bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using Graphene As a Conducting and Barrier Layer for Filling through Silicon Vias with Co-W Alloy
Authors: Chen Yi-Yong , Dow Wei-Ping , Chang Ping-He , Li Hong-Qing , Lin Jing-Yuan 
Published: February 2020

Usually, TSV fabrication is a dry process, including via formation by reactive ion etching, SiO2 isolation liner deposition, CVD or PVD TiN barrier layer and copper seed layer, and via filling with copper. Herein, we attempt to use graphene to simultaneously substitute the TiN barrier layer and the copper seed layer in order to simplify the TSV fabrication process. In addition, the coefficient of thermal expansion (CTE) of the filled copper often lead to failure in the TSV interconnects because the CTE of copper is much higher than that of silicon. The filled materials in the TSV with a high CTEs will induce large stresses at the interfaces between the filled material and silicon. To overcome this problem, we choose graphene to substitute the copper seed layer since the CTE of graphene is closer to that of silicon. Moreover, we select cobalt, which possesses not only a lower CTE but also a longer electromigration lifetime than those of copper, as the filled material of TSV. Tungsten can be co-deposited with cobalt, so that CoW alloy is formed in this work and the CTE of CoW alloy filled in TSV is lower than that of pure cobalt.
In this work, the effects of electroplating additives, electroplating baths and operating parameters on alloy composition, filling performance and thermal reliability performance of the electrodeposited CoW alloy from Co(NH2SO3)2•4H2O, NaWO4•2H2O, C6H8O7 and Na3C6H5O7•2H2O electrolyte are investigated. On the other hand, a linear sweep voltammetry (LSV) and galvanostatic measurements are carried out to electrochemically analyze these additives. The electrochemical behaviors of these electroplating additives are explored to explain the correlation between the suppression and the corresponding filling performance. The results indicate that the combination of suppressors with different molecular weights and a leveler can exhibit strong suppression and lead to CoW bottom-up filling of TSV.
A Cocoon-Shaped Copper Plating Filling Technique for through Hole Metallization
Authors: Mai Jhih-Jyun , Wen Shih-I , Dow Wei-Ping 
Published: February 2020

Recently, with the electronic products tending to be light, multifunctional and a high speed transmission, the IC substrates and printed circuit boards (PCBs) must increase circuit density and be able to accommodate a lot of elements in a single device. In order to accommodate more elements in a single device, the circuit density of PCB and IC substrate have to decrease line width and distance between conducting lines, but their overall thickness must be thinner than before. It means that the conducting via or through-hole (TH) will be small and a thin surface copper layer is necessary.
In this work, we developed a copper plating formula composed of several additives to perform TH filling of an IC substrate. The results show that the copper plating formula can perform a highly selective TH filling. Copper was mainly plated in the TH and a thin surface copper layer was obtained outside the TH. The plated copper shape in the TH looks like a cocoon according to its cross-section, which can solve the dimple issue of current TH filling technology, even it can be used as copper bump for copper-to-copper connection.
Keywords: Through-hole filling, Printed circuit board, IC substrate, Copper Plating, Cocoon

Reference

W. P. Dow, H. H. Chen, M. Y. Yen, W. H. Chen, K. H. Hsu, P. Y. Chuang, H. Ishizuka, N. Sakagawa, R. Kimizuka, “Through-Hole Filling

by Copper Electroplating”, Journal of The Electrochemical Society, 2008, 155, D750-D757.
Electromigration Effects upon Cu/Ni/Sn-Ag and Cu/Ni/Sn-Ag-Cu Interfacial Reactions
Authors: Chen Sinn-wen , Chen Jing-wei , Lin Yi-cheng , Chang Tao-chih 
Published: February 2020

Electromigration refers to the motion of atoms under the influence of an electric field. The electromigration effect most often is a result of momentum transfer from electrons, but it can be also caused by electrostatic force. The electromigration effect was discovered by Gerardin in 1861 [1]. The electromigration effect upon interfacial reactions and the resulted polarity phenomenon were first reported by Chen et al. [2,3], although electromigration effect upon the microstructures of a conduction line, such as void and whisker formation, had been intensively investigated much earlier. Understanding of electromigration effects upon interfacial reactions have become even more important nowadays because of thinner conduction lines, more interconnection joints, and higher electric current densities in the modern electronic products, such as products of 3D packaging. The interfacial reactions with and without passage of electric currents in the Sn-Ag/Ni/Sn-Ag, Sn-Ag/Ni/Cu/Ni/ Sn-Ag, Sn-Ag-Cu/Ni/Sn-Ag-Cu and Sn-Ag-Cu/Ni/Cu/Ni/Sn-Ag-Cu sandwich-type samples were examined at 150, 180 and 200oC. The main focus of this study is to understand the possible effects of Cu diffusion upon the Ni/Sn-Ag and Ni/Sn-Ag-Cu interfacial reactions. Two types of substrates were used, and they were 500mm-thick Ni foil and 500 mm-thick Cu foil plated with 50 mm-thick Ni. Two kinds of electricity-bias were conducted. One kind was with DC current and the other kind was with DC current but reversing the direction in the middle of the reaction time. Cu6Sn5 and Ni3Sn4 are observed in the couples with Sn-Ag-Cu solder. Electromigration effects are significant, but no Cu diffusion effects upon the solder/Ni reactions are observed.
[1] H. B. Huntington in “Diffusion in solids: recent developments”, edited by A. S.Nowich and J. J. Burton, Academic Press, New York, pp. 303-352, (1975).
[2] C.-M. Chen and S.-W. Chen, 1999, “Electric Current Effects Upon the Sn/Ag Interfacial Reactions”, Journal of Electronic Materials, Vol. 28(7), pp. 902-906.
[3] S.-W. Chen, C.-M. Chen, and W.-C. Liu, 1998, "The Electric Current Effects Upon the Sn\Cu and Sn\Ni Interfacial Reactions", Journal of Electronic Materials, Vol. 27(11), pp. 1193-1198.
Investigation of Mechanical Stress Distribution in Flexible Microelectronic System Under Bending Force By Finite Element Analysis
Authors: Seo Seung-ho , Lee Jea-Hak , Song Jun-Yeob , Lee Won-Jun 
Published: February 2020

The emerging demand on flexible microelectronic systems, such as wearable devices, flexible displays, biomedical and heathcare devices, leads to a continuous reduction of the chip thickness. The ultra-thin chips embedded in a flexible substrate would be deformed or fractured by repeated bending, stretching, or twisting under externally applied mechanical stress. Also, the carrier mobilities in the silicon die depend on mechanical stress during operation, resulting in malfunction of the circuitry. To solve these issues of mechanical and electrical reliability, the device layer of flexible system must be located at the “neutral line”, where the mechanical stress is zero. The mechanical stress of package system in rigid substrates was studied extensively, however, the mechanical stress distribution and the position of neutral line of package system in flexible substrates were rarely reported.
In the present work, we investigated the mechanical stress distribution in flexible microelectronic system under bending force by finite element analysis (FEA). Both the face-down packaging system using flip-chip bonding process and the face-up packaging system using wire bonding process were considered. Three-dimensional finite element models were constructed using different design parameters, and the static analysis was performed assuming elastic deformations of materials. The stress distribution of each component in the packaging systems, the position of the maximum stress and the neutral line were investigated. The effects of design parameters on the position of the neutral line position and the maximum value of von Mises stress were also discussed.
ACKNOWLEDGMENT: This research was supported by “Development of Interconnection System and Process for Flexible Three Dimensional Heterogeneous Devices” funded by MOTIE (Ministry of Trade, Industry and Energy) in Korea
Figure 1. The effect of the silicon die thickness on the mechanical stress distribution of the multilayered structure of silicon die/adhesive/polyimide substrate.

Figure 1
Surface Modification of Lithium Rich NMC for High Rate Lithium Ion Batteries
Authors: Ahn Juhyeon , OH Sihyoung , Kim Jong Hak , Cho Byung Won , Chung Kyung Yun 
Published: February 2020

Recently, lithium manganese-rich layered oxides like Li1+xM1-xO2 (M = Ni, Mn, Co) have been extensively scrutinized as one of the most promising cathode materials for the next-generation lithium rechargeable batteries primarily due to their high reversible capacity over 250 mAh/g. These materials are targeted to be potentially utilized in such mid- and/or large- scale applications as electric vehicles (EV) and commercial electricity storage systems (ESS). However, recent studies show that they exhibit a poor electrochemical performance at high power rate and suffer from structural instability in long-term cycling. During the repeated charge and discharge, severe cation mixing and segregations are reported to occur, which causes a series of phase transitions from layered to a defect spinel, and eventually to a rock-salt structure. This phenomenon deteriorates the high-rate performance significantly because it tends to block the diffusion channels for Li+ ions. Herein, we developed a novel surface-modified lithium manganese-rich layered oxide, which shows a substantial improvement in the high-rate performance and long-term cycle life stability. A thin nano-scaled zirconium-doped surface layer was formed on Li1.2Ni0.13Co0.13Mn0.54O2 particle by using potassium nitrate as an additive to guide the crystal habit during the synthetic process. The addition of potassium nitrate is critical in promoting the preferential development of crystal facets open for the diffusion channel. By the low surface barrier driven by the facets growth, zirconium ions could easily enter the lithium octahedral sites within the structure. The Zr-doped surface layer is formed possibly having a cation-disordered rock-salt structure of a few nano-meter scales. This thin surface layer is believed to prevent the adverse phase transitions and cation segregations as well as to shorten the diffusion path for Li+ion within the particle. As a result, the high rate performances are significantly enhanced; a specific capacity at 30 C-rate is observed to be as high as 110 mAh/g and stable performance was obtained for 300 cycles.
Figure. Zr-doped Li1.2Ni0.13Co0.13Mn0.54O2 nanoparticles (a) SEM image, (b) EDS mapping image of Zr-doped surface, (c) Z-contrast STEM-HADDF image taken along the [100] zone axis.
This work is supported by the National Research Foundation of Korea (NRF-2011-0030539).

Figure 1
Three-Dimensional Porous LiFePO4 Cathode Composite Decorated By Nitrogen-Doped Graphene Aerogel for Ultrafast Lithium Storage
Authors: Wang Bo , Liu Tiefeng , Liu Guijing , Wang Lei , Wang Dianlong , Zhao Xiusong 
Published: February 2020

Being a candidate of Lithium-ion batteries (LIBs) cathode material, olivine structured LiFePO4 (LFP) has various advantages, however, the major problems associated with LFP still lie in the fact of its poor electric conductivity and low Li+ diffusivity along the [010] direction only[1-2]. Based on this viewpoint, we wrapped (010) facet orientated LFP nanoplatelets (LFP NPs) with N-doped graphene aerogel (N-GA) to prepare a porous N-GA modified LFP composite (LFP@N-GA) through a facile electrostatic attraction treatment combined with a self-assembly process. In such a composite as shown in Figure. 1a-1i, LFP NPs are well surrounded by a N-GA constructed bicontinuous conductive network, which effectively facilitate both Li+and electron transport, and thus, effectively reducing the polarization[3-4].
Electrochemical test results demonstrated that the LFP@N-GA composite electrode indeed exhibited a ultrahigh rate capability (78 mAh·g−1at 100 C) and a stable cyclability (90% capacity retention over 1000 cycles at 10 C), as shown in Figure. 1j and 1k[5-6]. Such a LFP@N-GA cathode material may advance the development of high-power LIB for EVs and HEVs, and the preparation method is independent from the morphology and the synthesis process of the electrochemically active material, and therefore, compatible with many other energy-storage materials for different applications.

Figure 1.Characterization and electrochemical performance of LFP@N-GA composite: (a, b) SEM images at different magnification. (c-h) TEM and HRTEM images. Inset of d: FFT pattern of the HRTEM image, where B denotes the beam direction, indicating the (010) facet orientation. (i) HAADF-STEM image and elemental mapping results of LFP@N-GA. (j) and (k) Rate and cycling performance.

Reference
：

[1]Padhi A. K., Nanjundaswamy K. S., et al., J. Electrochem. Soc., 1997, 144, 1188-1194.
[2]Wang B., Xu B., et al., Nanoscale, 2014, 6 (2): 986-995.
[3]Wang B., Wang Q., et al., RSC Adv., 2013, 3 (43): 20024-20033.
[4]Wang B., Wang S., et al., Mater. Lett., 2014, 118: 137-141.
[5]Wang B., Al A. W., et al., Energy Environ. Sci., 2015, 8 (3): 869-875.
[6]Wang, B.; Wang D., et al., J. Mater. Chem. A, 2013, 1 (1): 135-144.

Figure 1
Very-Low Solid-Electrolyte/Electrode Interface Resistance in Li(Ni0.5Mn1.5)O4-Based Thin-Film Lithium Battery
Authors: Shiraki Susumu , Kawasoko Hideyuki , Suzuki Tohru , Shimizu Ryota , Hitosugi Taro 
Published: February 2020

All-solid-state lithium batteries with improved safety and larger capacity have been anticipated as a next-generation rechargeable battery. In particular, 5 V-class cathode material, LiNi0.5Mn1.5O4 (LNMO), has received considerable attention for the expected high power density. In all-solid-state LBs using LNMO, however, high interface resistance between an electrode and electrolyte hinders high power density. Thus, the reduction of the interface resistance and the investigation of the origins are of important issues. Recent progress in thin-film deposition techniques of electrodes and electrolytes has made it possible to fabricate all-solid-state thin film batteries with atomically controlled interfaces, and quantitative studies of the interface resistance values have been reported. In this study, we fabricated all-solid-state thin-film lithium batteries using LNMO epitaxial thin films and Li3PO4 solid electrolyte, and demonstrated a very low Li3PO4/LNMO interface resistance.
Figure 1 shows a structure of all-solid-state thin films battery (inset), and its charge and discharge curves. The fabricated thin film batteries consisted of an epitaxial cathode LNMO(100) film, an amorphous solid-electrolyte Li3PO4 film, a metallic anode Li film, a current collector LaNiO3(100) film, and Nb-doped SrTiO3(100) substrate. To ensure a clean Li3PO4/LNMO interface in the thin films batteries, the ultrahigh vacuum chambers used for the film depositions and characterizations were all directly connected each other. The LNMO thin-film battery exhibits good battery performance. The charge and discharge curves show redox reactions of LNMO (Ni2+/Ni4+ and Mn3+/Mn4+), and the capacity did not degrade even up to the 100th cycle.
We also evaluated the interface resistance using impedance spectroscopy, and found a very low interface resistance of ~5 Ωcm2. A Nyquist plot (Fig. 2) displays one semicircle at a higher frequency region (104~106 Hz), originating from the resistance of Li3PO4 (5×10-7 S/cm). In addition, a smaller semicircle at a lower frequency region (102~104 Hz) is attributed to the interface resistance at the Li3PO4/LNMO interface. The very low interface resistance of ~5 Ωcm2 is one order of magnitude smaller than those reported before, and implies that space charge layer formed at the Li3PO4/LNMO interface hardly results in high interface resistance.
This study was supported by NEDO, JST-ALCA, JST-CREST, and Kakenhi. The authors also acknowledge the support of Toyota Motor Corporation.
[1] S. Shiraki, H. Oki, Y. Takagi, T. Suzuki, A. Kumatani, R. Shimizu, M. Haruta, T. Ohsawa, Y. Sato, Y. Ikuhara, T. Hitosugi, J. Power Sources 267 (2014) 881-887.
[2] M. Haruta, S. Shiraki, T. Suzuki, A. Kumatani, T. Ohsawa, Y. Takagi, R. Shimizu, and T. Hitosugi, Nano Lett. 15 (2015) 1498-1502.

Figure 1
What Makes Si Anode Stabilized: Correlation of Electrochemical Performances with Si Local Structural Tranformations
Authors: Ogata Ken , Han Sungsoo , Jeon Seongho 
Published: February 2020

Silicon is an alternative anode material for future energy storage devices because it delivers 10 times greater theoretical (>3579 mAh/g) specific capacity than that of a traditional graphite anode (>370 mAh/g). However, Si-based anode materials face significant challenges due to its large volume expansion (~270-300%) upon lithium insertion. This large volume change causes cracking and pulverization of silicon, which leads to loss in electrical contact and drastic capacity fading. In addition, a continuous growth of solid electrolyte interphase (SEI) due to Si cracking causes low Coulombic efficiency, higher resistance to electronic/ionic transport. This will eventually deplete Li resevoir and limit the anode capacity.
To address this challenge, various strategies have been explored through nanostructured material design such as nano/micro-sized Si powders, nano-Si composites, Si nanowires/nanotubes, core-shell type nano/micron Si anodes.1 Despite the significant advances in Si anodes, there still remains critical challenges to overcome, one of the most basic which is poor Coulombic efficiencies (CEs) that unfortunately often remain to be examined.
Here we studied multiple factors that can lead higher CEs in both half and full cells. We link such electrochemical performance to Si structural transformations in long-term cycles, being probed via a variety of atomistic-level short/long range techniques, such as ex situ nuclear magnetic resonance (NMR),2
ex situ x-ray diffraction (XRD), 3
ex situ X-ray absorption fine structure (XAFS), and ex situ transmission electron microscopy (TEM). The detail will be presented at the conference.

References

1. Obrovac, M. N. & Krause, L. J. Journal of the Electrochemical Society
154, A103-A108, (2007)
2. Ogata, K. et al.
Nat Commun
5, 3217 (2014).

3. Li, J. & Dahn, J. R. Journal of the Electrochemical Society
154, A156-A161, doi:Doi 10.1149/1.2409862 (2007).
Realizing 200mAh g-1 Lithium Manganese Oxide Spinel in Lithium Ion Battery with Prelithiated Anode
Authors: Noh Hyun Kuk , Jeon Yu Ju , Song Hyun-Kon 
Published: February 2020

At present, the global market size of Li ion battery is dramatically increasing as its application in large scale system such as electric vehicle (EV) and energy storage system (ESS) expands intensely. Accordingly, the development of high-energy-density battery for their application is urgently needed. Today, energy density of Li ion battery largely depends on the specific capacity of cathode active material. The specific practical capacity of conventional cathode active materials such as LMO (Lithium Manganese Oxide Spinel, 4V region), LNMC (Lithium Nickel Manganese Cobalt Layered Oxide), and LFP (Lithium Iron Phosphate Olivine) is 100-170 mAh/g and the utilization of cathode active materials of even higher specific capacity is essential for the development of high-energy-density battery.
Cathode active materials such as sulfur, oxygen, LMO (3+4V region) have theoretically very high specific capacity (270 – 3800 mAh/g), however, cannot be adopted in today’s Li ion battery industry because in their structure they do not possess lithium which is vital for electrochemical reaction in Li ion battery. To utilize these non-lithiated cathode active materials, additional lithium must be provided to the cell. Li half-cell where Li-foil is used as the anode in the cell could be a candidate, however, the Li dendrite growth problem which might lead to battery explosion should be precedently solved for practical application. More desirable and rather easily applicable solution is the prelithiation strategy in which anode or cathode is chemically lithiated (via lithium intercalation or alloying) by short-circuit reaction between the electrode and lithium source such as lithium foil, gas or powder. The prelithiation of anode is preferred because the cathode prelithiation might yield safety problem with excessive generation of heat of reaction.
In this study, we propose an elegant prelithiation mechanism in graphite anode based on the results of electrochemical reaction and physico-chemical analyses. We demonstrate the prelithiation methodology that is directly applicable in practice with high prelithiation yield (efficiency) by controlling the relevant important variables. We also show that the developed prelithiation methodology can be applied for designing and operating full cell battery in which non- (or partially) lithiated LMO is adopted as cathode active material, which delivers ~200 mAh/g in 3+4V region with good cycle capability.
New Lithium-Excess High-Capacity Positive Electrode Materials with Mo3+/Mo6+ three-Electron Redox
Authors: Hoshino Satoshi , Ichikawa Shinnosuke , Ozaki Tetsuya , Inamasu Tokuo , Yabuuchi Naoaki 
Published: February 2020

The demand for the increase in energy density of lithium batteries are steadily growing. The use of three-electron redox of transition metals is expected to be a plausible strategy to further increase the energy density of positive electrode materials with less transition metal ions. Historically, three-electron redox reaction of transition metals is reported only for Cr3+/Cr6+, e.g., Li1.2Cr0.4Mn0.4O2.[1] In this study, the reaction of Mo3+/Mo6+ is targeted as electrode materials. Since conventional layered system, LiMo3+O2, has one mole of Li in the formula unit, only one-electron redox of Mo3+/Mo4+ is used. Therefore, Mo3+ is diluted in lithium-excess oxide, Li3NbO4 [2] as the model material, according to the chemical formula of x LiMoO2 – (1 – x) Li3NbO4 binary system. The highest reversible capacity based on Mo3+/Mo6+ is expected with x = 0.6 (Li9/7Nb2/7Mo3/7O2) in this binary system.
Our trials to synthesize Li9/7Nb2/7Mo3/7O2 were, however, failed by conventional solid-state reaction. Mixtures of LiMoO2 and Li3NbO4 were obtained regardless of different synthesis conditions. Therefore, Li9/7Nb2/7Mo3/7O2 was prepared by mechanochemical route from LiMoO2 and Li3NbO4 as precursors. A mixture of LiMoO2 and Li3NbO4 was mechanically ball-milled at room temperature with a ZrO2 container and balls. XRD patterns of LiMoO2, Li3NbO4, and Li9/7Nb2/7Mo3/7O2 prepared by ball-milling are compared in Figure 1a. An X-ray diffraction pattern of Li9/7Nb2/7Mo3/7O2 is assigned to a cation disordered rocksalt structure with low crystallinity. Electrochemical properties of Li9/7Nb2/7Mo3/7O2 before and after mechanical-milling were examined in Li cells as shown in Figure 1b. The sample before mechanical-milling shows initial discharge capacity of ca. 80 mAh g-1, and a voltage profile is the same with LiMoO2. On the other hand, the sample after mechanical-milling delivers a reversible capacity of ca. 290 mAh g-1, which nearly corresponds to that of theoretical capacity based on the redox reaction of Mo3+/Mo6+. Moreover, three-electron redox of Mo is supported by X-ray absorption spectroscopy without the contribution of Nb for charge compensation.
From these results, we will discuss the possibility of a new series of high-capacity positive electrode materials with three-electron redox of Mo3+/Mo6+ for rechargeable lithium batteries.

References
[1] B. Ammundsen et al., Journal of The Electrochemical Society, 149, A431 (2002).
[2] N Yabuuchi et al., Proceedings of the National Academy of Sciences, 112, 7650 (2015).

Figures

Figure 1