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Thermal applications of microbridges.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Thermal applications of microbridges./
Author:	Mastrangelo, Carlos Horacio.
Description:	1 online resource (399 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 53-07, Section: B.
Contained By:	Dissertations Abstracts International53-07B.
Subject:	Electrical engineering. -
Online resource:	click for full text (PQDT)
ISBN:	9798208281895

Thermal applications of microbridges.
Mastrangelo, Carlos Horacio.

Thermal applications of microbridges. - 1 online resource (399 pages)

Source: Dissertations Abstracts International, Volume: 53-07, Section: B.

Thesis (Ph.D.)--University of California, Berkeley, 1991.

Includes bibliographical references

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 x 3 x 1 μm³ suspendend 3 μm off the substrate and a constant-temperature bias circuit. The microbridge was enclosed in a silicon microfabricated package assembly with a 300 μm-high channel that constrained the flow. The circuit yielded a 35 mV signal for a nitrogen flow of 100 sccm at a microbridge temperature of 200°C. 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 10⁴ Pa, and it is implemented in a 14-mask, 4-μm NMOS technology merged with the microsensor process. The average sensitivity of the circuit was 2 V/decade for a 400 x 3 x 1 μm³ microbridge operating at an average temperature of 100°C above the substrate. Silicon-nitride-coated microbridges were used which reduce oxidation-induced signal drifts. This circuit demonstrates the integration of microbridges with MOS circuits to form monolithic measurement systems. 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+ polysilicon filament coated with silicon nitride and enclosed in a vacuum-sealed (≃80 mT) cavity in the silicon chip surface. The filament is formed beneath the surface and later released using sacrificial etching resulting in a microstructure that is protected from the external environment. The filament is electrically heated to reach incandescence at a temperature near 1400 K. The power required to achieve this temperature for a filament 510 x 5 x 1 μm³ is 5 mW yielding a total optical power of 250 μW with a peak distribution wavelength near 2.5 μm. The energy-conversion efficiency is 5%.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798208281895Subjects--Topical Terms:

596380
Electrical engineering.
Index Terms--Genre/Form:

554714
Electronic books.

Thermal applications of microbridges.
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100 1 $a Mastrangelo, Carlos Horacio. $3 1475304
245 1 0 $a Thermal applications of microbridges.
264 0 $c 1991
300 $a 1 online resource (399 pages)
336 $a text $b txt $2 rdacontent
337 $a computer $b c $2 rdamedia
338 $a online resource $b cr $2 rdacarrier
500 $a Source: Dissertations Abstracts International, Volume: 53-07, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Muller, Richard S.
502 $a Thesis (Ph.D.)--University of California, Berkeley, 1991.
504 $a Includes bibliographical references
520 $a 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 x 3 x 1 μm³ suspendend 3 μm off the substrate and a constant-temperature bias circuit. The microbridge was enclosed in a silicon microfabricated package assembly with a 300 μm-high channel that constrained the flow. The circuit yielded a 35 mV signal for a nitrogen flow of 100 sccm at a microbridge temperature of 200°C. 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 10⁴ Pa, and it is implemented in a 14-mask, 4-μm NMOS technology merged with the microsensor process. The average sensitivity of the circuit was 2 V/decade for a 400 x 3 x 1 μm³ microbridge operating at an average temperature of 100°C above the substrate. Silicon-nitride-coated microbridges were used which reduce oxidation-induced signal drifts. This circuit demonstrates the integration of microbridges with MOS circuits to form monolithic measurement systems. 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+ polysilicon filament coated with silicon nitride and enclosed in a vacuum-sealed (≃80 mT) cavity in the silicon chip surface. The filament is formed beneath the surface and later released using sacrificial etching resulting in a microstructure that is protected from the external environment. The filament is electrically heated to reach incandescence at a temperature near 1400 K. The power required to achieve this temperature for a filament 510 x 5 x 1 μm³ is 5 mW yielding a total optical power of 250 μW with a peak distribution wavelength near 2.5 μm. The energy-conversion efficiency is 5%.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2024
538 $a Mode of access: World Wide Web
650 4 $a Electrical engineering. $3 596380
650 4 $a Mechanical engineering. $3 557493
650 4 $a Materials science. $3 557839
655 7 $a Electronic books. $2 local $3 554714
690 $a 0544
690 $a 0548
690 $a 0794
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a University of California, Berkeley. $3 1183587
773 0 $t Dissertations Abstracts International $g 53-07B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9203640 $z click for full text (PQDT)