bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wafer Scale Cu Plating Process Optimization for Defectivity Improvement
Authors: Ahmed Shafaat , Huang Qiang , Cheng Tien , Findeis Paul , Gruszecki Craig R , Simon Andrew H , Mclaughlin Paul S , Lustig Naftali , Engbrecht Edward , Lakritz Mark N , Wang Pei I , Montgomery Christa L , Mittal Surbhi , Baumann Frieder H , Truong Connie-Nga , Baker-O'neal Brett C. , Grunow Sarah L , Chudzik Michael P , Grunow Stephan 
Published: February 2020

Defect-free copper damascene plating becomes more and more challenging as the BEOL interconnects continues to scale. In addition to the challenge from the small critical dimension, the thin liner/seed required for the overall resistance imposes even more challenges to the plating. The coverage of the Cu seed at the thickness used can be poor on the sidewalls of trenches and vias. The discontinuous Cu seed and the exposed or oxidized Ta liner are generally associated with the slit voids, cluster voids defects from plating. Furthermore, a non-optimized PVD etch back and re-sputtering process or its bias power could also cause a much localized variation of Cu-seed thickness along the side walls. When a trench side wall locally misses Cu seed void can easily form due to the lack of Cu nucleation during the entry and pulse step of plating, which is observed as slit hollow metal defect as being exposed after CMP. However, when the lack of Cu-seed occurs on both sidewalls of a trench a single line open hollow metal (shown below) defect is often observed, which we called HMS1 defects.
A typical PLY wafer map of HMS1 defect and its corresponding typical SEM review image (inset) is shown in Fig.1. Although this particular wafer shows the HMS1 defect signature spreading from 6:00-3:00 O’clock along the edge of the wafer, this defect signature can rotate 360 degree from wafer to wafer and/or lot to lot as shown by stacked map in Fig.1b. The stacked map also indicates that the density of HMS1 defects is high along the edge of the wafers at 6:00-3:00 O’clock position. Fig.2a-b shows a typical top down SEM images of HMS1 defect and its corresponding longitudinal cross-section TEM image respectively. Although the top surface shows the absence of the copper plating across the width of the line, its cross-sectional image confirms that copper was plated from the bottom of the trenches but stopped after the trench was partially filled. In this paper we will explain the mechanism of HMS1 defects formation and its modulation by co-optimization of Cu-seed process and plating entry condition. Detail failure analysis will also be presented to correlate the post plating defect with the localized absence of Cu-seed along the trench side wall where Cu did not nucleate during plating. The methodology in achieving a low defectivity on a wafer scale will be discussed.
Fig.1 (a) shows a HMS1 PLY defect map on a single wafer and (b) shows stacked map of this defect from 20 lots
Fig.2. (a) shows a typical top down HMS1 defect and (b) shows its corresponding x-section TEM image
Degradation of Electrode Materials in Vanadium Redox Flow Batteries
Authors: Pezeshki Alan , Sun Che-Nan , Zawodzinski Thomas A. , Mench Matthew M. 
Published: February 2020

Recent works in vanadium redox flow batteries (VRFBs) have been successful in improving the energy density by increasing vanadium solubility in the electrolyte1 and achieving high power density through electrode modification, membrane selection, and superior cell design 2,3. These accomplishments lead to significant reduction of the system cost and therefore enhance the economic attractiveness of VRFB technology.
To achieve market implementation, the large-scale energy storage system requires a balance between performance, cost, and durability. While power and energy densities have been recently improved, the investigation of component durability, which is equally important, has yet to be reported in significant detail.
In this work, we demonstrate an approach to study the electrode degradation in single-cell VRFBs.

Ex-situ electrolyte soaking experiments were used to determine conditions under which the electrodes degrade, and the extent of the degradation. Several techniques were adopted to characterize property changes in the degraded materials. Various carbon materials were investigated to determine viable candidates and characteristics required for long-term use in VRFB systems.
Additionally, in-situ cycling tests of various carbon materials have been carried out to illustrate the relationship between material degradation and cell performance decay. Declines in performance (Fig. 1) are monitored and correlated to changes in the material properties. Modification of the cycling parameters reveals operating conditions leading to the most severe decay in the carbon material, so that accelerated degradation protocols can be developed for evaluation of additional materials.

References

1. L. Li, S. Kim, W. Wang, M. Vijayakumar, Z. Nie, B. Chen, J. Zhang, G. Xia, J. Hu, G. Graff, J. Liu, Z. Yang, Adv. Energy Mater., 1, 394, (2011).
2. Q. H. Liu, G. M. Grim, A. B. Papandrew, A. Turhan, T. A. Zawodzinski, M. M. Mench, J. Electrochem. Soc.,
159, A1246, (2012).
3. D.S. Aaron, Q. Liu, Z. Tang, G.M. Grim, A.B. Papandrew, A. Turhan, T.A. Zawodzinski, M.M. Mench, J. Power Sources, 206, 450, (2012).
4. M. Zhang, M. Moore, J.S. Watzon, T.A. Zawodzinski, R.M. Counce, J. Electrochem. Soc., 159, A1183, (2012).
Laser-Perforated Carbon Paper Electrodes for High-Power Vanadium Redox Flow Batteries
Authors: Mayrhuber Immanuel , Dennison Christopher R , Kalra Vibha , Kumbur Emin Caglan 
Published: February 2020

Recently, there has been considerable effort to increase the power density and lower the cost of vanadium flow battery (VRFB) systems via new system architectures and optimized electrode materials. To date, research on electrodes has primarily focused on improving the surface area, surface chemistry, pore size distribution and resistivity of the material to improve the reaction kinetics, mass transport ability and the areal series resistance (ASR).While carbon felt materials have been conventionally used, the recent push for higher power densities has required the application of new electrode materials.
Carbon paper was proposed by Aaron et al. as high-performance VRFB electrode material [1]. This material has a reduced thickness and high active surface area, as compared to carbon felt, which reduces the ASR and overpotential, and significantly improves the current- and power density. In their study, the authors demonstrated a VRFB with a peak power of 557 mW cm-2 . Liu et al. further improved the performance of a VRFB with no-gap architecture by thermal pre-treatment of carbon paper electrodes in air [2]. The thermal treatment showed a 16% improvement in power density compared to the raw material.
Although carbon paper electrodes exhibit significantly higher power density than carbon felt electrodes, they have a significantly lower porosity and reduced pore size. As a result, mass transport is expected to be problematic in these materials. To address these limitations, we utilized a procedure similar to Manahan et al. [3] by introducing laser perforations to facilitate the transport of reactants within this type of electrodes. A CO2 laser was employed to cut different hole patterns in SGL 10AA carbon paper. Specifically, the hole diameter and hole density (number of holes per electrode) were varied in order to better understand the tradeoffs between improved mass transport and reduced surface area in these materials. It was found that a 30% improvement in power density (as compared to non-perforated electrode) was achieved through optimization of the perforation pattern. Interestingly, this condition corresponds to a loss of 15% of the original surface area due to laser perforation. The results of this study highlight the fact that by proper tailoring the transport pathways in the electrode structure, it is possible to achieve significantly higher power density with a low surface area electrode material.

References:

[1] D.S. Aaron, Q. Liu, Z. Tang, G.M. Grim, A.B. Papandrew, A. Turhan, T.A. Zawodzinski, M. M. Mench, Journal of Power Sources 206 (2012) 450-453.
[2] Q.H. Liu, G.M. Grim, A.B. Papandrew, A. Turhan, T.A. Zawodzinski, M.M. Mench, Journal of The Electrochemical Society 159 (2012) A1246-A1252.
[3] M.P. Manahan, M.C. Hatzell, E.C. Kumbur, M.M. Mench, Journal of Power Sources 196 (2011) 5573-5582.
Fundamental Properties of Organic Redox Couples for Aqueous Flow Batteries
Authors: Hoober-Burkhardt Lena , Yang Bo , Prakash G. K. Surya , Narayanan S. R. 
Published: February 2020

With penetration levels of renewable energy sources, such as wind and solar, nearing 33% in many places, large scale energy storage is desperately needed. Organic redox flow batteries (ORFB) are a promising solution, as they meet the demanding requirements for large-scale energy storage.1 They are environmentally friendly, easily scalable, highly efficient, and have low cost. Quinones are an excellent candidate for ORFB as they have a system cost of <$100/KWh and a charge capacity of 200-490 Ah/kg.
Organic molecules such as quinones are ideal for an aqueous redox flow battery system based not only on their fast kinetics, but also on their ability to be tuned for solubility and electrode potential. Addition of substituent groups affects not only solubility and electrode potential but also the kinetics and mechanism of the redox reactions. Electrochemical studies were undertaken to understand these effects. This understanding will be beneficial for the deployment of these organic reactions in an ORFB.
Electrochemical properties of various quinones in acidic media were studied in an electrochemical half-cell at a rotating disk electrode (Figure 1). Diffusion coefficients were found to be in the range of 10-6 – 10-7 cm2/sec, while rate constants were found to be in the range of 10-3-10-4 cm/sec (Figure 2,3). We have explored a range of quinones with different substituent groups to achieve the desired solubility and electrode potentials suitable for use in the full redox flow cell. We will present understanding of the relationship between the values of kinetic parameters and substituent group placement. Additionally, we have screened other water-soluble redox molecules such as quinoxalines and hydrazides. We will also present our current understanding of the electrochemistry of these compounds and their suitablity for redox flow batteries.

Acknowledgements

The work presented here was funded by ARPA-E and the Loker Hydrocarbon Institute of the University of Southern California.

Reference

1) Yang, B.; Hoober-Burkhardt, L.E. Prakash, G.K.; Narayanan, S.R. ECS Meeting, San Francisco, CA, USA, Oct 27-Nov 1, 2013
(Invited) Impurity Co-doping of Gallium Nitride Materials for Enhanced Light Emission
Authors: Zavada John M 
Published: February 2020

Impurity doping of silicon and other semiconductor materials has been an active research area for more than 20 years. There have been two main thrusts of this work, erbium doping to provide infrared light emission in silicon for telecommunications, and doping with other rare earths for full color displays and solid state lighting. Major advances in both of these areas have been achieved through metal-organic chemical vapor deposition synthesis of rare earth doped GaN thin films [1, 2]. However, the low efficiency emission in prototype devices has prevented commercial applications. In this talk, recent results concerning light emission from erbium doped and from europium doped GaN films will be discussed. Experimental data showing enhanced light emission through co-doping of the GaN films will be presented. The role of strain fields and theoretical simulations of location of rare earth ions in the GaN lattice will be included. These results indicate that significant ligh emission can be achieved through co-doping of GaN films.
[1] C. Ugolini, N. Nepal, J. Y. Lin, H. X. Jiang, and J. M. Zavada, Appl. Phys. Lett. 89 151903 (2006).
[2] A. Nishikawa, N. Furukawa, T. Kawasaki, Y. Terai, and Y. Fujiwara, Appl. Phys. Lett. 97, 051113 (2010).
[3] P. Kaur, S. S. Sekhon, J.M. Zavada, and Vijay Kumar, Phys. Rev. B (2012).
Magnéli Phase Titanium Oxide: Electrochemical Routes and Characterisation
Authors: Dunne Peter , Mieszala Maxime , Le Nader Victor , Philippe Laetitia , Michler Johann 
Published: February 2020

Wide bandgap semiconductors such as TiO2 are highly versatile and industrially attractive materials. It has excellent chemical and thermal stability useful in a wide range of applications such as biomedical implants [1], cosmetics [2], and MEMS [3]. It is optically transparent in the visible and near infrared, with a bandgap of ~3.3 eV at room temperature, is employed in anti-reflection coatings, dye sensitive solar cells, can become super-hydrophilic under UV exposure, and can act as a photocatalyst. It occurs primarily as rutile or anatase but other metastable polymorphs such as brookite or oxygen deficient Magnéli phases, TinO2n-1, are possible [4].
The oxide can be deposited in near-room temperature baths via electrochemically induced precipitation [5]. However, it is challenging to deposit crystalline TiO2, typically it is amorphous and post-annealing is required to attain a crystalline phase. Of particular interest are the family of sub-oxide Magnéli phases, characterised by high electrical conductivity, and chemical stability [6], which are already finding electrochemical applications in areas such as batteries, fuel cells, cathodic protection, synthesis and environmental treatment [6]. Here we demonstrate the electrochemical routes required to achieve highly crystalline TinO2n-1 from room temperature aqueous electrolytes.

References

[1] D. P. Macwan, P. N. Dave, and S. Chaturvedi, J. Mater. Sci. 46, 3669 (2011).
[2] L. Shi, J. Shan, Y. Ju, P. Aikens, and R. K. Prud’homme, Colloids Surfaces A Physicochem. Eng. Asp. 396, 122 (2012).
[3] J.-C. Orlianges, A. Crunteanu, A. Pothier, T. Merle-Mejean, P. Blondy, and C. Champeaux, Appl. Surf. Sci. 263, 111 (2012).
[4] J. L. Murray and H. A. Wriedt, J. Phase Equilibria 8, 148 (1987).
[5] P. Kern, P. Schwaller, and J. Michler, Thin Solid Films 494, 279 (2006).
[6] F. C. Walsh and R. G. A. Wills, Electrochim. Acta 55, 6342 (2010).
Figure 1 - SEM images of TiO2 deposit on FTO. Left: typical hexagonal morphology with an amorphous TiO2 underlayer. Right: detail of a flower-like feature.
Fabrication of Double Layered TiO2 Photoelectrodes Using Electrostatic Inkjet Printing
Authors: Seki Akie , Shimoyama Yuki , Ogawa Masafumi , Umezu Shinjiro , Kunugi Yoshihito 
Published: February 2020

Dye-sensitized solar cells (DSSCs) are one of the most attractive electrochemical devices capable of converting light energy into electrical energy because they can be fabricated at low cost in an eco-friendly manner. Photo-electrode film of TiO2 nanoparticles in DSSC plays a major role in the light absorption and charge carrier separation and collection process. Popular fabrication methods of the photo-electrode ﬁlm are screen-printing, spray-coating, spin-coating, and blade-coating. Inkjet printing of functional materials has been attracting significant attention in the light of recent attempts to manufacture various electronics such as light-emitting diodes, thin film transistors, solar cells, memory devices, sensors, biological devices, passive circuit elements, etc. However, it is well known that current inkjet printers such as thermal and piezoelectric printers cannot eject a droplet of high-viscous liquid. TiO2 paste consists of aqueous solution of TiO2 nano-particles, surfactant and polyethylene glycol, and is very high viscosity. Recently, we developed new inkjet technology, electrostatically-injected spray method. When the strong electric field was applied to a nozzle, small droplets were ejected by the electrostatic force. In this study, we apply this inkjet printing technique to develop double layered TiO2 photo-electrodes.
The TiO2 paste was printed by electric field-induced inkjet printing on fluorine-doped SnO2-coated (FTO) glass electrodes and sintered at 450 °C for 30 min. DSSCs were prepared by a conventional procedure. Photovoltaic properties of each solar cell were characterized using simulated AM 1.5 sunlight illumination with an output power of 100 mW/cm2.
We have successfully fabricated double layered TiO2 photo-anodes using an electrostatic inkjet printing technique. The structures and morphologies of the TiO2 film, which ultimately influence the cell performance, were controlled by changing the distance between the capillary nozzle and the FTO substrate (spraying distance). The TiO2 film formed by longer spraying distance yielded a large surface area and a highly porous structure.
Photocatalytic Activity of Pt3ti/WO3 Photocatalyst Under Visible-Light Irradiation
Authors: Hashimoto Masanari , Jeevagan Arockiam John , Tsuda Takashi , Saravanan Govindachetty , Gunji Takao , Kaneko Shingo , Miyauchi Masahiro , Matsumoto Futoshi 
Published: February 2020

In the past decades, enormous attention has been focused on semiconductor photocatalysis for environmental remediation because it can utilize solar energy to decompose various organic compounds in air and aqueous systems. Titanium dioxide (TiO2) is most widely studied photocatalysts because of its low cost, high reactivity and stability. However, only 5 % of solar energy can be use by TiO2 on account of its wide band gap energy. On the other hand, tungsten trioxide (WO3) is a visible-light responsive photocatalyst with a narrow band gap energy and similar valence band potential like that of TiO2. Hence, a much effort has been made to prepare WO3based photocatalyst for decomposition of organic compounds. In the present study, we have prepared photocatalysts (Pt, Pt3Ti) by thoroughly mixed with WO3 powder and precursor in a mortar. We have already reported that Pt3Ti ordered intermetallic compound is a promising catalyst for electrochemical oxygen reduction and methanol, ethanol oxidations.1,2 WO3 loaded photocatalysts were characterized by pXRD, UV, TEM and XPS. Further, we examine organic compounds decomposition under visible light irradiation over cocatalysts loaded WO3. The details about the synthesis, characterization and photocatalytic activity of catalysts would be discussed in the presentation.

References

1. H. Abe, F. Matsumoto, L.R. Alden, S. C. Warren, H. D. Abruna, and F.J. DiSalvo, J. Am. Chem. Soc.,130, 5452 (2008).
2. G. Saravanan, H. Abe, Y. Xu, N. Sekido, H. Hirata, S. Matsumoto, H. Yoshikawa, and Y. Y.-Mitarai, Langmuir, 26, 11446 (2010).
3. G. Saravanan, T. Hara, H. Yoshikawa, Y. Yamashita, S. Ueda, K. Kobayashi, and H. Abe, Chem. Commun., 48, 7441 (2012).
Mathematical Model for the Cathode of Ethanol PEM Fuel Cell
Authors: MESA Jesus ANTONIO , Lizcano Valbuena William Hernando , Camargo Amado Ruben de Jesus 
Published: February 2020

A new phenomenological mathematical model that describes the behavior of the cathode of a polymeric fuel cell was developed. It includes the modelling of liquid water and all cathode layers (gas collector, gas diffusion layer, microporous layer and catalyst layer); additionally, the catalyst layer is described as spherical agglomerates according to experimental evidence [1].
Since the performance of the fuel cell is highly dependent on the structure of the catalyst; [2] and cell flooding cause decrease in oxygen transport and loss of active catalyst surface [3] affecting fuel cell efficiency. The model considers these two important aspects in order to obtain a better description of the phenomena.
As a purely predictive model, it only requires the design specifications of the membrane electrolyte assembly (MEA). Once the data is provided (thickness of the catalyst layer, the catalyst load, the fraction by weight of platinum on carbon, the weight fraction of ionomer inside the catalyst layer and the ionomer density) all other model parameters are derived through the balance equations.
The model solution provides the current density, the cell potential, ethanol crossover rate and concentrations in the catalytic layer and in the membrane. It can be used to calculate and predict fuel cell behavior with high accuracy.
It takes into account liquid saturation in the pores and apply the spherical agglomeration method for describing the topology of the catalytic layer. The two-phase method is used for the macroscopic description of the system, resulting in a differential model, which is solved by the Runge-Kutta Fehlberg method with prediction and correction of error.
References
[1] G. Lin,W. He, T.V. Nguyen, Modeling liquid water effects in the gas diffusion and catalyst layers of the cathode of a PEM fuel cell, J. Electrochem. Soc. 151 (12) (2004) A1999–A2006.
[2] N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, Single domain PEMFC model based on agglomerate catalyst geometry, J. Power Sources 115 (2003) 81–89.
[3] U. Pasaogullari, C.-Y. Wang, Liquid water transport in gas diffusion layer of polymer electrolyte fuel cells, J. Electrochem. Soc. 151 (3) (2004) A399–A406.
Detection of TCE Using Electrochemical Testing: Analyzing the Purity of Water
Authors: Saraf Shashank , Sakthivel Tamil Selvan , Reid David , Hench Larry , Seal Sudipta 
Published: February 2020

Trichloroethylene (TCE) can be considered as one of the most dangerous and toxic organic pollutants. It is present in the groundwater with concentration as high as few ppm, as reported by the Environmental Protection Agency in USA. [1,2] Zero-Valent Iron sorbents are effective at removing TCE from water, but are too expensive to use for large quantity. One promising area of fly ash (FA) is its use as a sorbent, particularly to remove pollutants from water and wastewater in industry. However, raw fly ash has a relatively low surface area and is hydrophilic, hence in its raw form it is not efficient absorbent and easily mixes with water.
In this study, we set out to modify the fly ash into a zeolitic fly ash (ZFA) with high surface area (404 m2.g-1) by alkali fusion followed by hydrothermal treatment. The resulting zeolite material is subjected to hydrophobic surface treatments to produce a material that adsorbs organic components like TCE, and repels water. The concentration of TCE was measured by using simple characterization techniques such as UV-Vis spectroscopy and chronoamperometry measurements. TCE exhibits absorption maxima at 260 nm which was used to calibrate the concentration. The chronoamperometry measurements were done using stainless steel as working electrode. The TCE sorption capacity of the zeolitic fly ash is improved by the chemical modification and it was about three times higher than the as-received fly ash as shown in figure 1.
References:
1. Y. Liu, S. A. Majetich, R. D. Tilton, D. S Sholl, and G. V. Lowry, Environmental Science & Technology, 39(5) 1338 (2005).
2. J. Farrell, M. Kason, N. Melitas, and T. Li, Environmental Science & Technology, 34(3), 514 (2000).