High Temperature Pressure Sensor Research Articles

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.

Strain sensitive Pt–SiO2 nano-cermet thin films for high temperature pressure and force sensors

The strain sensitivity, i.e. the resistivity change due to mechanical strain of thin composite nano-cermet films of Pt–SiO2 was investigated. We prepared films with a thickness of 400nm by means of co-sputtering processes at substrate temperatures around 400°C. The specimens respond to uniform strain (ɛ=0.2‰) with gauge factors up to 18. These gauge factors remained high at least up to 250°C in air and also after further annealing up to 600°C in vacuum. Therefore we state these functional films might be suitable for high temperature pressure and force sensors. The films have a relatively high film resistivity of some MΩ/sq and exhibit temperature coefficients of resistance (TCR) in the range of −2000ppm/K up to −600ppm/K. X-ray diffraction revealed a single crystalline fcc platinum phase while transmission electron microscopy proved a typical granular structure of the films. Pt-clusters sized 5–10nm are embedded in an amorphous insulating matrix of silica. The composition of such nano-cermet films displaying high gauge factors is approx. 40at% Pt, 20at% Si and 40at% of O.

Growth and Characterization of Ca2Al2SiO7 Piezoelectric Single Crystals for High-Temperature Sensor Applications

The electrical properties of a piezoelectric single crystal of calcium aluminate silicate Ca2Al2SiO7 (CAS) were studied at elevated temperatures and its applicability to high-temperature pressure sensors was investigated. The CAS bulk single crystal was grown by the Czochralski method. The piezoelectric d14 and d36 constants were respectively evaluated as 6.04 and 4.04 pC/N by the resonance and antiresonance method. The temperature dependence of the piezoelectric constant was investigated at temperatures up to 500 °C. The electrical resistivity at 800 °C was on the order of 108 Ω·cm along both the crystallographic a- and c-axes. The measurement of direct piezoelectric response at 700 °C demonstrated that the CAS crystal could detect a pseudo-combustion pressure change of an automobile engine. Our observations suggest that CAS crystals are superior candidates for sensing pressure at high temperatures.

A Wireless Passive Pressure Microsensor Fabricated in HTCC MEMS Technology for Harsh Environments

A wireless passive high-temperature pressure sensor without evacuation channel fabricated in high-temperature co-fired ceramics (HTCC) technology is proposed. The properties of the HTCC material ensure the sensor can be applied in harsh environments. The sensor without evacuation channel can be completely gastight. The wireless data is obtained with a reader antenna by mutual inductance coupling. Experimental systems are designed to obtain the frequency-pressure characteristic, frequency-temperature characteristic and coupling distance. Experimental results show that the sensor can be coupled with an antenna at 600 °C and max distance of 2.8 cm at room temperature. The senor sensitivity is about 860 Hz/bar and hysteresis error and repeatability error are quite low.

CMOS-compatible ruggedized high-temperature Lamb wave pressure sensor

This paper describes the development of a novel ruggedized high-temperature pressure sensor operating in lateral field exited (LFE) Lamb wave mode. The comb-like structure electrodes on top of aluminum nitride (AlN) were used to generate the wave. A membrane was fabricated on SOI wafer with a 10 µm thick device layer. The sensor chip was mounted on a pressure test package and pressure was applied to the backside of the membrane, with a range of 20–100 psi. The temperature coefficient of frequency (TCF) was experimentally measured in the temperature range of −50 °C to 300 °C. By using the modified Butterworth–van Dyke model, coupling coefficients and quality factor were extracted. Temperature-dependent Young's modulus of composite structure was determined using resonance frequency and sensor interdigital transducer (IDT) wavelength which is mainly dominated by an AlN layer. Absolute sensor phase noise was measured at resonance to estimate the sensor pressure and temperature sensitivity. This paper demonstrates an AlN-based pressure sensor which can operate in harsh environment such as oil and gas exploration, automobile and aeronautic applications.

Design of 6H-SiC High Temperature Pressure Sensor Chip

Over the last decade, a relatively in-depth research on the different structures and types of the full SiC pressure sensors including the piezoresistive, the capacitive and the optical SiC pressure sensors etc. has been conducted with a view to realizing the pressure measurement in high temperature circumstances. The piezoresistive SiC pressure sensor has gradually become the focus of research due to its simple structure and convenience application. In our research, the piezoresistance strip is designed on the deep-etching sensitive circular diaphragm formed via deep etching. Firstly, the 6H-SiC strain coefficient GF value is compared on the radial direction and the transverse direction by analyzing the circular diaphragm deformation theory. It’s concluded that both in the radial direction, four resistance strips are assigned in the center of circular diaphragm and along the edge respectively, with equal number on these two locations. Better consistency and sensitivity are achieved by this solution. Secondly, the design size of the sensitive circular diaphragm and the pressure resistance strips are determined with the expected work temperature and the target measuring range being taken into consideration. The final layout scheme design of four pressure resistance strips is determined through simulation on the consideration of the thermal stress caused by the AlN packaging.

Intelligent Detector of Internal Combustion Engine Cylinder Pressure and Sensitivity Temperature Coefficient Compensation

The detecting device based on mechanical mechanism is far from the measurement of internal combustion engine cylinder explosion and compression pressure. This pressure detection is under the environment of pulsed gas (over 500 times per one minute) and mechanical impactive vibration. Piezoresistive detection with silicon on insulator (SOI) strain gauges to pressure seems to be a good solution to meet such special applications. In this work, separation by implanted oxygen (SIMOX) wafer was used to fabricate the high temperature pressure sensor chip. For high accuracy and wide temperature range application, this paper also presents a novel pressure sensitivity temperature coefficient (TCS) compensation method, using integrated constant current network. A quantitative compensation formula is introduced in mathematics. During experiments, the absolute value of the compensated TCS is easy to be 10 × 10−6/°C~100 × 10−6/°C by individual adjustment and calibration of each device’s temperature compensation. Therefore, the feasibility and practicability of this technology are tested. Again, the disadvantages are discussed after the research of the experiment data and the improvement methods are also given in the designing period. This technology exhibits the great potential practical value of internal combustion engine cylinder pressure with volume manufacturing.

A SiC high-temperature Pressure Sensor Operating in Severe Condition

The tranditional MEMS pressure sensor based on Silicon (Si) material has not been suitable for operating in severe condition such as high-temperature (>500°C). However, as an alternative material, Silicon Carbide (SiC) can be used in hash environment due to its unique properties. Hence this paper presents a touch mode capacitive pressure sensor with double-notches structure, which employs a special SiC-AlN-SiC sandwich structure to achieve high-accuracy pressure measurement in high-temperature environment. In order to get the relation of capacitance and external pressure, the large deflection theory is applied in simulation analysis of the diaphragm deformation. At the same time, the sandwich structure and technical process of the sensor are studied in the paper. The results showed that the sensor has excellent high-temperature performance due to application of SiC and AlN materials, and the sensor has higher sensitivity and longer linear range than traditional single-cavity structure. Consequently, the sensor can be applied to accuracy pressure measuremet in high-temperature and harsh environment. DOI: http://dx.doi.org/10.11591/telkomnika.v10i8.1692 Full Text: PDF

Design and Optimization of Elastic Diaphragm in Miniature High-Temperature Pressure Sensor

The differential stress distribution of rectangular diaphragm with different sizes is simulated and analyzed using ANSYS. The results show that the maximal differential stress region on the rectangular diaphragm is located at the diaphragm center and the long side center, and also it gradually increases as the length-width ratio decrease. When the ratio is less than 1:2.2, the increase degree is not obvious and even falls slightly. According to this, the length-width ratio of the rectangular strain diaphragm was optimized as 1:2.2. Furthermore, the influence of stain diaphragm with different thicknesses and temperatures in differential stress distribution is discussed. It proves that the differential stress of the diaphragm is less affected by temperature, when the diaphragm thickness is properly chosen. The present results will provide the prerequisite for the design of miniature high-temperature pressure sensor in the future.

High-temperature piezoresistive pressure sensor based on implantation of oxygen into silicon wafer

Silicon on insulator (SOI) substrates can be prepared using ion implantation of oxygen. For piezoresistive detection, the top layer (0.2μm thickness) of silicon is used as the active material due to its excellent monocrystalline properties. The piezoresistive effect of the top silicon layer of the SOI wafer is analyzed using a cantilever structure. Results show that under certain doping concentration conditions, the longitudinal piezoresistive coefficients of 〈110〉 crystal direction silicon decrease with temperature, while transverse piezoresistive coefficients are less affected by temperature. At 300°C, Si 〈110〉 crystal direction has larger longitudinal and transverse piezoresistive coefficients, which make it suitable for high temperature piezoresistive pressure sensor production. The pressure sensor chip structure is simulated and analyzed using the finite element method. The pressure gauge chips are manufactured using MEMS techniques. The manufactured sensors are measured with an applied pressure from 0 to 6.0MPa at 300°C. The test results show that the sensitivity is approximately 30mV/(mAMPa), the non-linearity is less than 1.5‰FS, and the repeatability is less than 0.3‰FS. This research shows that the SOI piezoresistive pressure sensor could reliably work at high temperatures up to 300°C.

Research and Analysis of a Laser-Type High Temperature Pressure Sensor Based on SiC Diaphragm

In the field of high temperature sensing applications, Silicon carbide (SiC) is a superior material due to its excellent mechanical, thermal and chemical properties. Laser triangulation is a technology of non-contact, rapidity, and high accuracy. Its characteristic of non-contact can realize the high temperature non-resistance components’ isolation from the high temperature components of the sensor effectively, so as to achieve measurement under high temperature. Meanwhile, its measurement accuracy can be further improved effectively by using the principle of lens imaging of magnification and constant focus, combining with the high-resolution photodetector. This paper first applied it to the measurement of pressure under high temperature, and proposed a laser-type high temperature pressure sensor using SiC diaphragm as the pressure-sensitive diaphragm. The sensor measured the center deflection of the circular SiC diaphragm caused by pressure and temperature using the laser triangulation, then created the corresponding relationship between the pressure, temperature and deflection according to the thermoelasticity theory. The paper first established the mathematical model of the high accuracy laser triangulation. Afterward did the thermomechanical finite element analysis of the SiC diaphragm using ANSYS. The research and analysis demonstrate that this technical scheme of measurement of pressure under high temperature is effective and feasible, and provide a forceful and important basis for the design and realization of the sensor.

High-temperature high-frequency turbine exit flow field measurements in a military engine with a cooled unsteady total pressure probe

The measurement of unsteady pressures within the hot components of gas turbine engines still remains a true challenge for test engineers. Several high-temperature pressure sensors have been developed, but so far, their applications are restricted to unsteady wall static pressure measurements. Because of the severe flow conditions such as turbine inlet temperatures of 1700 °C and pressures of 50 bar or more in the most advanced aero-engine designs, few (if any) experimental techniques exist to measure the time-resolved flow total pressure inside the gas path. This article describes the measurements performed at the turbine exit of a military engine with a cooled fast response total pressure probe. The probe concept is based on the use of a conventional miniature piezo-resistive pressure sensor, located in the probe tip to achieve a bandwidth of at least 40 kHz. Due to the extremely harsh conditions, the probe and sensor are heavily water cooled. The probe was designed to be continuously immersed into the hot gas stream to obtain time series of pressure with a high bandwidth and therefore statistically representative average fluctuations at the blade passing frequency (BPV). The experimental results obtained with a second-generation prototype are presented. The probe was immersed into the engine through the bypass duct between turbine exit and flame-holders of the afterburner of a Volvo RM12 engine, at exhaust temperatures above 900 °C. The probe was able to resolve the BPV (∼17 kHz) and several harmonics up to 100 kHz.

Evaluation of high temperature pressure sensors

It is becoming more important to measure the pressure in high temperature environments in many industrial fields. However, there is no appropriate evaluation system and compensation method for high temperature pressure sensors since most pressure standards have been established at room temperature. In order to evaluate the high temperature pressure sensors used in harsh environments, such as high temperatures above 250 °C, a specialized system has been constructed and evaluated in this study. The pressure standard established at room temperature is connected to a high temperature pressure sensor through a chiller. The sensor can be evaluated in conditions of changing standard pressures at constant temperatures and of changing temperatures at constant pressures. According to the evaluation conditions, two compensation methods are proposed to eliminate deviation due to sensitivity changes and nonlinear behaviors except thermal hysteresis.

CVD Grown Materials for High Temperature Electronic Devices : A Review

Chemical Vapour Deposition (CVD) remains an extremely popular area of fabricating electronic devices, operating at high temperature and in harsh environments. CVD offers an excellent process controllability and development of quality thin films on varieties of substrates that are compatible to standard IC technology. Plasma enhanced CVD (PECVD), atomic layer CVD (ALCVD), laser CVD and metal organic CVD (MOCVD) need special mention for their added advantages like low substrate temperature, high spatial resolution and precise doping, in addition to the high temperature stability of the films. In this review article, we critically discuss the various standard CVD processes for electronics industry and some high temperature non-oxide ceramic materials like SiC, III-nitrides and carbon nanotubes for electronic device applications. These include optoelectronics devices like laser diode, laser crystal cooling, microwave device, power semiconductor heat spreaders and high temperature pressure and chemical sensors. The prospect of the most recently reported CVD grown graphene for high temperature device applications has been highlighted.

Packaging Technology for High Temperature Capacitive Pressure Sensors

High temperature pressure sensors are critical sensing elements for the next generation of intelligent aerospace engine technology, as well as long-term exploration missions to Venus, where the surface temperature is 485°C. Various high temperature pressure sensors based on different sensing mechanisms are under development at the NASA Glenn Research Center. In order to test long-term performance and reliability of these sensors in a high temperature environment, and eventually commercialize these sensors, high temperature durable and long-term reliable packaging is essential. A prototype packaging technology for micro-sensors designated for applications in high temperature and high differential pressure environments has been developed and reported previously. Packaged high temperature silicon carbide pressure sensors have been successfully tested between room temperature and 500°C. This paper reports an improved version of this packaging technology and testing results of a packaged commercial Si capacitive pressure sensor at elevated temperatures. The parasitic parameters of the packaging are electrically characterized from room temperature to 500°C at 120Hz, 1kHz, 10kHz, and 100kHz. This packaging is primarily designed for high temperature capacitive pressure sensors, but it also applies to other high temperature sensors, especially those for high differential pressure environments.

Development of Zr/ZrO2 high temperature and high pressure sensors for in-situ measuring chemical parameters of deep-sea water

In order to in situ measure chemical parameters of deep-sea water and hydrothermal fluids at mid-ocean ridge (MOR), it is necessary to use high temperature and high pressure chemical sensors. Developing new sensors is essential to measure in-situ pH and other chemical parameters (dissolved H2, dissolved H2S) of deep-sea water and hydrothermal fluids in a wide temperature range (2°C–400°C) at MOR vents. The YSZ (Yttria Stabilized Zirconia, 9%Y2O3) ceramic-based (HgO/Hg) chemical sensors possess excellent electrochemical properties at high temperatures, which have been used to measure chemical parameters of hydrothermal fluids above 200°C. A novel Zr/ZrO2 oxidation/reduction electrode was constructed by oxidation of Zr wire in Na2CO3 melt. This Zr/ZrO2 electrode has good chemical stability while measuring pH of high-temperature aqueous solutions, combined with a Ag/AgCl reference electrode. Potentials of the Zr/ZrO2 sensor in association with a Ag/AgCl reference electrode vary linearly with pH over a wide pH range, as tested by various NaCl-HCl-H2O solutions (NaOH-NaCl-H2O for basic solutions), at temperatures in the range of 20°C–200°C. Thus, the Zr/ZrO2 sensors can be utilized in monitoring the fluids over the temperature range of 2°C–200°C. The Zr/ZrO2 electrode combined with Ag/AgCl, Ag/Ag2S, and Au electrodes has been used to measure pH and other chemical parameters (dissolved H2, dissolved H2S) of aqueous fluids from low to high temperatures and high pressures in the laboratory and to monitor those parameters of deep-sea water in South China Sea.

AFM testing of the nanomechanical behaviour of MEMS micromembranes

Abstract The nanomechanical behaviour of micromembranes for high temperature applications of a microelectro mechanical system pressure sensor has been studied by use of atomic force microscopy. A method was elaborated and used for measure nanometre deformation of the membrane under application of high loads. This method was also useful for identifying failures of a membrane, e. g., undesired position against the substrate of the structure. The tests were performed for a series of membranes. The characteristics of the mechanical behaviour were plotted for different geometrical features of the membranes to identify the influence of geometry and dimension. The method was found to be very effective for the process characterisation of the fabricated MEMS micromembranes devoted, e. g., to high temperature pressure sensors.

Study of a high-temperature and high-pressure FBG sensor with Al2O3 thin-wall tube substrate

A fiber Bragg grating (FBG) high-temperature and high pressure sensor has been designed and fabricated by using the Al2O3 thin-wall tube as a substrate. The test results show that the sensor can withstand a pressure range of 0–45 MPa and a temperature range of −10–300 °C, and has a pressure sensitivity of 0.0426 nm/MPa and a temperature sensitivity of 0.0112 nm /°C

Micro machining process of high temperature pressure sensor gauge chip based on SIMOX SOI wafer

The successful batch fabrication of a piezoresistive pressure sensor chip is described based on separation by implantation of oxygen (SIMOX) SOI wafer. The micro machining process mainly includes SIMOX, homoepitaxy silicon, and heavy dose of boron ion implantation doping, thermal oxidation, passivation layer of silicon nitride and standard optical lithography, Inductively Coupled Plasma (ICP), multi-layer metallisation and Au sputtering and so on. The sensor packaged with this kind of sensing chip is presented with high accuracy and a good long-term stability in high temperature testing experiments up to 250?C.