M.A. Dar

Synthesis of Magnesium Oxide Nanoparticles by Sol-Gel Process

Cubic shaped Magnesium oxide nanoparticles were successfully synthesized by sol-gel method using magnesium nitrate and sodium hydroxide at room temperature. Hydrated Magnesium oxide nanoparticles were annealed in air at 300 and 500°C. X-ray diffraction patterns indicate that the obtain nanoparticles are in good crystallinity, pure magnesium oxide periclase phase with (200) orientation. Morphological investigation by FESEM reveals that the typical sizes of the grown nanoparticles are in the range of 50-70nm. Powder composition was analyzed by the FTIR spectroscopy and the results confirms that the conversion of brucite phase magnesium hydroxide in to magnesium oxide periclase phase was achieved at 300°C.The Thermo-gravimetric analysis showed the phase transition of the synthesized magnesium oxide nanoparticles occurs at 280-300°C.

Electrochemically deposited ruthenium seed layer followed by copper electrochemical plating

Electrochemical deposition of ruthenium as a seed layer was investigated on Ti and TiN as barrier layers for Cu interconnects. The aqueous electrolyte, the N-bridged complex of ruthenium(IV) nitrosyl chloride (RuNC), for ruthenium electrochemical deposition was formed in situ. Electrochemical deposition of copper on the Ru seeded barrier layers was also demonstrated. The chemicals for the acid-bath ruthenium electrochemical deposition were ruthenium(III) chloride hydrate (RuCl 3 .3H 2 O), hydrochloric acid (HCI), sulfamic acid (NH 2 SO 3 H), and polyethylene glycol. The chemicals for the acid-bath copper electrochemical deposition were copper(II) sulfate hydrate (CuSO 4 .5H 2 O), sulfuric acid (H 2 SO 4 ), and polyethylene glycol. Results were analyzed by field-emission scanning electron microscopy, atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Ru-therford backscattering spectrometry. The Ru thin layer with equiaxial grains <10 nm on blanket Ti substrates were obtained by electrochemical deposition. Electrochemical Cu trench fill was successful on patterned TiN 130 nm 2.5 aspect ratio trenches with Ru as a seed layer.

A novel method for preparing stoichiometric SnO2 thin films at low temperature

Tin oxide is a well known nonstoichiometric material with dual valency. The invariance of stoichiometry is very intriguing. As of today no report is available for preparing perfect stoichiometric tin oxide. Here we report a novel method to prepare stoichiometric tin oxide by modifying the known plasma enhanced chemical vapor deposition technique using SnCl(4)-xH(2)O as precursor and O(2) as reactant gas at various temperatures from 300 to 800 degrees C. Tetragonal rutile structure of SnO(2) was found, grown along the [110] direction. X-ray photoelectron spectroscopic measurement showed constant Sn/O ratio. Sn 3d and O 1s were found composed of only Sn(4+) (487.2 eV) and O-Sn(4+) (531.2 eV) with equal peak widths. Raman band intensity ( approximately 633 cm(-1)) was found increasing with temperature, indicating the morphological changes. Sheet resistance of approximately 0.5 kOmega/at 300 degrees C was measured that reduces to approximately 0.1 kOmega/at 600 degrees C. It is found that film stoichiometry remains unaltered, while the structural morphology changes significantly.

Low temperature deposition and effect of plasma power on tin oxide thin films prepared by modified plasma enhanced chemical vapor deposition

This work presents low temperature (200 and 300°C) thin film deposition of tin oxide (SnO2) using modified plasma enhanced chemical vapor deposition as a function of radio frequency power (100–500W). Stannic chloride (SnCl4) was used as precursor and oxygen (O2, 300SCCM) as reactant gas. Fine granular morphology was observed with tetragonal rutile structure grown along the [110] direction, at all the deposition conditions. Higher plasma power resulted in smoother morphology, improved crystallinity, and enhanced conductivity. Electrical resistivity value of as low as ∼0.01Ωcm was obtained at the deposition temperature of 300°C and 250W of plasma power.

Nucleation of Diamond over Nanotube Coated Si Substrate Using Hot Filament Chemical Vapor Deposition (CVD) System

We studied the use of carbon nanotubes as a seeding layer for the nucleation of diamond on Si (100) substrate by using a hot filament chemical vapor deposition (HFCVD) system. Prior to deposition, substrates were seeded with multi-wall carbon nanotube (MWCNT) powder which was prepared separately. MWCNTs were used as nucleation precursors. The diamond grains grew essentially over the nanotubes with a higher growth density in comparison with the un-seeded substrates. The scanning electron microscopy (SEM) image of surface morphology shows crystallites of cauliflower shaped grains. The micro Raman spectroscopic results show a sharp peak at 1,332 cm-1 corresponding to diamond phase. X-ray photoelectron spectroscopic study show the presence of carbon (C1s) phase.