Characterization of lateral bipolar transistor structures

Abstract

Semiconductor devices are being scaled down into the submicron regime in order to meet technological demands for increased device-packing densities. Other factors considered for device design include low power dissipation, noise immunity, speed and high driving capability. Of these factors, high packing densities and low power dissipation can be derived using Coinplementary-Metal-Oxide-Semiconductor (CMOS) schemes. Bipolar-Junction-Transistor (BJT) schemes on the other hand provide driving capability, low noise performance and speed, at the expense however of greater device power- consumption. Combining CMOS and BJT technologies, a compromise can be struck between devicespeed and power dissipation. Most such combinations have resulted in vertical BJT requiring complex fabrication sequences. Recently, simpler lateral BJTs have been proposed for use in Bipolar CMOS processes. The viability of such semiconducting devices depends in part on the absence or controlled presence of structural defects. Diagnostic techniques are therefore required that are capable of high spatial resolution, for investigating the origin, behavior and possible elimination of fabrication-process-induced defects. Transmission electron microscopy (TEM) of device cross-sections can be effectively used for this purpose. In this study, lateral BJT structures are characterized using cross-section TEM and the results are correlated with electrical device-behavior.