Development of a sapphire optical pressure sensor for high-temperature applications

Mills, David; Alexander, Dylan; Subhash, Ghatu; Sheplak, Mark

doi:10.1117/12.2050598

Cited by 21 publications

(10 citation statements)

References 28 publications

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“…According to Formula (9), the average tensile strength of the cavity structure is ~8.01 MPa. The value is above the minimum acceptable bonding strength of 4–5 MPa required for most Micro-Electro-Mechanical Systems (MEMS) devices [ 25 ], which is sufficient for the bonding of diaphragm and back cavity in the pressure sensor.…”

Section: Resultsmentioning

confidence: 99%

Hermeticity Analysis on SiC Cavity Structure for All-SiC Piezoresistive Pressure Sensor

Tian

Shang

Zhao

et al. 2021

Sensors

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The hermeticity performance of the cavity structure has an impact on the long-term stability of absolute pressure sensors for high temperature applications. In this paper, a bare silicon carbide (SiC) wafer was bonded to a patterned SiC substrate with shallow grooves based on a room temperature direct bonding process to achieve a sealed cavity structure. Then the hermeticity analysis on the SiC cavity structure was performed. The microstructure observation demonstrates that the SiC wafers are tightly bonded and the cavities remain intact. Moreover, the tensile testing indicates that the tensile strength of bonding interface is ~8.01 MPa. Moreover, the quantitative analysis on the airtightness of cavity structure through leakage detection shows a helium leak rate of ~1.3 × 10−10 Pa⋅m3/s, which satisfies the requirement of the specification in the MIL-STD-883H. The cavity structure can also avoid an undesirable deep etching process and the problem caused by the mismatch of thermal expansion coefficients, which can be potentially further developed into an all-SiC piezoresistive pressure sensor employable for high temperature applications.

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Section: Resultsmentioning

confidence: 99%

Hermeticity Analysis on SiC Cavity Structure for All-SiC Piezoresistive Pressure Sensor

Tian

Shang

Zhao

et al. 2021

Sensors

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“…In the same way, we tested eight samples including a large cavity, a small cavity and no cavity structure, and obtained an average value of 6.71 MPa. To our best knowledge, the minimum bonding strength recommended in MEMS device manufacturing is 4–5 MPa [ 31 ]. It is enough to show that the application of our experiment to the pressure sensor has very good feasibility.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of SiC Sealing Cavity Structure for All-SiC Piezoresistive Pressure Sensor Applications

et al. 2020

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High hardness and corrosion resistance of SiC (silicon carbide) bulk materials have always been a difficult problem in the processing of an all-SiC piezoresistive pressure sensor. In this work, we demonstrated a SiC sealing cavity structure utilizing SiC shallow plasma-etched process (≤20 μm) and SiC–SiC room temperature bonding technology. The SiC bonding interface was closely connected, and its average tensile strength could reach 6.71 MPa. In addition, through a rapid thermal annealing (RTA) experiment of 1 min and 10 mins in N2 atmosphere of 1000 °C, it was found that Si, C and O elements at the bonding interface were diffused, while the width of the intermediate interface layer was narrowed, and the tensile strength could remain stable. This SiC sealing cavity structure has important application value in the realization of an all-SiC piezoresistive pressure sensor.

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“…The adhesive interface was pulled off under the load of 720 N and the bonding interface remained intact, indicating that the tensile strength of the bond interface exceeded 7.2 MPa. This value is in excess of the recommended 4–5 MPa minimum bond strength required for the manufacture of Micro-Electro-Mechanical-System (MEMS) devices [ 11 ].…”

Section: Resultsmentioning

confidence: 99%

“…Sapphire, with its characteristics of a high melting point of 2040 °C, resistance to chemical corrosion, high mechanical strength, and excellent optical qualities, has been considered an ideal material for high temperature sensing applications. Compared with the sapphire pressure sensors based on electrical detection mechanism [ 9 ], sapphire fiber optic pressure sensors have attracted considerable attention due to their advantages of being immune to electromagnetic interference and non-conductive properties [ 10 , 11 , 12 ]. An all-sapphire pressure sensor has the potential to achieve accurate pressure measurements at extremely high temperatures over 1500 °C [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

Interface Characteristics of Sapphire Direct Bonding for High-Temperature Applications

Liang

Chen

et al. 2017

Sensors

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In this letter, we present a sapphire direct bonding method using plasma surface activation, hydrophilic pre-bonding, and high temperature annealing. Through the combination of sapphire inductively coupled plasma etching and the direct bonding process, a vacuum-sealed cavity employable for high temperature applications is achieved. Cross-sectional scanning electron microscopy (SEM) research of the bonding interface indicates that the two sapphire pieces are well bonded and the cavity structure stays intact. Moreover, the tensile testing shows that the bonding strength of the bonding interface is in excess of 7.2 MPa. The advantage of sapphire direct bonding is that it is free from the various problems caused by the mismatch in the coefficients of thermal expansion between different materials. Therefore, the bonded vacuum-sealed cavity can be potentially further developed into an all-sapphire pressure sensor for high temperature applications.

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Development of a sapphire optical pressure sensor for high-temperature applications

Cited by 21 publications

References 28 publications

Hermeticity Analysis on SiC Cavity Structure for All-SiC Piezoresistive Pressure Sensor

Hermeticity Analysis on SiC Cavity Structure for All-SiC Piezoresistive Pressure Sensor

Fabrication of SiC Sealing Cavity Structure for All-SiC Piezoresistive Pressure Sensor Applications

Interface Characteristics of Sapphire Direct Bonding for High-Temperature Applications

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