• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.11 s.254
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• pp.1369-1375
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• 2006

In this work, mechanical characteristics of stainless steel diaphragm have been studied as a potential robust substrate and a diaphragm material for micromachined devices. Lamination process techniques combined with traditional micromachining processes have been adopted as suitable fabrication technologies. To illustrate these principles, capacitive pressure sensors based on a stainless steel diaphragm have been designed, fabricated and characterized. The fabrication process for stainless steel micromachined devices keeps the membrane and substrate being at the environment of 8.65MPa pressure and $175^{\circ}C$ for a half hour and then subsequently cooled to $25^{\circ}C$. Each sensor uses a stainless steel substrate, a laminated stainless steel film as a suspended movable plate and a fixed, surface micromachined back electrode of electroplated nickel. The finite element method is adopted to investigate residual stresses formed in the process. Besides, out-of-plane deflections are calculated under pressures on the diaphragm. The sensitivity of the device fabricated using these technologies is 9.03 ppm $kPa^{-1}$ with a net capacitance change of 0.14 pF over a range 0$\sim$180 kPa.

• Journal of Sensor Science and Technology
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• v.3 no.3
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• pp.45-53
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• 1994

A new type of Si diaphragm was fabricated using Si-wafer direct bonding and two-step electrochemical etch-stopping methods. Using the new diaphragm structure in mechanical sensors, more precise control of cavity depth and diaphragm thickness was achievable. Also, the propagation of the stress, which was generated near the bonding interface, to the surface can be avoided. Finally, a piezoresistive-type Si pressure sensor was fabricated utilizing the diaphragm and a digital pressure gauge, which can display units of pressure, was realized.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2961-2966
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• 2007

When the pressure at the weak spot established at a certain part of a high pressure vessel or piping system exceeds a design pressure, this weak spot is burst, and the pressurized gas emitted through the weak spot will cause a compression wave system. In this connection, in the present study, an experimental study by using a conventional shock tube facility is performed to estimate the effects of the material of diaphragm, curvature radius and thickness of materials on the valve opening time in diaphragm. Pressure sensor having 500kHz in natural frequency is installed at 35mm downstream of the rupture diaphragm to measure the static pressure history of propagating and being accumulated compression wave. 4 kinds of materials are used as diaphragm that is aluminium, copper, stainless steel and zinc. The diaphragm radii of curvature R are ${\infty}$, 120mm and 60, respectively. And the depth for $90^{\circ}$ groove is 0.04mm. It is found that the smaller the tensile strength and elongation of the rupture diaphragm is, the smaller the radius of curvature of the rupture diaphragm is, and for the same conditions the thinner the thickness of the rupture diaphragm is, the shorter the valve opening time becomes. Also, the tensile strength, elongation and the radius of curvature of the rupture diaphragm for the same conditions are smaller, the maximum pressure rise caused by the coalescences of the compression wave is smaller. Finally the pressure ratio is higher, the valve opening time is shortened and gradient of pressure increment is more steepen.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.225-229
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• 2011

In this study, capacitive type pressure sensors based on low temperature co-fired ceramics (LTCC) technology for environmental monitoring were demonstrated. The LTCC is one of promising technology than is based one since it has many advantages (e.g., low cost production, high manufacturing yields and easy realizing 3D structure etc.) for sensor application. Especially, it has good mechanical and chemical properties for robust environmental application. The 3D LTCC diaphragm with thickness of 400 ${\mu}m$ were fabricated by laminating 4 green sheets using commercial powder (NEG, MLS 22C). To evaluate the sensing properties of the different cavity areas, two types of diaphragm which had different cavity areas with 25, 49 $mm^2$ respectively, were fabricated. To realize capacitive type pressure sensor, the Au top electrode was fabricated using thermal evaporator and the bottome electrode was compressed using aluminium foil. The sensing properties of the fabricated sensors showed linear characteristic under different pressure (0~30 psi) using pressure measurement system.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.1
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• pp.51-56
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• 2017

In this paper, we have developed a differential pressure flow sensor designed as a single capacitive type. And the sensor was fabricated using a MEMS process. Differential pressure flow sensors are the most commonly used sensors for industrial applications. The sensing diaphragm and bonding joint of the MEMS pressure sensor are easily broken at high pressure. In this paper, we proposed a structure in which the diaphragm of the sensor was not broken at a pressure exceeding the proof pressure, and the differential pressure sensor was designed and manufactured accordingly. The operating characteristics of the sensor were evaluated at a pressure three times higher than the sensor operating pressure (0-3 bar). The developed sensor was $3.0{\times}3.0mm$ and measured with a LCR meter (HP 4284a) at a pressure between 0 and 3 bar. It showed 3.67 pF at 0 bar and 5.13 pF at 3 bar. The sensor operating pressure (0-3 bar) developed a pressure sensor with hysteresis of 0.37%.

• The Journal of the Acoustical Society of Korea
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• v.14 no.2E
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• pp.12-18
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• 1995

Capactive miro pressure sensor is simulated with finite element methods to analyze the effect of geometrical variation on its performace. Sensor material is th silicon single crystal. The sensor consists of a disk type diaphragm and several bridges connected to a rigid frame. Structural variables in consideration are the thickness of the diaphragm and the bridges, radius of the circular plate, and the number of bridges. Results of static, dynamic and sensitivity analyses reveal the best structure of the sensor among the fifteen cases under investigation.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.3
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• pp.364-369
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• 1986

Silicon diaphragms, 10 and 20 \ulcorner-thick and 1x1 mm\ulcornerarea, have been fabricated by means of the electrochemical P-N junction etch-stop technique. The P-type diffused resistors were formed on the diaphragm, and the piezoresistance effect was examined. It was been found that the fractional variation of the resistance is dependent on the diaphragm thickness, resistor location, and resistor length, etc. The 1.2 k\ulcornerfull-brige pressure sensor with 10\ulcorner-thick diaphragm exhibits a pressure sensitivity of 42 \ulcorner/V\ulcornermHg with a temperature coefficient of 2.3 mmHg/\ulcorner, and shows a good linearity in the pressure range from 0 to 300 mmHg.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.2087-2089
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• 2004

Capacitive pressure sensor는 Piezo type sensor에 비해 온도의 영향이 적어 공업계측, 전기용품 등 그 용도가 다양하여 폭넓게 사용되어지고 있지만, 측정값의 비선형성이 존재하여 측정값에 대한 신뢰도가 떨어지는 단점이 있다. 본 연구에서는 기존 capacitive pressure sensor의 비선형적 output을 개선하기 위한 방법으로 touch mode capacitive pressure sensor를 제안하였다. 또한, 실제 Device제작에 앞서 FEM 해석을 수행하였다. 2mm X 2mm 크기의 diaphragm, $25{\mu}m$의 두께, $20{\mu}m$의 gap을 갖는 Sensor를 Simulation하였으며 설계 변수를 추출하여 각각의 설계변수에 대한 해석을 실시하였다. 그 결과 15.2psi${\sim}$31psi의 영역에서 8.58pF${\sim}$54.31pF의 capacitance가 선형적으로 나타나는 sensor임을 확인하였다.

• Journal of Sensor Science and Technology
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• v.4 no.1
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• pp.29-34
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• 1995

The absolute silicon pressure sensors are fabricated using SDB(silicon direct bonded) wafer. The fabricated pressure sensors consist of four bridge type piezoresistances and a diaphragm which plays a role of mechanic amplifier to supplying pressure. In order to make the diaphragm cavity in low vaccum condition, we anodically bonded Si diaphragm with pyrex 7740 glass in 0.02mmHg, at $400^{\circ}C$. The sensitivity and offset voltage of the fabricated sensors were $30.4{\mu}V/VmmHg$ and 30.6mV, respectively.

• Journal of Sensor Science and Technology
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• v.5 no.4
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• pp.1-7
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• 1996

Optical intensity-type pressure sensor was fabricated by coupling optical fiber with a micromachined thin dielectric diaphragm, which consists of a 300 nm thick $SiO_{2}$ layer sandwiched between 150 nm thick top and bottom $Si_{3}N_{4}$ layers. At the wavelength of the sensor light source near $1.3\;{\mu}m$, the optical transmittance of the diaphragm was about 50 %, but it was decreased to a few percents by depositing $1,000\;{\AA}$ thick gold(Au) layer on the diaphragm, which is sufficient enough to be used as a light reflection layer of the sensor. From the optical output power-pressure characteristics of the sensors, it was found that the output power linearly decreased with increasing applied pressure from 0 to 77 torr regardless of the diaphragm size. The respective sensitivities were 0.52, 0.65, and 0.77 nW/torr for the diaphragm sizes of $3{\times}3$, $4{\times}4$, and $5{\times}5\;mm^{2}$, indicating that the sensitivity increases as diaphragm size decreases.