Nano-electric studies on advanced semiconductor devices by conductive AFM

Conductive atomic force microscopy (CAFM) was used to investigate nano-electric performances of semiconductor MOS (metal-oxide-semiconductor) devices. Due to the small tip size (as small as ~20 nm for PtSi probes), CAFM is capable of imaging both topography and current information of nano-device structures simultaneously with very high lateral resolution. Due to the use of wide ranges of current amplifier (sensitivity from 1pA/V to 1uA/V to 1mA/V), CAFM can detect current as small as sub-pA to relatively large current of uA to mA range. Furthermore, I-V measurement is capable of measuring current change as a function of bias voltage. In this study, we first use CAFM to measure a SRAM (Static Radom Access Memory) device as an example to show the CAFM capabilities and advantages in a general review of CAFM tip selection and sensitivity considerations, followed by selected examples of CAFM studies on different semiconductor devices for electric failure analysis (EFA) and faulty isolation.