POROUS SILICON BULK MICROMACHINING FOR THERMALLY ISOLATED MEMBRANE FORMATION

A novel low thermal budget technique is proposed for the preparation o f thermally isolated silicon membranes. The selective formation of por ous silicon in a p-type silicon wafer results in an undercut profile b elow the implanted n-type silicon regions. The sacrificial porous laye r is subsequently removed in a dilute KOH solution, A non stoichiometr ic LPCVD nitride layer combination forms the suspension of the single crystalline silicon membranes. This technique eliminates the need for epitaxial substrates and backside alignment, and proves to be very eff icient in the realization of a high-temperature micro-hotplate operati ng with minimum power consumption for the purpose of integrated gas se nsors.