bluuebunny/crossref_metadata_2025 huggingface dataset:
Dielectric/Si Interface Quality Characterization Using Room Temperature Photoluminescence
Authors: Yoo Woo Sik , Kim Byoung Gyu , Jin Seung Woo , Ishigaki Toshikazu , Kang Kitaek
Published: February 2020

Advanced metal-oxide-semiconductor (MOS) and metal-insulator-semiconductor (MIS) devices employ ultra thin dielectric gate layers. The physical dimensions are in the range of single digit to double digit nanometers. The effective oxide thickness (EOT) is significantly less than 10 nm. Pure SiO2 or combinations of SiO2and SiN layers are typically used as gate dielectrics. High dielectric constant materials (high-k dielectrics) and metal gates are also frequently used, depending on chip design.

Physical dimensions of dielectric layer(s) are typically measured using ellipsometry and high resolution cross-section transmission microscopy (HRXTEM). Electrical characteristics are typically characterized using either contact or non-contact C-V and I-V measurements tools. Non-contact characterization techniques are generally preferred for in-line monitoring applications. However, spatial resolution of non-contact C-V and I-V measurement techniques is in the range of a few millimeters, which are 3 orders of magnitude larger than typical dimensions of actual devices. High spatial resolution, non-contact dielectric/Si interface quality characterization techniques must be developed.

In this paper, ultra thin (~7 nm) SiO2/Si and ultra thin SiN/SiO2/Si wafers were prepared by low pressure thermal chemical vapor deposition (CVD) and thermal oxidation. Dielectric/Si interface quality was characterized by room temperature spectroscopic photoluminescence (PL) measurements. The PL intensity and spectra from Si were measured under different excitation wavelengths which have different probing depths. PL is an optical characterization technique which does not require any sample preparation and physical contact. Typical spatial resolution is in the range of a few microns. Small variations in dielectric/Si interface quality modulates electronic carrier behaviors significantly which results in large variations in PL intensity and spectra.

Significant variations in PL intensity and spectra were measured from ultra thin (~7 nm) SiO2/Si wafers prepared by and low pressure thermal CVD and thermal oxidation. Si wafers with thermal oxide films generally showed significantly stronger PL intensity than Si wafers with thermal CVD grown oxide films (Fig. 1). Trends in PL intensity and spectra indicate the SiO2/Si interface quality of the thermally oxidized SiO2/Si is superior to that of the thermal CVD grown SiO2/Si (Fig. 2). PL characterization is found to be very sensitive to the integrity of dielectric/Si interface and thus, is promising as an in-line, non-contact interface quality monitoring technique.

The excitation wavelength dependence of PL intensity and spectra of SiO2/Si and SiN/SiO2/Si will be discussed along with conventional physical and electrical characterization results.
Measuring CET of High-k Dielectrics with Novel Kinetic Approach Using Micro-Site Corona – Kelvin Method
Authors: Marinskiy Dmitriy , Loy Thye Chong , Yeh H. C. , Wilson Marshall , Lagowski Jacek
Published: February 2020

Freshly deposited surfaces of high-k dielectrics revealed a new set of challenges for monitoring capacitance equivalent thickness, CET, using micro-site corona – Kelvin metrology. Specifically, ions deposited by corona discharge may have a queue-time dependent high surface diffusivity, which causes charge spreading away from charging spot under the Kelvin voltage probe. This could result in underestimation of dielectric thickness and unrepeatable results.

To overcome this problem, we have developed a kinetic approach based on the analysis of the surface voltage transient after point source corona charging. The mathematical solution of the two-dimensional diffusion equation enables fitting of the voltage transient and reliable determination of two parameters: the surface diffusion coefficient and the dielectric capacitance. The latter one gives CET. The kinetic approach was applied to HfO2 layers deposited by atomic layer deposition. Repeatable CET measurements for a range of high-k surface conditions and thicknesses are presented. Elimination of queue-time dependence achieved with the novel kinetic approach is a significant advantage for fab-line monitoring.
Requirements and Difficult Challenges for Packaging in the Era of “More Than Moore”
Authors: Bottoms Wilmer R
Published: February 2020

The benefits of Moore’s Law are slowing as we reach the limits of scaling imposed by the laws of physics. The advantages of higher speed and lower power requirements no longer scale with device feature size. One approach to increase functional density as the benefits of scaling slow is to incorporate functional diversification within a single package. Combining analog, RF, power devices, optical devices, MEMS and other devices types into a single package enables this functional diversification. System-in-package (SiP) architectures combining these components with logic and memory that follow Moore’s Law offsetting much of the decreased benefits of scaling has been called “More than Moore”.

This sounds very simple but there are many difficult challenges that arise in incorporating components with diverse requirements into a single, high density package and delivering the reliable performance demanded by the markets. These challenges include:

Lack of adequate modeling and simulation tools for complex SiP packages

Thermal management with increased thermal density, “hot spots”, etc.

Stress and warpage associated with CTE differences between various components

Cross talk between components

Protecting fragile components such as thinned die, MEMS and compound semiconductors

Maintaining power integrity with widely varying power requirements of various components

Requirements for both hermitic and open packages for sensor environmental access

There are many other challenges as we increase the density of components and interconnect wiring, incorporate heterogeneous integration of both component types and materials used, support a wide range of supply voltages from below 400mV to several volts and incorporate 3D integration. Perhaps the most difficult challenge is to meet these expanding requirements while continuously driving down the cost per function demanded by the markets. Traditionally, packaging has not scaled down in cost with shrinking geometries as quickly as CMOS integrated circuits. Introduction of complex “More than Moore” SiP packages makes this cost challenge much more difficult.

The ITRS was established to forecast the difficult challenges that must be met to satisfy future requirements with sufficient lead time to allow implement a solution. This process has been very successful and, since the beginning of the ITRS, packaging challenges have not prevented continued end user product cost reduction and performance increases. The packaging solutions needed now to continue these improvements in size, cost and performance cannot be delivered by continuing down a known path as we did with CMOS scaled integrated circuits.

Everything has to change.

This includes package architectures, design and simulation tools, materials, connections, etc. Many of these changes are underway but there is much more to come. Specific examples of requirements, challenges and potential solutions for packaging in the Era of ‘More than Moore” identified in the 2013 ITRS will be discussed.
(Invited) Microwave-Based Metrology Platform Development: Application of Broad-Band RF Metrology to Integrated Circuit Reliability Analyses
Authors: You Lin , Okoro Chukwudi A , Ahn Jung-Joon , Kopanski Joseph J. , Obeng Yaw S.
Published: February 2020

Three dimensional stacked integrated circuits (3D-ICs), achieved using through-silicon vias (TSV), is an enabler for the continued miniaturization, increased performance and functional diversification of microelectronic devices. However, their introduction to the market has been hindered by many reliability challenges; in particular, stress related failures in this new technology are significantly worse than the traditional planar integrated circuits. For example, the large mismatch in the coefficient of thermal expansion (CTE) of the silicon matrix (~2.3 ppm/ºC) and the copper TSV (~17 ppm/ºC) interconnects, results in the buildup of stresses. This introduces a new reliability challenges such as the degradation of transistors and other front-end-of-line (FEOL) devices, in close proximity to the TSVs [2].

By and large, stress is the root cause of most microelectronic devices reliability failures; it has been reported that 65% of all microelectronic device failures are thermo-mechanical related, mostly due to thermally induced stresses and strains stemming from the mismatch in the neighboring dissimilar materials [1]. The stress evolution leads to stress buildup, resulting in the generation of defects such as cracks, voids, delamination, plastic deformation, warpage and buckling. These damages could ultimately lead to open or short circuits in the microelectronic chip, resulting in their failure.

Metrology for accurate understanding and quantification of the impact of stress evolution in 3D-ICs structures is key to addressing stress-related reliability challenges associated with the 3D-IC technology. In this presentation, we discuss our attempts to identify and characterize types of performance-limiting defects in three-dimensional (3-D) nanoelectronic devices, with special focus on 3-D interconnects, and relate the defects to the evolution of stress, where and why they form within the samples studied. In addition, we discuss non-destructive techniques for identifying such performance-limiting defects, without interrupting the responsible mechanistic phenomena [3].

References

B. Wunderle, B. Michel et al, “Progress in Reliability Research in the Micro and Nano Region.” Microelectronics and Reliability, Vol. 46, pp. 1685-1694.

A. Mercha et al, Comprehensive Analysis of the Impact of Single and Arrays of Through Silicon Vias induced Stress on High-k / Metal Gate CMOS Performances”, International Electron Devices Meeting (IEDM), Dec. 2010, San Francisco, CA, USA, pp. 2.2.1 -2.2.4.

C. Okoro et al., “Accelerated Stress Test Assessment of Through-Silicon Via using RF Signals,” IEEE Transaction on Electron Devices. Vol. 60, No.6, 2013, pp 2015-2021
Effect of Current Compliance on Resistive Switching Characteristics of Amorphous Ternary Rare Earth Oxide SmGdO3 Thin Films Grown by Pulsed Laser Deposition
Authors: Misra Pankaj , Sharma Yogesh , Katiyar Ram S.
Published: February 2020

Recently the electric-field controlled resistive switching phenomenon in metal oxides has drawn tremendous attention for the development of next generation low power, high speed, high density and nonvolatile resistive random access memory (RRAM) devices. The memory effect in RRAM devices is realized through switching of the resistance of the device between the two states (high and low) of resistances. Depending on the polarity of the applied bias voltages, the resistance switching (RS) characteristic can be classified into two types namely unipolar and bipolar. Among these, the unipolar resistance switching is more preferred due to large contrast in low and high resistance ratio. We have studied RS behavior in new amorphous high-k dielectric ternary rare earth oxide SmGdO3 (SGO) with high and linear dielectric constant of ~ 19. We observed multilevel resistance switching in Pt/SGO/Pt ReRAM device simply by controlling the compliance current during the transition from high to low resistance state. The 4-levels of resistance states with sufficient ratio of neighboring low and high resistances were observed, which is expected to enhance the data storage capability of ReRAM device by storing more data in a finite space. It was observed that the higher the ICC imposed on the device, the lower resistance value obtained in LRS. Under different ICC values between 1 to 5mA, we observed different distinguishable values of lthree ow resistance states and one high resistance state. Temperature dependent studies of the resistances in three low and one high resistances were carried out to understand the mechanism of RS which indicated that resistive switching could be explained by the formation/rupture of conductive filaments formed out of oxygen vacancies and metallic Gd atom. X-ray Photo electron spectroscopy of these samples supported this observations. Based on our experiments the observed multilevel conduction in the device was explained by the variation in the size and or density of conducting filament. Current conduction mechanisms in all the resistance states were also studied. The observed reproducible and nonvolatile multilevel resistive switching, good contrast between them and their good retention and endurance characteristics indicates that SGO may be a promising material for the future nonvolatile multi-bit ReRAM devices. Further studies are currently underway.
The Effect of Amino Acids on Step Height Reduction in STI CMP
Authors: Kim Kijung , Seo Jihoon , Moon Jinok , Kim Yehwan , Kim Sangkyun , Paik Ungyu
Published: February 2020

Shallow trench isolation (STI) process has been a crucial technology to isolate the transistors in ultra large scale integration (ULSI) device [1]. In STI process, step height of dielectric material is inevitably formed after gap-filling process due to the different pattern density. Chemical mechanical planarization (CMP) process has been employed to remove the step height. Remaining step height would cause defects such as dishing and erosion, therefore the reduction of step height can be considered as one of the critical issues in STI-CMP process.

Several groups have studied about the step height reduction using ceria due to its high removal rate of SiO2 [2]. Lim et al. reported that the effect of particle size on step height reduction. They showed that the large particle size could improve the step height reduction by its high removal rate. Recently, the needs of small particle have been increased because the defect control has been more important as the design rule is getting narrow. Therefore, it is inevitable to develop new methodology to enhance the step height reduction. Here, we used different amino acid to modify the surface of ceria and enhance the interaction between the ceria slurry and SiO2.

We investigated the effect of ceria slurries prepared with L-serine, proline, glutamine and amino butyric on step height reduction. We calculated the interaction forces between ceria with different amino acids and SiO2 film by Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The result shows that ceria slurry with L-serine or proline has higher attractive interaction forces with SiO2 than the slurry with glutamine or amino butyric acid (Fig. 1).

The results of SiO2 pattern as different pattern density and line width show that the ceria slurry with L-serine or proline produces higher step height reduction than the slurry with glutamine or amino butyric (Fig. 2). As a result, we found that the high interaction forces between ceria slurry and SiO2 contribute to high step height reduction and it is stronger in case of the slurry with L-serine or proline than the slurry with glutamine and amino butyric acid.
ALD W Metal Gate CMP
Authors: Yang Tao , Xu Qiang , Lu Yihong , Yue Zhang , Xu Jing , Wang Guilei , Cui Hushan , Li Junfeng , Yan Jiang , Zhao Chao
Published: February 2020

Beyond 32nm node, gate last integration scheme had become a mainstream because it ensures the thermal stability of high-kand metal gate stack by applying the metal gate after the high temperature source/drain activation anneal. During HKMG gate last CMOS integration, metal gate chemical and mechanical planarization (CMP) is an indispensable and key process step. Al metal gate is firstly introduced from 32nm node by Intel, which brought new process challenges for Al filling and correspondent CMP. We adopted W as metal gate using atomic layer deposition (ALD) method, besides of ALD W ideal fill capability, compatibility with traditional W CMP is also taken into account.

Different ALD W layers were prepared using B2H6 base and SiH4 base. Removal rate, surface roughness and electrochemical characteristic in W slurry were examined for two types ALD W. The removal rate of B2H6 base ALD W was high than that of SiH4 base. RMS of ALD W with SiH4 and B2H6 base were all less than 1nm after CMP. The adhesion of SiH4 base ALD W between W and barrier layer was stronger than that of B2H6 base ALD W. B2H6 base ALD W has better filling ability than that of SiH4 base ALD W for small size gate trench. Compared with single base ALD W filling metal gate, B2H6 base ALD W filling with SiH4 base ALD W pre-treatment was more benefit to decrease metal gate dishing after CMP process.
High Efficiency Anti-Reflectance Graphene-based Coating through Electrochemical Etching and Deposition
Authors: Jiang Xin , Zhu Hongwei
Published: February 2020

Antireflection (AR) coating is of great significance in controlling the reflection index (RI), which influences optical performance of the system. Comparing to the traditional absorbing materials, single layer graphene with much lower mass density, absorbs 2.3% of light at visible frequencies, which makes it an ideal candidate for use in mass-sensitive systems. The electrochemical anisotropic etching and electrophoretic deposition of graphene can minimize the RI of Aluminum material to 1%, meanwhile the mechanical properties of the coating is acceptable. Electrochemical anisotropic etching (EAE) with prior cathodic polarization during anodic etching, forms homogeneous digital AR structure on the centimeter-scale Aluminum material surface, with pit number density and size distribution controllable and improved interfacial binding force. Electrophoretic deposition (EPD) forms graphene-oxide-based nanostructures on the three-dimensional Aluminum surface from Graphene oxide aqueous suspension. The graphene-based AR coating is achieved through the catalytic reduction of graphene oxide by visible light with N-doped TiO2 as photocatalyst. By electrochemical treatment, we manufacture the high efficiency absorbtion ability and low RI optical surface of Aluminum material, through conducting digital AR structure and homogeneous AR coating.
Effect of Some New Organic Polymers As Green Corrosion Inhibitors for Metals in Different Media
Authors: Branzoi Florina , Branzoi Viorel , Stanca Angela
Published: February 2020

Pure metals and alloys react chemically/electrochemically with corrosive medium to form a stable compound, in which the loss of metal occurs. The compound so formed is called corrosion product and metal surface becomes corroded. Among the several methods of corrosion control and prevention, the use of organic corrosion inhibitors is very well known.

Using the microwaves energy new organic polymers were synthesized by radicalic polymerization. These new organic compounds have anticorrosive and antiscale properties and for this reason, were used for cooling water systems protection. The inhibition activity analysis of these new organic polymers was made by assuming that the mechanism of inhibition by organic molecules is chemisorptions and that the energetic of the corrosion process per se is unaffected by the addition of substituents on the parent compound. We presume that, these new organic polymers inhibit corrosion of carbon steel by a protective mechanism, forming insoluble iron complexes and repairing the porous oxide layers. The methods employed were potentiodynamic polarization, electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and metallurgical microscopy techniques. The addition of the organic inhibitors led in all the cases to inhibition of the corrosion process. The inhibition efficiency was high in all the studied cases. The corrosion parameters obtained from polarization curves and from EIS spectra are in good concordance and point out the inhibitory action of these new organic polymers. The adsorptions of the organic compounds on the carbon steels surface obeyed Langmuir’s isotherm. Further characterization using Fourier transform infrared spectroscopy (FT-IR) demonstrates the adsorption of organic inhibitors and the formation of corrosion products on the carbon steels and the brass surface.

The inhibition process was attributed to the formation of the adsorbed film on the metal surface that protects the metal against corrosive agents. The EIS measurements have confirmed this protection and pointed out the formation of adsorption layers on the electrode surface.
Study of Carbon Formed on Stainless Steel 304H in a Simulated Environment of the Convection Section of the Ethane Cracking Furnace System
Authors: Ramezanipour Farshid , Singh Anand , Paulson Scott , Farag Hany , Birss Viola , Thangadurai Venkataraman
Published: February 2020

The stainless steel 304H (SS304H) is one of the important alloys used in petrochemical industry, such as in the convection section of the ethylene production furnaces. The exposure to carburizing gases makes this alloy susceptible to carbon formation and potential carburization. The present study focuses on understanding the coking behavior of SS304H in ethane/steam environment and the effect of H2S at 700oC. Long-term (90 hours) experiments in such environment show that the addition of ppm amounts of H2S has a pronounced effect on the morphology of the carbon formed on the SS304H surface, as shown by scanning electron microscopy. In the absence of H2S, the deposited carbon forms distinct fibers, which are distributed homogeneously on the surface. The addition of 15 ppm H2S results in the formation of carbon clusters, consisting of very thin fibers that are tightly entangled. Also, experiments in the presence of H2S showed a systematic decrease in the amount of carbon as H2S increased from 1 to 2, 5, 7, and 10 ppm. At 10 ppm H2S, no carbon was observed on the SS304H surface after 4 h of exposure to ethane/steam at 700oC. Mass spectrometry studies showed that the addition of H2S does not affect the temperature or products of ethane cracking. The effect of the SS304H coupons on the ethane cracking products was also studied by mass spectrometry, and showed that the ethane cracking process is not significantly affected by the presence of the metal coupon.
Layered 2D Electrode Architecture for High-Power Lithium Ion Microbatteries
Authors: Shah Ankita , Kotz Sharon , Abraham K.M. , Somu Sivasubramanian , Busnaina Ahmed
Published: February 2020

The power density of a lithium ion battery is predominantly limited by poor ionic and electronic pathways in the battery electrodes. To overcome these limitations, we have fabricated positive electrodes composed of a two-dimensional (2D) layer-by-layer electrode architecture using electrophoretic deposition. In this architecture, alternating layers of multi-walled carbon nanotubes (MWNT) and active lithium metal oxide nanoparticles are electrophoretically assembled onto a current collector. Each active metal oxide nanoparticle is precisely placed to make intimate contact with the conductive MWNT layers, eliminating all other electrode additives such as carbon black and polymeric binder (figure 1). Lithium manganese oxide nanoparticles (LiMn2O4, 300nm) are used as a model active material while MWNT are used as the scaffold. These multilayer electrodes demonstrate excellent rate capability up to 10C and cycling stability for over the 100 cycles tested (figure 2) in a Li/liquid electrolyte/LiMn2O4 cell. We observe that the electrode capacity per cm2increases linearly with the number of stacked layersat a rate of 0.06 mAh/per layer. Therefore, the capacity per footprint area can be increased by increasing the number of stacked layers. These multilayer electrodes are fabricated at room temperature and atmospheric pressure, and the assembly time per layer is less than 60 seconds.

As the number of layers is increased, the dependence of the electrode morphology on rate performance and cycle life is studied though galvanostatic cycling, cyclic voltammetry, electrochemical impedance spectroscopy and physical characterization techniques such as atomic force microscopy (AFM) and scanning electron microscopy (SEM). Multi-layer electrodes with higher capacity active materials such as the lithium-rich layered nickel-manganese-cobalt oxide will also be fabricated to further increase the capacity per footprint area of the microbattery [1, 2].

Acknowledgment: Financial support for this work was provided by the Department of Defense.

1. Thackeray, M., Kang, SH., Johnson, CS., Vaughey, JT., Benedek, R., and Hackney, SA., Li2MnO3-stabilized LiMO2 (M = Mn, Ni, Co) electrodes for lithium-ion batteries. Journal of Materials Chemistry, 2007. 17: p. 15.

2. W.C. West, J.S., M.C. Smart, B. V. Ratnakumar, S. Firdosy, V. Ravi, M. S. Anderson, J. Hrbacek, E. S. Lee, and A. Manthiram, Electrochemical Behavior of Layered Solid Solution Li2MnO3-LiMO2 (M=Ni, Mn, Co) Li-Ion Cathodes with and without Alumina Coatings. Journal of the Electrochemical Society, 2011. 158: p. 7.
Electroless Deposition: History, Status and Future Directions
Authors: Djokic Stojan S.
Published: February 2020

Electroless deposition of metals, oxides, salts and other compounds is very important for many industrial and technological applications. These sophisticated processes have been used in different applications throughout many centuries, even though they were not recognized as such.

Based on the archeological discoveries some of the electroless deposition processes e.g. gold and silver were used in the early Mediterranean civilizations. Reduction of Ni(II) ions to the elemental nickel with hypophosphite was first discovered by Wurtz in 1846 [1]. Liebig discovered the reduction of Ag(I) to Ago, using the formaldehyde as a reducing agent [2]. In 1948, Brenner was the first who described proper conditions for the electroless deposition of nickel using hypophosphite as a reducing agent [3]. Significant developments in this area occurred in the second half of the 20th century and until now [4,5]. Metals of interest include of all the metals and alloys which can be electrodeposited from the aqueous solution i.e. Ni, Cu, Ag, Au, Pd etc, with particular attention given to nickel, copper, gold and silver.

Although many electroless depositions of nickel, cobalt, copper, silver, gold or similar are used in different industrial processes, there are many aspects of these processes that are not yet fully understood. It is well established that these processes are electrochemical by the nature, however, the mechanisms of the reactions governing the electroless deposition are not yet generally accepted by the researchers.

In this presentation a historical overview of the electroless processes used throughout centuries until present days will be given. Then, a classification of different electroless processes i.e., galvanic deposition, autocatalytic deposition and contact deposition will precisely be defined. Mechanisms of the electroless deposition and future directions for the electronic, biomedical, energy device, automotive and aero-space applications will be discussed.

Refernces:

A. Wurtz, C.R. Acad. Sci. Paris, 18 702 (1884); 21 149 (1845).

B. Liebeg, Ann. Chim et Phar. 14 140 (1835).

A.Brenner, G.E.Riddell, Proc.Am.Electropl.Soc., 33 16 (1946).

G.O. Malloy, J.B. Hajdu, Electroless Plating: Fundamentals and Applications, AESFS, Orlando, Florida, 1990.

S.S. Djokić, Electroless deposition of metals and alloys, Modern Aspects of Electrochemistry, No. 35, Ed. B. E. Conway, R.White and J.O’M Bockris,. pp.51-120, Kluwer Academic/Plenum Publishers, N.Y 2002.
Porous Conducting Membranes and Their Application in Vanadium Flow Battery
Authors: Li Xianfeng , Zhang Huamin
Published: February 2020

The vanadium flow battery (VFB) has received widely attention due to its attractive features for large scale energy storage. One of the central problems that hinder the commercialization of VFB is the high cost and low selectivity of currently used perfluorinated membranes (Nafion). Although the non-perfluorinated hydrocarbon polymers like sulfonated or quaternary ammoniated aromatic polymers are widely investigated, these membranes often suffer from poor chemical instability which is proved to be induced by the introduction of ion exchange groups. Recently, we reported the application of porous membranes in VFB1. The idea is based on separating vanadium ions from protons via pore size exclusion. The new design and concept can potentially overcome the traditional restriction from ion exchange membranes and provide more materials option. Followed our idea, different kind of porous membranes separators were explored and investigated in VFB. Quite impressive progress was achieved via optimizing the membrane materials and morphology.

In this presentation, the current status of VFB porous membranes, including morphology control, structure-relation will be discussed in detail.

References

[1] Hongzhang Zhang, Huamin Zhang, Xianfeng Li, Zhensheng Mai, Jianlu Zhang,
Energy & Environmental Science

2011, 4 (5), 1676 – 1679

[2] Xianfeng Li, Huamin Zhang*, Zhensheng Mai, Hongzhang Zhang, Ivo Vankelecom,
Energy & Environmental Science,

2011, 4 (4), 1147 – 1160
Study of the Chemical and Morphological Characteristics of Al2O3 and HfO2 Surfaces after Immersion in Time-Dependent pH Solutions
Authors: Molina Reyes Joel , Perez Ramos Berni Manolo
Published: February 2020

After immersion of ALD-Al2O3 materials in time-dependent pH solutions (solutions whose pH is changing over time), any possible change in the chemical and morphological characteristics of Al2O3 is correlated to the chemical sensitivity when used as active material in ion-sensitive devices. Morphological changes have been recorded by Atomic Force Microscopy (AFM), while the chemical characteristics have been quantified by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS). Experimental results suggest that the changes experienced by the films under immersion are highly dependent on immersion time and ion-strength (acidic or basic solutions), and this might be the main cause of drift in ion-sensitive solid state sensors. Moreover, the data shows that HfO2 and Al2O3 exhibit different chemical characteristics after immersion in pH solutions than Si3N4. Nonetheless, due to their high chemical sensitivity and higher dielectric constant, these materials are well suited for highly sensitive applications in pH-sensing devices.
Invited: Wireless Mechatronic Sensing Device for Long Tube Internal Deformation Inspection
Authors: Tang Liqiong , Fukuoka Morio
Published: February 2020

Chemical and process industry has high demand on inspection and measurement systems especially the sensing devices for thin and long tubes working under high temperature, high pressure and corrosive environment to encourage rapid chemical reactions. Such tubes are often high cost critical equipment in chemical production. The service life of these tube components is primarily ended when Creeps Shear damage is detected. Due to the complex combination of the multiple factors influencing the generation of Creep damage under the aggressive working condition during service, it is of significant benefit for process companies using condition-based assessment to judge the retirement of such components. To improve the reliability of the service life of the tubes, the use of non-destructive examination techniques on a regular basis during production turnarounds is essential. Different approaches have been presented in literature, some involved high-tech and expensive modern technologies. This research aims to explore the possibility of a sensing device that has potential to be a cost effective solution for a particular tube that plays a critical role in a chemical production process and is heavily used in a chemical process industry. The novel sensing device developed by this research is a wireless sensing system for checking internal geometric deformation for hundreds of these tubes within a required set time. The sensing device is designed with a mechatronic sensing mechanism to capture the geometric information of tube cross sections and wirelessly transfer the information to a data collection unit in real time. The sensing device consists of four major subsystems, which are sensing, communication, driving, and control systems. The driving and control systems are placed at one end of the tube. The sensing unit is sent into the tube and wirelessly communicates with the control system. Field testing was conducted on the prototype model in a chemical process company using an industrial testing platform to evaluate the functionality and performance of the sensing device. The field testing made on the prototype confirmed the sensing device was able to carry out tube inspection within the set time and reliably capture tube internal information and transfer the data wirelessly. Field testing data analysis also proved the data collected by the sensing device met the company’s requirements on measurement precision and data size.
Detection of Organic Molecules Using Conducting Materials
Authors: Chahma M'hamed , Enagala Sravya
Published: February 2020

Surface modification allows the immobilization of a variety of organic molecules and biomolecules such as peptides, proteins and DNA on electrode surfaces. The systems commonly used for surface immobilization are the covalent linkers S-Au and C-N. By reduction of thiols, disulfides and diazonium salts, organic motifs have been deposited on gold and carbon surfaces.

Our strategy is based on the deposition of conducting materials as an intermediate between the electrode and chiral sites that can detect molecules via hydrogen bond formation (Scheme 1). Using cyclic voltammetry, we found that the capacitive current of the chiral surface (1) decreased by 30 % once the chiral electrode is interacting with target molecules (2). The hydrogen bond formation has been characterized by NMR and IR.
Determination of the Antioxidant Capacity of Herbal Extracts Using a Biosensor Based on Laccase Trametes Versicolor
Authors: Juarez-Gomez Jorge , Ramirez-Silva Maria Teresa , Palomar-Pardavé Manuel , Romero-Romo Mario , Bernabé-Pineda Margarita
Published: February 2020

The polyphenolic compounds are antioxidant molecules having potentially beneficial implications to human health, so presently there is a strong interest in finding natural sources of antioxidants. Therefore, this work presents the results of the spectrophotometric studies using the DPPH radical method for the determination of the antioxidant capacity equivalent to caffeic acid in different extracts of Kohleria deppeana (topoya), Sedum morganianum (cola de borrego) and Alternanthera repens (tianguispepetla).The spectrophotometric method is contrasted with an electrochemical method using a biosensor based on the enzyme Laccase Trametes Versicolor immobilized on a polymeric membrane of polyvinyl alcohol.
Sensitive Electrochemical NO Sensors: Towards Measurement of Nitric Oxide on Primary Epithelial Cell Models
Authors: Bose Tiyash , Bomberger Thomas , Bayachou Mekki
Published: February 2020

Nitric oxide is an important physiologic metabolite implicated in both health and disease states. Accurate determination of NO in tissues and cells is of paramount importance. The major challenges with NO measurement are its short half-life and often low nanomolar concentrations in tissues. Electrochemical tools provide a mean to accurately measure this analyte in confined environments using miniaturized probes. In the past, our lab explored electrodeposited alternate layers of ruthenium oxide nanoparticles and a conductive sulfur-containing polymer on carbon microelectrode fibers for catalytic determination of NO.

In this work, we explore the performance of combined reference/working electrodes modified with ruthenium oxide in the detection of nitric oxide with the goal to measure nitric oxide at the level of single or collective cultured cells. This is a preliminary work towards preparing a device capable to measure nitric oxide levels in a cystic fibrosis cell line model. It has been found that exhaled NO levels remains unchanged or reduced in cystic fibrosis patients unlike other inflammatory lung diseases like asthma where it increases. However it is not clear whether the lower NO levels in cystic fibrosis correlate with lowered production of this metabolite in the bronchial epithelium. It was shown that levels of nitrite and nitrate, the primary stable end products of NO metabolism increases in the breath condensate of patients with cystic fibrosis. We will present preliminary results of our ruthenium oxide modified combined electrodes and how they can be applied to the study of cystic fibrosis at the cellular level.
Discriminative Detection of Neurotoxins by a Layer-by-Layer Based Carbon Nanotube/bi-enzyme Biosensor
Authors: Zhang Yuanyuan , Arugula Mary , Simonian Aleksandr
Published: February 2020

Multi-enzyme systems have attracted considerable interests due to the versatility for multiplexed detection of different analytes. In this study, a novel layer-by-layer (LbL) assembled multi-enzyme biosensor incorporating acetylcholinesterase (AChE) and organophosphate hydrolase (OPH) was proposed for discriminative detection between organophosphorus (OP) and non-organophosphorus (non-OP) neurotoxins. This was achieved through LbL assembly of electrostatically interacted enzyme armored carbon nanotubes (CNT-OPH and CNT-AChE) with a set of cushioning bilayers consisting of CNT-polyethyleneimine (PEI) and CNT-DNA on glassy carbon electrode with electrochemical detection. OPH catalyzes the hydrolysis of OPs (e.g. paraoxon) and AChE can be used for detection of both OPs and non-OPs (e.g. carbamate) through inhibition assays, and thus makes it possible for detection of OP neurotoxins from multi-analytes samples, and determination of the non-OP neurotoxins to their true concentration with AChE inhibition. Optimization of the LbL architecture was initially conducted with penetration analyses including position of active layer, number of total layers and impedance analyses with respect to different concentration of CNTs. Surface morphology and chemical analyses were characterized with Scanning Electron Microscopy and Raman spectroscopy to have a better understanding of the layered structure. The simple and inexpensive LbL approach can be further extended to a wide variety of enzymes in a multi-detection biosensing system, wherein each analyte could be “fingerprinted” with respect to its catalytic response to different enzymes.
Optical, Nanomechanical and Electrochemical Sensing on a DVD Disc
Authors: Boisen Anja
Published: February 2020

Our vision is to create a platform where optical, nanomecanical and electrochemical sensors can be integrated and read-out using the mechanics and the optics from DVDs and Blu-Rays. Integrating sensors on a disc allows us to use centrifugal microfluidis which has been developed for more than 50 years and which has proven to be a simple and powerful way to manipulate liquid samples without the need of external pumps [1]. As an example, serum can be separated from a whole blood sample in a few minutes by simply spinning the disc and allowing the cellular components to sediment.

Cantilever-like sensors have been integrated on a disc [2] and we now have a method of obtaining large amount of data – allowing us to do statistics on the measurements. Currently, we are studying the specific detection of biomarkers, such as suPAR [3]. Additionally, we try to implement optical microscopy on the spinning platform in order to study and count larger objects such as cells. In this way it will be possible to analyze a given sample for several parameters simultaneously.

Electrodes can also be integrated on the spinning platform [4] and hereby it is possible to perform electrochemical measurements at the same time as having the benefit of the centrifugal liquid handling. As an example it is simple to measure in flow conditions and to perform continuous cyclic voltammograms in different concentrations of electrolytes using built-in valves.

In conclusion, the merger of sensors and centrifugal microfluidcs combined with sensitive and compact read-out possibilities from optical pick-up heads makes it possible to realize full sample pretreatment and read-out in a both fast and compact manner.

References:

1. M. Madou et al., Lab on a CD, Annual Review of Biomedical Engineering, Vol. 8: 601-628, 2016

2. F.G Bosco et al., High throughput label-free platform for statistical bio-molecular sensing, Lab on a Chip, 11(14) 2411-2416, 2011

3. M. Bache et al., Nanomechanical recognition of prognostic biomarker suPAR with DVD-ROM optical technology, Nanotechnology 24 (44), 444011, 2013

4. A.L. Brøgger et al., Centrifugal microfluidic platform with real-time electrochemical detection, 224th Electrochemical Society Meeting, 2013
3D Gel Printers for Soft-Matter Innovation
Authors: Furukawa Hidemitsu , Kawakami Masaru , Gong Jin , Makino Masato , Kabir M. Hasnat , Saito Azusa
Published: February 2020

3D printing is getting quite attractive now and this technology will be useful to make new micro devices and systems for life-innovation. Recently our research group has developed several types of 3D gel printers and now focuses on the application of the 3D gel printers to create new soft and wet systems. We believe the 3D gel printers and their applications will give a huge breakthrough in industrial and mechanical engineering in future.
Unique Applications of Megasonic Energy to MEMS Single Substrate Wet Processes
Authors: Dussault Donald , Dragoi Viorel
Published: February 2020

The use of non-standard materials (e.g. specific substrates or polymer materials) for MEMS applications impose a requirement for the development of new techniques for even well-established process steps. Acoustic energy in the MHz frequency range has been used in the semiconductor industry for various processes such as post CMP cleaning, pre-bond and pre-deposition cleaning as well as photoresist development and stripping.

The work presented in this paper is introducing two different types of applications of acoustic energy in Micro- Electro- Mechanical Systems (MEMS) manufacturing processes: photoresist processing and single wafer cleaning for high cleanliness applications (wafer bonding).

A single wafer spin processer with triangular-shape transducer, the MegPie®, was used for both resist processing and substrate cleaning. The transducer covers a sector of the wafer and is placed in proximity to substrate surface (fig. 1).

The small gap between transducer and substrate is filled with the required process fluid. The shape and positioning of the transducer assure optimal acoustic energy transfer to the process fluid resulting in high uniformity.

Acoustic energy was used in the past in photolithography for enhancing the uniformity of, and accelerate resist development process, initially in LIGA applications.

The new MEMS applications, particularly the ones based on microfluidic structures built in polymer layers coated on a substrate raised the demand of new photolithography processes able to resolve high aspect ratio structures. Such an optimized process addresses new coating/soft baking procedures, new UV exposure techniques as well as new development methods or new resist stripping procedures (fig. 2).

Substrate cleaning during a process flow plays a crucial role for the final success of the process. The use of acoustic energy in the megasonic range in either batch or single wafer configurations is known to significantly enhance the cleaning results.

Wafer bonding is one of the MEMs processes that is very sensitive to particle contamination and demands the use of high efficiency cleaning processes with good uniformity and repeatability.

In a different process flow, particle neutrality and high particle removal efficiency were demonstrated for single wafer cleaning of Si wafers prior to fusion bonding. Experimental results showing the benefits of using acoustic energy for enhanced photoresist development and single wafer cleaning will be presented.

Figure 1. Horizontal spinner chuck system with fluid delivery and MegPie® transducer.
Wafer Bonding for MEMS Vacuum Packaging
Authors: Dragoi Viorel , Pabo Eric
Published: February 2020

Wafer bonding emerged into a powerful technology providing robust solutions for specific manufacturing challenges in Micro- Electro- Mechanical Systems (MEMS) fabrication. Various wafer bonding processes based on different physical and chemical principles can be used in MEMS manufacturing based on the desired level of performance.

Among the MEMS devices which are built using one or more wafer bonding steps the devices operating under vacuum raised new challenges for bonding-based fabrication: the need for achieving vacuum levels down to 10-4 mbar, long term stable, had to be accommodated.

From the broad range of wafer bonding processes only few are compatible with vacuum applications: fusion bonding, anodic bonding, glass frit bonding and metal-based bonding. The outgassing at the bonded interface or of the bonding layer material is extremely important for vacuum applications as a high level of outgassing has a significant impact on final vacuum level in manufactured device. Additionally it has to be considered that the inner surfaces of a device cavity are expected to outgas so this is another factor imposing the low outgassing amount requirement for bonding process and bonding surfaces.

The vacuum levels required would further restrict the process type for specific applications. Applications requiring high vacuum levels are very sensitive to any outgassing during bonding so in some cases a small amount of getter material may be used inside the device cavity in order to compensate for the inner surfaces’ outgassing.

This work reviews the principles of vacuum encapsulation using wafer bonding. Examples showing the suitability of each process for specific applications types will be presented.

A significant challenge in vacuum MEMS fabrication is the lack of analytical methods needed for process characterization or reliability testing. A short overview of the most used methods and their limitations will be presented. Specific needs to be addressed will be introduced with examples.
Analysis of the Loss of Steel-Concrete Bond Due to the Migration of Ions
Authors: Garcia Jorge Pedro , Vazquez Erika Del Carmen , Cardenas Angel Ismael , Barrios Carlos Paulino , Nuñez Rosa Elba
Published: February 2020

ABSTRACT

In this work, the degradation of bond between steel and concrete under cathodic protection conditions (-1000mV≤ E ≤ -850mV vs. Ag/AgCl) and cathodic overprotection ((E < -1000 mV vs Ag/AgCl) by impressed current applied in two mixtures submerged in a solution of 3.5% wt. NaCl was evaluated; the first fabricated from ordinary Portland cement (OPC) and the second by substituting 15% of the cement with fly ash(OPCFA). According to the results of chemical analysis and Electrochemical impedance spectroscopy on the steel-concrete interface, was found an increase in the concentration of potassium, sodium (K+, Na+) and hydrogen (H+) ions . In addition, was observed that for specimens subjected to overprotection presented a higher bond loss, this based on pull out test results also realized.