Assessing the Oxidative Degradation of N-Methylpyrrolidone (NMP) in Microelectronic Fabrication Processes by Using a Multiplatform Analytical Approach

During the construction of recording head devices, corrosion of metal features and subsequent deposition of corrosion by-products have been observed. Previous studies have determined that the use of N-methylpyrrolidone (NMP) may be a contributing factor. In this study, we report the use of a novel multiplatform analytical approach comprising of pH, liquid chromatography/UV detection (LC/UV), inductively coupled plasma optical emission spectroscopy (ICP-OES), and LC/mass spectrometry (LC/MS) to demonstrate that reaction conditions mimicking those of general photoresist removal processes can invoke the oxidation of NMP during the photolithography lift-off process. For the first time, we have confirmed that the oxidation of NMP lowers the pH, facilitating the dissolution of transition metals deposited on wafer substrates during post-mask and pre-lift-off processes in microelectronic fabrication. This negatively impacts upon the performance of the microelectronic device. Furthermore, it was shown that, by performing the process in an inert atmosphere, the oxidation of NMP was suppressed and the pH was stabilized, suggesting an affordable modification of the photolithography lift-off stage to enhance the quality of recording heads. This novel study has provided key data that may have a significant impact on current and future fabrication process design, optimization, and control. Results here suggest the inclusion of pH as a key process input variable (KPIV) during the design of new photoresist removal processes.

Download Full-text

Increased Aluminum Content in Certain Brain Structures is Correlated with Higher Silicon Concentration in Alcoholic Use Disorder

Molecules ◽

10.3390/molecules24091721 ◽

2019 ◽

Vol 24 (9) ◽

pp. 1721 ◽

Cited By ~ 9

Author(s):

Cezary Grochowski ◽

Eliza Blicharska ◽

Jacek Bogucki ◽

Jędrzej Proch ◽

Aleksandra Mierzwińska ◽

...

Keyword(s):

Inductively Coupled Plasma ◽

Optical Emission ◽

Brain Structures ◽

Brain Regions ◽

Protective Role ◽

Emission Spectrometry ◽

Inductively Coupled ◽

Al Content ◽

And Control ◽

The Brain

Introduction: Alcohol overuse may be related to increased aluminum (Al) exposure, the brain accumulation of which contributes to dementia. However, some reports indicate that silicon (Si) may have a protective role over Al-induced toxicity. Still, no study has ever explored the brain content of Al and Si in alcoholic use disorder (AUD). Materials and methods: To fill this gap, the present study employed inductively coupled plasma optical emission spectrometry to investigate levels of Al and Si in 10 brain regions and in the liver of AUD patients (n = 31) and control (n = 32) post-mortem. Results: Al content was detected only in AUD patients at mean ± SD total brain content of 1.59 ± 1.19 mg/kg, with the highest levels in the thalamus (4.05 ± 12.7 mg/kg, FTH), inferior longitudinal fasciculus (3.48 ± 9.67 mg/kg, ILF), insula (2.41 ± 4.10 mg/kg) and superior longitudinal fasciculus (1.08 ± 2.30 mg/kg). Si content displayed no difference between AUD and control, except for FTH. Positive inter-region correlations between the content of both elements were identified in the cingulate cortex, hippocampus, and ILF. Conclusions: The findings of this study suggest that AUD patients may potentially be prone to Al-induced neurodegeneration in their brain—although this hypothesis requires further exploration.

Download Full-text

Influence of the epitaxial composition on N-face GaN KOH etch kinetics determined by ICP-OES

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.11.4 ◽

2020 ◽

Vol 11 ◽

pp. 41-50 ◽

Cited By ~ 1

Author(s):

Markus Tautz ◽

Maren T Kuchenbrod ◽

Joachim Hertkorn ◽

Robert Weinberger ◽

Martin Welzel ◽

...

Keyword(s):

Inductively Coupled Plasma ◽

Chemical Vapour ◽

Optical Emission ◽

Small Time ◽

Organic Chemical ◽

Icp Oes ◽

Light Emitting ◽

Inductively Coupled ◽

Lift Off ◽

White Light Emitting Diodes

Roughening by anisotropic etching of N-face gallium nitride is the key aspect in today’s production of blue and white light emitting diodes (LEDs). Both surface area and number of surface angles are increased, facilitating light outcoupling from the LED chip. The structure of a GaN layer stack grown by metal organic chemical vapour deposition (MOCVD) was varied in the unintentionally doped u-GaN bulk region. Different sequences of 2D and 3D grown layers led to a variation in dislocation density, which was monitored by photoluminescence microscopy (PLM) and X-ray diffraction (XRD). Thin-film processing including laser lift off (LLO) was applied. The influence of epitaxial changes on the N-face etch kinetics was determined in aqueous KOH solution at elevated temperature. Inductively-coupled plasma optical emission spectroscopy (ICP-OES) was used to measure the etch progress in small time increments with high precision. Thereby, the disadvantages of other techniques such as determination of weight loss or height difference were overcome, achieving high accuracy and reproducibility.

Download Full-text

Estimation of human daily boron exposure in a boron-rich area

British Journal Of Nutrition ◽

10.1017/s000711450770911x ◽

2007 ◽

Vol 98 (3) ◽

pp. 571-575 ◽

Cited By ~ 21

Author(s):

Mehmet Korkmaz ◽

Uğur Şaylı ◽

Bekir Sıtkı Şaylı ◽

Sezgin Bakırdere ◽

Serap Titretir ◽

...

Keyword(s):

Inductively Coupled Plasma ◽

Reference Value ◽

Optical Emission ◽

Emission Spectrometry ◽

Inductively Coupled ◽

Boron Exposure ◽

Safe Limits ◽

Plasma Optical Emission Spectrometry ◽

And Control ◽

The City

Although, the safe limits of human daily boron (B) exposure are not absolutely clear, there is a growing interest in B and its effects on human health. The aim of the present study was to estimate daily B exposure in 66 males in Turkey living in a B-rich area using water containing at least 2 mg/l boron, with an average age of 38·55 (se 1·66) years and an average number of years of residence in the B-rich area of 35·89 (se 1·73). Another group of males (n 57), living in the city centres of Balıkesir and Ankara, were taken as controls; the average age and number of years of residence for this group were 29·44 (se 1·43) and 10·26 (se 1·83) years, respectively. As it is assumed that the B level in urine reflects daily B exposure, the amount of urinary B of both the study and control groups was analysed by using an inductively coupled plasma optical emission spectrometry (ICP-OES) technique. The average daily B exposure value was calculated as 6·77 (se 0·47) mg in the study group and 1·26 (se 0·1) mg in the controls. The results of this study are expected to contribute to creating a reference value for a safe daily B exposure.

Download Full-text

Determination of Toxic Metals Content in Iranian and Italian Flavoured Olive Oil

Acta Technologica Agriculturae ◽

10.2478/ata-2019-0012 ◽

2019 ◽

Vol 22 (2) ◽

pp. 64-69 ◽

Cited By ~ 2

Author(s):

Parisa Ziarati ◽

Fatemehsadat Mirmohammad Makki ◽

Sergij Vambol ◽

Viola Vambol

Keyword(s):

Heavy Metals ◽

Olive Oil ◽

Inductively Coupled Plasma ◽

Cultural Practices ◽

Optical Emission ◽

Emission Spectrometry ◽

Inductively Coupled ◽

Olea Europea ◽

And Control

Abstract Cultural practices and control of diseases and insects are widely used for cultivation of Olea europea L. These are considered potential contaminants. Aim of this investigation lies in determination of concentrations of contaminants in several edible olive oils. All test samples were purchased in three consecutive seasons. They were analysed in compliance with standardized international protocols of wet digestion methods. Ion concentrations were determined in three replicates using method of inductively coupled plasma optical emission spectrometry. We have registered a positive correlation between storage time and heavy metals contents. It was particularly high in Iranian brands and varied significantly. Investigation results show that all obtained heavy metals contents in pepper-flavoured olive oil samples were significantly lower than in other samples. Considering the fungi-flavoured samples, levels of Pb and Cd were prominent and exceeded the maximum permissible level set in the majority of cases. The further monitoring is needed as all these metals are toxic and their detrimental effect becomes obvious only after several years of exposure.

Download Full-text