Toward extending the capabilities of scanning spreading resistance microscopy for fin field-effect-transistor-based structures

Abstract

In this work, the authors investigate the present capabilities of scanning spreading resistance microscopy (SSRM) to map the carrier distribution in fin field-effect-transistor- (FinFET) based structures. Whereas for a planar metal-oxide-semiconductor transistor the distance to the back-contact is noncritical, this no longer holds true for a FinFET-based device as the limited cross-section of the fin may induce an important series resistance. The authors examine theoretically and experimentally the influence of the back-contact distance and the fin dimensions on the dominance of the spreading resistance. Based on the study, the authors propose a maximum distance for the back-contact that is needed to obtain a reliable two-dimensional map of the spreading resistance of fins with uniform doping concentration and fins with junction using SSRM. As the back-contacts are FIB deposited, the authors also study the influence of the Ga+ beam energy on the back-contact resistance, which adds critically to the bulk resistance of the fin, giving rise to a higher total resistance. Finally, the authors compare the fin dimensions obtained with SSRM and transmission electron microscopy micrograph.