Characterization of silicon cantilevers with integrated pyramidal metal tips in atomic force microscopy

Scanning spreading resistance microscopy (SSRM) and scanning capacitance microscopy (SCM) are two different methods for carrier profiling on semiconductor devices based on the atomic force microscope (AFM). The crucial part of these characterization tools is the tip which should have a small radius of curvature and a high electrical conductivity. It is obvious to use metal as tip material due to its excellent electrical conductivity. Therefore, we have developed a process for the fabrication of pyramidal metal tips which are integrated into a silicon cantilever. The fabrication scheme is presented and is discussed in more detail from the point of view of batch fabrication. The fabricated probes were used in the AFM for topography measurements and for electrical measurements. We demonstrate that these probes can be operated in contact mode as well as in tapping mode(TM). The behavior of the metal tips in carrier profiling was extensively studied. Results are presented concerning the application of such probes for two-dimensional SCM measurements on silicon and InP device structures. We demonstrate that silicon cantilevers with integrated metal tips are very well suited for SSRM measurements on InP structures.