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Silicon MEMS probe using a simple adhesive bonding process for permittivity measurement
Kim, Jung-Mu,Oh, Dong Hoon,Yoon, Jeonghoon,Cho, Sungjoon,Kim, Namgon,Cho, Jeiwon,Kwon, Youngwoo,Cheon, Changyul,Kim, Yong-Kweon IOP 2005 Journal of micromechanics and microengineering Vol.15 No.11
<P>We developed a silicon MEMS probe for permittivity measurements using an adhesive bonding process. Only two photolithographic masks are required to fabricate the probe, which can be implemented through simple bonding processes using silicon substrates and a benzo cyclo butene (BCB) adhesive layer. Undoped silicon substrates with thicknesses of 300 ?m are used as the dielectric layers of the proposed probe. BCB layers, which have good electrical properties at high frequencies as well as adhesive properties for the bonding process, play the role of bonding materials between the two silicon substrates. The length of the probe is 30 mm, and the aperture located at the tip of the probe is 1.1 mm ? 0.62 mm. The permittivity of 0.5% saline was measured, and the results agreed with the values obtained through the Cole–Cole equation. To validate the feasibility of this probe for practical biological applications, we also performed <I>in vivo</I> measurements of the muscle, skin and blood of mice. Due to the simple fabrication process, the cost of the probe can be reduced in comparison with the previous micromachined probe (<A article='0960-1317/15/3/015'>Kim <I>et al</I> 2005 <I>J. Micromech. Microeng.</I> <B>15</B> 543–50</A>) as well as the conventional laser machined probe. Low cost leads to disposability, which is an important factor for practical biomedical applications; and thus, coupled with the probe's capabilities of MMIC integration and CMOS compatibility, this probe has excellent potential in the field of microwave permittivity measurements.</P>
Through-Silicon Via Capacitance–Voltage Hysteresis Modeling for 2.5-D and 3-D IC
Kim, Dong-Hyun,Kim, Youngwoo,Cho, Jonghyun,Bae, Bumhee,Park, Junyong,Lee, Hyunsuk,Lim, Jaemin,Kim, Jonghoon J.,Piersanti, Stefano,de Paulis, Francesco,Orlandi, Antonio,Kim, Joungho IEEE 2017 IEEE transactions on components, packaging, and ma Vol.7 No.6
<P>We propose, for the first time, an explicit semiconductor physics-based through-silicon via (TSV) capacitance-voltage (CV) model. The effect of TSV CV hysteresis is demonstrated in the model, and the TSV capacitance is modeled with respect to dc bias voltage and the dimension of the TSV. The proposed model is verified by comparison to the measurement results. The effect of hysteresis in the model correlates well with the measurement results. This model can be utilized in a circuit level simulation to expand the possible application of the model to, but not limited to, hierarchical power distribution network impedance analysis, RC delay analysis, input-output power consumption analysis, and crosstalk and eye diagram simulation in any 3-D-IC systems using TSVs.</P>
Kim, Youngwoo,Cho, Jonghyun,Kim, Jonghoon J.,Cho, Kyungjun,Kim, Subin,Sitaraman, Srikrishna,Sundaram, Venky,Raj, Pulugurtha Markondeya,Tummala, Rao R.,Kim, Joungho [Institute of Electrical and Electronics Engineers 2017 IEEE transactions on electromagnetic compatibility Vol.59 No.3
<P>In this paper, we propose glass interposer electromagnetic bandgap (EBG) structure to efficiently suppress power/ground noise coupling. We designed, fabricated, measured, and analyzed a glass interposer EBG structure for the first time. Glass interposer EBG structure test vehicles were fabricated using a thin-glass substrate, low-loss polymer layers, and periodic metal patches with through glass vias (TGVs) in glass interposer power distribution network. Using the dispersion characteristics, we thoroughly analyzed and derived f(L) and f(U) of the glass interposer EBG structure. We experimentally verified that the proposed glass interposer EBG structure achieved power/ground noise suppression (below -40 dB) between f(L) of 5.8 GHz and f(U) of 9.6 GHz. Derived f(L) and f(U) based on dispersion analysis, full three-dimensional electromagnetic (3-D-EM) simulation and measurement achieved good correlation. In the glass interposer EBG structure, tapered structure of the TGV and thickness of the low-loss polymer used for metal-layers lamination affected the noise suppression bandgap significantly. The effectiveness of the proposed glass interposer EBG structure on suppression of the power/ground noise propagation and coupling to high-speed TGV channel was verified with 3-D-EM simulation. As a result, the proposed glass interposer EBG structure successfully and efficiently suppressed the power/ground noise propagation and improved eye-diagram of the high-speed TGV channel.</P>
Youngwoo Kim,Jonghyun Cho,Kyungjun Cho,Junyong Park,Subin Kim,Dong-Hyun Kim,Gapyeol Park,Sitaraman, Srikrishna,Raj, Pulugurtha Markondeya,Tummala, Rao R.,Joungho Kim IEEE 2017 IEEE transactions on components, packaging, and ma Vol.7 No.9
<P>In this paper, we propose glass-interposer (GI) electromagnetic bandgap (EBG) structure with defected ground plane (DGP) for efficient and broadband suppression of power/ground noise coupling. We designed, fabricated, measured, and analyzed a GI-EBG structure with DGP for the first time. The proposed GI-EBG structure with DGP is thoroughly analyzed using the dispersion characteristics and estimated stopband edges, f(L) and f(U). We experimentally verified that the proposed GI-EBG structure with DGP achieved power/ground noise isolation bandgap (below -30 dB) between f(L) of 5.7 GHz and f(U) of 11 GHz. Estimation of f(L) and f(U) using dispersion analysis, full 3-D electromagnetic (EM) simulation results, and measurement results achieved good correlation. Effectiveness of the proposed GI-EBG structure with DGP on suppression of the power/ground noise coupling to high-speed through glass via (TGV) channel is verified with 3-D EM simulation. As a result, the proposed EBG structure successfully and efficiently suppressed the power/ground noise coupling and improved the eye diagram of the TGV channel. Lastly, we embedded thin alumina film in the proposed EBG structure and achieved even broader power/ground noise suppression between 2.1 and 14.7 GHz.</P>
Kim, Youngwoo,Hong, Byung Woo,Kim, Seung Ja,Kim, Jong Hyo Published for the American Association of Physicis 2014 Medical physics Vol.41 No.7
<P>A major challenge when distinguishing glandular tissues on mammograms, especially for area-based estimations, lies in determining a boundary on a hazy transition zone from adipose to glandular tissues. This stems from the nature of mammography, which is a projection of superimposed tissues consisting of different structures. In this paper, the authors present a novel segmentation scheme which incorporates the learned prior knowledge of experts into a level set framework for fully automated mammographic density estimations.</P>
Novel MMIC protection technique in plasma etching process for mechanically movable RF mems antenna
Kim, Jung-Mu,Lee, Sanghyo,Kim, Yongsung,Kim, Jong-Man,Cheon, Changyul,Kwon, Youngwoo,Kim, Yong-Kweon Wiley Subscription Services, Inc., A Wiley Company 2008 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS - Vol.50 No.12
<P>In this article, we proposed the novel monolithic microwave integrated circuit (MMIC) protection technique in plasma etching process for MMIC mounted mechanically movable RF MEMS antenna. We could eliminate the distortion of radiation pattern caused by RF feed line on antenna frame and torsional hinge as using MMIC direct mounting on antenna plate instead of using external RF power source. Silicon-based mechanically movable RF MEMS antenna was released using DRIE process, which was performed on the backside of silicon substrate after MMIC mounting on RF MEMS antenna plate. An aluminum layer on the front side of RF MEMS antenna plays a role of etch stop layer for DRIE process. We measured the radiation pattern as rotating the moving plate along the vertical- and horizontal-direction hinge mechanically. We could obtain the radiation pattern without gain reduction and distortion of radiation pattern. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3089–3093, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23870</P>
Kim, Jong-Man,Chu, Kyongtae,Lee, Sanghyo,Lee, Dong-Kyu,Kim, Yongsung,Kim, Jung-Mu,Baek, Chang-Wook,Kwon, Youngwoo,Kim, Yong-Kweon IOP 2006 Journal of micromechanics and microengineering Vol.16 No.10
<P>This paper describes two types of novel compact low-loss millimeter-wave filters using an overlay coplanar waveguide (OCPW) line for lowpass filters and an inverted overlay coplanar waveguide (IOCPW) line for bandpass filters with periodic defected ground structures (DGSs). The OCPW and IOCPW lines are utilized to reduce the conductor and the substrate dielectric loss of the transmission lines. Also, these lines can provide a wide impedance range by controlling the overlapped area. The DGSs implemented on the transmission line have the role of size reduction and harmonic suppression of the filters. The combination of transmission lines having suspended structures and DGSs can provide great potential in terms of compact size, band rejection property and low-loss characteristics. The proposed filters are fabricated by using a micromachining technology and their RF performances are measured and analyzed. One of the proposed filters is a lowpass filter with a five-section stepped impedance topology having a periodic high–low impedance section. In this filter, the low impedance section is composed of the OCPW line with dumbbell-shaped DGSs and its length can be reduced by 52.7% compared to the OCPW line without DGSs. The measured insertion loss of this filter is lower than 0.2 dB up to 9 GHz, and significant spurious bands are not observed up to 40 GHz, resulting in a wide stop band. The other work that is presented here deals with a pi-shaped bandpass filter. This filter consists of three high impedance sections and two low impedance sections, and the line length of the high impedance section can be reduced by using the IOCPW line with spiral-shaped DGSs. The measured center frequency of the fabricated filter is 19 GHz, and the passband loss is 2.3 dB at the measured center frequency. The use of DGSs on the transmission line also enables us to suppress effectively the third-order harmonic component at 57 GHz.</P>