Temperature Coefficient Of Gauge Factor Research Articles

Current-induced recrystallization of polycrystalline silicon nano thin films deposited at different temperatures and its influences on piezoresistive sensitivity and temperature coefficients

To improve the performance and yield of piezoresistive sensors based on polycrystalline silicon nano thin films (PNTFs), the 80 nm-thick PNTFs were deposited on silicon (1 1 1) substrates by LPCVD at different temperatures and fabricated into cantilever beams. The electrical trimming characteristics and the dependences of gauge factor, temperature coefficient of resistance (TCR) and temperature coefficient of gauge factor (TCGF) on resistor trim with different deposition temperatures were measured. Based on the interstitial-vacancy model, the electrical trimming is explained as the mobility increase caused by current-induced recrystallization of grain boundaries. The conclusions indicate that the changes in gauge factor, TCR and TCGF with resistor trim are due to the grain boundary state variation (including scattering center, grain boundary width, tunneling current, localized and extended state conductions). And the electrical trimming method is testified to be applicable for the resistor trimming of PNTF-based sensors after packaging.

초고온용 다결정 3C-SiC 마이크로 압력센서의 제작

High temperature micro pressure sensors were fabricated by using polycrystalline 3C-SiC piezoresistors grown on oxidized SOI substrates by APCVD. These have been made by bulk micromachining under <TEX>$1{\times}1mm^2$</TEX> diaphragm and Si membrane thickness of <TEX>$20{\mu}m$</TEX>. The pressure sensitivity of implemented pressure sensors was 0.1 mV/<TEX>$V{\cdot}bar$</TEX>. The nonlinearity and the hysteresis of sensors were <TEX>${\pm}0.44%{\cdot}FS$</TEX> and <TEX>$0.61%{\cdot}FS$</TEX>. In the temperature range of <TEX>$25^{\circ}C{\sim}400^{\circ}C$</TEX> with 5 bar FS, TCS (temperature coefficient of sensitivity), TCR (temperature coefficient of resistance), and TCGF (temperature coefficient of gauge factor) of the sensor were -1867 ppm/<TEX>$^{\circ}C$</TEX>, -792 ppm/<TEX>$^{\circ}C$</TEX>, and -1042 ppm/<TEX>$^{\circ}C$</TEX>, respectively.

New thick-film strain gauge

Thick-film strain gauges having strain characteristics with small temperature dependency have been developed. Their gauge factor is more than ten times higher than that of a thin-film strain gauge and nearly half the value of a semiconductor gauge. This strain gauge is a thick film composed of 15 wt. % WO3⋅15 wt. % RuO2⋅70 wt. % glass (weight percent ratio). Its gauge factor is 40 to 55, its temperature coefficient of resistance is 0 to −200 ppm/°C, and its temperature coefficient of gauge factor is about −400 ppm/°C. The change of gauge factor in a repeat test after a strain had been applied to the gauge was smaller than 1%. The gauge was also very stable.

Some effects of strain and temperature on the resistance of thin gold-glass cermet films

Thin gold-glass cermet films have been prepared by r.f. sputtering in an argon atmosphere. The strain sensitivity (gauge factor) and the temperature coefficient of resistance (TCR, α) have been measured for films with resistances in the range 100 ω to 1 Mω/□. Low resistance films exhibit gauge factors and TCRs consistent with a metallic conduction process whilst high resistance films exhibit gauge factors and TCRs consistent with an activated conduction process. These results are discussed in terms of the film structures observed by transmission electron microscopy. Measurements of gauge factors in the range 20°–100°C have led to the concept of a temperature coefficient of gauge factor (β). Mathematically it can be shown that β = - α. Experimental results are discussed confirming this relationship.