Failure Mechanisms in MEMS Based Silicon Carbide High Temperature Pressure Sensors

Okojie, Robert S.; Nguyen, Phong; Nguyen, Vu Dat; Savrun, Ender; Lukco, Dorothy; Buehler, John D.; McCue, Terry R.

doi:10.1109/relphy.2007.369928

Cited by 15 publications

(10 citation statements)

References 2 publications

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“…Okojie et al [14] had previously reported V oz drifts in SiC pressure sensors at 500 o C, which provided an insight to the correlation between the contact metallization at the bondpad and the observed drift. Since the target environment for these sensors is between 300 o C (i.e., long-term, remote pressure monitoring in geothermal and oil wells, and in nuclear power plants) and 600 o C (i.e., short duration engine ground and flight tests), it becomes necessary to develop SiC pressure sensors with significantly suppressed drifts within that temperature regime.…”

Section: Effect Of Contact Resistance On Offset Driftmentioning

confidence: 90%

Zero offset drift suppression in SiC pressure sensors at 600

et al. 2010

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Temporal drifts in zero pressure offset voltage, V oz , observed in piezoresistive silicon carbide (SiC) pressure sensors at 600 o C were significantly suppressed to allow reliable operation. By modifying the bondpad/contact metallization, the V oz relative drift velocity at 600 o C was suppressed to within ± 0.5 mV.hr-1 , for over 1000 hours. Microstructural changes within the contact metallization were analyzed with Auger Electron Spectroscopy (AES) and Scanning Electron Microscopy (SEM). This metallization scheme may improve SiC pressure sensor reliability in short duration ground/flight tests and lower temperature (~300 o C) remote pressure monitoring (i.e., geothermal, and deep well drilling). I.

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Section: Effect Of Contact Resistance On Offset Driftmentioning

confidence: 90%

Zero offset drift suppression in SiC pressure sensors at 600

et al. 2010

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“…After photolithographic pattern definition the Pt layer was etched in 10:9:1 mixture of H 2 O:HCl:HNO 3 (aqua regia) at 67 o C for 8 minutes, then 70 o C for 35 seconds to create four contacts on the piezoresistors. This was the standard scheme used previously that did not completely prevent Au diffusion to the SiC interface, which compromise the integrity of the Ti ohmic contact to SiC [5,6]. In this present work, it was necessary to increase the contact metallization stack with alternating layers of TaSi 2 and Pt, which, upon reacting to form multiple PtSi layers, would create an effective diffusion barrier against Au to the SiC interface.…”

Section: Sample Preparationmentioning

confidence: 98%

“…3(c), which showed smaller relative changes from previous values compared to sensors 200 and 201. Based on prior reported results [4][5][6], it is believed that the improved performance of sensor 202 was due to the fact that it experienced the lowest temperature (605 °C). …”

Section: (C) Sensor 202 (605 °C)mentioning

confidence: 99%

“…However, existing long term reliability challenges, largely due to drifting zero pressure offset voltage, V oz , have prevented its permanent insertion into operational systems. Previous efforts have been made to understand the mechanisms of drifting V oz during high temperature operation with the goal of developing more stable and operationally functional pressure sensors [4][5][6]. The V oz drift is unpredictable, which does not lend itself to active correction or temperature compensation.…”

Section: Introductionmentioning

confidence: 99%

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Temperature Induced Voltage Offset Drifts in Silicon Carbide Pressure Sensors

Okojie

Lukco

Nguyen

et al. 2012

Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT)

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We report the reduction of transient drifts in the zero pressure offset voltage in silicon carbide (SiC) pressure sensors when operating at 600 °C. The previously observed maximum drift of ± 10 mV of the reference offset voltage at 600 °C was reduced to within ± 5 mV. The offset voltage drifts and bridge resistance changes over time at test temperature are explained in terms of the microstructure and phase changes occurring within the contact metallization, as analyzed by Auger electron spectroscopy and field emission scanning electron microscopy. The results have helped to identify the upper temperature reliable operational limit of this particular metallization scheme to be 605 o C.

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“…Therefore, it is important to raise the reliability temperature ceiling higher, which would assure increased device reliability when operated at nominal temperature. There are also instances that require devices to operate and survive for prolonged periods of time above 600 o C [2,3]. This is specifically needed in the area of hypersonic flight where robust sensors are needed to monitor vehicle performance at temperature greater than 1000 °C, as well as for use in the thermomechanical characterization of high temperature materials (e.g.…”

Section: Introductionmentioning

confidence: 99%

Development of an Extreme High Temperature n-Type Ohmic Contact to Silicon Carbide

Evans

Okojie

Lukco³

2012

MSF

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Abstract. We report on the initial demonstration of a tungsten-nickel (75:25 at. %) ohmic contact to silicon carbide (SiC) that performed for up to fifteen hours of heat treatment in argon at 1000 °C. The transfer length method (TLM) test structure was used to evaluate the contacts. Samples showed consistent ohmic behavior with specific contact resistance values averaging 5 x 10 -4 Ω-cm 2 . The development of this contact metallization should allow silicon carbide devices to operate more reliably at the present maximum operating temperature of 600 °C while potentially extending operations to 1000 °C.

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Failure Mechanisms in MEMS Based Silicon Carbide High Temperature Pressure Sensors

Cited by 15 publications

References 2 publications

Zero offset drift suppression in SiC pressure sensors at 600

Zero offset drift suppression in SiC pressure sensors at 600

Temperature Induced Voltage Offset Drifts in Silicon Carbide Pressure Sensors

Development of an Extreme High Temperature n-Type Ohmic Contact to Silicon Carbide

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