A Wafer-Level Vacuum Package Using Glass-Reflowed Silicon Through-Wafer Interconnection for Nano/Micro Devices

Jin, Juyoun; Yoo, S. D.; Yoo, Byung Woo; Kim, Yong-Kweon

doi:10.1166/jnn.2012.6353

Cited by 15 publications

(9 citation statements)

References 16 publications

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“…Generally, a cavity with a certain depth is necessary to be fabricated in the lid wafer to provide the motion space of fragile sensitive structures and act as the capacitive gap or the reference pressure chamber. Sometimes, non-evaporable getter is even required to be deposited in the cavity to realize and maintain high vacuum for high quality factor [1] and high thermal stability [20,21]. Herein, the glass and silicon in specific regions are required to be etched away respectively to the same depth to form the cavity in the glass-silicon composite substrate.…”

Section: Introductionmentioning

confidence: 99%

Research on the Protrusions Near Silicon-Glass Interface during Cavity Fabrication

Zhang

Yang

et al. 2019

Micromachines

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Taking advantage of good hermeticity, tiny parasitic capacitance, batch mode fabrication, and compatibility with multiple bonding techniques, the glass-silicon composite substrate manufactured by the glass reflow process has great potential to achieve 3D wafer-level packaging for high performance. However, the difference in etching characteristics between silicon and glass inevitably leads to the formation of the undesired micro-protrusions near the silicon-glass interface when preparing a shallow cavity etched around a few microns in the composite substrate. The micro-protrusions have a comparable height with the depth of the cavity, which increases the risks of damages to sensitive structures and may even trigger electrical breakdown, resulting in thorough device failure. In this paper, we studied the characteristics of the chemical composition and etching mechanisms at the interface carefully and proposed the corresponding optimized solutions that utilized plasma accumulation at the interface to accelerate etching and bridge the gap in etching rates between different chemical compositions. Finally, a smooth transition of 131.1 nm was achieved at the interface, obtaining an ideal etching cavity surface and experimentally demonstrating the feasibility of our proposal. The micromachining solution is beneficial for improving the yield and structural design flexibility of higher performance micro-electromechanical systems (MEMS) devices.

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Section: Introductionmentioning

confidence: 99%

Research on the Protrusions Near Silicon-Glass Interface during Cavity Fabrication

Zhang

Yang

et al. 2019

Micromachines

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“…Compared with lateral feedthrough with the problems of step coverage, it is easier to realize good hermetic encapsulation with the vertical feedthrough [9]. The vertical interconnection structures fabricated by a Pyrex glass reflow process, where the low-resistivity silicon pillars surrounded by the insulated glass act as the medium to transmit an electrical signal, has the advantages of good isolation, negligible parasitics, and low crosstalk [10], in addition to good compatibility with anodic bonding. The technology has been widely applied to MEMS pressure sensors [11,12], radio frequency (RF) resonators [12,13,14], and gyroscopes [15].…”

Section: Introductionmentioning

confidence: 99%

Research on a 3D Encapsulation Technique for Capacitive MEMS Sensors Based on Through Silicon Via

Zhang

Yang

et al. 2018

Sensors

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A novel three-dimensional (3D) hermetic packaging technique suitable for capacitive microelectromechanical systems (MEMS) sensors is studied. The composite substrate with through silicon via (TSV) is used as the encapsulation cap fabricated by a glass-in-silicon (GIS) reflow process. In particular, the low-resistivity silicon pillars embedded in the glass cap are designed to serve as the electrical feedthrough and the fixed capacitance plate at the same time to simplify the fabrication process and improve the reliability. The fabrication process and the properties of the encapsulation cap were studied systematically. The resistance of the silicon vertical feedthrough was measured to be as low as 263.5 mΩ, indicating a good electrical interconnection property. Furthermore, the surface root-mean-square (RMS) roughnesses of glass and silicon were measured to be 1.12 nm and 0.814 nm, respectively, which were small enough for the final wafer bonding process. Anodic bonding between the encapsulation cap and the silicon wafer with sensing structures was conducted in a vacuum to complete the hermetic encapsulation. The proposed packaging scheme was successfully applied to a capacitive gyroscope. The quality factor of the packaged gyroscope achieved above 220,000, which was at least one order of magnitude larger than that of the unpackaged. The validity of the proposed packaging scheme could be verified. Furthermore, the packaging failure was less than 1%, which demonstrated the feasibility and reliability of the technique for high-performance MEMS vacuum packaging.

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“…In this paper, fully micromachined tungsten-coated through glass silicon via (TGSV) structures based on the glass reflow technique have been demonstrated to realize TGVs of a glass interposer platform for RF/microwave applications. The glass substrates with silicon vias using a reflow process have already been reported in microelectromechanical systems (MEMS) community for wafer-level 3D interconnects or packaging of the microsystems [ 15 , 16 , 17 ], but its application to RF/microwave devices is limited due to the relatively low electrical conductivity of pure silicon vias compared to the metallic vias. In this work, two-step deep reactive ion etching (DRIE) of silicon vias and selective tungsten coating onto them using a shadow mask are combined with glass reflow technique to realize metal-coated TGSVs that can effectively replace the conventional metallic TGVs without any degradation of RF performances of the device.…”

Section: Introductionmentioning

confidence: 99%

Millimeter-Wave Substrate Integrated Waveguide Using Micromachined Tungsten-Coated Through Glass Silicon Via Structures

Hyeon

Baek

2018

Micromachines

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A millimeter-wave substrate integrated waveguide (SIW) has been demonstrated using micromachined tungsten-coated through glass silicon via (TGSV) structures. Two-step deep reactive ion etching (DRIE) of silicon vias and selective tungsten coating onto them using a shadow mask are combined with glass reflow techniques to realize a glass substrate with metal-coated TGSVs for millimeter-wave applications. The proposed metal-coated TGSV structures effectively replace the metallic vias in conventional through glass via (TGV) substrates, in which an additional individual glass machining process to form micro holes in the glass substrate as well as a time-consuming metal-filling process are required. This metal-coated TGSV substrate is applied to fabricate a SIW operating at Ka-band as a test vehicle. The fabricated SIW shows an average insertion loss of 0.69 ± 0.18 dB and a return loss better than 10 dB in a frequency range from 20 GHz to 45 GHz.

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A Wafer-Level Vacuum Package Using Glass-Reflowed Silicon Through-Wafer Interconnection for Nano/Micro Devices

Cited by 15 publications

References 16 publications

Research on the Protrusions Near Silicon-Glass Interface during Cavity Fabrication

Research on the Protrusions Near Silicon-Glass Interface during Cavity Fabrication

Research on a 3D Encapsulation Technique for Capacitive MEMS Sensors Based on Through Silicon Via

Millimeter-Wave Substrate Integrated Waveguide Using Micromachined Tungsten-Coated Through Glass Silicon Via Structures

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