bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potential CCP Pulsed Plasma Application at Beol AIO Etch Process
Authors: Zhang Cheng-Long , He Qi-Yang , Zhang Hai-Yang 
Published: February 2020

Plasma etching has been extensively used for more than 30 years in semiconductor manufacturing industry [1]. Typically, plasma reactor RF power sources have constant average power to excite the plasma in a vacuum chamber. Such mode of operation is termed as continuous-wave (CW) RF mode [2]. As COMS is being scaled down to 28nm node and beyond, CW plasmas etching processes are reaching their limits to satisfy the multiply stringent requirements, such as better uniformity, higher selectivity, less plasma induced damage, tighter critical dimension and profile control.
The RF pulsed plasma is one of promising knobs to increase the flexibility of plasma processing by enlarging the range of operating conditions [3-5]. There are two main parameters characterizing the RF pulse: one is the pulsed frequency at which the RF power is turned on and off per second; the other is the pulse duty cycle, which is defined as the ratio between the pulse on time and the total pulse duration. As the multiple-frequency RF powers have been introduced for the better control plasma flux and energy in CCP system, the effect of different RF power pulsing varies, bias only, source only and synchronized pulsed plasmas also shows quite different performances.
In this work, self-aligned via (SAV) based all-in-one (AIO) etch processes were performed in one commercial etcher, and the effects of pulsed plasmas on the etch process were analyzed. The different pulsed mode, pulsed duty cycle, pulsed frequency on CCP chamber were tested on the SAV based AIO etching process in BEOL copper interconnect system. We compared the bias only, source only and synchronized pulsed plasma performances, checked the duty cycle effects, which varies from 10% to 90%. The Physical performances were analyzed by CDSEM, SEM, TEM, and TK. Compared with conventional CW plasmas, the performances of AIO etching process could be significantly improved via pulsed plasma, such as more rounding chamfer profile, via bottom CD control, and better SAC process with higher selectivity to metal hard mask.
Acknowledgement
This work is sponsored by Shanghai Rising-Star Program (B type).
REFERENCES
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[2] S. Banna, A. Agarwal, K. Tokashiki, H. Cho, S. Rauf, V. Todorow, K. Ramaswamy, K. Collins, P. Stout, J. Y. Lee, J. Yoon, K. Shin, S. J. Choi, H. S. Cho, H. J. Kim, C. H. Lee, and D. Lymberopoulos. IEEE Trans. Plasma Sci., vol. 37, 2009, pp. 1730-1746.
[3] R. W. Boswell and D. Henry. Appl. Phys. Lett., vol. 47, 1985, pp. 1095-1097.
[4] P. Subramonium and M. J. Kushner. Appl. Phys. Lett., vol. 79, 2001, pp. 2145-2147.
[5] A. Rousseau, E. Teboul, N. Lang, M. Hannemann, and J. Ropcke. J. Appl. Phys., vol. 92, 2002, pp. 3463-3471.
Effects of Additives on Ag Nanoparticles Catalyzed Electroless Copper Deposition Using Glyoxylic Acid As a Reducing Agent
Authors: Chang Yu-Chen , Chou Shih-Cheng , Wu Pu-Wei , Chen Po-Chun , Huang Meng-Chi , Wang Yu-Ming , Hsueh Chang-Jung 
Published: February 2020

By using nanoparticulate Ag as the activator to replace Pd, glyoxylic acid to replace formaldehyde as the reducing agent, 2,2’–bipyridine, K4Fe(CN)6, PEG-2000, Ascorbic acid, and Bis-(3-sodiumsulfopropyl disulfide) (SPS) as additives, we develop a Cu electroless plating bath to deposit Cu on activated polyimide substrates for flexible electronic devices. Polarization curves are recorded to elucidate the effect of additives over anodic behaviors of glyoxylic acid on activated substrates. Cyclic voltammetric measurements are carried out to clarify the responses of additives on both anodic and cathodic reactions occurring during electroless Cu deposition. SEM is used for observing the morphology of Cu deposition on Ag nanoparticle catalyzed polyimide substrates. XRD is adopted to determine the crystalline structure of Cu deposit. The quality of Cu deposit is inferred from electrical resistivity measurements. We demonstrate an optimized formula for relatively smooth Cu film with strong adhesion to the substrate.
in Situ Transmission Electron Microscopy Studies on Silicon Anodes in Lithium Ion Batteries
Authors: Lee Hyun-Wook , Lee Seok Woo , Cui Yi 
Published: February 2020

Extensive research for new energy storage materials has created a high demand for experimental techniques that can provide real-time, single-particle-level information on the dynamic electrochemical processes taking place at the electrode materials during battery charge/discharge cycles. In situ transmission electron microscopy (TEM) on lithium ion batteries has been offered exceptional opportunities for monitoring the dynamic processes of electrode materials during electrochemical reaction at both spatial and temporal resolution.
In this talk, I will introduce in situ TEM studies on Si anodes which suffers the anomalous volumetric changes and fracture during lithiation process. Previously, the lithiation behaviour of a single Si particle has been explained in detail by simulation data and experimental observation. However, in real batteries, since lithiation occurs simultaneously in clusters of Si in a confined medium, understanding how the individual Si structures interact during lithiation in a closed space is necessary. In this regard, I demonstrated physical and mechanical interactions of swelling Si structures during lithiation using well-defined Si nanopillar pairs. Ex situ SEM and in situ TEM studies reveal that compressive stresses change the reaction kinetics so that preferential lithiation occurs on free surfaces when the pillars are mechanically clamped. Such mechanical interactions enhance the fracture resistance of lithiated Si by lessening the tensile stress concentrations in Si structures. This experiment reveals the surprising effects of nanostructure shape, size, and void space for lithiation and the results will contribute to improved design of Si structures at the electrode level for high-performance Li-ion batteries.
(Invited) In-Situ Spectroscopic Observation of Lithium Sulfur Batteries upon Cycling
Authors: Hwang Bing Joe , Tsai Mon-Che , Lee Felix , Lin Ming-Hsien , Cheng Ju-Hsiang , Su Wei-Nien , Huang Chen-Jui , Partovi-Azar Pouya , Kaghazchi Payam 
Published: February 2020

Sulfur, with its a high theoretical specific capacity (1675 mAh/g), is an abundant, low cost, and environmentally friendly element that has been extensively studied as a promising electrode material for rechargeable lithium batteries. However, low sulfur utilization and a poor cycle life are among the issues limiting its commercialization. Several of these issues are related to the electronically insulating nature of elemental sulfur and the dissolution of the resulting lithium polysulfides (Li2Sn, 2 ≤ n ≤ 8) formed during the discharge process, especially in a battery comprising of liquid electrolytes. As a result, these polysulfide species readily diffuse to the anode side causing formation of a highly resistant layer on the lithium metal anode that leads to the reduction of Li+ ion mobility and rapid capacity fading during cycling. The interactions between the support and elemental sulfur/lithium polysulfides play an important role in sulfur utilization and cycling stability. To obtain a better understanding of the interactions, in situ Raman and X-ray absorption Spectroscopic techniques together with DFT computation were developed and employed in this work. The Raman peaks observed were assigned successfully by the conjunction with the computational and experimental approaches. The results based on the spectroscopic characterization of the different components reveal that the undesired shuttle mechanism causing the passivation of Li anode can be suppressed due to the preferential interaction between elemental sulfur/lithium polysulfides with the designed supports or polymer electrolytes. This work has opened a new path towards the development of new supports and polymer electrolytes for lithium sulfur battery applications.
(Invited) To Understand Local Structure Evolution and Ion Dynamics of the Electrode/Electrolyte Materials Combined with Different Spectroscopic Techniques
Authors: Yang Yong 
Published: February 2020

Li-ion battery has become the most important energy systems for portable electronics, power tools and automobile applications such as hybrid and plug-in electric vehicles. However, it is still necessary to enhance their electrochemical performance such as energy density and cycle life, for promoting their competition capability as vehicle power system. Obviously, electrode materials, especially positive electrode materials either working voltage or reversible capacity determine the energy density of the Li-ion batteries at mostly[1,2].
In the presentation, some recent work about in-situ or ex-situ characterization of local structural evolution and Li-ion dynamics of new electrode/electrolyte materials combined with different techniques, such as synchtron X-ray diffraction, X-ray absorption spectroscopy (XAS), neutron diffraction, High-resolution transmision microscopy and solid state NMR techniques. The investigated electrode/electrolyte systems include Ti-doped LiMn2O4, FeF3, Na3V2(PO4)2F3
, Zn2+-doped P2- Na0.66Ni0.33Mn0.67O2and Garnet-type electrolytes.
Acknowledgement: Financial support from National Natural Science Foundation of China ( Grant No. 21233004, 21473148, 21428303) are gratefully acknowledged

References

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X. H. Wu, et al, to be submitted

D. W. Wang, et al Chem. Mater.; 2015, 27, 6650−6659
Layer Number Dependence of Li+ Intercalation on Few-Layer Graphene and Electrochemical Imaging of Its Solid-Electrolyte Interphase Evolution
Authors: Hui Jingshu , Burgess Mark , Zhang Jiarui , Rodríguez-López Joaquín 
Published: February 2020

Bulk and surface electrochemical reactivity converge on ultrathin electrochemical interfaces such as few-layer graphene (FLG). In spite of the many recent works regarding the use of exfoliated graphene materials for charge storage, we still lack a detailed mechanistic understanding of how Li+ intercalates in FLG. Li+ intercalation in graphitic carbon is known to proceed through a staging mechanism, where intercalation occurs at selected interlayers at a time, rather than randomly on any available empty interlayer galleries, until reaching the nominal composition LiC6. Thus, on graphite this process is strongly dependent on the number of neighboring empty galleries at any given time. FLG naturally displays a limited number of galleries, therefore, we hypothesize that this process will also necessarily be distributed unevenly.
In this study, we applied FLG (1-10 layers) to explore the alkaline ion uptake mechanisms. Chemical vapor deposition methods with varies recipes were applied to grow double and multilayer graphene. By multicycle wet transfer of bilayer graphene, 2-8 layer graphene with well-defined area and low defect density. Direct growth of multilayer graphene (>10 layers) serves as control group. Photolithography method was used to generate micro patterns on graphene as “point of entry” for Li+intercalation.
Lithium ion intercalation on FLG, as measured via cyclic voltammetry, shows a staging-type process, which has strong dependence on the number of layers of graphene sheets that compose the electrode. On a graphene electrode with less than five layers, the numbers of intercalation/de-intercalation peaks were limited due to the lack of graphene interlayer galleries to stabilize Li ions. Those peaks broaden and increase in number as the layer number increases to six. Despite these mechanistic differences on ion intercalation, the formation of a solid-electrolyte interphase (SEI) was observed on all electrodes. Scanning electrochemical microscopy (SECM) in the feedback mode was used to demonstrate spatial resolved changes in the surface conductivity of FLG during SEI evolution. The fabrication of “ionic channels” on the FLG electrode provided preferential positions for Li ion insertion. The role of these channels can be evidenced using a Li-ion sensitive SECM imaging technique through localized flux measurements. This work highlights the impact of nano-structure and micro-structure on macroscopic electrochemical behavior and provides guidance to the mechanistic control of ion intercalation using atomically thin graphene interface.

Figure 1
Liquid Phase Scanning Electron Microscopy: A New Approach to Investigate Lithium Dendrite Formation in Liquid Electrolytes
Authors: Zhang Yuegang 
Published: February 2020

Scanning electron microscopy (SEM) is a widely used tool for investigating the surface morphology of materials with a reasonable spatial resolution. Comparing with the high-resolution transmission electron microscopy (TEM), the beam-induced damage is much less in a SEM. With a proper scan rate, some relatively slow dynamic process, such as the lithium dendrite growth, can be observed in real time using a SEM. To mimic the real environment of a lithium battery, we designed a micro-liquid-electrochemical cell in which organic electrolytes could be introduced. We investigated the lithium deposition and dissolution processes in such a cell using electrolytes with different additives, and studied their effects on suppressing dendrite growth during lithium deposition. The results should shed light on developing more stable batteries using lithium metal as the anode material.
Investigation of Interfacial Phenomena of High-Voltage Li-Ion Battery with Li-Rich Layered Oxide Cathode
Authors: Pham Hieu Quang , Kwon Young-Gil , Hwang Eui-Hyung , Song Seung-Wan 
Published: February 2020

Enabling the high energy density Li-ion batteries requires the use of high-capacity cathode material such as Li-rich layered oxide cathode (xLi2MnO3·(1-x)LiMO2 (M=Mn,Ni,Co)) that can be charged to high-voltage above 4.5 V vs. Li/Li+. A critical limiting factor for high-voltage battery operation is however the anodic and thermal instability of conventional electrolyte, which causes rapid performance fade and safety issue, in particular, at elevated temperatures. Our recent research results have shown that the use of functional additives enables the cell operation in such harsh conditions. Spectroscopic surface analysis data indicated that structural degradation of both Li-rich layered oxide cathode and graphite anode materials and instability of surface film at cathode during cycling in the conventional electrolyte were the main reasons for the rise of interfacial resistance and performance fade. Nonetheless, those problems can be resolved through interfacial stabilization using appropriate electrolyte additives. In this presentation, we report the interfacial phenomena and high-energy performance of Li-rich layered oxide cathode under a harsh condition of high charge cut-off voltage above 4.6 V vs. Li/Li+. The mechanistic studies of surface film/solid electrolyte interphase (SEI) layer formation and composition of cathode and anode using ex situ ATR FTIR spectroscopy combined with X-ray photoelectron spectroscopy and scanning electron microscopy, and structural changes using Raman spectroscopy, and the correlation between interfacial phenomena and high-voltage cycling performance would be discussed.
In Situ Characterization of Gassing Processes in Lithium-Ion Batteries By Dems-Deirs
Authors: Berkes Balázs B. , Schiele Alexander , Michalak Barbara , Sommer Heino , Brezesinski Torsten , Janek Jürgen 
Published: February 2020

Gas evolution has a profound effect on the functioning of state of the art lithium-ion batteries. On the one hand, it is the natural concomitant of SEI formation; on the other hand, because of the demand for high terminal voltages, it is the consequence of electrolyte or electrode material oxidation. This happens on the expense of the efficiency. Furthermore, the presence of gases in the cell raises safety problems.
In general it is important to understand gas formation processes. First, to be able to develop novel electrolyte mixtures or tailor electrolyte additives that form a stable SEI. Second, to optimize the surface and/or structure of cathode materials to influence both their bulk oxidative properties upon delithiation and electrocatalytic activities. Differential electrochemical mass spectrometry (DEMS) is one of the most appropriate tools to qualitatively elucidate gas evolution reactions in electrochemical systems.
Herein, we report on the in situ gas analysis by means of differential electrochemical mass spectrometry and infrared spectroscopy (DEMS-DEIRS) of various battery systems. We analyze the SEI formation on different anode materials and the influence of various electrolyte additives. The impact of temperature and constant voltage/OCV periods on the first charge cycle (so-called formation process) is investigated. Their effect on both the gassing and electrolyte salt decomposition is described.
The stability problem of the most common electrolytes at high voltages is discussed through the example of either NMC (LiNixMnyCozO2) type materials or with high voltage spinels (LiNi0.5Mn1.5O4). The electrocatalytic activity of the individual active material particles seems to play a decisive role in the oxidative decomposition processes. Through the application of modified cathode surfaces a relation between surface activity and the amount of produced gases is revealed. Beyond the decomposition of the electrolyte, oxygen evolution is the crucial factor at high cathode potentials. This effect is particularly apparent for overlithiated and high Ni content materials. Monitoring gassing over 20 cycles uncovers interesting changes being only recognizable in “long term” tests. We demonstrate the importance of potentiodynamic cycling in addition to the traditional galvanostatic test with DEMS-DEIRS in the exploration of reaction mechanisms. Pressure measurements complete the analysis in terms of validation of gas amounts.
Direct Observation of Electrophoretic Flow of Solvent Molecules with Lithium Ions By NMR Imaging
Authors: Kawamura Junichi , Iwai Yoshiki , Endo Shotaro , Kuwata Naoaki , Takekawa Reiji , Ohzu Masato 
Published: February 2020

Lithium ion transport in the organic liquid electrolyte is a key process in conventional lithium ion batteries, where the lithium ion shuttles between the positive and negative electrodes while the charging and discharging process. The translational motion of the lithium ion in the liquid electrolyte is accompanied by the coordinating organic solvent molecules such as EC, DMC etc., which must be detached from the lithium ion at the electrodes by the desolvation process. On the other hand, the counter anions such as PF6
- is thought to move opposite direction, although the local concentration is the same to that of lithium cation in order to keep the electroneutrality condition.
Although this picture is based on many evidences by electrochemical measurements, the direct observation of the correlated motion of the lithium ions and solvated molecules has not been reported.
In this paper, we first demonstrate the direct observation of the translational motion of solvent molecules (EC,DEC) with the lithium ions by using NMR micro-imaging technique.
NMR microimaging is observed by Avance 400 spectrometer equipped with mini-Imaging probe by Bruker Co. The 1H and 19F NMR imaging are observed in this measurement. Model cell is constructed in NMR spectrometer, which is composed by LiMn2O4 cathode, lithium metal anode and liquid electrolyte of EC/DMC+LiPF6. The cell is connected to an electrochemical charge-discharge set-up to operate the cell. Small desolution of Mn2+ from the cathode acts as a contrast agent to enhance the flow image of the cell.
Some vertical images of the cell in a charge-discharge process are shown in Fig. 1, where the LiMn2O3 positive electrode is located at the bottom and the lithium metal anode is on the top. Constant current mode of 25 mA is used. While the charging current is set upward from LiMn2O3 cathode to the lithium anode, namely the Li+ cations move upward, then the proton NMR imaging observing the motion of the EC and DMC molecules is confirmed to upward, which is the same direction as that of the Li+ ions. Moreover, the flowing current of the solvent moves toward left and right directions near the lithium anode, where the EC and DMC should release the Li+ to the anode and move aside. This continuous flow generates an electroconvection which can be seen in Fig. 1 as a vortex curling from center to the side wall.
On the other hand, when the current is reversed to discharge, the flow of the solvent changes its direction from the top (anode) to the bottom (cathode), which generate the reverse vortex as shown in Fig. 1.

Figure 1
In-Situ Microfluidic Study with Kinetic-Monte Carlo Simulations to Investigate Zn Electroplating Morphology at High Overpotentials
Authors: Gupta Tanya , Davies Greg , Park Jeung Hun , Steingart Daniel A 
Published: February 2020

Despite the low cost and high energy density, use of Zinc anode in secondary batteries is limited due to the associated shape change of Zn during cycling. Vast literature on morphological studies of Zn in alkaline electrolyte indicates formation of varied structures ranging from mossy, to boulder-like and dendritic morphologies,1 primarily depending on the plating potential.
Recently, Zinc plating at extremely high overpotentials 2 is shown to form a highly porous, conductive, ramified foam like morphology, called Hyper Dendritic Zinc (HD Zn). HD Zn has been demonstrated to act as an efficient secondary anode, with improved cycle life and kinetics 3. The fine (~60 nm) needle-like crystallite core microstructure that forms the dendrite makes this morphology unique. An important distinguishing feature from the previously known morphologies is that it grows in conformal layers, giving it an appearance of dense branching morphology, but instead of DLA like motifs it has Dendritic motifs.
In this work, in-situ microfluidic studies coupled with Kinetic-Monte Carlo simulations are used to investigate plating and cycling behavior of HD Zn. While Monte Carlo simulations have been implemented in the past 4 to show growth of DLA like structures, we extend these to incorporate effect of crystal anisotropy in electrochemical systems. We hypothesize that growth at high overpotentials leads to the formation of a space charge region at the electrolyte/electrode interface due to high potential gradient. This space charge region is where migration becomes important. The migration length along with high concentration gradient built at the growth overpotentials gives rise to the HD Zn morphology.
1. Naybour, R. D. et al. Electrochimica Acta 13.4 (1968): 763-769.
2. M. Chamoun et al., NPG Asia Materials, 7, e178 (2015).
3. T. Gupta et al., J. Power Sources, 305, 22–29 (2016).
4. Erlebacher, J. et al. Physical review letters 71.20 (1993): 3311.