Fabrication of a silicon based nanometric oscillator with a tip form mass for scanning force microcopy operating in the GHz range

The detectable force resolution of a mechanical oscillator used in scanning force microscopy call be improved by increasing its natural frequency f(o) and quality factor Q, and by decreasing the spring constant k and the temp erature of operation T. For an oscillator having a structure that can be mo deled as a concentrated mass-spring model, decreasing the mass of the oscil lator is desirable since high f(o) can then be obtained without increasing the spring constant k. We have developed a novel fabrication technique for fabricating a nanometric oscillator by selective etching of silicon on insu lator (SOI) wafers. The oscillator has the form of a tip supported by an el astic neck, and the tip serves as the mass. The tip and the neck length mea sure approximately 100 nm when fabricated using a separation by implanted o xygen wafer, and are around 1000 nm when fabricated using a bonded SOI wafe r. The tips were made of silicon and the necks were made of silicon dioxide . The oscillator could be tailored to have its natural frequency in the ran ge of 0.01-1 GHz and a spring constant between 10(-1) and 10(2) N/m. The th in neck, whose diameter is of the order of 10 nm is not brittle and can sur vive angular bending of around 30 degrees. (C) 2000 American Vacuum Society . [S0734-211X(00)05902-3].