTI-ELECTRODE ELECTRON OPTICS


Patent No. 9,905,322
Issue Date February 27, 2018
Title Multi-electrode Electron Optics
Inventorship Marco Jan-Jaco Wieland, Delft (NL)
Willem Henk Urbanus, Delft (NL)
Assignee MAPPER LITHOGRAPHY IP B.V., Delft (NL)

Claim of US Patent No. 9,905,322

1. A collimator electrode stack, comprising:
at least five collimator electrodes for collimating an electron beam along an optical axis, wherein each collimator electrode
comprises an electrode body with an electrode aperture for allowing passage to the electron beam, wherein the electrode bodies
are spaced along an axial direction which is substantially parallel with the optical axis, and wherein the electrode apertures
are coaxially aligned along the optical axis; and

a plurality of spacing structures provided between each pair of adjacent collimator electrodes and made of an electrically
insulating material, for positioning the collimator electrodes at predetermined distances along the axial direction, and wherein
each of the collimator electrodes is electrically connected to a separate voltage output for providing electric potentials
to the collimator electrodes,
wherein each of the collimator electrodes is configured to be kept at a fixed electric potential during operation of the collimator
electrode stack, wherein two adjacent collimator electrodes are configured to be kept at different fixed electric potentials
during operation of the collimator electrode stack resulting in an electric potential difference between two adjacent collimator
electrodes, wherein two adjacent collimator electrodes form a pair of adjacent collimator electrodes, and wherein the at least
five collimator electrodes are configured to be kept at the fixed electric potentials during operation of the collimator electrode
stack such that the electric potential differences in successive pairs of adjacent collimator electrodes have step-wise varied
magnitudes and result in a relatively smoothly varying of an electric field distribution along the axial direction, wherein
the electric field distribution acts as a lens on the electron beam.