FABRICATION OF IMPROVED PIEZORESISTIVE SILICON CANTILEVER PROBES FOR THE ATOMIC-FORCE MICROSCOPE

This paper describes an improved design for a monolithic silicon atomi c force microscope (AFM) probe using piezoresistive sensing. The probe is V shaped, with a sharp tip at the free end and two piezoresi stors at the root, and is fabricated using silicon-on-insulator (SOI) start ing material. The maximum sensitivity of the AFM probe is measured to be 4.0(+/-0.1) X 10(-7) Angstrom(-1), which is larger than that of the previous parallel-arm piezoresistive AFM probe The measured results a re in reasonable agreement with the values predicted by theory. The mi nimum detectable force and minimum detectable deflection Of the AFM pr obes are predicted to be 1.0 X 10(-10) N and 0.29 Angstrom(r.m.s.), re spectively, using a Wheatstone bridge arrangement biased at a voltage of +/-5 V and bandwidth of 10 Hz(-1) kHz.