Search

Knowledge of the mechanical behavior of strategically important materials such as silicon at nano scale is the key for building next generation devices. In this paper, we investigate the Young’s Modulus of nanomechanical beams [1-8 mm long, 200-400 nm wide, and 193 & 255 nm in thickness] fabricated from silicon-on-insulator (SOI) wafers. The beams of different dimensions were defined in PMMA resist using e-beam lithography. A layer of chrome deposited using lift-off technique, acted as an etch-mask for silicon to fabricate the beams by using RIE. The samples were dipped in BOE (Buffered Oxide Etch) to etch the oxide underneath and the beams were released using critical point drying. Using a Scanning Probe System, nanomechanical beams were bent using AFM silicon tapping mode probes. A controlled amount of force was applied by varying the voltage applied to the Z-axis piezoactuator. The values of beam deflection and the net force applied enabled us to plot the Load vs. Displacement graph for the bending of the nanomechanical beams. Using Euler - Bernoulli beam bending equations, the Young’s Modulus of the Silicon beams was measured to be 174 GPa. This value agrees within 5% of the known value of bulk silicon Young’s modulus of 169GPa. Thus we conclude that the value of Young’s modulus of Si beams does not change when the size is reduced to nanometer regime.

There have been several cantilever-based actuators which provide movement in a direction transverse to the length of the cantilever. Here we describe a novel actuator which gives movement in the same direction as that of the length of the element. This is achieved by a curling up action of a bimetal like 'metal on silicon dioxide' straight element due to large differences in the coefficients of linear expansions and the high temperature which is obtained during the metal deposition.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We have designed, fabricated and tested a balanced doubly suspended versatile, torsion and flexural, MEMS resonator structure. The doubly suspended structure has been used earlier for very precise high Q resonators but we wished to study the various vibration modes of such a structure. FEM analysis has been used to compute the most likely 6 modes and their frequencies of free vibration. These modes include flexure, torsion and mixed modes. The arms of the resonator are deposited with magnetic films so as to give desired bending/twisting moments to the structure. The location of the films decides the symmetry and thus result in one of the six vibrational modes that are predicted by the FEM analysis. This paper describes the design, fabrication and measurements on resonator structures made at TIFR.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.