• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2000년도 Proceedings of 5th International Joint Symposium on Microeletronics and Packaging
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• pp.29-33
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• 2000

MEMS, Micro Electro-Mechanical Systems, present one of the greatest advanced packaging challenges of the next decade. Historically hybrid technology, generally thick film, provided sensors and actuators while integrated circuit technologies provided the microelectronics for interpretation and control of the sensor input and actuator output. Brought together in MEMS these technical fields create new opportunities for miniaturization and performance. Integrated circuit processing technologies combined with hybrid design systems yield innovative sensors and actuators for a variety of applications from single crystal silicon wafers. MEMS packages, far more simple in principle than today's electronic packages, provide only physical protection to the devices they house. However, they cannot interfere with the function of the devices and often must actually facilitate the performance of the device. For example, a pressure transducer may need to be open to atmospheric pressure on one side of the detector yet protected from contamination and blockage. Similarly, an optical device requires protection from contamination without optical attenuation or distortion being introduced. Despite impediments such as package standardization and complexity, MEMS markets expect to double by 2003 to more than ＄9 billion, largely driven by micro-fluidic applications in the medical arena. Like the semiconductor industry before it. MEMS present many diverse demands on the advanced packaging engineering community. With focused effort, particularly on standards and packaging process efficiency. MEMS may offer the greatest opportunity for technical advancement as well as profitability in advanced packaging in the first decade of the 21st century! This paper explores MEMS packaging opportunities and reviews specific technical challenges to be met.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1537-1540
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• 2003

MEMS technology with micro scale is complete system utilized as the sensor. micro electro device. The metallization of MEMS is very important to transfer the power operating the sensor and signal induced from sensor part. But in the MEMS structures local stress concentration and deformation is often happened by geometrical shape and different constraint on the metallization. Therefore. this paper studies the effect of supporting type and thickness ratio about thin film thickness of the substrate thickness for the residual stress variation caused by thermal load in the multi-layer thin film. Specimens were made from materials such as Al, Au and Cu and uniform thermal load was applied, repeatedly. The residual stress was measured by FEA and nano-indentation using AFM. Generally, the specimen made of Al induced the large residual stress and the 1st layer made of Al reduced the residual stress about half percent than 2nd layer. Specimen made of Cu and Au being the lower thermal expansion coefficient induce the minimum residual stress. Similarly the lowest indentation length was measured in the Au_Cu specimen by nano-indentation.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.1016-1021
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• 2005

A piezoresistive pressure sensor using a silicone rubber membrane has been fabricated on the selectively diffused (100)-oriented n/n+/n silicon substrates by a unique silicon micromachining technique using porous silicon ething. The width, length and thickness of the beam were 120${\mu}m$, 600${\mu}m$ and 7${\mu}m$, respectively and the thickness of the silicone rubber membrane was 40${\mu}m$. By the fusion of silicon beam and silicone rubber membrane, the mechanical strength of the pressure sensor could be highly improved due to smaller shear stress. The effectiveness of the sensor was confirmed through an experiment and FEM simulation in which the pressure sensor was characterized.

• 한국전기전자재료학회논문지
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• 제30권7호
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• pp.407-412
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• 2017

This paper introduces a biocompatible packaging system for implantable medical device having a hermetic sealing, such that a perfect physical and chemical isolation between electronic medical system and human body (including tissue, body fluids, etc.) is obtained. The hermetic packaging includes an electronic MEMS pressure sensor, power charging system, and bluetooth communication system to wirelessly measure variation of capacitance. The packaging was acquired by Quartz direct bonding and $CO_2$ laser welding, with a size of width $ 6cm{\times}length\;10cm{\times}lheight\;3cm$. Hermetic sealing of the packaged system was tested by changing the pressure in a hermetic chamber using a precision pressure controller, from atmospheric to 900 mmHg. We found that the packaged system retained the same count or capacitance values with sensor 1 - 25,500, sensor 2 - 26,000, and sensor 3 - 20,800, at atmospheric as well as 900 mmHg pressure for 5 hours. This result shows that the packaging method has perfect hermetic sealing in any environment of the human body pressure.

• 센서학회지
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• 제29권5호
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• pp.354-359
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• 2020

The high vacuum hermetic sealing technique ensures excellent performance of MEMS resonators. For the high vacuum hermetic sealing, the customization of anodic bonding equipment was conducted for the glass/Si/glass triple-stack anodic bonding process. Figure 1 presents the schematic of the MEMS resonator with triple-stack high-vacuum anodic bonding. The anodic bonding process for vacuum sealing was performed with the chamber pressure lower than 5 × 10^-6 mbar, the piston pressure of 5 kN, and the applied voltage was 1 kV. The process temperature during anodic bonding was 400 ℃. To maintain the vacuum condition of the glass cavity, a getter material, such as a titanium thin film, was deposited. The getter materials was active at the 400 ℃ during the anodic bonding process. To read out the electrical signals from the Si resonator, a vertical feed-through was applied by using through glass via (TGV) which is formed by sandblasting technique of cap glass wafer. The aluminum electrodes was conformally deposited on the via-hole structure of cap glass. The TGV process provides reliable electrical interconnection between Si resonator and aluminum electrodes on the cap glass without leakage or electrical disconnection through the TGV. The fabricated MEMS resonator with proposed vacuum packaging using three-layer anodic bonding process has resonance frequency and quality factor of about 16 kHz and more than 40,000, respectively.

• 센서학회지
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• 제32권6호
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• pp.470-474
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• 2023

In this study, a diaphragm-type pressure sensor was developed using multi-layer(four-layer) graphene produced at 1 nm thickness by thermally transferring single-layer graphene produced by chemical vapor deposition (CVD) to a 6" silicon wafer. By measuring the gauge factor, we investigated whether it was possible to produce a pressure sensor of consistent quality. As a result of the measurement, the pressure sensor using multilayer graphene showed linearity and had a gauge factor of about 17.5. The gauge factor of the multilayer graphene-based pressure sensor produced through this study is lower than that of doped silicon, but is more sensitive than a general metal sensor, showing that it can be sufficiently used as a commercialized sensor.

• Journal of Welding and Joining
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• 제30권4호
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• pp.38-43
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• 2012

Using a fiber laser heat source, an oil pressure sensor was fabricated to measure the pressure in commercial vehicles. A stepping motor was used for the rotational and translational motion in the diaphragms and hardware joining. Laser welding process algorism including shielding gas control and vision system was integrated by using LabVIEW software for the high quality welding and in-line monitoring purpose. For the maximum flexibility in pressure transmission to the pressure sensor, thin sheet metal diaphragm, $25{\sim}50{\mu}m$(SUS-316L), was used and the diaphragms were optimally designed with FEM analysis. The welded samples were cross-sectioned the observation showed that the maximum depth ratio was more than seven times of diaphragms. The maximum welding speed was measured to be as high as 50in/mm by the developed automation mechanism. The fabricated prototypes were tested for the proof pressure, spring constant and sealing. The FEM results of spring constant measurement was as accurate as up to 80% of the design value and the sensor was safely operated up to the nominal pressure of 10bars.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권4호
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• pp.355-360
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• 2013

A wireless intraocular (IOP) pressure sensor based on micro electro mechanical system (MEMS) technology is proposed. The proposed IOP sensor uses variable inductance according to the external pressure. The proposed sensor is composed of two flexible membranes: a ferrite bottom part, an inductor, and a capacitor. The inductance of the sensor varies according to the external pressure. The resonance frequency of the sensor is also varied, and this frequency is detected using an external coil. The external coil is designed with an FR-4 printed circuit board. The feasibility of the proposed sensor structure using variable inductance to detect the external pressure is successfully demonstrated.

• ETRI Journal
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• 제38권4호
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• pp.685-694
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• 2016

A surface micromachined piezoresistive pressure sensor with a novel internal substrate vacuum cavity was developed. The proposed internal substrate vacuum cavity is formed by selectively etching the silicon substrate under the sensing diaphragm. For the proposed cavity, a new fabrication process including a cavity side-wall formation, dry isotropic cavity etching, and cavity vacuum sealing was developed that is fully CMOS-compatible, low in cost, and reliable. The sensitivity of the fabricated pressure sensors is 2.80 mV/V/bar and 3.46 mV/V/bar for a rectangular and circular diaphragm, respectively, and the linearity is 0.39% and 0.16% for these two diaphragms. The temperature coefficient of the resistances of the polysilicon piezoresistor is 0.003% to 0.005% per degree of Celsius according to the sensor design. The temperature coefficient of the offset voltage at 1 atm is 0.0019 mV and 0.0051 mV per degree of Celsius for a rectangular and circular diaphragm, respectively. The measurement results demonstrate the feasibility of the proposed pressure sensor as a highly sensitive circuit-integrated pressure sensor.

• 대한기계학회논문집A
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• 제28권5호
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• pp.532-538
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• 2004

MEMS technology applying to the sensors and micro-electro devices is complete system. These microsystems are made by variable processes. Especially, the mentallization process has very important functions to transfer the power operating the sensor and signal induced from sensor part. But in the structures of MEMS the local stress concentration and deformation are often yielded by an irregular geometrical shape and different constraint. Therefore, this paper studies the effect of supporting type and thickness ratio about thin film of the substrate on the residual stress variation when the thermal loads is applied to the multi-layer thin film fabricated by metallization process. Specimens were made from several materials such as Al, Au and Cu. Then, uniform thermal load was applied, repeatedly. The residual stress was measured by FE Analysis and nano-indentation method using AFM. Generally, the specimen made of Al induced the larger residual stress than that of made of other materials. Specimen made of Cu and Au having the low thermal expansion coefficient induces the minimum residual stress. Similarly, the lowest indentation length was measured by nano-indentation method in the Si/Au/Cu specimen. Particularly, clusters are created in the specimen made of Cu by thermal load and the indentation length became increasingly large by cluster formation.