Cantilever with integrated resonator for application of scanning probe microscope

A silicon cantilever with a small torsional resonator is designed by finite element method (FEM) and fabricated by silicon micromachining technology. The mechanical elements of the probe consist of the cantilever beam for act uation and the small torsional resonator for force detection. The torsional resonator with small mass (width of 8 mu m X length of 21 mu m) is integra ted at the end of the cantilever beam (width of 36 mu m X length of 150 mu m) and the resonator is suspended by thin two beams (width of 1 mu m X leng th of 2.5 mu m). High resonance frequency can be achieved by reduction of t he resonator size and the smaller resonator with high resonance frequency i s insensitive to thermo-mechanical noise that is inversely proportional to the resonance frequency. By flowing a current to the small metal lines on t he resonator, the torsional resonator is vibrated. A force interaction betw een the tip and the sample is directly measured by the induced electromotiv e force. The high resonance of the cantilever beam is favorable for obtaini ng a high scanning speed in SPM operation instead of conventional piezo-tub e scanner. In the vertical direction, the fabricated cantilever beams has a static deflection of 1 mu m when flowing a de current of 40 mA to the wire on the cantilever beam and applying magnetic field of 2000 G. The oscillat ion amplitude of the resonator is 28 nm when an ac current of 4 mA is appli ed to the wire on the resonator. The resonance frequency of the torsional, resonator as measured in air was 3.4 MHz, with a quality factor of 203. The fabricated resonator has a thermal noise vibration amplitude of 6.3 X 10(- 15) m. At room temperature, the minimum detectable force of the resonator c an reach 6.75 X 10(-14) N. (C) 2000 Elsevier Science S.A. All rights reserv ed.