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This work presents a novel low thermal-budget technique for sealing micromachined cavities in silicon. Cavities are sealed without deposition, similar to the silicon surface-migration sealing process. In contrast to the 1100 °C furnace anneal required for the migration process, the proposed technique uses short excimer laser pulses (24 ns), focused onto an area of 23 mm2, to locally heat the top few microns of the substrate, while the bulk substrate remains near ambient temperature. The treatment can be applied to selected regions of the substrate, without the need for special surface treatments or a controlled environment. This work investigates the effect of varying the laser pulse energy from 400 mJ cm−2 to 800 mJ cm−2, the pulse rate from 1 Hz to 50 Hz and the pulse count from 200 to 3000 pulses on sealing microfabricated cavities in silicon. An analytical model for the effect of holes on the surface temperature distribution is derived, which shows that much higher temperatures can be achieved by increasing the hole density. A mechanism for sealing the cavities is proposed, which indicates how complete sealing is feasible.

This paper presents two novel architectures for realizing high performance bulk micromachined gyroscopes based on Silicon-on-Insulator (SOI) technology. The designs have a simulated Brownian noise floor of to 0.014 o /hr, a sensitivity 115 mV/ o /s, and a signal to noise ratio (SNR) of 1,437 mV/º/hr. These performance characteristics were achieved at resonance frequencies of few kilohertz. The backbone idea behind the proposed gyroscopes was the utilization of an out-ofplane suspension configuration comprising vertical beams, in which the latter can suspend a seismic proof mass of 1.6 mg. Measurements of the fabricated gyroscopes prove, for the first time, the concept of building MEMS devices using a vertical suspension arms.