PRIMARY BEAM MOVEMENT EFFECTS IN ELECTRON-BEAM PROBING

This paper addresses the phenomenon of primary beam movements in Electron Beam (E-Beam) probing. Experiments carried out on an NMOS microprocessor IC have shown that the primary beam is deflected predominantly by magnetic fields which exist in the plane of the chip. These fields arise from large switching currents that flow through the bond wires and the package during certain parts of the test cycle. Experiments carried out to measure the beam shift as a function of the electron beam energy also confirm that the shift is primarily caused by magnetic fields. Some methods to minimize or eliminate the effect of the shift are also proposed.