High Temperature Pressure Sensor Research Articles

Direct bonding of silicon carbide with hydrofluoric acid treatment for high-temperature pressure sensors

Direct bonding of single-crystal silicon carbide (SiC) is a critical process for the fabrication of pressure sensors used in harsh environments. In this paper, we present a direct bonding process with a surface treatment using hydrofluoric acid to remove the oxide on the SiC surface and eliminate the oxide interlayer between the bonded SiC wafers. After direct bonding with hydrofluoric acid treatment, the oxide interlayer is almost invisible in the field emission scanning electron microscope and energy dispersive spectrometry analyses. The bonding strengths of the SiC samples bonded under various bonding temperatures and bonding times are evaluated. Compared to the sample with an oxide interlayer, the bonding strength obtained with direct bonding is improved by 49%. The maximum bonding strength reaches 6.96 MPa with a bonding temperature of 1100 °C, a uniaxial pressure of 50 MPa, and a bonding time of 4 h. In addition, the vacuum tightness of the bonded cavity was also investigated, and the results indicate that the vacuum sensor cavity was effectively sealed with the direct bonding method.

Fiber-optic Fabry-Perot pressure sensor based on sapphire direct bonding for high-temperature applications.

In this study, a fiber-optic Fabry-Perot (FP) high-temperature pressure sensor based on sapphire direct bonding is proposed and experimentally demonstrated. The sensor is fabricated by direct bonding of two-layer sapphire wafers, including a pressure diaphragm wafer and a cavity-etched wafer. The sensor is composed of a sensor head that contains a vacuum-sealed cavity arranged as an FP cavity and a multimode optical fiber. The external pressure can be measured by detecting the change in FP cavity length in the sensor. Experimental results demonstrate the sensing capabilities for pressures from 20kPa to 700kPa up to 800°C.

A Ceramic Diffusion Bonding Method for Passive LC High-Temperature Pressure Sensor.

Alumina ceramic is a highly promising material for fabricating high-temperature pressure sensors. In this paper, a direct bonding method for fabricating a sensitive cavity with alumina ceramic is presented. Alumina ceramic substrates were bonded together to form a sensitive cavity for high-temperature pressure environments. The device can sense pressure parameters at high temperatures. To verify the sensitivity performance of the fabrication method in high-temperature environments, an inductor and capacitor were integrated on the ceramic substrate with the fabricated sensitive cavity to form a wireless passive LC pressure sensor with thick-film integrated technology. Finally, the fabricated sensor was tested using a system test platform. The experimental results show that the sensor can realize pressure measurements above 900 °C, confirming that the fabricated sensitive cavity has excellent sealing properties. Therefore, the direct bonding method can potentially be used for developing all-ceramic high-temperature pressure sensors for application in harsh environments.

Wireless passive pressure sensor based on sapphire direct bonding for harsh environments

This study presents a wireless passive high-temperature pressure sensor based on sapphire direct bonding technology. The design, fabrication, and measurement of the sensor are demonstrated and discussed. Single-crystal sapphire is used to fabricate the sensor owing to its outstanding characteristics, and the prototype sensor consists of an inductance, a variable capacitance, and an embedded vacuum-sealed cavity formed by sapphire direct bonding. Compared with other manufacturing technologies, the sapphire direct bonding process is simple and can effectively avoid the deformation and collapse of the embedded cavity, thereby leading to a better sensor performance. A more compact sensor with greater sensitivity has been fabricated in this study. The copper interrogating antenna is employed to detect the variation in the sensor’s resonant frequency caused by the pressure applied. The characterization in high-temperature pressure environments successfully demonstrates the sensing capabilities for pressures from 20 kPa to 600 kPa up to 600 °C. At 600 °C, the sensor sensitivity reaches as high as 10 kHz/kPa. The proposed sensor can be applied for the monitoring of gas pressure in harsh environments, such as environments with high temperatures and chemical corrosion.

High-temperature mechanical and thermodynamic properties of silicon carbide polytypes

Silicon carbide is widely used as ultra high-temperature ceramics, semiconductors, and pressure sensors with promising potentials for high-temperature, high-endurance, and radiation hardened applications. Daunting difficulties in experimental investigations of thermophysical properties hinder the better understanding of high-temperature material behaviors of silicon carbide. We present a comprehensive study of temperature-dependent mechanical and thermodynamic properties of SiC polytypes by first-principles methods. The obvious anisotropy of linear expansion and elasticity is found for 3C-SiC, while it is not distinct for other non-cubic SiC polytypes. Results show that the temperature dependences of mechanical properties exhibit the softening behavior, in which small linear reduction (∼4.4%) in Vickers hardness and shear modulus but large linear reduction (∼7.0%) in Young's modulus are detected. The heat-resistant properties of SiC polytypes are ranked as 3C-SiC < 4H-SiC < 6H-SiC < 15R-SiC < 2H-SiC. The present predictions are in favorable accord with available measured data in the literature.

A Passive Wireless Microelectromechanical Pressure Sensor for Harsh Environments

A microelectromechanical systems (MEMS) capacitive-type passive wireless pressure sensor designed to operate in harsh environments at temperatures up to 1000 °C is presented. The pressure sensor has a sapphire-based diaphragm and structural body, and a platinum-based capacitive element. The capacitive element is configured as a part of a slot patch antenna that is designed to operate in a far-field sensing mechanism with a Ku-band electrical resonant frequency of 15 GHz. The electrical ground plane resides on the backside of the diaphragm, which deflects in response to an applied pressure. The electrical resonant frequency of the pressure sensor changes as a function of the applied pressure to the diaphragm. An increase in the applied pressure, for example, results in a decrease in the electrical resonant frequency. The sensitivity of the pressure sensor is related to the change in applied pressure to the change in the electrical resonant frequency. Three proof-of-concept dynamic pressure sensors are reported using silicon-based diaphragms with antenna diameters of 5.6, 5.7, and 5.8 mm, and measured sensitivities of 2.2, 2.2, and 5.1 kHz/Pa, respectively, up to 900 Pa. In addition, three proof-of-concept static pressure sensors are reported with corresponding measured sensitivities of 3.4, 3.1, and 2.5 kHz/Pa up to 900 Pa. A high-temperature dynamic pressure sensor designed for harsh environments is also reported using a sapphire-based diaphragm with an antenna diameter of 3.8 mm and measured sensitivity of 21.7 kHz/Pa up to 800 Pa. [2017-0210]

Properties of Ceramic Substrate Materials for High‐Temperature Pressure Sensors for Operation above 1000°C

In order to identify suitable substrate materials for sue in high‐temperature pressure sensors that can operate above 1000°C, the high‐temperature properties of four high‐performance ceramics (99% pure Al2O3 (99Al2O3), 97% pure Al2O3 (97Al2O3), sapphire, and ZrO2) were investigated. Three‐point bend testing was used to measure the flexural strengths and flexural moduli of these ceramics, and transient laser emission was used to measure their thermal conductivities. The samples were prepared by hot‐press sintering: plates with the dimensions of 3.5 × 5 × 50 mm3 for the bend testing and rods of φ12.5 × 1.5 mm3 for the thermal conductivity measurements. Curves showing the dependence of flexural strength, flexural modulus, and thermal conductivity on temperature were obtained. The results show that the flexural strength and thermal conductivity of sapphire are much greater than those of the other ceramics tested. Thus, we conclude that sapphire is the most appropriate of these materials for use in high‐temperature pressure sensors for operation at up to 1000°C.

The Tamessa project: a practical application of a 225°C multilayer PCB/SMT/COB system

Abstract The Tamessa project has developed a high-temperature, multilayer, Printed Circuit Board and component assembly process that is capable of withstanding 225°C operating temperatures in a non-hermetic environment. This paper describes the practical application of this project's work to the electronic interface for a high temperature pressure sensor. The PCB used in Tamessa has been made from novel materials and the Surface Mount Technology (SMT) component attach process is a solder-less process that uses an adhesive. Additionally, the project has developed and proved a Chip on Board (COB) system. The combination has enabled the development of a complete assembly system that has been shown to withstand temperature excursions up to 250°C in a non-hermetic environment. The successful application to a pressure sensor, designed to resist temperatures of 210°C, was a further test to demonstrate its practical capability in a real-life situation.

An arc tangent function demodulation method of fiber-optic Fabry-Perot high-temperature pressure sensor

A new demodulation algorithm of the fiber-optic Fabry-Perot cavity length based on the phase generated carrier (PGC) is proposed in this paper, which can be applied in the high-temperature pressure sensor. This new algorithm based on arc tangent function outputs two orthogonal signals by utilizing an optical system, which is designed based on the field-programmable gate array (FPGA) to overcome the range limit of the original PGC arc tangent function demodulation algorithm. The simulation and analysis are also carried on. According to the analysis of demodulation speed and precision, the simulation of different numbers of sampling points, and measurement results of the pressure sensor, the arc tangent function demodulation method has good demodulation results: 1 MHz processing speed of single data and less than 1% error showing practical feasibility in the fiber-optic Fabry-Perot cavity length demodulation of the Fabry-Perot high-temperature pressure sensor.

Development and Calibration of High Temperature Pressure Sensor

High temperature pressure sensors are widely used in petrochemical, aerospace, metallurgy, gas machine. According to the mechanism, the recent research on high temperature pressure sensors is reviewed. The comparison and analysis about working temperature and sensitivity among different pressure sensors are completed. High temperature pressure calibration system has less research, reasonable system design and calibration method is needed to further studies.

波纹膜片对结构型高温压力传感器性能影响的研究

分析了一体化高温压力传感器中波纹膜片的结构参数对其性能的影响，详述了通过对带有圆弧形外波纹的波纹膜片的综合设计和工艺优化处理，研制出线性度好、灵敏度高的波纹膜片，使结构型高温传感器可工作在220℃环境，经试验测试结果表明：传感器的线性小于0.2% FS，迟滞小于0.2% FS，具有线性度好、灵敏度高和迟滞小的特点。 The corrugated diaphragm structure parameters affect the performance of the integration of high temperature pressure sensor is analyzed, by designing various conditions and optimizing technologic processes, good linear and sensitive corrugated diaphragm is produced, high temperature transducer works in temperature span 220˚C, the experimental results show that Linear is less than 0.2% FS, hysteresis is less than 0.2% FS, has the characteristic of good linearity, good sensitivity and small hysteresis.

Passive Resistor Temperature Compensation for a High-Temperature Piezoresistive Pressure Sensor.

The main limitation of high-temperature piezoresistive pressure sensors is the variation of output voltage with operating temperature, which seriously reduces their measurement accuracy. This paper presents a passive resistor temperature compensation technique whose parameters are calculated using differential equations. Unlike traditional experiential arithmetic, the differential equations are independent of the parameter deviation among the piezoresistors of the microelectromechanical pressure sensor and the residual stress caused by the fabrication process or a mismatch in the thermal expansion coefficients. The differential equations are solved using calibration data from uncompensated high-temperature piezoresistive pressure sensors. Tests conducted on the calibrated equipment at various temperatures and pressures show that the passive resistor temperature compensation produces a remarkable effect. Additionally, a high-temperature signal-conditioning circuit is used to improve the output sensitivity of the sensor, which can be reduced by the temperature compensation. Compared to traditional experiential arithmetic, the proposed passive resistor temperature compensation technique exhibits less temperature drift and is expected to be highly applicable for pressure measurements in harsh environments with large temperature variations.

A High-Temperature Piezoresistive Pressure Sensor with an Integrated Signal-Conditioning Circuit.

This paper focuses on the design and fabrication of a high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit, which consists of an encapsulated pressure-sensitive chip, a temperature compensation circuit and a signal-conditioning circuit. A silicon on insulation (SOI) material and a standard MEMS process are used in the pressure-sensitive chip fabrication, and high-temperature electronic components are adopted in the temperature-compensation and signal-conditioning circuits. The entire pressure sensor achieves a hermetic seal and can be operated long-term in the range of −50 °C to 220 °C. Unlike traditional pressure sensor output voltage ranges (in the dozens to hundreds of millivolts), the output voltage of this sensor is from 0 V to 5 V, which can significantly improve the signal-to-noise ratio and measurement accuracy in practical applications of long-term transmission based on experimental verification. Furthermore, because this flexible sensor’s output voltage is adjustable, general follow-up pressure transmitter devices for voltage converters need not be used, which greatly reduces the cost of the test system. Thus, the proposed high-temperature piezoresistive pressure sensor with an integrated signal-conditioning circuit is expected to be highly applicable to pressure measurements in harsh environments.

Offset stable piezoresistive high-temperature pressure sensors based on silicon

Abstract. The exploitation of new application fields and the drive to size reduction even in highly stable pressure sensing systems makes the extension of the operating temperature range of the microelectromechanical sensors (MEMS) essential. For this reason a silicon-based pressure sensor with an application temperature ranging up to 300 °C and the associated manufacturing technology was developed. With special design and manufacturing approaches mounting stress-insensitive sensors with high linearity, excellent offset stability, low hysteresis and low sensitivity changes over the entire temperature range were developed. At the moment, the sensors are tested till 300 °C at wafer level and between 135 and 210 °C as a first-level package.

Note: High temperature pressure sensor for petroleum well based on silicon over insulator.

In order to meet the requirements in petroleum well, a novel structure of high temperature pressure sensor based on the silicon over insulator (SOI) technology is proposed in this paper. The SOI sensor chip is bonded with a glass ring by electrostatic bonding. By controlling the inner diameter of the glass ring, the size of the circle membrane is obtained precisely. And the detailed parameters of the structure are established through analysis. Then, the sensor is fabricated. The test results show that this type sensor has high sensitivity and accuracy. It is able to measure at the temperature up to 180 °C and the measuring range is 60 MPa. Moreover, the results we got are closer to the actual situation.

A Wireless Pressure Microsensor Fabricated in HTCC Technology for Dynamic Pressure Monitoring in Harsh Environments

The partially stabilized zirconia (PSZ) ceramic has wide applications due to its excellent mechanical toughness and chemically inert and electrical properties for fabricating various devices. In this paper, a novel high temperature pressure sensor with the PSZ was designed and fabricated. The sensor was designed based on the small deflection theory, which enables its theoretic pressure-capacitance capability up to 60 bar. HTCC process technology was used to fabricate the sensor, which would realize a completely passive LC resonant circuit integrated on the ceramic substrate. According to the coupling principle, noncontact testing is achieved using the designed readout system, with average sensitivity up to 38 kHz Bar−1 presented. Compared to the fabrication and measurement of traditional sensors, excellent packaging process is demonstrated, and the sensor can be completely tested from 0 to 60 bar.

A novel SOI pressure sensor for high temperature application

The silicon on insulator (SOI) high temperature pressure sensor is a novel pressure sensor with high-performance and high-quality. A structure of a SOI high-temperature pressure sensor is presented in this paper. The key factors including doping concentration and power are analyzed. The process of the sensor is designed with the critical process parameters set appropriately. The test result at room temperature and high temperature shows that nonlinear error below is 0.1%, and hysteresis is less than 0.5%. High temperature measuring results show that the sensor can be used for from room temperature to 350 °C in harsh environments. It offers a reference for the development of high temperature piezoresistive pressure sensors.

A Passive Pressure Sensor Fabricated by Post-Fire Metallization on Zirconia Ceramic for High-Temperature Applications

A high-temperature pressure sensor realized by the post-fire metallization on zirconia ceramic is presented. The pressure signal can be read out wirelessly through the magnetic coupling between the reader antenna and the sensor due to that the sensor is equivalent to an inductive-capacitive (LC) resonance circuit which has a pressure-sensitive resonance frequency. Considering the excellent mechanical properties in high-temperature environment, multilayered zirconia ceramic tapes were used to fabricate the pressure-sensitive structure. Owing to its low resistivity, sliver paste was chosen to form the electrical circuit via post-fire metallization, thereby enhancing the quality factor compared to sensors fabricated by cofiring with a high-melting-point metal such as platinum, tungsten or manganese. The design, fabrication, and experiments are demonstrated and discussed in detail. Experimental results showed that the sensor can operate at 600 °C with quite good coupling. Furthermore, the average sensitivity is as high as 790 kHz/bar within the measurement range between 0 and 1 Bar.

Static Characteristic Test of High Temperature Pressure Sensor

In this article, the necessity of static characteristic test of high temperature pressure sensor was discussed; the principle static characteristic test of high temperature pressure sensor is illustrated; the static testing of high temperature pressure sensor is completed; the static experimental model of high temperature pressure sensor is established; the main technical indexes was established, it provides an important theoretical basis for the application and test of high temperature pressure sensor.

A study on the deep etching and ohmic contact process of 6H-SiC high-temperature pressure sensor

In all the process steps of manufacturing high-temperature pressure silicon carbide sensors, deep etching and ohmic contact are two crucial processes. Reactive ion etching is used for the deep etching of silicon carbide in our experiment, and the surface has a high quality after etching. Using nickel as the mask material on the C layer by electroplating, the depth of deep etching reaches about 81 µm and the thickness uniformity is fairly good, fluctuating within 200 nm or less. The Ti–TiN–Pt system is proposed for metallization, in which Ti, TiN and Pt are used as the contact layer, the diffusion impervious layer and the lead interaction layer, respectively. The Kelvin test shows that stable ohmic contact is achieved and a specific contact resistivity of 8.42 × 10−4Ω cm2 is detected. The etching depth of 81 µm meets the requirement of forming a sensitive circular membrane, and the metal system of Ti–TiN–Pt ensures reliable connection and stable ohmic contact between the metal and semiconductor at high temperatures.