Ph.D. Proposal Presentation by Heungjoo Shin
Wednesday, April 6, 2005
(Dr. Peter J. Hesketh, Chair)
"Fabrication of Atomic Force Microscope Probes Integrated with Electrodes for Micro Four-Point Probe and SECM-AFM"
This study shows the development of tools for electrical characterization of semiconductor devices and sensor devices, and for electrochemical imaging respectively. The both tools were designed on the basis of the AFM (Atomic Force Microscope) cantilevers that allow for highly accurate control of the probe positioning, low contact force, micro-size and topological image scanning.
Miniaturization of the electronic devices to submicron dimensions on integrated circuits has increased the demand for namometer scale diagnostic tools used for characterizing device properties. The electrical carrier concentrations in semiconductors are commonly determined using the four-point probe method. The four-point probe is particularly suited for systems with slow spatial conductivity variations compared to the electrode spacing. For systems that exhibit rapid spatial conductivity variations or has small separated doped area, it is preferable to reduce the electrode spacing below the characteristic scale of the variations. This study presents a fabrication method for a micro four-point probe with solid nickel tips and experimental results using the probe. The fabrication method introduces selective conical metal tip etching in silicon dioxide etching chambers. The probe body was made of electroplated nickel or PECVD silicon carbide.
A novel batch fabrication method for SECM-AFM (Scanning Electrochemical Microscope-Atomic Force Microscope) tip integrated with a ring electrode was developed as a tool for electrochemical imaging. The electroactive area at an exactly defined distance above the apex of the AFM tip is fabricated using an inverse silicon mould technique. The electrode at a deliberately chosen distance from the end of a scanning probe tip allows one to obtain the electrochemical data separated from the topographical image. The new probe is based on the integration of ring electrode geometry, which has theory well established for SECM application.
The performance of these novel different AFM probes will be examined by using a conventional AFM system.