bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Design of Effective Pulse Deposition Process for Functional Cr Coatings from Cr3+ Electrolyte
Authors: Ahmadi Kamyar , Hall Timothy D. , Taylor E. J. , Robles Francisco , Brankovic Stanko 
Published: February 2020

The presented work investigates the pulse current deposition as an approach for electrodeposition of functional Cr films. Our data suggest that observed growth stress during DC Cr deposition are negative, i.e. compressive with steady state values in the range below -100 MPa. The negative stress is associated with blistering in Cr films and accumulation of different defects on the Cr film surface during deposition which indicated significant amount of dissolved hydrogen either as interstitial impurity or as a part of chemically bonded H as Cr-hydride. Stress, impedance and optical results undoubtedly suggest that weakened structure of the Cr films by oxidation process has a true origin in Cr-hydride formation and subsequent oxidation of its degradation by-products (H and Cr). Therefore, the electrodeposition process that produces less Cr-hydride in the deposit should be more desirable when the crack free Cr films are the goal. Our pulse current function design is therefore driven by the goal to achieve Cr-films with minimum amount of Cr-hydride phase. The off time of the pulse current cycle is designed to allow break up and decomposition of hydride phase which has been formed in preceding current on part of the pulse cycle. Our in situ stress data show that using such approach, it is possible to completely change the sing of the insitu stress in Cr films during deposition from compressive to tensile. More importantly, we will show the first indications that pulse electrodeposited Cr films have similar micro-cracked structure as Cr films electrodeposited from Cr6+ solutions.
This work is supported by Gift Grant from NASF-AESF Research Foundation.
Effect of Ionic Liquid Additives on the Product Selectivity and Activity in CO2 Electroreduction over Cu Catalysts
Authors: Sharifi Golru Samaneh , Biddinger Elizabeth J 
Published: February 2020

Electrochemical reduction of CO2 has been proposed as a promising way to attenuate the CO2 level in the atmosphere and consequently, mitigate the global warming. Furthermore, several valuable chemicals and fuels can be produced by CO2 electroreduction. Although copper catalysts are of interest due to their ability to produce hydrocarbons and alcohols, they produce a wide verity of products and need high overpotentialsin traditional aqueous electrolytes1. One of the methods to address these obstacles is to use ionic liquids (ILs) in the electrolyte. ILs are cation-anion couples which have unique properties such as high CO2 solubility. In CO2 electroreduction, ILs can play different roles such as co-catalyst, electrolyte, or CO2 absorbent. It has been reported that product selectivity and the reaction rate in CO2 electrocution is significantly impacted when using ionic liquids2, 3.
Here, the effect of using ionic liquids in CO2 electroreduction on product selectivity and activity of Cu catalysts has been studied. For this purpose, Cu foils were first electropolished in 1M phosphoric acid for 300 sec. CO2 electroreduction was then performed on Cu catalysts for 30 mins at different potentials. According to the results, ionic liquids affected the product selectivity even in a diluted IL/water mixture. The results showed that adding 10 mM 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTF2]) to the 0.1 M KHCO3 electrolyte leads to a 63% increase in the total current density at -1.1 V (vs RHE). A 50% increase in formate faradaic efficiency at -0.91 V was also detected when adding the IL to the electrolyte. Moreover, the faradaic efficiency of methane increased by 80% at -1.1 V (vs RHE) in the ionic liquid/water mixture. The results demonstrate how ILs influence the CO2 reduction on Cu catalysts.

Hori, Y., Electrochemical CO2 reduction on metal electrodes. In Modern Aspects of Electrochemistry, Vayenas, C. G.; White, R. E.; Gamboa-Aldeco, M. E., Eds. Springer: New York, 2008; Vol. 42, pp 89-189.

Mu, T.; Chen, Y., Conversion of CO2 to value-added products mediated by ionic liquids. Green Chemistry
2019.

Zhou, F.; Liu, S.; Yang, B.; Wang, P.; Alshammari, A. S.; Deng, Y., Highly selective and stable electro-catalytic system with ionic liquids for the reduction of carbon dioxide to carbon monoxide. Electrochemistry Communications
2015,
55(0), 43-46.
Towards Durable, Selective Catalysts and Electrodes for CO2 Electroreduction to Value-Added Chemicals and Fuels
Authors: Nwabara Uzoma O , Cofell Emiliana R. , Henckel Danielle A. , Lu Shawn , Gewirth Andrew A. , Kenis Paul J.A. 
Published: February 2020

Rising atmospheric carbon dioxide (CO2) levels and the associated rise in global temperatures are major global concerns. Annual atmospheric CO2 emissions have risen from about 2 Gt to 10 Gt in the last 5 decades.1 Electricity production and transportation are large atmospheric CO2 contributors (~70% of total emissions), and therefore scientists have developed renewable energies and fuel cells vehicles as a mitigation strategies.2,3 Another widely-studied mitigation approach is the electrochemical reduction of CO2 (CO2RR) to value-added chemicals and fuels. Depending on the electrocatalyst and operating conditions used for CO2RR, a variety of products including carbon monoxide, formic acid, ethylene, ethanol, and acetate can be made, which can serve as chemical feedstock for a variety of chemical processes.4

Most research on the CO2RR has focused on developing catalysts around four metrics: high product Faradaic efficiency (selectivity), high current density (activity), low overpotentials (high energy efficiency), and robust durability/stability. Product selectivity greatly affects economic feasibility (separation costs). Many groups have successfully concentrated on catalyst selectivity and activity. State-of-the-art catalysts for CO2 electroreduction can produce CO and HCOOH at high selectivity (>80%), but the selective production of high energy density hydrocarbons and oxygenates is still lacking.5 Moreover, increasing electrode and system durability aids in decreasing costs. Specifically, benchmarks set by technoeconomic analyses suggests system CO2RR lifetimes of >3000h.7,8 However, a majority of durability studies show lifetimes of <20h.
In the first part of this talk, we will focus on developing selective electrocatalysts and defining their stability in an alkaline flow electrolyzer at ambient conditions. The second part of this talk addresses durability, specifically cathodes and the mechanisms by which they fail. With this, we explore strategies for developing more robust CO2RR cathodes and propose accelerated testing protocols to determine durability in a timely fashion.

Acknowledgement

We gratefully acknowledge financial support from Royal Dutch Shell, I2CNER and the SURGE Fellowship for UN.

References

Hansen, P. Kharecha, et al., PLoS One, 2013.

Oerlemans, Science, 2005, 308(5722), 675-677.

https://www.eia.gov Accessed 05/29/2017.

R.M. Jhong, S. Ma, P.J.A. Kenis, Curr. Opin. Chem. Eng., 2013, 2, 191-199.

J. Martin, G.O. Larrazabál, J. Pérez-Ramírez. Green Chem., 2015, 17(12), 5114-5130.

Verma, B. Kim, H.R.M. Jhong, S. Ma, P.J.A. Kenis, ChemSusChem, 2016, 9(15), 1972-1979

Jouny, W. Luc, F. Jiao, Ind. Eng. Chem. Res,
2018, 57(6), 2165-2177
Liquid Fuels Synthesis from Carbon Dioxide on Membrane-Electrode-Assembly (MEA) Under Ambient Conditions
Authors: Adegoke Kayode Adesina , Radhakrishnan Shankara G. , Roduner Emil 
Published: February 2020

The undeniable emission of anthropogenic greenhouse gases into the atmosphere remain a foremost cause of global climate changes threatening global peace [1-3]. A number of thermal catalysts are available that can convert carbon dioxide (CO2) to methanol with reasonable yield and selectivity at significantly elevated temperature and pressure, using gaseous molecular hydrogen. Hydrogen has to be produced first in a separate, preceding step via water electrolysis. However, renewable energy is available primarily in the form of electrical power. Currently, the available catalysts for electrochemical reduction of CO2 stop at CO or formic acid as the reduction products. At present, the copper is the only catalyst that can convert CO2 to products beyond CO or formic acid to higher order alcohols.
In this study, we have developed a metal oxide catalyst that is capable of converting formic acid to C1, C2 and C3 alcohols at an overall efficiency of >60%. The electrochemical characteristics were thus examined via linear sweep voltammetry and chronoamperometric (CA) methods. The formic acid reduction reaction result revealed a current density of 62 mA/cm2 at 2.4 V with ohmic resistance of 5.8 Ωcm2. The Tafel slope was also used to evaluate the rate-determining step for the electrochemical reaction of formic acid reduction reaction which is 580 mV/dec. Tafel values of 40 cycles were consistent with each other and with the bulk metal, therefore it can be concluded that there were perhaps no significant changes in the mechanism of reduction. However, the chronoamperometry result at 2.4 V showed the current density of 33 mA/cm2; during which methanol, ethanol and isopropanol were detected as products of formic acid reduction reactions (Fig. 1). First experiment with CO2 electroreduction was also conducted, the findings and the reliance of the study shall be presented. This study therefore successfully developed and converted a thermal metal oxide catalyst to an electrocatalyst that could do the conversion of formic acid and CO2 near room temperature and with water as a source of hydrogen.
[1] C. F. Shih, T. Zhang, J. Li, C. Bai, Joule
2018, 2, 1925.
[2] O. Martin, A. J. Martín, C. Mondelli, S. Mitchell, T. F. Segawa, R. Hauert, C. Drouilly, D. Curulla-Ferré, J. Pérez-Ramírez, Angew. Chemie Int. Ed.
2016, 55, 6261.
[3] L. Wang, Y. Yi, H. Guo, X. Tu, ACS Catal.
2018, 8, 90.

Figure 1
Electrochemical Reduction of Carbon Dioxide to Formate on Tin and Polyaniline-Modified Tin Electrocatalysts
Authors: Portela James M. , Lucas Francisco Willian Souza , Lima Fabio H. B. 
Published: February 2020

Tin is one of the most efficient electrocatalysts for the carbon dioxide reduction to formate1, but the real feature that is responsible for such activity is not yet well-understood2. Herein, the carbon dioxide electrochemical reduction to formate ions was studied on Sn and on polyaniline-modified Sn electrocatalysts. The results showed that tin foil electrodes, even having different initial degree of oxidation, as revealed by XPS, exhibited similar faradaic efficiencies, ca. 92%, suggesting that the oxidation state is not the principal factor that control the electrocatalytic activity. Interestingly, when Sn foils and Sn nanoparticles were superficially modified by polyaniline, the rate of formate production was considerably increased, and the faradaic efficiency to formate was maintained close to 92%. In this study, the main features that actually govern the faradaic efficiency of Sn electrodes, and the role of the alkaline nitrogen atoms of polyaniline on detaining CO2 molecules in the vicinities of the electrode producing an increased reaction rate are discussed.
References
[1] J. Wu, F. G. Risalvato, F-S. Ke, P. J. Pellechia, X-D. Zhou, J. Electrochem. Soc., 159 (7) (2012) F353-F359.
[2] C. Cui, J. Han, X. Zhu, X. Liu, H. Wang, D. Mei, Q. Ge, J. Catal. 343 (2016) 257 - 265.
Acknowledgements
The authors gratefully acknowledge financial support from FAPESP (2016/13323-0 and 2013/16930-7), CNPq (306469/20162), and Capes.
(Invited) Capillary Pattern Collapse: Prediction and Prevention from Past to Future
Authors: Bassett Derek W 
Published: February 2020

In the past twenty years, the collapse of semiconductor features due to capillary forces has evolved from a curious phenomenon to a major hurdle requiring increasing amounts of research, experiments, and innovation in order to avoid and overcome. The first paper to analyze capillary pattern collapse was by Tanaka et al in 1993, where they successfully quantified the effects of pattern geometry, material stiffness, wetting liquid surface tension, and contact angle on whether a wetted feature is likely to collapse or not. Although they were looking specifically at photoresist pattern collapse, the analysis has proven remarkably robust and has applied equally well to stiffer structures with a much higher aspect ratio, and is still used today essentially unchanged in form.
This paper will first summarize analytical efforts to understand and predict capillary pattern collapse: starting from Tanaka's paper, then continuing from there looking at additional effects such as repeating geometry, collapse of pillars instead of only lines, more complex feature shapes, modeling of stiction and restoration, 3D effects, and time dependent effects. Though useful as a qualitative predictor as to how susceptible to collapse features are in comparison to each other, there appears to be a disconnect between these analytical models and a true quantitative prediction of when capillary pattern collapse will occur. The paper will discuss what missing effects may cause this.
For the next section the paper will review what techniques have been used and are currently being used to try to reduce and prevent capillary pattern collapse and showing how they relate directly to the analysis of the system: first in reducing the surface tension by changing the liquid from water to IPA, improving the drying technique, then increasing the contact angle with surface chemical treatment, and then to methods currently being researched: a solid phase eliminated by pyrolysis/sublimation and supercritical dry. It will also discuss what metrology has traditionally been used and brie y present new methods being looked at to better understand capillary pattern
collapse.
For the last section, the paper will discuss the future and the ultimate limits of both analysis and prevention of pattern collapse. The decreasing of feature size in state of the art devices will take us to a point where continuum modeling will no longer be able to provide meaningful results and so molecular dynamic simulations might be the only way to effectively model these nano-systems.
Effect of SiO2 Etching Inhibitor to H3PO4 for the Selective Si3N4 Wet Etching of 3D NAND
Authors: Kim Taehyeon , Son Changjin , Park Taegun , Lim Sangwoo 
Published: February 2020

As the number of stacked layers of the 3D NAND structure increases, the memory density of 3D NAND flash memory device increases [1]. In the fabrication of 3D NAND device, it is essential to selectively etch Si3N4 by an etchant flowing along a narrow slit followed by metal deposition. However, as the number of Si3N4/SiO2 multi-stack increases, selective etching of Si3N4 becomes difficult. In order to increase the Si3N4-to-SiO2 etch selectivity, SiO2 etching inhibitor should be added to H3PO4. Unfortunately, most of SiO2 etching inhibitors added to H3PO4 generate oxide regrowth around SiO2 layer on the Si3N4/SiO2 multi-stack structure. In this study, the mechanism of oxide regrowth occurred on the 3D NAND structure was investigated.
Patterned Si3N4/SiO2 multi-stack structures were prepared. Etching experiments were performed using coupon wafers in 85% H3PO4 or etching inhibitor-added H3PO4 at 160 °C. The Si3N4 and SiO2 etching rates and Si3N4-to-SiO2 etch selectivity were measured using spectroscopic ellipsometry and oxide regrowth on the Si3N4/SiO2 multi-stack structure was analyzed using FE-SEM and HR-TEM.
When the Si3N4/SiO2 multi-stack structure was etched in the SiO2 etching inhibitor-added H3PO4, oxide regrowth was observed on the SiO2 layered trenches on the Si3N4/SiO2 multi-stack structure, as shown in Fig. 1. The oxide regrowth occurred intensively at the corner of SiO2 layered trench and oxide regrowth occurred heavily at the bottom of Si3N4/SiO2 multi-stack structure as compared to the top. The overall amount of oxide regrowth on the SiO2 layered trench increased as the concentration of SiO2 etching inhibitor added to H3PO4 increased. In addition, it is shown that generation rate of etching product is an important factor to occur oxide regrowth. Based on the results, it is suggested that etching inhibitor addition and high generation rate of etching product and mass transfer limitation are responsible for the oxide regrowth. Through their optimization, selective Si3N4 etching on the Si3N4/SiO2 multi-stack structure without oxide thinning and regrowth could be obtained, as shown in Fig. 2.
References
[1] S. Aritome, NAND flash memory technologies, p. 273, John Wiley & Sons, Hoboken, NJ (2015).
[2] J. Jang, et al, in Symp. VLSI Tech. Dig., 192 (2009).

Figure 1
Proactive Contamination Control for Sub 10nm Particle in Advanced Semiconductor Manufacturing
Authors: Libman Slava , Van Schooneveld Gary , McIntosh Bob 
Published: February 2020

Advanced Semiconductor Manufacturing has reached the limits of metrology measuring contamination and defects on both the wafers and in the high purity materials (i.e., killer size particles in liquid chemicals and ultrapure water). Furthermore, ability of the most advanced filters to control particles in sub-10nm range is also limited. High purity materials used in liquid delivery systems have never been qualified for sub-10nm size particles. Finally, particle shedding of sub-10nm particles from high-purity components located post-filter cannot be directly measured and only be estimated using power-law extrapolation.
Yield Enhancement IFT (international focus team) of IRDS (International Roadmap for Devices and Systems) is working together with the Liquid Chemical Committee of SEMI Standards to establish the methodology to enable proactive technology management in the space of contamination control.
This presentation will provide the most recent experimental data generated by UPW IRDS team and SEMI Standards Liquid Chemical task forces, demonstrating the issues related to the contamination occurrence. The presentation will also include information about the SEMI standards and corresponding systematic approach that supports supply chain effort for developing and commercialization of new solutions to proactively address the contamination issues.
(Invited) Selective Area Growth of Deactivating Polymers
Authors: Wojtecki Rudy James 
Published: February 2020

As the semiconductor community continues scaling, area selective atomic layer deposition (ASD) offers the potential to relax down-stream processing steps by enabling self-aligned processes (e.g. self-aligned via). ASD can be achieved under a variety of conditions and, with the use of organic inhibiting materials, exhibit some of the highest levels of selectivity. However, the organic materials exploited are generally relegated to small molecules and may require multiple cycles of etch-back processes followed by renewal of the surface protection coating. The chemical composition of polymeric materials offers significant potential to broaden the number and film compositions that can be selectively deposited as they draw from such a vast number of chemical functionalities that can be exploited to tailor surface properties [1,2]. There are two approaches to exploiting polymers for ASD, (i) grafting to a substrate with polymer brushes or (ii) growing polymers from a surface. Grafting polymer brushes, with materials shown to inhibit ALD film growth and functionalized with metal binding ligands, exhibited poor selectivity to surfaces and resulted in high defectivity on patterned surfaces where polymer particles were observed on both a metal and dielectric. Growing polymers from a substrate is an attractive strategy, though difficult to realize experimentally. Using a facile synthetic route, a surface binding monomer was engineered that maintained high activity for surface polymerizations and which selectively adheres to a nanoscale metal features, in a field of dielectric material. The resulting surface afforded the ability to produce polymers in an area selective manner and chemically engineer the surface, as desired. The resulting surface polymers were both thermal and chemically stable under ALD conditions and highly selective at guiding the ALD of several films including TiO2 and ZnO for extended periods of time that allow the growth of film thicknesses greater than 48nm, relevant in a number of device applications. This method was also found to be scalable where initial experiments were carried out on laboratory scale experiments and could be scaled to a full 300mm wafer. Furthermore, the mechanism of inhibition was shown where ALD films inhibition is the result of precursor solubility in the polymer film. This unique strategy of growing polymers in an area selective manner and the inhibiting mechanism, present a set of design rules for engineering surfaces to direct the formation of inorganic films.

References:

[1] J. Vac. Sci. Technol. A,
2019, 37(2), 020923-1.
[2] ACS Appl. Mater. Interfaces, 2018, 10(44), 38630.

Figure 1
(Invited) Selective Atomic Layer Deposition Strategies for Catalytic Applications
Authors: Chen Rong , Cao Kun , Liu Xiao , Cai Jiaming , Shan Bin , Wen Yanwei 
Published: February 2020

Atomic layer deposition (ALD) is a mainstay of the semiconductor industry since it allows depositing nanometer thin layers of a desired material onto a substrate in a very controlled and uniform manner. Recently, ALD has been adapted to design and synthesize composite catalysts that allow them to enhance multiple chemical reactions. In fabrication of composite catalysts, the selective approaches of ALD are of great importance to exert spatial control of deposition to fabricate three dimensional nanostructures.
In this talk, strategies for selective ALD and enabled nanostructures for catalytic applications will be discussed. The atomically ccomposite nanostructures allows motivations of selective-ALD enable directionally and precisely tailoring of the structural parameters, interfaces, and active sites, that is of great significance for advanced catalysis. Both metal and oxide selectively decorated nanoparticle catalysts will be discussed. With these methods, core shell structures, oxide overcoating structures, facet selective structures are fabricated. The DFT calculations for precursors’ chemisorption and binding energies are carried out to verify the results. These strategies of selective ALD have demonstrated unique advantages to design and fabricate highly active and thermal stable catalysts in atomic scale, and also provided insights to understand the structure–activity relationship.