Enhanced Spatial Resolution Electrical Scanning Probe Microscopy By Using Carbon Nanotube Terminated Tips

摘要

Electrical scanning probe microscopes (SPMs), such as the scanning capacitance microscope for two dimensional dopant profiling, scanning Kelvin force microscope for surface potential measurements, and the tunneling atomic force microscope for dielectric integrity measurements, are important tools for the characterization of CMOS and nanoelectronic devices. A significant limitation of all these techniques is the stray capacitance from the shank of the tip and cantilever, which causes signal averaging over an area much wider than expected from the terminal tip dimensions. We have used conventional SPM tips terminated with a welded carbon nanotube (CNT) to overcome this limitation. We have examined with scanning capacitance microscopy and scanning Kelvin force microscopy, using both conventional and CNT terminated tips, ultra-shallow junctions, high-κ gate stacks, low-κ intermetal dielectrics, and FINFET devices in cross-section. We have also measured the electrical properties of the CNT terminated tips. Substantial improvement in the spatial resolution was observed with the CNT terminated tips as compared to the conventional tips, but additional artifacts could also be introduced by the CNT tips. CNT terminated tips provided enhanced spatial resolution when used for electrical characterization measurements useful for nanoelectronics.