Ultralow voltage imaging

Low‐voltage (<1 kV) electron beams have become widely used in the semiconductor industry for nondestructive imaging of integrated circuits. By focusing the electron beam onto the device at an energy close to EII, the unity‐yield point of the material, charging can be minimized. In addition, the penetration depth of the beam into the device is greatly reduced, generating images which carry more surface information and minimizing beam‐induced damage. In this paper we discuss electron beam imaging at ultralow voltages (100–800 V). Within this range, the landing energy is optimal for many insulating materials used in semiconductor devices. Resolution better than or equal to 5 nm is attainable at 600 eV landing energy, and the weak dependence of resolution on landing energy allows the selection of an appropriate energy for a particular material or contrast mechanism.