| The thermal applications of electrically-heated polycrystalline-silicon microbridges are explored. An electrothermal model based on the balance of heat dissipation and heat losses is developed which determines the microbridge electrical characteristics. The model has been adapted for inclusion into the SPICE3 circuit simulator. Complementary to the model, all relevant thermal properties of the microbridge mechanical materials have been studied and measured using newly developed methods. Various microbridge electrical biasing schemes have been considered to determine the most desirable circuit interface.;The microbridge heat losses, hence its electrical characteristics, are dependent on its environment. Thus this device is useful as a transducer. We constructed and tested a gas flow sensor with a microbridge sensor 270 ;A thermal absolute pressure sensor of the heated microbridge types has been integrated with an active constant-resistance bias circuit and an 8-bit successive approximation register A/D converter. The chip, which contains more than 1000 MOSFETs, is sensitive to variations in absolute gas pressure between 10 and 10;As a last thermal application, a silicon-filament vacuum-sealed incandescent light source has been fabricated using IC technology and subsurface micromachining. The incandescent source consists of a heavily-doped p... |
