Silicon Cleaning Methods Compared at Metal Concentrations Below 1E10 atoms/cm2

AbstractAn alkaline aqueous silicon wafer cleaner has been developed which reduces trace metal contamination levels on “p-type” unpatterned silicon wafers to below 1E10 atoms/cm2 without acidic cleaning. This patented technology uses a specially formulated buffering system consisting of an oxidation resistant chelating agent and salt of a weak acid. The aqueous cleaner maintains a stable pH of about 9.5 over a wide range of dilutions, temperatures, hydrogen peroxide concentrations and bath aging times. A single-step bath, megasonic bath or spray clean with this formulation leaves the chemical oxide on the silicon wafer surface free of particles, atomically smooth, free of organics and lower in trace metal contamination levels than similar surfaces cleaned with conventional formulations.An analytical method was developed which allows the reliable detection of trace metals on silicon wafer surfaces down to 1E8 atoms/cm2 for aluminum, calcium, copper, iron, nickel, sodium and zinc. The procedure uses an ICP-MS with a concentric nebulizer and a desolvator. The acids used were ultrapure to keep the blanks to a very minimum and analyses were run in a class 10 clean room. The trace metals on the wafer were extracted using known amounts of ultrapure acids and were directly aspirated using a special arrangement with the concentric nebulizer. The J.T. Baker cleaner was compared to and outperformed the conventional RCA-1&2 clean and dilute RCA-1&2 chemistries using ultrapure ammonium hydroxide, hydrochloric acid and hydrogen peroxide.

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Impact of municipal solid waste dumpsites on trace metal contamination levels in the surrounding area: a case study in West Africa, Abidjan, Cote d’Ivoire

Environmental Science and Pollution Research ◽

10.1007/s11356-021-13987-3 ◽

2021 ◽

Author(s):

Naminata Sangaré Soumahoro ◽

N’guessan Louis Berenger Kouassi ◽

Koffi Marcellin Yao ◽

Edith Kouassi Kwa-Koffi ◽

Aka Marcel Kouassi ◽

...

Keyword(s):

West Africa ◽

Trace Metal ◽

Municipal Solid Waste ◽

Solid Waste ◽

Cote D'ivoire ◽

Metal Contamination ◽

Surrounding Area ◽

Trace Metal Contamination ◽

Contamination Levels

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Analysis of Trace Metal Contamination in Pahang River and Kelantan River, Malaysia

MATEC Web of Conferences ◽

10.1051/matecconf/201926604003 ◽

2019 ◽

Vol 266 ◽

pp. 04003 ◽

Cited By ~ 1

Author(s):

Norpadzlihatun Manap ◽

Kavitha Sandirasegaran ◽

Noor Shahifah Syahrom ◽

Amnorzahira Amir

Keyword(s):

Trace Metals ◽

Trace Metal ◽

Metal Contamination ◽

Sediment Quality ◽

Primary Objective ◽

Trace Metal Concentration ◽

Trace Metal Contamination ◽

Quality Guidelines ◽

Fish Samples ◽

Negative Impacts

The primary objective of this study is to determine trace metal contamination in environmental samples obtained from Pahang River and Kelantan River, Malaysia which may help to identify the risk of sustainable dredging in these areas. This research also proceeds to compare the trace metal concentration with the National Water Quality Standards of Malaysia, Interim Canadian Sediment Quality Guidelines and Malaysian Food Act 1983 to determine its limits and risks. Samples of water, sediment, snails and fishes were collected and analyzed for As, Cu, Cd, Cr, Fe, Pb, Ni, Mn, and Hg by using atomic absorption spectrophotometer. It was found that the concentration of trace metals namely As, Cu, Cd, Cr, Pb, Ni, and Hg in river water, sediment, snail and fish samples in Pahang River were lower than the maximum allowable limits, except for Fe and Mn. In Kelantan River, the concentration of trace metals indicating that it is contaminated with Fe, Mn, Pb, Cr, Cu, Hg, and As as all trace metals exceeded the maximum allowable limits. Negative impacts may arise, and the river may contaminate more in future if there is no proper management to tackle this issue during execution of dredging activities.

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Contamination Identification of Trace Metals in Roadway Dust of a Typical Mountainous County in the Three Gorges Reservoir Region, China, and its Relationships with Socio-Economic Factors

Sustainability ◽

10.3390/su12145624 ◽

2020 ◽

Vol 12 (14) ◽

pp. 5624

Author(s):

Huiyun Pan ◽

Xinwei Lu ◽

Kai Lei

Keyword(s):

Trace Metal ◽

Metal Contamination ◽

Road Dust ◽

Economic Factors ◽

Agricultural Activities ◽

Three Gorges ◽

Trace Metal Contamination ◽

The Three Gorges ◽

Contamination Levels ◽

Socio Economic Factors

Trace metal contamination in urban road dust has attracted global concern due to its potential risk to the urban environment and human health. Compared to big cities, relative studies in counties and small towns have not been well quantified. This research identified the trace metal contamination characteristics and possible sources in the road dust of a typical mountainous county and a town in the Three Gorges Reservoir region, southwest China, and their associations with major regional socio-economic factors. The trace metal concentrations were determined, and the contamination levels were assessed. Concentrations of Zn, Pb, and Cu were relatively high in both locations, and a significant accumulation of them was confirmed by the geo-accumulation method. Multivariate analysis and geographic information system (GIS) mapping were combined to explore the sources of trace metals in the investigated area. Anthropogenic activities predominantly affected the contamination levels of Zn, Pb, Cu, and Co, and traffic emission, agricultural activities, and fossil fuel combustion were their main sources. The significant accumulation of Zn should attract special concern for its wide use in industrial and agricultural activities. Population and vehicle density were the main factors that controlled the trace metal contamination levels in the roadway dust. Rapid urbanizing promoted trace metal accumulation in counties and towns. Therefore, it is urgent to make appropriate strategies for trace metal pollution mitigation in the process of urbanization.

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A suitable model for the biomonitoring of trace metal bioavailabilities in estuarine sediments: the annelid polychaete Nereis diversicolor

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315406012872 ◽

2006 ◽

Vol 86 (1) ◽

pp. 71-82 ◽

Cited By ~ 44

Author(s):

Laurence Poirier ◽

Brigitte Berthet ◽

Jean-Claude Amiard ◽

Anne-Yvonne Jeantet ◽

Claude Amiard-Triquet

Keyword(s):

Trace Metals ◽

Trace Metal ◽

Metal Contamination ◽

Estuarine Sediments ◽

Suitable Model ◽

English Channel ◽

Metal Concentrations ◽

Trace Metal Contamination ◽

Nereis Diversicolor ◽

Total Sediment

The need to use biomonitors representative of the sedimentary compartment has been recognized, particularly in estuaries. Thus, trace metal contamination has been monitored in an infaunal polychaete worm Nereis diversicolor and sediments in the Seine estuary and comparatively in the relatively clean Authie estuary (French coast of the English Channel) over two years taking samples every three months at both sites. No correlations were shown between total metal (Ag, Cd, Cu, Pb, Zn) concentrations in raw sediments and ragworms. Because these worms are known to be good biomonitors of the bioavailabilities of sedimentary trace metals, it follows that total sediment metal concentrations have a poor predictive ecotoxicological value. Using a correction factor to minimize the influence of weight, it is possible to make a good estimation of the average metal concentrations in a population of worms at a given site, sampling only a limited number of specimens. Metallothioneins are often considered to be good biomarkers of the presence of significant availabilities of trace metals. Metallothionein-like proteins (MTLPs) are present in N. diversicolor, but there is no significant relationship between MTLPs and metal concentrations. This situation might result from the importance of metal-containing granules, both extra- and intracellular, in ragworms.

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Trace metals as tracers of dredging activity in Cleveland Bay — field and laboratory studies

Marine and Freshwater Research ◽

10.1071/mf9941237 ◽

1994 ◽

Vol 45 (7) ◽

pp. 1237 ◽

Cited By ~ 48

Author(s):

AJ Reichelt ◽

GB Jones

Keyword(s):

Trace Metals ◽

Trace Metal ◽

Metal Contamination ◽

Laboratory Studies ◽

Dredged Sediment ◽

Trace Metal Contamination ◽

Acid Leach ◽

Pollutant Concentrations ◽

Before And After ◽

Copper Zinc

This study has investigated in detail trace metal concentrations in Cleveland Bay in the central Great Barrier Reef and assessed the significant carrier phases of several metals during a simulated disturbance of sediments designed to investigate the effects of dredging. Organic, iron oxide and carbonate phases were shown to be important carrier phases for several trace metals. The application of an acid-leach technique to monitor labile or pollutant concentrations of copper, zinc, lead and nickel in sediments collected from coral reefs sampled before and after two dredging events in 1991 yielded useful information on the fate of dredged sediment. Trace metal contamination close inshore was attributed to port activities, sewage discharge and urbanization.

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Farmland Trace Metal Contamination and Management Model—Model Development and a Case Study in Central Taiwan

Sustainability ◽

10.3390/su122310066 ◽

2020 ◽

Vol 12 (23) ◽

pp. 10066

Author(s):

Hsin-Yi Yang ◽

Sheng-Kung Chen ◽

Jiun-Shiuan Wang ◽

Chih-Jen Lu ◽

Hung-Yu Lai

Keyword(s):

Water Quality ◽

Trace Metals ◽

Trace Metal ◽

Paddy Soil ◽

Irrigation Water ◽

Metal Contamination ◽

Metal Species ◽

Management Model ◽

Trace Metal Contamination ◽

Central Taiwan

In this study, the water quality of the irrigation system and concentration of trace metals in the sediments were combined to establish a farmland trace metal contamination and management model (FTM_CMM). The purpose of this model was to clarify the main sources of the trace metals that have caused the contamination of paddy soil in central Taiwan. The results of the model simulation showed that the trace metals in the paddy soil mainly came from the irrigation water and especially from the sediments in the irrigation channels. The contribution of the sediments in the irrigation channel to the individual trace metals in the paddy soil ranged from 56% to 72% as the contributions for Cr, Cu, Ni, and Zn were 72%, 68%, 56%, and 62%, respectively. The trace metal species according to their concentration in the contaminated soil ranked in the order of Zn > Cr ≈ Cu > Ni, which is about the same as in the channel sediment. During the simulation process, Cr, Cu, Ni, and Zn exceeded the control standards for farmlands in the 18th, 12th, 13th, and 17th years, respectively. This highlights that, in addition to the management of irrigation water quality, the management of trace metal contaminated sediment in adjacent canal irrigation systems is also an important part of the prevention of trace metal contamination in farmland.

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Evaluation of Mitigation Methods to Manage Contaminant Transfer in Urban Watersheds

Water Quality Research Journal ◽

10.2166/wqrj.2009.002 ◽

2009 ◽

Vol 44 (1) ◽

pp. 1-15 ◽

Cited By ~ 4

Author(s):

Julia Brydon ◽

Iwata Oh ◽

Julie Wilson ◽

Ken Hall ◽

Hans Schreier

Keyword(s):

Trace Metals ◽

Trace Metal ◽

Metal Contamination ◽

Traffic Volume ◽

Traffic Density ◽

Spatial And Temporal Variability ◽

Benthic Organism ◽

Urban Stormwater ◽

Wide Range

Abstract Three case studies on trace metal contamination in urban stormwater are presented from the Greater Vancouver area of British Columbia. In the first case study, the spatial and temporal variability in trace metals in sediments were determined in the completely urbanized Brunette watershed. A natural lake in the middle of the watershed acts as a sediment detention system, and an analysis of the sediment core showed the historic accumulation of metal and selective organic contaminants in sediments since the early 1800s. Suspended sediments transported during storm events showed significantly higher concentrations of trace metals than bedload sediments, and the largest proportion of the geochemically active metals was found to be associated with the organic-sulphur-based fraction. Benthic organism survival tests showed mixed results with lower survival and growth in urban sediments than in control sediments from a forested watershed. In the second case study, significant correlations were obtained between percent impervious cover and trace metal concentrations in 28 subwatersheds with various degrees of urbanization. It is shown that imperviousness combined with traffic density can significantly improve the prediction of metal contamination in highly urbanized watersheds. In the third case study five urban stormwater detention systems were examined over one year to determine how effective these systems were in removing metal contamination. The results were highly variable depending on a wide range of physical conditions, land use activities, traffic volume, and detention system designs. The range of total metal detention was between −15 to +72% for copper (Cu), lead (Pb), and zinc (Zn), while iron (Fe) and manganese (Mn) retention was generally poor. Labile Zn was more effectively retained in four of the five ponds, and a significant relationship was found between percent imperviousness, traffic volume, and Zn concentrations in water, sediment, and labile form.

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Method of Detecting Trace Metal Contamination in Thick-Film SOI Device

ISTFA 2005: Conference Proceedings from the 31st International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2005p0220 ◽

2005 ◽

Author(s):

Yasunori Goto ◽

Hiroomi Eguchi ◽

Masaru Iida

Keyword(s):

Trace Metal ◽

Thick Film ◽

Metal Contamination ◽

Semiconductor Device ◽

Trace Element Analysis ◽

Silicon On Insulator ◽

Element Analysis ◽

Trace Metal Contamination ◽

Trace Metal Elements ◽

Output Characteristics

Abstract In the automotive IC using thick-film silicon on insulator (SOI) semiconductor device, if the gettering capability of a SOI wafer is inadequate, electrical characteristics degradation by metal contamination arises and the yield falls. At this time, an automotive IC was made experimentally for evaluation of the gettering capability as one of the purposes. In this IC, one of the output characteristics varied from the standard, therefore failure analysis was performed, which found trace metal elements as one of the causes. By making full use of 3D perspective, it is possible to fabricate a site-specific sample into 0.1 micrometre in thickness without missing a failure point that has very minute quantities of contaminant in a semiconductor device. Using energy dispersive X-ray, it is possible to detect trace metal contamination at levels 1E12 atoms per sq cm. that are conventionally detected only by trace element analysis.

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