Development of surface micromachining techniques compatible with on-chip electronics

Abstract

Silicon has long been known to have excellent mechanical properties although the full potential of the material was not realized until micromachining techniques enabled the fabrication of true mechanical structures. The first types of structure were fabricated using bulk micromachining techniques, where the silicon wafer is etched to leave free-standing mechanical structures. More recently surface micromachining techniques have received considerable attention. In this case the mechanical structures are fabricated in thin films deposited on the silicon wafer surface. This development has yielded structures considerably smaller than those fabricated in bulk micromachining. In this paper the development of surface micromachining techniques is reviewed. This includes the modifications required to achieve compatibility with standard electronic circuitry.

Silicon Photodetectors with a Selective Spectral Response

“…This anneal is carried out in situ, in the same reactor where the deposition has been performed, at 600 8C for 1 h in N 2 . These processing conditions were optimized to obtain a low-stress (internal strain *600 lstrain, tensile) polysilicon film for micromachining purposes, with good mechanical and electrical characteristics [23].…”

Micromechanical voltage reference using the pull-in of a beam

“…Generally, a taut beam is desirable, which implies a low tensile stress in the material. Thermal anneal is required to convert the compressive stress in the as-deposited material into such low tensile stress layer [11]. The pull-in voltage of a double-sided clamped structure reduces with compressive stress, due to the dependence on by the strain energy -.…”

Properties of polycrystalline silicon films obtained by rapid thermal processing for micromechanical sensors

“…In the last decade, applications of micromechanical devices, fabricated using surface micromachining technologies, required low stress polycrystalline silicon (poly-Si) films, as structural layers, deposited on insulator (SOI structures) [1,2]. Moreover, the control of electrical properties of poly-Si is critical, because they significantly affect the performance of sensor devices (e.g.…”