Plasma Damage Research Articles

The influence of low-level laser therapy on parameters of oxidative stress and DNA damage on muscle and plasma in rats with heart failure.

In heart failure (HF), there is an imbalance between the production of reactive oxygen species and the synthesis of antioxidant enzymes, causing damage to the cardiovascular function and increased susceptibility to DNA damage. The aim of this study was to evaluate the influence of low-level laser therapy (LLLT) on parameters of oxidative stress and DNA damage in skeletal muscle and plasma of rats with HF. Wistar rats were allocated into six groups: "placebo" HF rats (P-HF, n = 9), "placebo" Sham rats (P-sham, n = 8), HF rats at a dose 3 J/cm(2) of LLLT (3 J/cm(2)-HF, n = 8), sham rats at a dose 3 J/cm(2) of LLLT (3 J/cm(2)-sham, n = 8), HF rats at a dose 21 J/cm(2) of LLLT (21 J/cm(2)-HF, n = 8) and sham rats at a dose 21 J/cm(2) of LLLT (21 J/cm(2)-sham, n = 8). Animals were submitted to a LLLT protocol for 10 days at the right gastrocnemius muscle. Comparison between groups showed a significant reduction in superoxide dismutase (SOD) activity in the 3 J/cm(2)-HF group (p = 0.03) and the 21 J/cm(2)-HF group (p = 0.01) compared to the P-HF group. 2',7'-Dihydrodichlorofluorescein (DCFH) oxidation levels showed a decrease when comparing 3 J/cm(2)-sham to P-sham (p = 0.02). The DNA damage index had a significant increase either in 21 J/cm(2)-HF or 21 J/cm(2)-sham in comparison to P-HF (p = 0.004) and P-sham (p = 0.001) and to 3 J/cm(2)-HF (p = 0.007) and 3 J/cm(2)-sham (p = 0.037), respectively. Based on this, laser therapy appears to reduce SOD activity and DCFH oxidation levels, changing the oxidative balance in the skeletal muscle of HF rats. Otherwise, high doses of LLLT seem to increase DNA damage.

Diamond field effect transistors with a high-dielectric constant Ta2O5 as gate material

A Ta2O5/Al2O3 bilayer gate oxide with a high-dielectric constant (high-k) has been successfully applied to a hydrogenated-diamond (H-diamond) metal-insulator-semiconductor field effect transistor (MISFET). The Ta2O5 layer is prepared by a sputtering-deposition (SD) technique on the Al2O3 buffer layer fabricated by an atomic layer deposition (ALD) technique. The ALD-Al2O3 plays an important role to eliminate plasma damage for the H-diamond surface during SD-Ta2O5 deposition. The dielectric constants of the SD-Ta2O5/ALD-Al2O3 bilayer and single SD-Ta2O5 are as large as 12.7 and 16.5, respectively. The k value of the single SD-Ta2O5 in this study is in good agreement with that of the SD-Ta2O5 on oxygen-terminated diamond. The capacitance–voltage characteristic suggests low interfacial trapped charge density for the SD-Ta2O5/ALD-Al2O3/H-diamond MIS diode. The MISFET with a gate length of 4 µm has a drain current maximum and an extrinsic transconductance of −97.7 mA mm−1 (normalized by gate width) and 31.0 ± 0.1 mS mm−1, respectively. The effective mobility in the H-diamond channel layer is found to be 70.1 ± 0.5 cm2 V−1 s−1.

Protective effect of Euterpe oleracea Mart (açaí) extract on programmed changes in the adult rat offspring caused by maternal protein restriction during pregnancy.

This study examined the effect of açaí (Euterpe oleracea Mart.) seed extract (ASE) on cardiovascular and renal alterations in adult offspring, whose mothers were fed a low-protein (LP) diet during pregnancy. Four groups of rats were fed: control diet (20% protein); ASE (200 mg/kg per day); and LP (6% protein); LP + ASE (6% protein + ASE) during pregnancy. After weaning, all male offspring were fed a control diet and sacrificed at 4 months old. We evaluated the blood pressure, vascular function, serum and urinary parameters, plasma and kidney oxidative damage, and antioxidant activity and renal structural changes. Hypertension and the reduced acetylcholine-induced vasodilation in the LP group were prevented by ASE. Serum levels of urea, creatinine and fractional excretion of sodium were increased in LP and reduced in LP + ASE. ASE improved nitrite levels and the superoxide dismutase and glutathione peroxidase activity in LP, with a corresponding decrease of malondialdehyde and protein carbonyl levels. Kidney volume and glomeruli number were reduced and glomerular volume was increased in LP. These renal alterations were prevented by ASE. Treatment of protein-restricted dams with ASE provides protection from later-life hypertension, oxidative stress, renal functional and structural changes, probably through a vasodilator and antioxidant activity.

Etching of pentacene film using atomic hydrogen generated on heated tungsten

An etching method for organic semiconductor materials called atomic hydrogen treatment was investigated. In this method, the high-density atomic hydrogen is generated on a heated tungsten surface by a catalytic cracking reaction. Also pentacene films are etched at 0.07 nm/s in tungsten temperature of 1700 °C and sample holder of 60 °C. It is considered that the patterning of organic films using atomic hydrogen at low temperatures without plasma damage is useful for the realization of flexible semiconductor devices.

(Invited) High Pressure Sputtering for High-K Dielectric Deposition. Is It Worth Trying

(Invited) High Pressure Sputtering for High-K Dielectric Deposition. Is It Worth Trying

Processing Challenges of CMOS Integration of Finfets with All-Last Gate Stacks

FinFETs with 20nm BEOL with one generation improvement in performance and power efficiency has announced for mass production by leading IC companies. The processing details, however, have never been reported. In this talk, processing challenges of CMOS integration of FinFETs with all-last gate stacks is presented based on our recent results. Special processing issues in Fin and the replacement gate (RMG) formation, RMG filling with high-k/metal gate and self-aligned contact (SAC) module will be discussed. It is found that the etching of dummy gate of FinFETs behaves differently from that in planar MOSFETs. Thick enough dummy SiO2 is needed for protecting the Fin from plasma damage during dummy gate etch. Wet removal of dummy SiO2 in gate area faces also the risk of Fin damage, due to galvanic corrosion, and thus prefers to a thin SiO2 for control of the wet processing window. It is shown that TaN coverage of the channel area is important in single dielectric dual metal gate stack, where a p-FET stack is first deposited in both n- and p-area, and then the top work function metals in n-area will be removed before n-FET metal deposition. ALD TaN is studied systematically for the the etch stopper application. It is found that the largest issue in the CMOS integration of the FinFETS is n-work function metal deposition. Poor TiAl coverage induces large Vt variation. ALD TiAl could be a good solution for n-work function metal deposition. Filling of the RMG, which has extremely large AR in FinFETs, and SAC is a big challenge. A systematic study of ALD W shows that its advantage in properties such as adhesion, conformality and good constraint by TiN barrier enables good fill of the gaps. Electrical characterizations of the FinFETs are presented in order to show the impact of the above issues to device behavior variation.

Stunting is characterized by chronic inflammation in Zimbabwean infants (620.4)

Background Stunting affects one‐third of children in developing countries, but the causes remain unclear. The objective of this study was to investigate whether low‐grade inflammation suppresses the growth hormone‐IGF axis and mediates stunting.Methods We conducted a case‐control study of 202 HIV‐unexposed Zimbabwean infants who were stunted (height‐for‐age Z‐score (HAZ)<‐2; cases) or non‐stunted (HAZ>‐0.5; controls) at 18mo. We measured biomarkers of intestinal damage (I‐FABP), inflammation (CRP, AGP, IL‐6) and growth hormone‐IGF axis (IGF‐1, IGFBP3) in infant plasma at 6w and 3, 6, 12 and 18mo, and in paired maternal‐infant plasma at birth. Adjusted mean differences between biomarkers were estimated using regression models. Multivariate odds ratios of stunting were estimated by logistic regression.Results At birth, cases were shorter than controls and their mothers had lower levels of IGF‐1 (adjusted mean difference(95%CI) ‐21.4(‐39.8, ‐3.1) ng/mL). From 6w‐12mo of age, levels of CRP and AGP were consistently higher and IGF‐1 and IGFBP3 lower in cases versus controls; IGF‐1 correlated inversely with inflammatory markers at all time‐points. I‐FABP increased between 3‐12mo, indicating extensive intestinal damage, which was similar in cases and controls. In multivariate analysis, higher levels of CRP (aOR 3.06 (95%CI 1.34, 6.99); P=0.008) and AGP (aOR 7.87 (95%CI 0.74, 83.74); P=0.087) during infancy were associated with stunting.Conclusions Stunting began in utero and was associated with low maternal IGF‐1 at birth. Inflammatory markers were higher in cases than controls from 6w of age and were associated with lower levels of IGF‐1 throughout infancy. Higher levels of CRP and AGP during infancy were associated with stunting. These findings suggest that an extensive enteropathy occurs during infancy and that low‐grade chronic inflammation may impair infant growth.Grant Funding Source: Supported by Wellcome Trust (UK)

Effect of Sub 2-Nm Pt Nanoparticle on the Conduction Properties of Graphene Based Field Effect Transistor

Graphene-based transistors are attractive platforms due to graphene’s promising electrical properties. Currently, depositing and controlling the size distribution of metal nanoparticles (NPs) on a support surface, such as graphene, without damaging the support is an issue faced in applications involving metal (NPs) in new age electronics. To overcome this barrier, we have developed a low power tilted target sputtering process for achieving sub-2 nm metal (NPs) on graphene with controlled sizes, number densities, and narrow size distributions. In this report, we study the unique properties of platinum (Pt) NPs and their applications in graphene-based FETs by modifying the conduction channel with sub-nm Pt NPs. By using ultra-small size Pt NPs with quantized energy level, we influence the electrical properties of large area single layer graphene through both electron transfer and carrier scattering, resulting in large Dirac point shifting (0.15MV/m for 300nm of SiO2 as blocking oxide) in the I-V characteristics and change in conductivity, respectively; all of which could be helpful to better understand the metal NP-Graphene interaction. We also show that the plasma damage created on the graphene surface from the sputter deposition of metal nanoparticles can be removed by 250 oC annealing in hydrogen.

Interface and plasma damage analysis of PEALD TaCN deposited on HfO2 for advanced CMOS studied by angle resolved XPS and C–V

Plasma enhanced atomic layer deposition (PEALD) TaCN deposited on HfO2 was studied by X-ray photoelectron spectroscopy (XPS) to understand the reactions taking place at the interface and connect them with C–V electrical characteristics of MOS devices. Moreover, angular resolved XPS (AR-XPS) was used for composition depth profiling of TaCN/HfO2/SiO2/Si stacks. Clear oxidation of the metal electrode through TaO bonding formation and migration of N in the dielectric with HfN are shown. These modifications of chemical bonding give an insight on the electrical results. Low equivalent oxide thicknesses (EOT), as low as 0.89nm and current leakage improvement by more than 5 decades, are observed for deposition with low plasma power and can be related to HfN content in HfO2 layer. The increase of plasma power used for TaCN deposition results in densification of the layer and promotes the creation of TaC in TaCN material. However H2 plasma has an impact on HfO2 with a reduction and scattering of the measured current leak gain. TaCN/HfO2 interface is also impacted with further creation of TaOx, leading to an increase of EOT when plasma power is increased. Based on these findings, reaction mechanisms with the corresponding Gibbs free energy are proposed.

Damage of Cr film by oxygen plasma

This work systematically investigates damage of Cr film grown on Si, SiO2 or SiNx-topped Si substrates and the adhesive Cr layer in Cr/Au or Cr/Cu/Au multilayers by oxygen plasma ashing. When the microwave power and substrate temperature are set below the critical conditions, the oxygen plasma does not attack the Cr film. However, beyond the critical parameters, the Cr film is not secure in oxygen plasma. Without additional heating, the Cr films grown on Si substrate and on SiO2 and SiNx-topped Si substrate are etched by oxygen plasma under power ≥300W and ≥200W, respectively. When the substrate is heated up to 100°C, a microwave power of 100W is enough to remove the Cr film. The adhesive Cr layer in metal multilayers is untouched by oxygen plasma until the microwave power rises up to 400W and the substrate is heated up to 100°C, this could result from a thicker Cr2O3 layer. When subjected to energetic oxygen ions or radicals bombardment, the top Cr2O3 layer could be dissociated to volatile Cr oxides, and at the same time, the underneath Cr film is further oxidized as Cr2O3 and volatile Cr oxides, the thicker the Cr2O3 layer, the higher the resistance of the Cr film to attack by oxygen plasma. These studies provide an important guideline for avoiding damage of oxygen plasma to the device.

Plasma Damage Improvement during Cu Capping Layer Deposition for Advanced Nodes

Cu capping layer deposition plays an important role in BEOL plasma induced damage. In this paper, PID issue by Cu capping layer deposition process studied. The PID performance was studied with Cu capping layer deposition recipe optimization. And, the impact on PID performance of different Cu capping layer equipment was also compared. The PID performance is different with antenna ratio increase, both NMOS and PMOS PID performance with different antenna ratio have been investigated. In order to get clear supporting evidence for plasma damage, plasma charged voltage of wafer surface is also studied by Quantax in this paper. Finally we developed an optimized Cu capping layer deposition process with acceptable PID performance and without any reliability degradation.

The Study of How to Reduce ILD Loss in High-k and Metal Gate Last Process

High-k last and metal gate last process becomes the main stream in 20nm and beyond technology. In high-k last process, the thermal dummy gate oxide (DGO) must be removed before the growth of interfacial layer (IL). In conventional process, to avoid the plasma damage to the device, wet etch is the most popular process to remove DGO. Because the etch rate of ILD(inter layer dielectric) oxide and CESL(CT etch stop layer) layers is much higher than thermal oxide, during the removal of DGO, serious ILD and CESL loss is observed, which will induce many of following process issues, such as high-k/metal residue, gate height variation, work function shift, etc. In this paper, multi-methods are studied to reduce the loss of ILD and CESL layer. The study mainly includes improvements on film quality and optimization of removal process. Finally, the selectivity of ILD oxide and CESL to thermal dummy gate oxide can reach ~1:1.

Stunting is characterized by chronic inflammation in Zimbabwean infants.

BackgroundStunting affects one-third of children in developing countries, but the causes remain unclear. We hypothesized that enteropathy leads to low-grade inflammation, which suppresses the growth hormone-IGF axis and mediates stunting.MethodsWe conducted a case-control study of 202 HIV-unexposed Zimbabwean infants who were stunted (height-for-age Z-score (HAZ) <−2; cases) or non-stunted (HAZ >−0.5; controls) at 18 months. We measured biomarkers of intestinal damage (I-FABP), inflammation (CRP, AGP, IL-6) and growth hormone-IGF axis (IGF-1, IGFBP3) in infant plasma at 6 weeks and 3, 6, 12 and 18 months, and in paired maternal-infant plasma at birth. Adjusted mean differences between biomarkers were estimated using regression models. Multivariate odds ratios of stunting were estimated by logistic regression.ResultsAt birth, cases were shorter (median (IQR) HAZ −1.00 (−1.53, −0.08) vs 0.03 (−0.57, 0.62,); P<0.001) than controls and their mothers had lower levels of IGF-1 (adjusted mean difference (95%CI) −21.4 (−39.8, −3.1) ng/mL). From 6 weeks to 12 months of age, levels of CRP and AGP were consistently higher and IGF-1 and IGFBP3 lower in cases versus controls; IGF-1 correlated inversely with inflammatory markers at all time-points. I-FABP increased between 3–12 months, indicating extensive intestinal damage during infancy, which was similar in cases and controls. In multivariate analysis, higher log10 levels of CRP (aOR 3.06 (95%CI 1.34, 6.99); P = 0.008) and AGP (aOR 7.87 (95%CI 0.74, 83.74); P = 0.087) during infancy were associated with stunting. There were no associations between levels of I-FABP, IL-6, sCD14 or EndoCAb and stunting.ConclusionsStunting began in utero and was associated with low maternal IGF-1 levels at birth. Inflammatory markers were higher in cases than controls from 6 weeks of age and were associated with lower levels of IGF-1 throughout infancy. Higher levels of CRP and AGP during infancy were associated with stunting. These findings suggest that an extensive enteropathy occurs during infancy and that low-grade chronic inflammation may impair infant growth.

Micro‐chemical investigation of thick W coating on AISI 420 martensitic steel

Tungsten is a favorable material for protecting mechanical components such as thermal shields and divertor parts from plasma damage in nuclear fusion reactors. A thick coating of W has been developed on AISI 420 martensitic stainless steel substrate by means of plasma spray technique. Plasma spraying has been used for its simplicity, the possibility to cover complex and extended surfaces and the relatively low cost. An appropriate interlayer has been optimized to increase the adhesion of W coating on the steel substrate and to provide a soft interface with intermediate thermal expansion coefficient for better thermo‐mechanical compatibility. The present work describes and discusses the results of micro‐chemical investigations on coating and interface by X‐ray photoelectron spectroscopy and Auger electron spectroscopy. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Parasites in the City: Degree of Urbanization Predicts Poxvirus and Coccidian Infections in House Finches (Haemorhous mexicanus)

BackgroundUrbanization can strongly impact the physiology, behavior, and fitness of animals. Conditions in cities may also promote the transmission and success of animal parasites and pathogens. However, to date, no studies have examined variation in the prevalence or severity of several distinct pathogens/parasites along a gradient of urbanization in animals or if these infections increase physiological stress in urban populations.Methodology/Principal FindingsHere, we measured the prevalence and severity of infection with intestinal coccidians (Isospora sp.) and the canarypox virus (Avipoxvirus) along an urban-to-rural gradient in wild male house finches (Haemorhous mexicanus). In addition, we quantified an important stress indicator in animals (oxidative stress) and several axes of urbanization, including human population density and land-use patterns within a 1 km radius of each trapping site. Prevalence of poxvirus infection and severity of coccidial infection were significantly associated with the degree of urbanization, with an increase of infection in more urban areas. The degrees of infection by the two parasites were not correlated along the urban-rural gradient. Finally, levels of oxidative damage in plasma were not associated with infection or with urbanization metrics.Conclusion/SignificanceThese results indicate that the physical presence of humans in cities and the associated altered urban landscape characteristics are associated with increased infections with both a virus and a gastrointestinal parasite in this common songbird resident of North American cities. Though we failed to find elevations in urban- or parasite/pathogen-mediated oxidative stress, humans may facilitate infections in these birds via bird feeders (i.e. horizontal disease transmission due to unsanitary surfaces and/or elevations in host population densities) and/or via elevations in other forms of physiological stress (e.g. corticosterone, nutritional).

A Remote-Oxygen-Plasma Surface Treatment Technique for III-Nitride Heterojunction Field-Effect Transistors

We present a paper on the influence of an oxygen-plasma treatment technique for III-nitride (III-N) heterojunction field-effect transistors (HFETs) using a plasma-enhanced atomic layer deposition (PE-ALD) system. The oxygen plasma is excited in a remote location to avoid the plasma damage. After the plasma treatment, the threshold voltage was shifted from -0.25 to 0 V and a two-orders-of-magnitude reduction of the drain leakage current was observed in recessed-gate AlGaN/AlN/GaN HFETs. The capacitance-voltage characteristics of gate diodes showed indistinguishable hysteresis. Improved gate-lag and lowered dynamic ON-resistance were also observed in the fabricated AlGaN/AlN/GaN HFETs after the oxygen-plasma treatment. The results indicate that the oxygen-plasma treatment using a PE-ALD system could be a promising approach to improve the device switching performance in III-N HFETs.

Improvements in passivation effect of amorphous InGaZnO thin film transistors

The performance of amorphous InGaZnO thin film transistors (a-IGZO TFTs) degrades apparently due to “passivation effect”, i.e. back-channel plasma damage from passivation layer deposition. In this letter two effective measures were taken to improve this effect. Double-stacked channel layer (DSCL), a novel active-layer structure, was proposed with which a-IGZO TFTs might suffer less plasma damage from passivation layer deposition, as was confirmed by investigation with high resolution transmission electron microscope (SRTEM). Moreover, two-stage annealing (TSA) method showed more advantages over conventional heat treatment at one fixed temperature in curing back-channel plasma damage caused by passivation deposition. The a-IGZO TFTs, Combined with these two improving methods, exhibited fine performance parameters (μFE of 2.0cm2/Vs, SS of 1.5V/decade, Ion/Ioff of 106 and Vth of 1.5V) as well as satisfactory ambient stability, meeting the requirements for their applications in flat panel displays.

Oxygen plasma immersion ion implantation treatment to enhance data retention of tungsten nanocrystal nonvolatile memory

Data retention characteristics of tungsten nanocrystal (W-NC) memory devices using an oxygen plasma immersion ion implantation (PIII) treatment are investigated. With an increase of oxygen PIII bias voltage and treatment time, the capacitance–voltage hysteresis memory window is increased but the data retention characteristics become degraded. High-resolution transmission electron microscopy images show that this poor data retention is a result of plasma damage on the tunneling oxide layer, which can be prevented by lowering the bias voltage to 7 kV. In addition, by using the elevated temperature retention measurement technique, the effective charge trapping level of the WO3 film surrounding the W-NCs can be extracted. This measurement reveals that a higher oxygen PIII bias voltage and treatment time induces more shallow traps within the WO3 film, degrading the retention behavior of the W-NC memory.

Increased Oxidative DNA Damage in Seminal Plasma of Infertile Men with Varicocele

Objective: To investigate the oxidative DNA damage in the seminal plasma and spermatozoa of infertile men with varicocele and to evaluate the potential relationship between oxidative DNA damage and varicocele. Methods: This case-control study recruited 180 infertile men with varicocele and 199 infertile men without varicocele and 168 fertile male control subjects. Semen parameters, seminal plasma 8-hydroxy-2-deoxyguanosine (8-OHdG) and sperm DNA Fragmentation Index (DFI) were assessed. Results: Compared to the infertile men without varicocele and control subjects, infertile men with varicocele exhibited lower sperm concentration, lower progressive motility, lower vitality and lower percentage of normal morphology (all P=0.0001). The seminal content of 8-OHdG and sperm DFI were higher in infertile men with varicocele than in infertile men without varicocele and in the control group (all P<0.001). A positive correlation was observed between the 8-OHdG levels and DFI (P<0.001). However, There were negative correlations between seminal plasma 8-OHdG levels or sperm DFI with sperm concentration, progressive motility, vitality, and normal forms in the varicocele group (all P<0.001). Furthermore, the seminal plasma 8-OHdG content and sperm DFI was significantly higher in grades II and III than in grade I after controlling age, BMI, abstinence period and semen parameters. Conclusions: Infertile men with varicocele have greater oxidative DNA damage in seminal plasma and spermatozoa than the subjects without varicocele. The degrees of varicocele and DNA damage were associated with decreased semen quality in infertile men with varicocele.

Correlation between Plasma Damage and Dielectric Reliability for Ultra-Porous Low-k Materials

The effects of plasma damage on dielectric reliability were studied using voltage ramp stress experiments. Altering ramp rates allowed us to identify the main mechanisms for failure, namely intrinsic and metal catalyzed failure. Failure mechanisms are identified using ∂ln (tBD)/∂ln (R) trends for pristine and plasma damaged SiCOH films. Failure dynamics are discussed for 7% and 25% porous SiCOH films. O2 plasma treatment was found to lower the breakdown strength of 7% SiCOH from 79.5 V to 67.1 V at low ramp rates (0.01 V/s), and from 135.7 V to 109.3 V at fast ramp rates (20 V/s). The breakdown strength of 25% SiCOH films was enhanced from 41.0 V to 55.4 V after plasma treatment at slow ramp rates. However, at fast ramp rates, the plasma treatment lowered the breakdown voltage from 112.0 V to 99.7 V. The enhancement in breakdown strength for highly porous samples under slow ramp rates is attributed to film densification upon plasma treatment, while the deterioration at fast ramp rates is associated with the generation of defects catalyzing dielectric failure.