Laser Pulsed E-Beam System for High Speed I.C. Testing

There has been much discussion recently on different techniques for non-contact picosecond probing of internal nodes of integrated circuits fabricated on any substrate material/1–3/. All these techniques, however, use an optical probe and as such are limited in spatial resolution to about 1μm which is already large compared to feature sizes in some modern devices and wiring geometries. Electron probe techniques which do not suffer from this disadvantage have been used for many years to test I.C. circuits but have in general been limited by their poor temporal resolution. In this paper we describe a novel type of instrument that combines the advantages of conventional SEM voltage contrast techniques /4/ (including a spatial resolution of order 100A and beam steerability) with an order of magnitude improvement in temporal resolution.