Glass Interposer Electromagnetic Bandgap Structure for Efficient Suppression of Power/Ground Noise Coupling

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>

Signal Integrity Design and Analysis of Silicon Interposer for GPU-Memory Channels in High-Bandwidth Memory Interface

Cho, Kyungjun,Kim, Youngwoo,Lee, Hyunsuk,Kim, Heegon,Choi, Sumin,Song, Jinwook,Kim, Subin,Park, Junyong,Lee, Seongsoo,Kim, Joungho IEEE 2018 IEEE transactions on components, packaging, and ma Vol.8 No.9

<P>In this paper, for the first time, we designed and analyzed channels between a graphic processing unit and memory in a silicon interposer for a 3-D stacked high bandwidth memory (HBM). We thoroughly analyzed and verified the electrical characteristics of the silicon interposer considering various design parameters, such as the channel width and space, redistribution layer via, and under bump metallurgy pads. In particular, we also considered the meshed ground planes used for the proposed transmission lines, which are microstrip and strip lines. Signal integrity (SI) of the proposed channels in the silicon interposer was successfully analyzed and verified using a full 3-D electromagnetic solver and circuit simulations. Based on the extracted lumped circuit resistance, inductance, conductance and capacitance parameters, we thoroughly analyzed the channel characteristics and identified the parameters that dominantly affect SI in relation to each frequency range. From the analyzed insertion loss and far end crosstalk, we verified SI of the silicon interposer by eye-diagram simulations in terms of eye-height voltage and timing jitter in the time domain. In the worst case, the eye-height voltage and timing jitter of the proposed microstrip lines are 0.911 V and 36.8 ps, respectively, with 72 mV of signal coupling. The eye-height voltage and timing jitter of the proposed strip line are 0.887 V and 42.1 ps with 34 mV of single couplings. We show that the proposed channels of the silicon interposer can successfully transfer data at a 2-Gb/s data rate. Finally, we propose concepts and solutions for the next-generation HBM interface with higher data rates up to 8 Gb/s.</P>

Glass-Interposer Electromagnetic Bandgap Structure With Defected Ground Plane for Broadband Suppression of Power/Ground Noise Coupling

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>

청소년 또래멘토링의 효과에 대한 질적 연구

김경준(Kim, Kyungjun),김지혜(Kim, Jihae),김영지(Kim, Younggi) 한국청소년정책연구원 2013 한국청소년연구 Vol.24 No.3

최근 우리 사회에서 청소년멘토링에 대한 관심과 참여가 확대되고 있으며, 특히 청소년들이 멘토로 참여하는 청소년 또래멘토링은 청소년 사회참여의 수단이자 청소년 자원봉사활동의 문제점을 극복할 수 있는 대안으로 새롭게 진행되고 있다. 이 연구의 목적은 청소년 또래멘토링 활동이 멘토와 멘티에게 미치는 효과와 효과에 영향을 미치는 요인을 확인하는 것이다. 이를 위해 2011년 2월부터 2012년 8월까지 청소년 또래멘토링 활동에 참여한 멘토 8명과 멘티 8명을 대상으로 심층면접을 진행하고 그 결과를 분석하였다. 연구 결과, 멘토링 활동을 통해 멘토는 책임감 향상과 성취감 경험, 정서적 친밀감, 진로와 학습에 도움 제공, 타인에 대한 배려와 이해 증가 등의 효과를, 멘티는 정서적 안정, 산만함과 공격성 감소, 집중력과 배려심 증가, 학습태도 향상, 역할모델, 대인관계 향상 등의 효과를 보였다. 멘토링 효과에 영향을 미치는 요인으로는 멘토와 멘티의 욕구에 기초한 결연과 재결연시스템, 멘토의 관계형성기술, 멘토의 성실성, 멘토링에 대한 멘토의 기대, 멘티교육, 코디네이터의 적절한 개입, 다양한 활동프로그램 및 활동 장소 등이 분석되었으며, 연구결과를 토대로 청소년 또래 멘토링 활성화 방안을 제시하였다. Youth peer mentoring is where students, at middle school, high school, and university levels, participate as mentors; and mentoring as described here is currently courting increased interest and participation. The object of this study was to identify the impact on mentors and mentees of youth peer mentoring respectively and to investigate and determine the factors which can lead to either the success or failure of mentoring programs. 16 mentors and mentees were interviewed and the interview data thus collected were analyzed to fulfill the above objectives. This research revealed that mentoring programs seemed effective for mentors in developing a sense of responsibility and a sense of achievement, in providing emotional stability and career and learning opportunities, and in recognizing the importance of consideration and understanding for others. They also proved helpful for mentees in providing emotional stability, improving concentration, nurturing consideration for others, and social relations, improving attitudes toward learning, but also tended to reduce incompactness and aggression. The factors which can lead to either the success or failure were matching and re-matching systems which are based on needs of mentors and mentees, the mentors’ human relationship skills, the mentors’ sincerity, the mentors’ expectations of the mentoring process, the level of education of the mentee, appropriate intervention programs for coordinators, various activity programs and spots. By way of conclusion, this study also proposed a number of alternatives for activating youth peer mentoring programs.

Signal Integrity Design and Analysis of Differential High-Speed Serial Links in Silicon Interposer With Through-Silicon Via

Cho, Kyungjun,Kim, Youngwoo,Lee, Hyunsuk,Song, Jinwook,Park, Junyong,Lee, Seongsoo,Kim, Subin,Park, Gapyeol,Son, Kyungjune,Kim, Joungho IEEE 2019 IEEE transactions on components, packaging, and ma Vol.9 No.1

<P>In this paper, we, for the first time, designed and analyzed differential high-speed serial links of the silicon interposer including differential through-silicon-via (TSV) channels for a high-bandwidth memory (HBM) graphic module. The meshed ground plane and various parameters were considered in designing the silicon interposer. In addition, superior designs were proposed to improve signal integrity (SI) for the differential channels in the redistribution layer, TSVs, and the meshed ground. SI of the silicon interposer was successfully analyzed, and the corresponding results were verified based on a full 3-D electromagnetic solver and circuit simulations. A number of RLGC parameters were extracted and calculated, then adopted to verify the simulation results. The simulation results for the differential characteristic impedance and insertion loss were compared with those of the equivalent circuit. A mixed-mode conversion matrix was utilized to analyze differential-mode transmission. Moreover, a model for differential TSV channels was proposed to precisely analyze the electrical characteristics. The eye-diagram simulation was conducted to evaluate SI of the proposed designs in terms of an eye-opening voltage and timing jitter. The eye-opening voltage of the proposed design was 0.594 V, which is 45.69% of a peak-to-peak voltage of the assumed peripheral component interconnect (PCI)-express 4.0 interfaces. It is expected that the analysis and design methodologies of differential high-speed serial links for a silicon interposer could be widely adopted in the semiconductor industry.</P>

High-Frequency Electrical Characterization of a New Coaxial Silicone Rubber Socket for High-Bandwidth and High-Density Package Test

Park, Junyong,Kim, Hyesoo,Kim, Jonghoon J.,Kim, Dong-Hyun,Son, Kyungjune,Kim, Subin,Lee, Seongsoo,Cho, Kyungjun,Bae, Bumhee,Ha, Dongho,Bae, Michael,Kim, Joungho IEEE 2018 IEEE transactions on components, packaging, and ma Vol.8 No.12

<P>This paper, for the first time, proposes and verifies a new coaxial silicone rubber socket for high-bandwidth and high-density package test using a fabricated sample. In addition, this paper also characterizes and verifies the coaxial silicone rubber socket. Because of the proposed coaxial socket’s novel coaxial structure, the proposed socket successfully achieves the electrical performance improvement. For verification, we compare the proposed socket and the previous noncoaxial socket in time domain. The proposed socket has greater eye height and eye width in the measured eye diagram than those of the noncoaxial socket. Moreover, the slope in the eye diagram is also improved in the case of the proposed socket. Therefore, the measured eye diagram for the coaxial socket shows the improvement in electrical performances. This paper also characterizes the equivalent RLGC model for the coaxial silicone rubber socket. In order to verify the RLGC model, we compare the insertion losses and eye diagrams from measurement, 3-D electromagnetic simulation, and the proposed RLGC model, respectively. Their insertion losses are comparable up to 20 GHz. Furthermore, the obtained eye diagrams are almost identical at the data rate of 9.6 Gb/s. In conclusion, this paper successfully proposes, verifies, and characterizes a new coaxial silicone rubber socket for the first time.</P>

Analysis of noise generation and electric conduction at grain boundaries in CVD-grown MoS₂ field effect transistors

Kim, Jae-Keun,Song, Younggul,Kim, Tae-Young,Cho, Kyungjune,Pak, Jinsu,Choi, Barbara Yuri,Shin, Jiwon,Chung, Seungjun,Lee, Takhee IOP Pub 2017 Nanotechnology Vol.28 No.47

<P>Grain boundaries in a chemical vapour deposition (CVD)-grown monolayer of MoS<SUB>2</SUB> induce significant effects on the electrical and low frequency noise characteristics of the MoS<SUB>2</SUB>. Here, we investigated the electrical properties and noise characteristics of MoS<SUB>2</SUB> field effect transistors (FETs) made with CVD-grown monolayer MoS<SUB>2</SUB>. The electrical and noise characteristics of MoS<SUB>2</SUB> FETs were analysed and compared for the MoS<SUB>2</SUB> channel layers with and without grain boundaries. The grain boundary in the CVD-grown MoS<SUB>2</SUB> FETs can be the dominant noise source, and dependence of the extracted Hooge parameters on the gate voltage indicated the domination of the correlated number-mobility fluctuation at the grain boundaries. The percolative noise characteristics of the single grain regions of MoS<SUB>2</SUB> were concealed by the noise generated at the grain boundary. This study can enhance understanding of the electrical transport hindrance and significant noise generation by trapped charges at grain boundaries of the CVD-grown MoS<SUB>2</SUB> devices.</P>

Self-Assembled Plasmonic Nanoparticles on Vertically Aligned Carbon Nanotube Electrodes via Thermal Evaporation

Kim, Youngmin,Lee, Seungjae,Lee, Kyungjun,Shim, Sangdeok,Kim, Jin Young,Lee, Hyung Woo,Choi, Dukhyun American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.22

<P>This study details the development of a large-area, three-dimensional (3D), plasmonic integrated electrode (PIE) system. Vertically aligned multiwalled carbon nanotube (VA-MWNT) electrodes are grown and populated with self-assembling silver nanoparticles via thermal evaporation. Due to the geometric and surface characteristics of VA-MWNTs, evaporated silver atoms form nanoparticles approximately 15–20 nm in diameter. The nanoparticles are well distributed on VA-MWNTs, with a 5–10 nm gap between particles. The size and gap of the self-assembled plasmonic nanoparticles is dependent upon both the length of the MWNT and the thickness of the evaporated silver. The wetting properties of water of the VA-MWNT electrodes change from hydrophilic (∼70°) to hydrophobic (∼120°) as a result of the evaporated silver. This effect is particularly pronounced on the VA-MWNT electrodes with a length of 1 μm, where the contact angle is altered from an initial 8° to 124°. Based on UV–visible spectroscopic analysis, plasmonic resonance of the PIE systems occurs at a wavelength of approximately 400 nm. The optical behavior was found to vary as a function of MWNT length, with the exception of MWNT with a length of 1 μm. Using our PIE systems, we were able to obtain clear surface-enhanced Raman scattering (SERS) spectra with a detection limit of ∼10 nM and an enhancement factor of ∼10<SUP>6</SUP>. This PIE system shows promise for use as a novel electrode system in next-generation optoelectronics such as photovoltaics, light-emitting diodes, and solar water splitting.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-22/am505999e/production/images/medium/am-2014-05999e_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am505999e'>ACS Electronic Supporting Info</A></P>

Transparent Large-Area MoS₂ Phototransistors with Inkjet-Printed Components on Flexible Platforms

Kim, Tae-Young,Ha, Jewook,Cho, Kyungjune,Pak, Jinsu,Seo, Jiseok,Park, Jongjang,Kim, Jae-Keun,Chung, Seungjun,Hong, Yongtaek,Lee, Takhee American Chemical Society 2017 ACS NANO Vol.11 No.10

<P>Two-dimensional (2D) transition-metaI dichalcogenides (TMDCs) have gained considerable attention as an emerging semiconductor due to their promising atomically thin film characteristics with good field-effect mobility and a tunable band gap energy. However, their electronic applications have been generally realized with conventional inorganic electrodes and dielectrics implemented using conventional photolithography or transferring processes that are not compatible with large-area and flexible device applications. To facilitate the advantages of 2D TMDCs in practical applications, strategies for realizing flexible and transparent 2D electronics using low-temperature, large-area, and low-cost processes should be developed. Motivated by this challenge, we report fully printed transparent chemical vapor deposition (CVD)-synthesized mono layer molybdenum disulfide (MoS2) phototransistor arrays on flexible polymer substrates. All the electronic components, including dielectric and electrodes, were directly deposited with mechanically tolerable organic materials by inkjet-printing technology onto transferred monolayer MoS2, and their annealing temperature of <180 degrees C allows the direct fabrication on commercial flexible substrates without additional assisted-structures. By integrating the soft organic components with ultrathin MoS2, the fully printed MoS2 phototransistors exhibit excellent transparency and mechanically stable operation.</P>

A method for guaranteeing highly reliable network service for a mobile application

Kyungjun Kim(김경준),Jin Man Kim(김진만) 한국통신학회 2017 한국통신학회 학술대회논문집 Vol.2017 No.1