Fabrication and Characterization of RF MEMS Package Based on LTCC Lid Substrate and Gold-Tin Eutectic Bonding

Bang, Yong-Seung; Kim, Jong-Man; Kim, Yongsung; Kim, Jung-Mu; Kim, Yong-Kweon

doi:10.1109/sensor.2007.4300583

Cited by 14 publications

(6 citation statements)

References 6 publications

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“…As regards bonding strength between the lid and the sensor, scratch tests showed a shear strength of 71.5-108.5 MPa (average: 94.75 MPa), which is as good or better than with eutectic bonding using metal alloys. 21,22 The cross-section shown in Figure 5B confirms that polishing does not cause delamination and that the lid is bonded to the sensor with resin. Such cross-sectional observations were used to examine the variations in thickness of lids, bonding material, and sensors across the wafer.…”

Section: Results Of Thin Strain Sensor Prototypingmentioning

confidence: 59%

Fabricating process of thin‐strain sensor by utilizing wafer‐level‐packaging techniques

Aono,

Kanamaru,

Ikeda

2024

Elect Comm in Japan

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This research has developed a fabricating process of thin‐strain sensor by utilizing wafer‐level‐packaging (WLP) techniques. The thickness of sensor makes thinner, its performance is able to highly increase. However, the thinner sensor was fragile, and so it was difficult to handle in post processes. Thus, a thin sensor with lid by utilizing WLP techniques, which is tough to break even when handled, is proposed in this research. More than 250‐µm‐deep grooves were fabricated around the lid by deep reactive ion etching. After the lid substrate was bonded on the sensor substrate with a resin, the sensor and lid substrates were respectively polished to 50 and 200 µm thickness. The lids were released along the grooves, and the 50‐µm‐thick strain sensors were able to be fabricated by utilizing WLP techniques. This sensor was used as a diaphragm to measure pressure. The sensors were assembled on a stainless steel housing without breakage. The performance of the developed sensor was almost showed with a conventional pressure sensor.

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Section: Results Of Thin Strain Sensor Prototypingmentioning

confidence: 59%

Fabricating process of thin‐strain sensor by utilizing wafer‐level‐packaging techniques

Aono,

Kanamaru,

Ikeda

2024

Elect Comm in Japan

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“…The averaged strength shows 80 MPa at 300 °C under a load of 4 MPa in the figure, while it is 42.7 MPa in [22] at a bonding temperature of 310 °C under a load of 0.9 MPa and is 45.53 MPa in [23] at a bonding temperature of 310 °C under a load of 7 MPa. Therefore, the bonding condition extracted from the MD simulations has been greatly improved in the shear strength.…”

Section: Shear Strength Test Results For Wlpmentioning

confidence: 95%

Eutectic-based wafer-level-packaging technique for piezoresistive MEMS accelerometers and bond characterization using molecular dynamics simulations

Aono¹,

Kazama²,

Okada³

et al. 2018

J. Micromech. Microeng.

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We developed a eutectic-based wafer-level-packaging (WLP) technique for piezoresistive micro-electromechanical systems (MEMS) accelerometers on the basis of molecular dynamics analyses and shear tests of WLP accelerometers. The bonding conditions were experimentally and analytically determined to realize a high shear strength without solder material atoms diffusing to adhesion layers. Molecular dynamics (MD) simulations and energy dispersive x-ray (EDX) spectrometry done after the shear tests clarified the eutectic reaction of the solder materials used in this research. Energy relaxation calculations in MD showed that the diffusion of solder material atoms into the adhesive layer was promoted at a higher temperature. Tensile creep MD simulations also suggested that the local potential energy in a solder material model determined the fracture points of the model. These numerical results were supported by the shear tests and EDX analyses for WLP accelerometers. Consequently, a bonding load of 9.8 kN and temperature of 300 °C were found to be rational conditions because the shear strength was sufficient to endure the polishing process after the WLP process and there was little diffusion of solder material atoms to the adhesion layer. Also, eutectic-bonding-based WLP was effective for controlling the attenuation of the accelerometers by determining the thickness of electroplated solder materials that played the role of a cavity between the accelerometers and lids. If the gap distance between the two was less than 6.2 µm, the signal gains for x- and z-axis acceleration were less than 20 dB even at the resonance frequency due to air-damping.

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“…However, this technique also has disadvantages, such as insulation failure, large dielectric loss, complex process, mismatched thermal expansion coefficient between metal and silicon, and high cost. Other approaches of vertical interconnects have been developed in 3D MEMS packaging, such as silver via in low temperature co-fired ceramic (LTCC) [9,10], vertical vias formed by etching silicon-on-insulator (SOI) cap [11], through-glass via (TGV) [12], vertical vias in silicon thin film [13][14][15]. However, the complicated process limits their wide applications.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the bonding quality between the cap and device wafers is significant for long-term operation of MEMS devices, which is highly dependent on bonding material and bonding process. Au-Sn solder bonding have been used in 3D vacuum MEMS packaging, due to their high yield strength, corrosion and creep resistance, and good electrical conductivity [4][5][6][7][8][9]. Au 0.8 Sn 0.2 solder has been previously studied.…”

Section: Introductionmentioning

confidence: 99%

A low feed-through 3D vacuum packaging technique with silicon vias for RF MEMS resonators

Zhao

Yuan

Kan

et al. 2016

J. Micromech. Microeng.

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This paper presents a wafer-level three-dimensional (3D) vacuum packaging technique for radio frequency microelectromechanical systems (RF MEMS) resonators. A Sn-rich Au–Sn solder bonding is employed to provide a vacuum encapsulation as well as electrical conductions. Vertical silicon vias are micro-fabricated by glass reflow process. The optimized grounding, via pitch, and all-round shielding effectively reduce feed-through capacitance. Thus the signal-to-background ratios (SBRs) of the transmission signals increase from 17 dB to 20 dB, and the quality factor (Q) values of the packaged resonators go from around 8000 up to more than 9500. The measured average leak rate and shear strength are (2.55 ± 0.9) × 10−8 atm-cc s−1 and 42.53 ± 4.19 MPa, respectively. Furthermore, thermal cycling test between −40 °C and 100 °C and high temperature storage test at 150 °C show that the resonant-frequency drifts are less than ±7 ppm. In addition, the SBRs and the Q values have no obvious change after the tests. The experimental results demonstrated that the proposed encapsulation technique is well suited for the applications of RF MEMS devices.

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Fabrication and Characterization of RF MEMS Package Based on LTCC Lid Substrate and Gold-Tin Eutectic Bonding

Cited by 14 publications

References 6 publications

Fabricating process of thin‐strain sensor by utilizing wafer‐level‐packaging techniques

Fabricating process of thin‐strain sensor by utilizing wafer‐level‐packaging techniques

Eutectic-based wafer-level-packaging technique for piezoresistive MEMS accelerometers and bond characterization using molecular dynamics simulations

A low feed-through 3D vacuum packaging technique with silicon vias for RF MEMS resonators

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