Stable and Corrosion-Resistant Sapphire Capacitive Pressure Sensor for High Temperature and Harsh Environments

Kimura, Syo; Ishikura, Yuki; Kataoka, Toshiki; Soeda, M.; Masuda, Takashi; Yoshikawa, Yutaka; Nagata, M.

doi:10.1007/978-3-642-59497-7_123

Cited by 6 publications

(4 citation statements)

References 2 publications

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“…Sapphire wafer direct bonding by hydrophilic wafer bonding was also examined; high-temperature annealing (>800 °C) is necessary. [38][39][40] Considering alkali gas cell fabrication and other applications in MEMS packaging, a simple, high-throughput, and low-temperature bonding process in gas ambient is required.…”

Section: Introductionmentioning

confidence: 99%

Surface activated room-temperature bonding in Ar gas ambient for MEMS encapsulation

Takagi

Kurashima

2017

Jpn. J. Appl. Phys.

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Surface activated room-temperature bonding of Si and sapphire wafers in high-purity inert gas ambient was examined. Although surface activated bonding has been mainly performed in high vacuum, Si and sapphire wafers were successfully bonded in Ar gas ambient up to 90 kPa, which is almost atmospheric pressure. The dicing test proved that the bonding prepared in Ar gas ambient was strong enough for MEMS packaging, although the bonding strength was slightly decreased compared with that prepared in vacuum. Transmission electron microscope observation revealed that the bonding interface prepared in Ar gas ambient is almost the same as that prepared in vacuum. It means that Ar atoms in the bonding ambient do not hamper the interatomic bond formation at the bonding interface. Room-temperature bonding in gas ambient enables hermetic packaging of MEMS devices, such as inertia sensors, MEMS switches, and Cs vapor cells for MEMS atomic clocks at various pressures.

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Section: Introductionmentioning

confidence: 99%

Surface activated room-temperature bonding in Ar gas ambient for MEMS encapsulation

Takagi

Kurashima

2017

Jpn. J. Appl. Phys.

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“…To sense the pressure, the low fatigue characteristics of monocrystalline Al 2 O 3 membranes even under harsh environmental conditions are most beneficially combined with the piezoresistive properties of monocrystalline silicon [8]. However, reliable operation is still limited to a maximum temperature load up to about 400 • C even when a capacitive sensing principle is applied, thus avoiding any semiconductor-metal junction, which is one of the most probable sources of device failure during operation [9]. Most recently, a pressure sensor element is reported for high temperature applications, combining the excellent mechanical and electrical material properties of sapphire as substrate with those of platinum thin films applied for the realization of robust and long-term stable strain gauges [10].…”

Section: Introductionmentioning

confidence: 99%

High temperature measurement set-up for the electro-mechanical characterization of robust thin film systems

Fricke¹,

Friedberger²,

Seidel³

et al. 2013

Meas. Sci. Technol.

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Due to economic and environmental requirements there is a strong need both to increase the efficiency and to monitor the actual status of gas turbines, rocket engines and deep drilling systems. For these applications, micromachined pressure sensors based on a robust substrate material (e.g. sapphire) as well as strain gauges made of platinum for long-term stable operation are regarded as most promising to withstand harsh environments such as high temperature levels, aggressive media and/or high pressure loads. For pre-evaluation purposes, a novel, custom-built measurement set-up is presented allowing the determination of electro-mechanical thin film properties up to 850 °C. Key components of the measurement set-up are the one-sided clamped beam made of Al2O3 ceramics which is deflected by a quartz rod and a high precision encoder-controlled dc motor to drive the quartz rod. The specific arrangement of the infrared halogen heaters in combination with the gold coated quartz half shells ensures a high degree of temperature homogeneity along the beam axis. When exposed to tensile as well as compressive load conditions, the corresponding gauge factor values of 1 µm thick platinum thin films show a good comparison at room temperature and in the temperature range from 600 up to 850 °C where the effects originating from grain boundaries or from the film surfaces are negligible. Between 150 and 600 °C, however, a strong deviation in the gauge factor determination depending on the mechanical load condition is observed, which is attributed to the gliding of adjacent grains.

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“…The demand of research in developing sapphire as a pressure sensor is significantly growing owing to the excellent elastic properties of sapphire as well as its good resistance to corrosion and heat. 1 The very high hardness (2300 HV) of sapphire accounts for its outstanding ability to resist scratching and wear. According to the company report, 2 artificial sapphire is a singlecrystal (SC), transparent, and colorless mineral, whereas ruby is red colored owing to the presence of chromium; both sapphire and ruby conform to the formula Al 2 O 3 .…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of the Reaction Layer Formed during Sapphire–Sapphire Brazing Using a Ag–Cu–Ti Filler Metal for Gas-Pressure Sensors

Zaharinie

Huda

Ibrahim

et al. 2022

ACS Appl. Electron. Mater.

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The present research paper introduces a reliable and economical method for direct brazing using an active Ag−Cu−Ti filler metal that can ensure effective brazing. The sapphire−sapphire brazing process has been conducted at temperatures in the range of 830−900 °C for durations in the range of 15−30 min in a high-vacuum (10 −4 Pa) furnace. Material and microstructural characterization involved the use of scanning electron microscope-energy-dispersive system (SEM-EDS) and transmission electron microscope (TEM) for investigating the bonding joint morphologies. Two uniform reaction layers were observed to have formed at the sapphire/brazed area interface. On the sapphire side, the first reaction layer, which was uniform and had a thickness in the range of 0.13−0.17 μm, was identified as a TiO phase, whereas the second layer was identified as a Cu 3 Ti 3 O phase with a thickness in the range of 1.72−2.43 μm. The uniformity of the Cu 3 Ti 3 O phase was found to decrease with increasing brazing temperature and time. Therefore, in this research, a lower brazing temperature and time (830 °C/15 min) were chosen so as to avoid bonding degradation.

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Stable and Corrosion-Resistant Sapphire Capacitive Pressure Sensor for High Temperature and Harsh Environments

Abstract: ABSTRACT

Cited by 6 publications

References 2 publications

Surface activated room-temperature bonding in Ar gas ambient for MEMS encapsulation

Surface activated room-temperature bonding in Ar gas ambient for MEMS encapsulation

High temperature measurement set-up for the electro-mechanical characterization of robust thin film systems

Analysis of the Reaction Layer Formed during Sapphire–Sapphire Brazing Using a Ag–Cu–Ti Filler Metal for Gas-Pressure Sensors

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