bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluating Resistive Memory Devices for Neuromorphic Computing Using Ultrashort Voltage Pulses
Authors: Jacobs-Gedrim Robin Bay , Hughart David R. , Agarwal Sapan , Finnegan Patrick Sean , Goeke Ronald S. , Van Heukelom Michael , Nowlin Joshua , Wagner Jamison , James Conrad D. , Marinella Matthew J. 
Published: February 2020

A special purpose neural algorithm accelerator based on resistive memory could potentially reduce the energy requirements of neural algorithm implementation by six orders of magnitude over conventional general purpose GPU/CPU hardware (1). The device requirements for such a neural algorithm accelerator depend on attributes including write variability, write linearity, and read noise, as described in reference (2). Devices with multiple resistance states accessible via symmetric voltage pulses of constant magnitude are highly desired for neuromorphic hardware implementations. Tantalum oxide resistive memory devices have been previously shown to have low energy requirements and better control of conductivity during switching in the ultrashort time domain (3). We will report on how employing voltage pulses with ultrashort pulse widths allow for finer control of tantalum oxide based device conductance change per pulse (ΔG/G) unlocking additional neuromorphic states. A parameter space of pulse voltage and time is used to elucidate switching kinetics and switching energy expenditure during device operation. Lastly, the performance of several different resistive memory device structures will be comparatively evaluated for suitability in implementing a neural algorithm accelerator.
This work was supported by Sandia National Laboratories’ Laboratory Directed Research and Development (LDRD) Program under the Hardware Acceleration of Adaptive Neural Algorithms Grand Challenge. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
REFERENCES:
1. Kadetotad, Deepak, et al. "Parallel architecture with resistive crosspoint array for dictionary learning acceleration." IEEE Journal on Emerging and Selected Topics in Circuits and Systems, 5.2 (2015): 194-204.
2. S. Agarwal, et. al. “Resistive Memory Device Requirements for a Neural Algorithm Accelerator,” International Joint Conference on Neural Networks, (2016)
3. Strachan, John Paul, et al. “Measuring the switching dynamics and energy efficiency of tantalum oxide memristors” Nanotechnology22.50 (2011): 505402.

Figure 1
(Invited) The Challenges and Opportunities in Plasma Etching of Functionally Enhanced Complex Material Systems
Authors: Chen Jack Kun-Chieh , Kim Taeseung , Chang Jane P. 
Published: February 2020

The introduction of new and functionally improved materials into silicon based integrated circuits is a major driver to enable the continued down-scaling of circuit density and performance enhancement in analog, logic, and memory devices. Many new materials, such as multiferroics, magnetic materials and phase change materials, are much harder to pattern, thereby posing significant challenges to the design and selection of plasma etching chemistries. While ion milling is effective in patterning some of these functionally improved materials, such as complex magnetic material stacks used in magnetic tunnel junctions, it limits the scalability and integration of devices. These challenges point to the growing needs of identifying and developing viable etch chemicals and processes that are more effective in patterning complex materials and material systems.
In this talk, a generalized approach based on combined thermodynamic assessment and kinetic validation is presented to identify and validate the efficacy of various plasma chemsitries. Specifically, potential reactions between the dominant vapor phase/condensed species at the surface are considered at various temperatures and reactant partial pressures. The volatility of etch product was determined to aid the selection of viable etch chemistry leading to improved etch rate of reactive ion etching process. Based on the thermodynamic screening, viable chemistries are tested experimentally to corroborate the theoretical prediction. Some of the above mentioned material systems such as magnetic materials used in magnetic tunnel junctions are used as examples to demonstrate the broad applicability of this approach.
Self-Aligned Contact Etch Process Optimization with Pulsing Plasma Technology
Authors: Zheng Er-Hu , Zhang Yi-Ying , Zhang Hai-Yang 
Published: February 2020

The self-aligned contact (SAC) is a key process in developing the next generation ultra-large scale integrated (ULSI) devices because its advantage on providing an efficient reduction of active array areas, decreasing the transistor gate features, and alignment margin improvements in photolithography. [1-2] With the transistor gate feature size continuously scaled down, pattern density and aspect ratios continuously increase, conversely. It requires a robust etch process to solve the multiple issues such as nitride hard mask loss loading between trench/hole, nitride shoulder profile, free necking profile. [3] In this work, we examined the impact of various pulsing technologies on the extremely high aspect ratio SAC etch process, including source pulsing/bias pulsing/synchronous pulsing and the hybrid method. Results indicate the introduction of pulsing function could significantly reduce the nitride loss while avoid the contact open. The synchronous pulsing scheme shows its superior capability on improving the trade-off between nitride loss and profile control. Finally we achieved a manufacturable SAC process without any side effect.
References

S. Kim, J. Vac. Sci. Technol. A 23(4), 7(2005).

J. Kim, J.Vac.Scl. Technol. B 20(5), 9(2002)

E.H. Zheng, A study of self-aligned contact etch of NOR flash, China Semiconductor Technology International Conference (2015).
(Invited) Atmospheric Pressure Microplasma Jet: Properties and Applications in Synthesis of Nanoparticles
Authors: Zhong Xiao-Xia 
Published: February 2020

Atmospheric pressure microplasma jet: properties and applications in syntheses of nanoparticles (invited)

Xiao-Xia Zhong
State Key Laboratory of Advanced Optical Communication Systems and Networks and key Laboratory for Laser Plasmas (Ministry of Education), Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China. Atmospheric pressure microplasma jets are usually characterized with vacuum free, high electron temperature (several eV), and low gas temperature (room temperature). Being with the clear advantages such as clean or environmental friendly, fast, more and more attentions have been paid on atmospheric pressure microplasma assisted electrochemistry and its application in nanofabrication. In this talk, non-equilibrium properties, instability and nonlinearity of atmospheric microplasma jet are presented. [1-6] The non-equilibrium state of microplasma was studied as a function of capillary size, gas distance, gas flux and composition, etc. The unstability and nonlinearity of microplasma was discussed with water acting as anode and cathode respectively. The understanding of the thermodynamics and the nonlinearity of the plasma will help us to get an atmospheric pressure microplasma jet with controllable plasma density and temperature. Ecofriendly syntheses of Au Nps, Ag Nps, Au-Ag nanoalloys, carbon nanodots are also presented. [7-10] Experimental parameters such as plasma power, solution composition, process time, etc. play an important role in the syntheses of nanoparticles and deep investigations are still under way.References: [1] Y. Lu, S. F. Xu, X. X. Zhong et al., Europhys. Lett. 102(2013) 15002 [2] S. F. Xu, X. X. Zhong, Appl. Phys. Lett. 103 (2013) 024101 [3] S. F. Xu, X. X. Zhong, Phys Plasma 22 (2015) 103519 [4] S. F. Xu, X. X. Zhong, Phys Plasma 22 (2015) 033502 [5] S. F. Xu, X. X. Zhong, Phys Plasma 22 (2015) 103519 [6] A. Majeed, X. X. Zhong, S. F. Xu et al., Plasma Process. Polym. 2016, DOI: 10.1002/ppap.201500199. [7] X. Z. Huang, X. X. Zhong et al., Nanotechnol. 24 (2013) 095604 [8] X. Z. Huang, Y. S. Li, X. X. Zhong et al., Nanoscale Res. Lett. 9 (2014) 572 [9] T. T. Yan, X. X. Zhong et al., Chem. Commun. 50 (2014) 3144 [10] X. Z. Huang, Y. S. Li, X. X. Zhong et al., Plasma Process. Polym. 12 (2015) 59
Plasma-Assisted Deposition of Carbon Nanowalls for Detection of Organic Vapours
Authors: Cvelbar Uros , Slobodian Petr , Kondo Hiroki , Sekine Makoto , Hori Masaru 
Published: February 2020

One of the grand challenges in material science is to develop the efficient and low-cost sensors for quick detection of various toxic and carcinogenic molecules, which require rather lengthy procedures or costly techniques for detection. These challenges can be tasked with carbon nanowall-based sensors, where the thin film maze-like structures are deposited on silicon substrates with plasma-enhanced chemical vapour depositions. These sensors demonstrate the high sensitivity in response, selectivity and reversibility for the vapour detection of volatile organic compounds, when tested by an electrical resistance method during adsorption and desorption cycles. The maze-like structures of carbon are composed of several layers of vertically aligned sheets - mostly graphene.[1,2] The structures are deposited from two different plasma gas mixtures generated either in CH4 or C2F6 with H2. [3] Herein the neutral H atoms are generated in surface wave plasma region driven by a 2.45 GHz microwave power supply and then mixed with CH4 / C2F6 and deposited in capacitively coupled plasma region operating at 100 MHz. By variating plasma processing parameters, we are able to achieve even different wall-to-wall distances ranging from 50 nm and 300 nm when prepared on silicon wafer substrate. [4] Further these structures are subjected to different organic vapours of: DMA; urea; iso-pentane; diethyl ether; acetone; methanol; different hydrocarbons; etc. in order to evaluate the relationship between the change in resistance, molecular weight of the adsorbent, the polarity and the bonding/interaction type. [4] For assessment and unravelling the detection mechanisms different surface analyses methods (XPS, Raman, FTIR, SIMS, UV-Vis) are applied prior, between and at the end of molecule detection. The properties of carbon nanowalls are then linked, and will be discussed in respect to the properties of detected molecules.
References:
[1] M. Hiramatsu, M. Hori, Carbon Nanowalls: Synthesis and Emerging Applications, Springer, Wien, 2010.
[2] M. Ito, K. Murata, K. Aiso, M. Hori and T. Goto, Appl. Phys. Lett., 1997, 70, 2141.
[3] M H.J. Cho, H. Kondo, K. Ishikawa, M. Sekine, M. Hiramatsu and M. Hori, Carbon, 2014, 68, 380.
[4] P. Slobodian, U. Cvelbar, P. Riha, R. Olejnik, J. Matyas, G. Filipič, H. Watanabe, S. Tajima, H. Kondo, M. Sekine and M. Hori, RCS Advances, 2015, 5, 90515-90520.
Curcit Formation on Glass Substrate Using a Titanium-Copper Oxide Catalytic Adhesion Layer for Copper Plating
Authors: Okabe Kyohei , Cordonier Christopher Ernest John , Noh Joohyong , Honma Hideo , Takai Osamu 
Published: February 2020

Introduction
Glass has characteristics such as transparency, smooth surface, chemical and thermal stability, coefficient of thermal resistance similar to silicon, high dielectric constant, electrical insulation and physical strength, deaming it an attractive substrate material for electronic devices. Examples of application are 2.5D/3D electronic device and RF module packaging. Glass can be metallized electroless plating however, problems remain, the most predominant being inadequate adhesion between glass and plated films. Using a catalytic Ti-Cu oxide adhesive layer formed on the glass, adhesion strength of 0.5 kN/m has been obtained1
) In this study, circuit formation by semi-additive process that’s often used in the formation of fine circuit and the influence of the Ti-Cu oxide layer on post-treatment steps was investigated.
Experimental
Schott Co., Ltd. Tempax 50 mm × 50mm × t 0.7 mm was used as the test substrate. Circuit formation by the semi-additive process is shown in figure 1. After the circuit formation, the removal of the Ti-Cu oxide layer was accomplished by immersion in an aqueous sodium hydroxide 100 g/dm3, trisodium citrate 5 g/dm3 solution at 80 ℃ for 10 min. Electroless NiP plating was performed as a post-process to evaluate the effectiveness of the Ti-Cu oxide layer removal method.
Results and Discussion
Circuits of L / S = 50/50~200/200 µm and t=10 µm dimension were formed using the semi-additive process where adhesion after circuit formation was maintained. After the circuit formation, average roughness (Ra) was observed by atomic force microscopy (AFM) and elemental analysis was performed by X-ray photoelectron spectroscopy (XPS). The Ra was 6.4 nm and 14.9 %Ti was detacted prior to removal and when performing electroless NiP plating as the post-treatment, abnormal deposition occurs between the wiring patterns. On the other hand, after performing Ti-Cu oxide layer removal treatment, the Ra was 0.5 nm and 0.3%Ti detected. Abnormal deposition of electroless nickel does not occur, therefore it was possible to deposit the electroless plating selectively on the copper circuit.
Conclusions
L / S = 50/50 ~ 200/200 um circuits formed on a smooth glass substrate was possible.The adhesion layer of Ti-Cu oxide can be removed by an alkaline solution. By performing the Ti-Cu oxide layer removal process, abnormal deposition of electroless nickel plating in a post-treatment step can be prevented.

Acknowledgments
This work was funded in part by the “MEXT-supported Program for the Strategic Research Foundation at Private Universities” and the “Tokyo Ohka Foundation for the promotion of Science and Technology.”

References
1)K. Okabe, T. Kagami, Y. Horiuchi, O. Takai, H. Honma, and C. E. J. Cordonier, “Copper Plating on
Glass Using a Solution Processed Copper-Titanium Oxide Catalytic Adhesion Layer”, Journal of The
Electrochemical Society, Vol.163, No.6, p. D201-D205, (2016)

Figure 1
Low Temperature Electroless Deposition of Hard Magnetic Alloys for the Metallization of Additive Manufactured Functional Microstructures
Authors: Bernasconi Roberto , Credi Caterina , Levi Marinella , Magagnin Luca 
Published: February 2020

In the last few decades additive manufacturing is finding applications in the field of microdevices production. Techniques like sterolithography (SLA), two photons lithography (TPL) and others [1] have the potential to reach the micrometric scale required for the realization of devices like polymeric based microelectromechanical systems (MEMS) or magnetically actuated microdevices. The most precise and versatile additive technologies however use polymers as materials. For this reason a fundamental step of the manufacturing process is the application of a metallic layer to provide conductivity, essential for MEMS, or to make sensitive the device to the presence of a magnetic field.
Many different metallization methods can be applied, but one of the most attractive in terms of cost and flexibility is electroless deposition [2]. The use of this all-wet technique introduce however some major issues when plating on the resins usually employed in SLA or TPL. The main problem is in particular related to the temperatures typical of some electroless baths, which makes them incompatible with polymers that in some cases present reversible transition temperatures as low as 40 °C. To successfully metallize SLA and TPL resins a great attention must be devoted to the choice and optimization of compatible electroless processes.
Between the possible metallic layers that can be applied in relation to the type of microstructure produced, hard magnetic alloys are of great interest. Such materials, and in particular their ability to retain magnetization, can be used to actuate or manipulate different classes of devices. Examples may include magnetically actuated microswitches, sensors or others [3].
In the present work two processes to deposit hard magnetic CoNiP, operating at two different temperatures, are presented and applied to the plating of microsized functional structures. The main advantages or disadvantages of using one temperature with respect to the other are discussed as a function of the target application. Some general problems related to the plating of stereolithography printed small structures are analyzed as well. These include difficulties coming from the chemical and physical properties of the resins, from the activation step or from the solution itself.
[1] M. Vaezi, H. Seitz, S. Yang; Int. J. Adv. Manuf . Technol. (2013) 67, 1721–1754
[2] Y. Yan, A. A. Bettiol, Photonics Global Conference (PGC), 2010, pp. 1 – 4
[3] S. Kim et al.; Adv. Mater. 2013, DOI: 10.1002/adma.201301484
Comparative Study of Electroless Platinum Deposition Using Multivalent Metal Ions or Hydrazine As Reducing Agents
Authors: Norkus Eugenijus , Stankeviciene Ina , Jagminiene Aldona , Tamasauskaite-Tamasiunaite Loreta , Naujokaitis Arnas , Buzas Vytenis , Maciulis Laurynas , Tumonis Liudas 
Published: February 2020

Two new type electroless plating processes for deposition of continuous platinum layer are proposed and compared with known process of electroless platinum daeposition using hydrazine as reducing agent.
In this study investigation of the kinetics of electroless Pt deposition, using reducing agents such as Co(II)/Co(III) and Ti(III)/Ti(IV) redox systems, is presented. The Pt layers were deposited on the copper or nickel surfaces. The morphology of Pt layers deposited using different reducing agents was investigated by means of Field Emission Scanning Electron Microscopy (FESEM). Kinetics of deposition rate of Pt was investigated by means of the Electrochemical Quartz Crystal Microgravimetry (EQCM).
It was found that the deaeration of the electroless Pt plating solutions with argon, using Co(II)/Co(III) or Ti(III)/Ti(IV) redox systems as reducing agents, results in higher deposition rates of Pt. When using Co(II)/Co(III) redox system as a reducing agent, the rate of electroless deposition of Pt is ca. 0.3 µg cm-2 min-1 when using Ar-deaerated plating solution, whereas the one in non-deaerated plating solution is significantly lower, e.g. 0.02 µg cm-2 min-1. When, using the Ti(III)/Ti(IV) redox system as reducing agent, the Pt deposition rate in Ar-deaerated plating solution is higher compared with that using CoII)/Co(III) redox couple.
It should be noted that the obtained Pt layers deposited on the surface of Cu using Co(II)/Co(III) or Ti(III)/Ti(IV) redox pairs as reducing agents are continuous and compact.
The kinetic data of the mentioned reactions is discussed and compared with that obtained using hydrazine as reducing agent.

Acknowledgment

This research was funded by a Grant (No. TEC-06/2015) from the Research Council of Lithuania.
(Invited) A Single-Molecule Spin-Based Transistor
Authors: Schwarzacher W. , Brooke Richard , Szumski Doug , Nichols Richard , Mao Bing-Wei , Jin Chengjun , Thygesen Kristian 
Published: February 2020

Single molecule devices are of great interest for what they reveal about fundamental aspects of electron transport and metal-molecule interactions. They represent the ultimate level of miniaturization in molecular electronics and are also of potential interest in sensor applications. We have used an electrochemical approach to realize a single molecule transistor based on 4,4′-bipyridine contacted by Ni. The top and bottom Ni contacts are an insulated Ni STM tip and an electrodeposited Ni film respectively, which are maintained free of oxide by being held in an aqueous electrolyte under potential control. The 4,4′-bipyridine molecules are initially present in the electrolyte and contacted using the STM break junction method. From numerous repeated experiments we build up a histogram of the measured conductance. This conductance depends strongly on the potential of tip and substrate relative to the reference electrode. This is a manifestation of electrostatic gating and shows that the device functions as a transistor. Remarkably, it shows a significantly higher gain than a similar transistor with Au electrodes. Calculations show that the current in the Ni-4,4′-bipyridine-Ni transistor is highly spin-polarized and therefore the device represents a true spin-based single molecule transistor.
A Novel Approach to Coal Processing - Electrochemical Solutions to Pollution Reduction and Material Synthesis
Authors: Yazdani Aliakbar , Botte Gerardine G , Vijapur Santosh H. , Wang Dan , Wang Yuxuan , Sheets Ben 
Published: February 2020

Several scientific research have shown that the coal industry is responsible for a large array of pollution including small particle pollution near populated areas, toxic heavy metals and acid rains1. In 2011, EPA estimated that power plants are responsible for half of the mercury air pollutant in the U.S.2 These environmental concerns garnered the interest of both the general public and governments to find new ways to effectively reduce the pollution related to coal power plants. Furthermore, the current worldwide electricity generation is heavily reliant on coal comprising 41.3% accentuating the need for clean coal energy3.
For decades coal has been seen as a mere inexpensive fuel for generating energy in power plants. However, a closer look at coal reveals that coal is a heterogeneous and complex mixture of hydrocarbons, rich with minerals4. It has been reported that electrolyzing a slurry of fine coal particles in acidic media can produce hydrogen, consuming less energy than water-electrolysis5. The hydrogen produced by this method is pure enough to be used directly in a commercially available hydrogen fuel-cell.
Our research group have successfully electrolyzed coal to synthesize graphene by chemical vapor deposition method (CVD)6. Extensive optimization and control of process parameters was required to produce the graphene structure. The findings from the graphene synthesis process motivated the development of a comprehensive process to generate clean energy and produce high value materials from inexpensive coal.
The main advantages of the new process proposed in this study to process coal via electrochemical methods are (i) easy adaptation to the existing infrastructure of the coal industry to facilitate quicker and low-cost integration of the new process, (ii) decreasing the sulfur content of coal after each step to reduce pollution, and (iii) retrieving the metallic content leached from coal to the slurry to avoid toxic and heavy metals such as mercury poisoning of the air and also generate revenue to reduce operating cost.
Figure 1 represents a brief comparison between the current coal process and the new coal process proposed in this study. Various optimizations in every step of this coal process such as increasing hydrogen generation during electrolysis, decreasing energy consumption during pyrolysis and CVD, and electrochemical-recovery of minerals will be done with the focus on the process economy.

References

1. https://www3.epa.gov/radtown/docs/coal-fired-power-plants.pdf.
2. O. of A. and R. US EPA, https://www3.epa.gov/mats/.
3. http://www.iea.org/publications/freepublications/publication/KeyWorld_Statistics_2015.pdf.
4. Y. De Abreu, P. Patil, A. I. Marquez, and G. G. Botte, Fuel, 86, 573–584 (2007).
5. X. Jin and G. G. Botte, J. Power Sources, 171, 826–834 (2007).
6. S. H. Vijapur, D. Wang, and G. G. Botte, ECS Solid State Lett., 2, M45–M47 (2013).

Figure 1