bluuebunny/crossref_metadata_2025 huggingface dataset:
NMR Investigation of Transport in Polybenzimidazole/Polyphosphoric Acid Membranes Prepared Via Novel Synthesis Route
Authors: Garaga Mounesha G , Murdock Laura , Pranto Tawhid , Suarez Sophia , Greenbaum Steven G. , Benicewicz Brian
Published: July 2021

Previous work by the some of us has demonstrated enhanced electrochemical performance of polybenzimidazole (PBI) membranes with high phosphoric acid content prepared by the so-called PPA process.1 Methods of PBI synthesis that involve casting from an organic solvent cannot incorporate the more rigid PBIs characteristic of the PPA process due to their limited solubility. Recently, a carefully controlled drying method has been discovered in which a gel PBI membrane, made in the PPA process, is transformed into a dense PBI film. This method provides a synthetic route to PBI films without the use of any organic solvents. The dense PBI films with repeat unit para-PBI (Fig.1), were originally developed for flow battery applications. However they also can be re-doped in phosphoric acid to be used as a membrane in high-temperature fuel cells.

The re-doped PBI films have displayed unprecedented ionic conductivity at elevated temperatures, similar to the starting PBI gel membranes prepared by the PPA process1, while also exhibiting enhanced mechanical properties. Temperature-dependent conductivity data for two of these films are displayed below. Sample A is the dried, densified, and re-acidified version of sample B, with a much lower acid content, ~18 mol PA/PBI repeat unit compared to 30 mol PA/PBI RU, respectively, but exhibits comparable conductivity (Fig. 2). Thus, in high-temperature fuel cell operation the electrochemical performance is similar, but performance degradation due to mechanical creep is reduced, leading to greater durability of the Version A PBI.

In attempting to understand the enhanced proton conductivity of the modified PBI membrane despite its lower acid content, we performed both 1H and 31P nuclear magnetic resonance (NMR) measurements. Proton self-diffusion coefficients for four membranes two (A,C) prepared by the modified process and two (B,D) by the original PPA process, were measured by pulsed gradient NMR and plotted in Fig. 3.

The results show significantly enhanced proton diffusivity, both in magnitude and in lower activation energy for sample A, which is consistent with its high conductivity despite lower acid content compared to the original PPA-processed membranes (B, D). We have also performed solid state 1D 31P and 2D 31P{1H} HETCOR NMR measurements, which yield additional information on structural differences between the membranes and how these differences may affect transport properties.

Multinuclear NMR Study of the Effect of Acid Concentration on Ion Transport in Phosphoric Acid Doped Polybenzimidazole Membranes, N. Suarez, N.K.A.C. Kodiweera, P. Stallworth, S.G. Greenbaun, S. Yu, and B. Benicewicz, Journal of Physical Chemistry B, 116, 12545-51(2012).

Figure 1
The Influence of Inclusions on the Electrochemical Behavior of FeCrNiCoMn and Fecrnico Alloys
Authors: Hsu Kuo Min , Chen Sz-Han , Lin Chao-Sung
Published: July 2021

FeCrNiCoMn and FeCrNiCo, which are familiar types of high entropy alloys, have drawn a lot of attention due to their promising mechanical properties at cryogenic temperature. In this research, the microstructure and corrosion behavior of the passive films on the homogenized-hot rolled FeCrNiCoMn and FeCrNiCo alloys were studied in 0.5 M H2SO4. (Mn,Cr)(O,S), (Cr,Mn)O, and MnS were the three main inclusions present in FeCrNiCoMn while CrO was the primary inclusion in FeCrNiCo, as identified by energy dispersive x-ray spectroscopy shown in Figure (a) as representative. After pickling with HF-HNO3 mixed solution according to the standard of ASTM A380M-17, the inclusions were barely found in both alloys.

The corrosion resistance of the passive film was investigated using electrochemical impedance spectroscopy after pickling, as displayed in Figure (b). It was found that the resistance of FeCrNiCoMn improved while FeCrNiCo deteriorated following the pickling. Therefore, inclusions containing Mn were deduced to be detrimental to the corrosion resistance for FeCrNiCo-type high entropy alloys.

Figure 1
Recent Developments in Mechanistic Modeling of Mild Steel Corrosion in H2s Environments
Authors: Sharifi Abdar Payman , Bagheri Hariri Mohiedin , Kahyarian Aria , Nesic Srdjan
Published: July 2021

The corrosion of mild steel in hydrogen sulfide (H2S) environments, as a serious concern in the oil and gas transmission pipelines, has been investigated over the past decades. However, the mechanisms of corrosion of mild steel in H2S environments have been studied in more detail only in recent years. In the present study, a comprehensive mathematical model was developed based on the recent advancement in the mechanistic understanding of corrosion processes in aqueous H2S environments in order to predict the corrosion rate and the polarization response of steel in this system. In this model, the cathodic reaction was developed based on H2S dissociation and its buffering effect. The only cathodic reaction in the system is hydrogen ion reduction. The results confirmed that H2S buffering capacity can thoroughly explain the “double wave” characteristics of the cathodic polarization as well as the increased cathodic limiting current densities of steel in this system. In addition, the anodic iron dissolution reaction was revised by considering the effect of hydrogen sulfide on this reaction. On that account, a reaction pathway with the sulfide intermediates was introduced parallel to the acidic iron dissolution reaction. The developed model was then compared with the available experimental data in the literature, and it was shown that it could reasonably represent the characteristic electrochemical behaviors of H2S corrosion of steel. Furthermore, the predicted corrosion rates are shown to be in good agreement with experimental data over a wide range of experimental conditions.
A Facile in-Situ Electric Field Processing for Li-Ion Battery Electrodes
Authors: Pham Hiep , He Yufang , Li Jie , Sarkar Susmita , Park Jonghyun
Published: July 2021

In this work, an innovative method is proposed during electrode fabrication to improve Lithium ion batteries (LIBs) performance. Conventional electrodes are fabricated using tape-casting, which produces a randomly mixed particle network during casting. Because the particles are randomly placed, the performances of LIBs can be limited due to interferences in Li ion transport caused by bottles and discontinuities in the diffusion path. To address this issue, one possible solution is through electrode micro-structure modification is required to improve electrode performance. It is known that particles tend to form “pearl chains” under the influence of electric field (EF) due to the dipolar interactions between particles. This work investigates the potential of a unique and facile method that applies an EF combined with conventional tape-casting to further improve electrode performance via microstructure modification. We found that the electric field treatment combined with conventional tape-casting can improve battery performance easily and without the need for complex procedures. An analysis considering particle size, slurry rheology, and resulting microstructure was conducted to reveal insight on how the EF could produce the observed improved performance.
Corrosion Behavior of Laser Powder Bed Fusion Fabricated Stainless Steel 316L
Authors: Trisnanto Satria Robi , Wang Xianglong , Brochu Mathieu , Omanovic Sasha
Published: July 2021

Metal additive manufacturing techniques have been recognized for their capability of controlling the crystallographic orientations of stainless steels. However, the inherent anisotropic corrosion behavior has not been extensively studied. In this study, the corrosion properties of 316L stainless steels prepared by Laser Powder Bed Fusion (LPBF) additive manufacturing were investigated. The effects of different crystallographic textures, namely {100}, {110} and {111} on both general and pitting corrosion were characterized by several electrochemical measurements, including Electrochemical Impedance Spectroscopy (EIS), potentiodynamic polarization and Mott-Schottky analysis. The results were also compared to the polycrystalline and wrought 316L counterparts. It was found that the LPBF-{111} sample offered the highest general corrosion resistance, followed by the LPBF-{100}, LPBF-polycrystalline and LPBF-{110} samples (Figure 1). The origin of this trend was related to the atomic surface density. The LPBF-{111} surface exhibited a stronger atomic bonding than that of LPBF-{100} and LPBF-{110} samples, resulting in a higher corrosion activation energy and thus a higher general corrosion resistance. All the LPBF samples also offered a significantly higher pitting corrosion resistance (Figure 2), which was attributed to the lower concentration of oxygen vacancies (donor levels) in the passive film that serve as pits nucleation sites, as observed by the Mott-Schottky analysis (Figure 3).

Figure 1
Effect of Alloy Microstructure on the Corrosion Behavior of Binary Mg-Y Alloys
Authors: Su Yu-You , Chu Peng-Wei
Published: July 2021

In recent years, magnesium alloys continue to receive attention due to their low density and high specific strength compared to other metallic materials. However, the main disadvantage of magnesium alloys originates from the low standard reduction potential of magnesium (-2.37 VSHE), resulting in high reactivity in water-containing environments and susceptibility to corrosion reaction. This kind of corrosion phenomenon exists in most magnesium alloys, thus limiting their practical applications.

At present, many studies showed that adding yttrium to magnesium can simultaneously improve its creep and corrosion resistance. Also, the standard reduction potential of yttrium is similar to that of magnesium, which implies that the galvanic corrosion effect due to the second phases or precipitates would be less pronounced with the addition of yttrium. Therefore, in this study, we investigated the influence of alloy microstructure on the corrosion behavior of two binary magnesium-yttrium (Mg-Y) alloys with different yttrium content.

To understand the dominant features during corrosion tests, this study used an in situ optical microscope (OM)/three-electrode setup to monitor the evolution in corrosion potential and surface corrosion morphology with immersion times of the Mg-Y alloys. With this setup, serious localized corrosion was observed on the Mg-1wt%Y sample. In contrast, localized corrosion on the Mg-7wt%Y sample is mitigated, and the corrosion rate is maintained at a similar level over time. Even though the addition of more Y results in more second phases or precipitates, which could cause some galvanic effect, the corrosion propagation is delayed by the second phase distribution. Through further observation in scanning electron microscope (SEM) and focused ion beam (FIB) systems, the corrosion mechanism of binary Mg-Y alloys will be discussed based on the distribution of local cathodes and anodes on the alloy surface.

Figure 1
(Invited) CMP Market and Technology Trends for 2021
Authors: Rhoades Robert
Published: July 2021

The technology of chemical mechanical polishing (CMP) continues to evolve in multiple dimensions. As one of the key enabling processes for advanced digital devices, such as microprocessors and high-speed memory, CMP is expected to deliver surfaces that are planarized flat and smooth to insanely small dimensions (below 3 nm) while also avoiding even the smallest micro-scratches and without leaving a trace of unwanted residue. These applications also involve tuning the selectivity between two or more different materials to enable topography control at the nanoscale level. CMP also plays a key role in many other emerging markets, such as certain MEMS devices, SiC substrates for power devices, and many more. Examples and information from numerous sources will be combined to provide a wide view of the CMP market and to highlight several trends which have both technical and commercial implications for the near future.
A Method of Chemical-Mechanical Polishing of a Thick Silver Layer on Patterned Silicon Wafer
Authors: Danilkin Evgeny V , Gaydeday Valentina A , Valdez Jose , Piguzov Mikhail Y , Krupnik Vladimir M , Ivanov Igor , Niu Licheng , Ermakov Sergey S
Published: July 2021

Microfluidics-based biochips for biochemical analysis are receiving much attention nowadays. These composite microsystems, also known as lab-on-a-chip or bio-MEMS, offer a number of advantages over conventional laboratory procedures. They automate highly repetitive laboratory tasks by replacing cumbersome equipment with miniaturized and integrated systems, and they enable the handling of small amounts, e.g., micro- and nano-liters, of fluids. Thus they are able to provide ultra-sensitive detection at significantly lower costs per assay than traditional methods, and in a significantly smaller amount of laboratory space. Advances in microfluidics technology offer exciting possibilities in the realm of enzymatic analysis (e.g., glucose and lactate assays), DNA analysis (e.g., PCR and nucleic acid sequence analysis), proteomic analysis involving proteins and peptides, immuno-assays, and toxicity monitoring.

Biochips can be used to detect molecules and/or sequence nucleic acid molecules with aid of an array of electrochemical detector cells containing one or more electrodes per cell where each cell being electrically isolated at a wafer level. For many applications it is beneficial to form a non-planar working electrode using a metal which will corrode during CMP steps.

We’ve developed a novel Ag and Cu integration process which a) solves problems of metal corrosion over 3D topography during CMP step and b) prevents metal surface contamination with CMP residual slurry and polishing byproducts not usually removable by brush or megasonic cleaning.

Electrochemical studies show corrosion behavior of thick Ag layers in different CMP slurries used in this process. SEM images of cross-sectioned metal lined electrochemical cells (vias) clearly demonstrate advantages of new process (right) without traces of corrosion vs conventional CMP process (left).

This process can be used also for polishing of other metals and dielectrics over topography where aggressive cleaning post-CMP steps are not desirable.

Figure 1
Challenges and Solutions for Post-CMP Cleaning of Ceria Particles for Advanced Technology Nodes
Authors: Seo JIhoon , Gowda Akshay , Babu S.V.
Published: July 2021

It has been very difficult to remove smaller ceria particles from oxide surfaces after polishing. As the particle size decreases from 90 to 10 nm, cleaning efficiency of SC1 solution decreases from ~94 % to ~19 %, presumably because smaller ceria particles with a higher surface concentration of Ce3+ are more strongly coupled with silicon dioxide surfaces via strong Ce-O-Si bonding. (1) As was reported earlier, where the cleaning of oxide surfaces of ceria particles from slurries containing no additives, we reported that equimolar solutions containing H2O2 and NH4OH (4.2 mol l−1 each of H2O2 and NH4OH), aided by ultrasonic cleaning, and at high pH could almost completely remove even 10 nm sized ceria particles from silicon dioxide film surfaces. (1)

However, a cleaning solution containing H2O2 and NH4OH at equal molar (4.2 mol l−1) was not effective in cleaning oxide and nitride surfaces contaminated with ceria particles in the presence of additives such as proline and citric acid. (2) Recently, we reported a cleaning solution comprising 1 wt% ascorbic acid, 1 wt% ammonium carbonate and 50 ppm Triton X-100 at pH 12, aided by ultransonic energy, to clean ~30 nm ceria particles from both oxide and nitride films with ~ 99% cleaning efficiencies. The binding between the additive-covered ceria particle particles and the oxide/nitride surfaces could be broken by the nucleophilic attack of hydroxyl ions. Ascorbic acid and ammonium carbonate prevent ceria particle redeposition by adsorbing on the surface of the removed particles and blocking the active Ce3+ species. Triton X-100 reduces adhesion between the particle and the film surfaces during cleaning.

(1) Seo, J., Gowda, A., & Babu, S. V. (2018). Almost complete removal of ceria particles down to 10 nm size from silicon dioxide surfaces. ECS Journal of Solid State Science and Technology, 7(5), P243.

(2) Gowda, A., Seo, J., Ranaweera, C. K., & Babu, S. V. (2020). Cleaning Solutions for Removal of∼ 30 nm Ceria Particles from Proline and Citric Acid Containing Slurries Deposited on Silicon Dioxide and Silicon Nitride Surfaces. ECS Journal of Solid State Science and Technology, 9(4), 044013.
The Effects of Weak Viscoelasticity on Enhanced Particle Removal for CMP
Authors: Cashen Ryan , Ozbek Sebnem , Conradt Jason , Basim Gul Bahar , Walker Travis
Published: July 2021

Highly elastic solutions have been shown to increase particulate removal from silicon wafers, indicating the possibility for reduced reliance upon hazardous chemicals and expensive technologies during post-CMP cleaning processes. We explored the onset of this enhanced removal using micron-sized silica particles in rinsing and siphoning experiments with polymer fluids of high molecular weights that ranged from dilute to entangled concentrations. Increases in particle removal with less than 100 ppm of polymer were observed using both methods, with 10% increased removal observed in the rinsing experiment and 4% increased removal in the siphoning experiment relative to water. Further increases in polymer concentration increased removal significantly, as the solutions entered the semidilute regime. Highly concentrated solutions showed “streaking” patterns, consistent with the viscoelastic nature of the solution. Additionally, we examined particle removal as a spatially dependent parameter in siphoning experiments, showing a plateau of significant removal near the siphon with a sharp decay to a constant value at distances farther away from the siphon.

Rheological characterization of the siphoning and rinsing polymer solutions was used to explore relationships between observed removal and solution properties. Increases in particle removal with solutions having nearly indistinguishable shear rheology and immeasurable extensional character were observed, indicating the need for more precise methods for extensional characterization of dilute polymer solutions. The application of polymer solutions to particle-removal processes has the potential to simplify post-CMP cleaning and reduce the environmental impact that is associated with present particle-removal chemistries.

Figure 1: Removal profile of micron-sized silica particles on glass slides that were subjected to fluid siphoning. Crosshairs indicate the point on the glass slide directly under siphon. Siphoning solutions consisted of water (a), and poly (ethylene oxide) at concentrations of 50, 100, 500, 1000, and 5000 parts-per-million (b-f, respectively). Particulate area was determined by the total pixel count of silica particles in each image. Removal profiles for dilute solutions (a-c) show similar spatial dependence with mild increases in average removal. Removal profiles for semidilute solutions (d-e) show clear radial dependence while the concentrated solution showed behavior associated with significant elastic character.

Figure 1
Understanding the Role of Slurry Additive Molecular Structure on Modulating the Interfacial Dynamics for Oxide CMP Applications
Authors: Wortman-Otto Katherine , Keleher Jason J.
Published: July 2021

As feature sizes continue to shrink well beyond the 7-nm node, understanding the delicate balance present in the chemical mechanical planarization (CMP) process is of utmost importance. In order to achieve high through-put and defect-free CMP processes it is critical to develop predictive analytical techniques that directly correlate to macroscopic STI CMP performance metrics (i.e. oxide/nitride removal, defectivity, and dishing/erosion). This work employed a suite of techniques to monitor the CeO2 nanoparticle interfacial redox processes in the presence of structurally diverse rate modulating additives. Specifically, utilizing a UV-Vis spectroscopic technique, the Ce3+/Ce4+ ratio in the presence of different slurry additives was monitored and proved to directly correlate to removal rate performance (i.e. an increase in Ce3+/Ce4+ ratio shows an increase in rate). This finding coupled with the rate of dissolved O2 evacuation and a modified QCM technique determined the mode of interaction/adsorption which validates that the mechanism of oxide removal does not strictly depend on redox capacity, but also depends on the dynamic O2 equilibrium at the CeO2 nanoparticle surface. In this work, the additives selected provide multiple modes of interaction spanning from noncovalent surface adsorbers to redox active functional groups. It was determined that the modulation of oxide removal was directly related to the distribution of interactions (i.e. steric vs redox) and was highly dependent on the slurry additive functionality.
Observation of Polymer Additive Absorption on Substrates for STI CMP Slurries
Authors: Nomura Satoyuki , Lee Sangchul , Yanagisawa Masahiro , Homma Takayuki
Published: July 2021

High SiO2 to SiN removal rate selectivity and SiN removal rate suppression are indispensable for the shallow trench isolation (STI) CMP slurry and those characteristics are achieved by the polymer additives such as poly-acrylic acid (PAA). Recently, it is reported that the polymers containing hydrophobic and hydrophilic moieties show high selectivity and SiN removal rate suppression [1, 2]. For further improvement of these characteristics, it is important to clarify the mechanisms of the effects of the polymer additives. Several studies have reported that polymer additives preferentially adsorbs on the SiN film resulting high rate selectivity [2, 3]. However, evaluation of adsorption properties of the polymer additives are limited to thermal or electrochemical analysis and few studies have been reported on the direct observation of adsorbed polymers on the SiO2 and SiN surfaces. In this study, we have investigated adsorption properties of the polymer additives by using surface enhanced Raman scattering (SERS) suitable for analysis of trace organic substance on surface in water.

Figure 1 schematically illustrates the measurements of SERS spectra. The SiN/SiO2=30/70 m patterned wafer chip with 1% polymer solution is putted on the quartz glass with Ag nanoparticles, resulting high Raman scattering intensity. Figure 2 show the spectra measured on the SiO2 and SiN films in PAA solution. The peak of CH stretching mode of the PAA polymer chain was observed at approximately 2935 cm-1 on the SiO2 and SiN. This result implies that the polymer is adsorbed both on the SiO2 and SiN. Meanwhile, the case in the polymer containing hydrophobic moiety, the peak attributed to the hydrophobic group is observed at approximately 1000 cm-1. Its intensity is stronger on the SiO2 than SiN, indicating the preferential adsorption of polymer on the SiO2 surface.

The ratio of peak intensity of polymer on the SiN to SiO2 (SiN/SiO2) for PAA (0.26) is higher than the polymer containing hydrophobic moiety (0.03), implying that the adsorption of polymer with hydrophobic moiety to the SiN film is lower than PAA. This suggests that the nitride removal suppression effect is not caused by the adsorption of the polymer on the SiN surface. The influence of other components, such as abrasive, dispersant, pH adjuster is under investigation.

[1] T. Otsuki, US Pat. 2019/0136089 (2019).

[2] N. K. Penta et. al, Appl. Surf. Sci., 283, 986(2013)

[3] S. Kim et. al., J. Colloid Interface Sci., 319, 48 (2008).

Figure 1
Applicate Tangential Flow Filtration System to Improve Post CMP-Cleaning Performance
Authors: Lee Jaewon , Seo Hyeonmin , Park Sang-hyeon , Hong Seokjun , Kim Taesung
Published: July 2021

Chemical mechanical polishing (CMP) is one of the important process steps in semiconductor manufacturing. Several types of abrasives are used in the CMP process, among these, ceria slurry is commonly used through its excellent polishing performance in terms of oxide MRR. However, ceria particles remain on the wafer surface after polishing process as contaminants, and small ceria particles are difficult to remove from wafer surface [1].

In this respect, we focused to treat small ceria particles that interfere with the cleaning process and we applicate the tangential flow filtration (TFF) system before the CMP process. TFF system is a system for separation of particles by Brownian motion, shear-induced diffusion and the mechanism shown in Fig. In this experiment, separation of small ceria particles successfully and it was evaluated by scanning mobility particle sizer (SMPS) analysis. Furthermore, TFF system did not affect the slurry properties of particle mean diameter, pH value, and zeta potential.

In this study, concentration of ceria particles on the wafer surface after CMP process were evaluated by ICP-MS analysis. We calculated the cleaning efficiency with and without TFF separation system. As a result, cleaning efficiency was improved by using TFF system. In addition, the removal rate of SiO2 was almost maintained and the deviation decreased.

References

[1] J. Seo, A. Gowda and S. Babu, ECS Journal of Solid State Science and Technology, 7, P243 (2018).

Figure 1
Prediction of Pad Profile with Pressure Distribution on Diamond Disk at Pad Edge
Authors: KIM Eungchul , Kim Taesung
Published: July 2021

The conditioning process in chemical mechanical polishing (CMP) has an important role to maintain the uniform CMP performance using the diamond attached on a rotating disk. This process maintains the uniform surface roughness and profile of the pad, which results in the steady material removal rate (MRR) and within wafer non-uniformity (WIWNU). The pad uniformity varies greatly by mechanical action in the conditioning process, which is controlled by three mechanical actions: pad/conditioner rotation and sweeping motion of the conditioner arm.

When diamonds scratch on a pad, it is possible to assume that the pressure distribution of a diamond disk is uniform when the disk fully contacts the pad, however, the pressure distribution on a diamond disk is not uniform anymore in a condition with the disk getting off the pad edge. For this reason, when a disk is set to sweep over the pad edge, there were problems with a hump area at the near edge of the pad. This hump area can affect the WIWNU and disturb the elimination of waste matter from the results of CMP.

In this study, the process of conditioning in CMP was analyzed topologically and the program was developed through it. First, the movement of diamond grits calculated and the wear amount was obtained by accumulating the number of points in the mesh containing the coordinates of the diamonds moving at a specific time or distance. Second, indentation depth was analyzed according to the structural properties of a disk and the wear depth of the pad was analyzed in uniform-pressure condition. Third, the pressure distribution on a disk at the pad edge was analyzed as shown in Fig. 1 and adapted to an algorithm predicting pad profile. Finally, we got a simulated pad profile by the algorithm and the results were compared with experimental results in the same condition as shown in Fig. 2.
SEMI Standards for Consumables for Chemical Mechanical Planarization (CMP)
Authors: Tregub Alex , Nguyen Laura
Published: July 2021

IC manufacturing is a sophisticated multistep process where parameters need to be monitored and controlled very tightly. Chemical-mechanical polishing (CMP) is an important step in IC manufacturing that is required to achieve global and local planarity for subsequent lithography processes. CMP has been one of the fastest-growing segments of the semiconductor industry for the past 20 years.

The CMP process is highly critical for achieving sustainable yields in IC manufacturing. This area is also one of the most difficult to control. Quality issues in the CMP process are extremely expensive and can have a significant impact to device yields and reliability. It is known that CMP consumables, such as CMP pads, CMP slurries, and CMP conditioning disks are critical to achieve the target performance in IC manufacturing processes. As such, reducing the variations in CMP consumables properties through standardized metrology tools and processes has become a high priority for advanced IC manufacturing nodes.

In this presentation we will focus on measuring and reporting critical parameters for such critical and widely used consumables in the CMP industry, as CMP pads ([Ref. 1-4]), retainer rings, and conditioning disks.

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For more information please visit our main Web site and current events page. If you have any questions regarding SEMI Standards activities, please contact your local SEMI Standards staff.

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References

1. Jianfeng Luo, David A. Dornfeld: IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING, VOL. 14, NO. 2, MAY 2001

2. SEMI C100 - Guide for Reporting Chemical Mechanical Planarization (CMP) Polishing Pads Hardness Usedpublished by SEMI Standards (https://store-us.semi.org/products/c10000-semi-c100-guide-for-reportingchemical-mechanical-planarization-cmp-polishing-pads-hardness-used-in-semiconductor-

3. A. Tregub, G. Ng, J. Sorooshian and M. Moinpour, "Thermoanalytical characterization of thermoset
Single Particle Inductively Coupled Plasma Mass Spectrometry Study of Ceria Nanoparticle Size Distribution from 300mm Wafer Oxide CMP with Microreplicated Pads
Authors: Zazzera Lawrence , Chan Qilin , Stomberg Jaimie , Simpson Alex , Loesch Chris , Lehuu Duy , Muradian David , Lagudu Uma Ramesh Krishna , Mader Brian
Published: July 2021

This work describes the use of Single Particle Inductively Coupled Plasma Mass Spectrometry (spICP-MS) to measure ceria particle number concentrations and compare changes in size distributions to silicon dioxide wafer removal rates from different chemical mechanical planarization (CMP) processes. Particle number concentrations were measured for the 21 to 559 nm size range at 1nm size resolution. Changes in the ceria particle size distribution after CMP included a decrease in large (>130 nm) particles, an increase in small (<40 nm) particles, an increase in the total number of particles, and a decrease in median particle size. The decrease in median size was as high as 7% and influenced by slurry flow rate, wafer pressure and pad type. A novel microreplicated CMP pad was used which requires no pad conditioning to ensure consistent pad surface features, and the effect of different pad types on removal rate and particle size was isolated. A decrease in the median particle size correlated with higher silicon dioxide removal rates (R2=0.96) for a series of pad types with unique combinations of chemistry and surface features. This new combination of nano particle metrology and control of pad surface features is an improved tool set for modeling advanced CMP processes.
Effect of Retainer Ring Pressure in Ceria Based CMP
Authors: Oh Seungjujn , Kwak Donggeon , Kim Juhwan , Kim Taesung
Published: July 2021

Consumable of Chemical mechanical polishing (CMP) process for global planarization can be divided by pad, conditioner, and slurry. Wafer is applied to pressure on the pad with Slurry. Among the abrasives contained the slurry, although ceria has a low concentration, the removal rate is higher than the silica on inter-layer dielectric (ILD)/inter-metal dielectric (IMD) CMP process. Removal rate (RR) increased by Preston’s equation in proportion to the pressure and rpm (RR=KPV). Where K is a Preston’s constant, P is the main pressure, and V is the relative velocity. Yield improvement method in the semiconductor is a large uniform area after CMP process. In other words, wafer edge area should be minimized. It is important to control uniform pressure distribution. Head structure can be divided by main pressure for removal and retainer ring pressure for prevention out of course. In this research, pressure distribution is demonstrated by controlling the different pressure wafer pressure and retainer ring in a single pressure structure. Removal rate changed by different pressure due to pad deformation. Relative pressure difference changed from 150 to 30 g/cm2 to demonstrate for the reason. In case of the low pressure (1, 2psi), the smaller relative pressure difference increases the uniformity, but the removal rate is decreased. In the high pressure (3, 4 psi), the removal rate and uniformity are not big changes according to relative pressure difference. But parameters of temperature and coefficient of friction are not same. This research investigated the mechanism of how to affect the ceria in ILD/IMD CMP through each parameter.

Figure 1. Removal rate according to relative pressure difference of retainer ring, (a) low pressure, and (b) high pressure.

Figure 1
A Novel Core@Shell Structure of NMC811 with Porous Al2O3 Nanoparticles Adsorbed By LiTFSI in EMMI-TFSI for 18650 Lithium-Ion Batteries
Authors: Chiochan Poramane , Duriyasart Farkfun , Tomon Chanikarn , Jangsan Chonticha , Kullawattanapokin Pattranit , Tejangkura Worapol , Sawangphruk Montree
Published: July 2021

High-Ni layered metal oxide such as LiNi0.8Co0.1Mn0.1O2 (NCM811) is believed to be the next-generation cathode material of high-energy lithium-ion batteries for electric vehicles. Despite its high specific energy > 220 mAh/g, this material usually suffers from poor cyclability as well as sluggish kinetics of lithium diffusion in the thick electrode system, limiting its commercialization. Herein, we have developed the core@shell structure through the dry particle fusion technique, so-called mechanofusion. The amount of finely tuned 2 M LiTFSI in EMMI-TFSI was loaded inside into the pore of alumina oxide (denoted as Li-IL/Al2O3), used as the shell of NMC811 (denoted as NMC@Li-IL/Al2O3). As a result, the Li-IL/Al2O3 shell can elevate and alleviate kinetics and phase transition at H2 to H3, respectively. Consequently, the NMC-based thick electrode in 18650-cylindrical cells can significantly improve an overall cell performance, including a specific discharge capacity, rate capability, and cyclability.
(Invited) Extend Calendar Life of Si Based Li-Ion Batteries
Authors: Zhang Ji-Guang , Yi Ran , Li Qiuyan , Chae Sujong , Cao Xia , Li Xiaolin , Xu Wu
Published: July 2021

Although significant progress has been made in increasing the specific energy and cycle life of silicon (Si) based Li-ion batteries (Si-LIBs), calendar life of these batteries is still less than two years, which is far less than the 10 year life-time required for electrical vehicle applications.1 Graphite anodes undergo only ~10% volume change during cycling, so SEI formed during the initial process does not experience significant mechanical stress during the subsequent cycles. However, the SEI layer formed on Si anodes experiences tremendous mechanical stress during repeated cycles. Most SEI layers formed on the Si surface in conventional electrolytes break down, exposing fresh, lithiated Si or SiO to electrolyte. Thus, significant Si corrosion and electrolyte consumption continuously occur during battery storage, especially in the fully lithiated conditions and elevated temperatures required for the accelerated calendar life test.2 As a result, the impedance of the Si anode will increase much faster than a graphite anode and shorten its calendar life, as observed in nearly all Si-LIBs. In this work, we will report the results of our recent investigation on the fundamental mechanism behind the limited calendar life of Si-LIBs. Several approaches that alleviated degradation of SEI layer and increasing cycle life of Si-LIBs will be discussed, including the nanostructured Si designs that can minimize the external size expansion, minimized particle surface area, and formation of stable SEI layers by localized high concentration electrolyte tailored for Si anode. The combination of these methods can largely extend the calendar life of Si-LIBs and accelerate the application of these batteries for large-scale electrical vehicles and consumer electronics applications.

References:

Brain Cuttingham, Presentation in 2020 AMR review meeting. https://www.energy.gov/eere/vehicles/2020-vehicle-technologies-office-amr-presentations-program
2020.

Idaho-National-Laboratory, United States Advanced Battery Consortium Battery Test Manual For Electric Vehicles. http://www.uscar.org/commands/files_download.php?files_id=517
2020.
Glyoxales As New Electrolytes for Si/Graphite-Anodes in Lithium-Ion Batteries: Analysis of the Solid-Electrolyte Interphase
Authors: Gehrlein Lydia , Leibing Christian , Pfeifer Kristina , Balducci Andrea , Maibach Julia
Published: July 2021

Electrolytes play a crucial role when considering the safety aspects of a Lithium-ion battery. Most commonly, linear and cyclic carbonate-based electrolytes are used commercially. Their advantage lies in the combination of low viscosity and high dielectric constant. However, they display various safety issues such as a limited temperature stability window and high toxicity of the used Li-salt[1]. A new promising alternative are glyoxal based electrolytes using solvents such as tetraethoxy glyoxal (TEG) and tetramethoxy glyoxal (TMG)[2]. Both solvents display low viscosity, low toxicity, high flash points, and very low melting points. Previous works have shown that TEG containing electrolytes display good electrochemical performance in graphite and lithium iron phosphate half-cells as well as in NMC||graphite full-cells[2],[3],[4].

With this work, we report the first use of TEG and TMG based electrolytes for silicon-graphite anodes. Our results show that in terms of capacity retention the TEG-based electrolyte outperforms TMG as well as the 2 reference electrolytes, namely LP30 (LiPF6 in EC/DMC) and L-E/D (LiTFSI-EC/DMC) (see figure). In this presentation, we focus on is the analysis of the solid electrolyte interphase (SEI) formed by these electrolytes. The interphase was studied by photoelectron spectroscopy (XPS) at specific potentials during SEI formation in the first cycle as well as after 100 cycles. We correlate SEI composition and thickness with the electrochemical performance depending on electrolyte composition, suggesting that TEG shows a thinner yet more stable SEI.

References

[1] S. Nowak, M. Winter, J. Electrochem. Soc., 2015, 162 (14) A2500-A2508.

[2] L. H. Hess, A. Balducci, ChemSusChem, 2018, 11, 1919-1920.

[3] L. H. Hess, S. Wankmüller, L. Köps, A. Bothe, A. Balducci, Batteries & Supercaps, 2019, 2, 1-7.

[4] J. Atik, S. Röser, R. Wagner, D. Berghus, M. Winter, I. Cekic-Laskovic, J. Electrochem. Soc., 2020, 167, 040509.

Figure 1
(Invited) Electrolyte Design for Alloys Anodes
Authors: Wang Chunsheng , Borodin Oleg
Published: July 2021

Lithium batteries with Si, Al or Bi microsized (>10 µm) particle anodes promise a high capacity, ease of production, low cost and low environmental impact, yet they suffer from fast degradation and a low Coulombic efficiency. Here we demonstrate that a rationally designed electrolyte (2.0 M LiPF6 in 1:1 v/v mixture of tetrahydrofuran and 2-methyltetrahydrofuran) enables 100 cycles of full cells that contain microsized Si, Al and Bi anodes with commercial LiFePO4 and LiNi0.8Co0.15Al0.05O2 cathodes. Alloy anodes with areal capacities of more than 2.5 mAh cm−2 achieved >300 cycles with a high initial Coulombic efficiency of >90% and average Coulombic efficiency of >99.9%. These improvements are facilitated by the formation of a high-modulus LiF–organic bilayer interphase, in which LiF possesses a high interfacial energy with the alloy anode to accommodate plastic deformation of the lithiated alloy during cycling. This work provides a simple yet practical solution to current battery technology without any binder modification or special fabrication methods.
Improving Cycle Stability of Silicon Anodes Via Control of Charge/Discharge Protocols
Authors: Liu Bingyu , Luo Mei , Ashuri Maziar , Wang Ziyong , Shaw Leon
Published: July 2021

It is well-known that silicon anodes experience large volume expansion (> 300%) when fully lithiated. By introducing engineered voids into a Si/C core-shell structure to form Si@void@C structure, volume expansion of Si@void@C particles can be minimized, thereby improving the cycle stability of the Si@void@C electrode. This study reveals that by adjusting charge/discharge protocols the cycle stability of the Si@void@C electrode can be further enhanced. It is shown that both lower and upper cutoff voltages during charge and discharge, respectively, have strong influence on the cycle stability of the Si@void@C electrode. These phenomena are interpreted based on volume expansion and shrinkage of the Si@void@C electrode as a function of lower and upper cutoff voltages. The post-mortem analysis of the thickness change in the cycled electrode cross-section offers corroborating evidence to support the enhancement of the cycle stability of Si@void@C electrodes via control of charge/discharge protocols to minimize the volume change of Si@void@C electrodes with a small sacrifice in their specific capacity.
The Role of Native Oxide in Silicon Anode Lithiation Investigated By in-Situ X-Ray Photoelectron Spectroscopy
Authors: Frisco Sarah , Teeter Glenn
Published: July 2021

Understanding fundamental aspects of silicon anode lithiation is important for designing improved battery chemistries with more stable interfaces. The present study focuses on the role that native SiO2 plays in early-stage lithiation and its conversion into relevant inorganic components of the solid-electrolyte interphase (SEI) on a silicon anode. The study uses the virtual-electrode (VE) approach to deliver a square-wave pulsed flux of Li+ ions to a native-SiO2/Si(001) wafer anode surface while monitoring compositional and chemical-state changes via in situ X-ray photoelectron spectroscopy (XPS). Lithiation proceeds initially by conversion of the native SiO2 layer into two distinct LiySiOx phases. Consistent with the Li-Si-O equilibrium phase diagram, the onset of LixSi formation is observed only after all SiO2 has been converted to lithium silicate phases. As lithiation proceeds and an increasing fraction of the Si0 observable within the XPS information depth (~10nm) is converted to LixSi, evidence for a third LiySiOx phase was observed. As these phase transformations occurred, the pulsed VE-XPS approach revealed chemically resolved changes in overpotential via transient Li+ion-induced shifts of core-level binding-energies (BEs) associated with the various phases. Through this analysis, we show how nanoscale native SiO2 significantly contributes to net overpotential during the initial stages of lithiation, and how overpotential dramatically decreases as SiO2 converts to LiySiOx.
Esters As Cosolvents for Improving Low Temperature Cycling Performance of Ncm 523/Graphite Cells
Authors: Rodrigo Undugodage Nuwanthi Dilhari , Lucht Brett L.
Published: July 2021

Lithium-ion batteries (LIB) are known to have high energy density and power density compared to other electrochemical storage devices. However, LIB’s applications and performances are vastly limited by the working temperature range of electrolyte formulation, particularly at low temperatures. In current state-of-the-art LIB electrolytes, low temperatures cause a drastic decrease in Li+ ion conductivity while increasing cell resistance which ultimately leads to a large capacity drop. However, using electrolyte solvents with a high dielectric constant and low melting points improves the ionic conductivity and gives a lower viscosity. Furthermore, incorporating film forming additives can improve the sluggish Li+ ion transfer kinetics at the electrode/electrolyte interphase by forming a thin and conductive solid electrolyte interphase (SEI). In this study, two ester cosolvents, namely methyl propionate (MP) and methyl acetate (MA), were used in a tertiary electrolyte formulation made of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) along with film forming additives, 2% fluoroethylene carbonate (FEC) or 2% vinylene carbonate (VC) in order to improve the low temperature performance in NCM 523/Graphite full cells at -20 °C. Ex-situ surface film analysis of extracted electrodes was carried out by X-ray photoelectron spectroscopy (XPS) and attenuated total reflection infrared (ATR-IR) spectroscopy to better understand the improved cycling performance seen with the ester formulations.
Revealing Ageing Mechanisms of Ni-Rich NCA in State-of-the-Art Commercial High-Energy Li-Ion Cells
Authors: Mikheenkova Anastasiia , Smith Alexander James , Roy Chowdhury Niladri , Thiringer Torbjörn , Wreland Lindström Rakel , Pay Gómez Cesar , Lacey Matthew , Berg Erik J.
Published: July 2021

Ni-rich Li[NixCoyAlz]O2 (NCA) positive electrode materials are today found in the state-of-the-art high-energy Li-ion batteries [1]. Considering the high production cost of these batteries combined with the scarcity and environmental impact of the included transition metals, large benefits would be gained by prolonging the lifetime of the Li-ion cells. Although NCAs are the key to a high energy density, they are generally believed to be the main culprit behind the failure of the cell [2]. The NCAs are subjected to adverse structural phase transformation and display increased surface reactivity towards the electrolyte upon electrochemical charging [3]. Particle cracking, surface reconstruction and associated electrolyte decomposition are well-known processes leading to both Li+ inventory loss and increased cell impedance. Yet, several aspects governing these underlying ageing mechanisms remain to be explained, particularly for Ni-rich NCAs contained in state-of-the-art commercial Li-ion cells today.

Herein we present a combined structural and electrochemical study based on detailed X-ray diffraction analysis, electron microscopy, and intermittent current interruption cycling. The extent and impact of the various ageing mechanisms at each stage of battery life will be assessed and discussed [4].

Reference
s
:

[1] Yuliya Preger et al 2020 J. Electrochem. Soc. 167 120532

[2] A. Manthiram, B. Song, and W. Li, Energy Storage Mater. 6 (2017) pp. 125–139.

[3] E. Flores, P. Novák, U. Aschauer, and E. J. Berg, Chem. Mater. 2020, 32, 1, 186–194

[4] Mikheenkova et al. In preparation.