Patent ID: 8785879

Claim:
An electron beam wafer imaging system, comprising: an emitter for emitting an electron beam, wherein the emitter is a cold field emitter, a thermally assisted field emitter, or a Schottky emitter; a power supply for applying a voltage between the emitter and the column housing of at least 20 kV; an objective lens for focusing the electron beam on a wafer, wherein the objective lens has a magnetic lens component and an electrostatic lens component, wherein the magnetic lens component and the electrostatic lens component substantially overlap each other, wherein the electrostatic lens component has a first electrode, a second electrode and a third electrode; and a control electrode positioned along an optical axis from the position of the third electrode to the position of a specimen stage, wherein the control electrode is configured for control of signal electrons; a controller to switch between a first operational mode and a second operational mode, wherein the controller is connected to a further power supply for switching between the first operational mode and the second operational mode, where said first operational mode corresponds to moderate landing energies and said second operational mode corresponds to low landing energies.