Site-specific and high-spatial-resolution scanning spreading resistance microscopy (SSRM) and its applications to Si devices

In this study, we review on SSRM studies on 2D carrier profiles of various devices applications including S/D engineering and failure analysis in real SRAM devices. The correlation of SSRM images with junction leakage current of nMOSs was confirmed. We also directly observed carbon (C) co-doped Si:C nMOSs, clarifying the C doping effect on phosphorous diffusion and therefore on device characteristics. With utilizing the site-specific SSRM, we succeeded in observing the pn-junction boundary within a thin SRAM poly-Si gate with the size of less than 60 nm. We also directly observed fail bits of pMOSs with V_th variations in SRAM, clarified that the failure is originated from the phosphorus anomalous diffusion into the pMOS gate bottom. Site-specific SSRM is demonstrated having high potential for failure analysis and for characterization of further scaled devices.