Silicon based nanometric oscillator for scanning force microscopy operating in the 100 MHz range

Abstract

The detectable force resolution of a mechanical oscillator used in scanning force microscopy can be improved by increasing its natural frequency fo, quality factor Q, and by decreasing the spring constant k and the temperature of operation T. For an oscillator having a structure that can be modeled as a concentrated mass-spring model, decreasing the mass of the oscillator is desirable, since high fo can then be obtained without increasing the spring constant k. We have developed a novel fabrication technique for a head-neck shaped nanometric oscillator by selective etching of a laminated silicon substrate known as SIMOX. The oscillator head or mass measures 60 nm or 170 nm in thickness and 100 nm to 500 nm in diameter, depending on the size of the mask. The neck, which serves as an elastic support for the mass, measures 100 nm in length. The oscillator could be tailored to have its natural frequency in the range of 0.01 GHz to 0.5 GHz, and a spring constant between 10-1 N/m and 102 N/m.