File:Direct electric field visualization in semiconductor planar structures (IA directelectricfi109452398).pdf

A new technique for imaging the 2D transport of free charge in semiconductor structures is used to directly map electric field distributions in operating devices. Direct transport imaging is demonstrated in a scanning electron microscope, using an optical microscope and a high sensitivity charge coupled device. Transport behavior under the combined influence of both diffusion and drift is predicted by modeling the drift and diffusion in 2D following generation at a point source. This is the first demonstration of a technique that allows the mapping of the electric field by determining not only the direction but especially the magnitude of the electric field with high resolution. The measured results show excellent agreement with theoretical predictions simulated with COMSOL software. The transport imaging technique also allows measurement of the contact resistance in a new way that is nondestructive and based on a two-point contact only. The technique illustrates the device's characteristics by determining the exact activation point of the diode and the deviations from an ideal I-V behavior. The method is extremely useful since the complexity and miniaturization of current devices do not allow for multiple wiring that standard four point measurement demands. Finally, a suggestion for further research of the effects of electromigration by using the direct transport imaging technique is offered. The latter is a subject of high importance in electronic device reliability.

Subjects: Systems engineering; Physics; Electronics; Scanning electron microscopes; Semiconductors; Methodology