Growth and characterization of thin sio2 and ta2o5 dielectric layers nd : yag laser oxidation

Download

index.pdf

Date

2005

Author

Aygün Özyüzer, Gülnur

Metadata

Show full item record

Item Usage Stats

183
views

100
downloads

Our aim was to establish a methodology for laser assisted oxidation of semiconductor and metal surfaces. One advantage of laser oxidation is the fact that radiation is heavily absorbed in a thin surface layer of the sample and the other is its ability for local oxidation. In addition to this, laser beam can be directed into some areas that other processes cannot reach. For these reasons, Nd:YAG pulsed laser working at 1064 nm wavelength is used for the oxidation purposes of Si and Ta films. First, SiO2 layer was obtained for various O2 pressures and laser powers. The thickness, refractive index, structural, dielectric, electrical and optical characteristics of the SiO2 layers have been determined. We have established that there exists an interval of laser power in which the oxidation occurs without surface melting. The oxidation process is controlled by the laser power rather than by the substrate temperature (673 ا 748 K). It was found that better film quality is obtained at higher substrate temperatures and laser power greater than 3.36 J/cm2. Second, rf-sputtered Ta films were oxidized by laser, because Ta2O5 appears to be a good promising candidate to replace SiO2 because of its high dielectric constant, high breakdown voltage and relevant small leakage current values. It was found that the substrate temperature is an important parameter to obtain denser layers with reduced amount of suboxides and the most suitable substrate temperature range is around 350 C to 400 C. β-orthorhombic crystal structure was obtained when the substrate temperature is 350 ا 400 C for thinner films (up to 20 ا 25 nm) and 300 ا 350 C for thicker films (40 nm). The refractive index values of laser grown thin tantalum oxide films were between ~1.9 and 2.2 being close to those of bulk Ta2O5 (2.0 ا 2.2). Oxide thicknesses in uniform Gaussianاlike shapes were measured as around the twice of

Subject Keywords

Sound., Sound.

URI

http://etd.lib.metu.edu.tr/upload/3/12605968/index.pdf
https://hdl.handle.net/11511/15143

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Cepstral deconvolution method for measurement of absorption and scattering coefficients of materials Aslan, Gökhan; Çalışkan, Mehmet; Department of Mechanical Engineering (2006) Several methods are developed to measure absorption and scattering coefficients of materials. In this study, a new method based on cepstral deconvolution technique is proposed. A reverberation room method standardized recently by ISO (ISO 17497-1) is taken as the reference for measurements. Several measurements were conducted in a physically scaled reverberation room and results are evaluated according to these two methods, namely, the method given in the standard and cepstral deconvolution method. Two meth...
Computer simulation of grain boundary grooving and cathode voiding n bamboo interconnects by surface diffusion under capillary and electromigration forces Akyıldız, Öncü; Oğurtanı, Tarık Ö.; Department of Metallurgical and Materials Engineering (2004) The processes of grain boundary grooving and cathode voiding which are important in determining the life times of thin films connecting the transistors in an integrated circuit are investigated by introducing a new mathematical model, which flows from the fundamental postulates of irreversible thermodynamics, accounting for the effects of applied electric field and thermal stresses. The extensive computer studies on the triple junction displacement dynamics shows that it obeys the first order reaction kinet...
An experimental study on off-design performance and noise in small pumps Şahin, Fatma Ceyhun; Eralp, O. Cahit; Department of Mechanical Engineering (2007) This thesis study is focused on experimentally investigating pump noise at design and off-design operations and its relations with pressure fluctuations. Small size pumps are placed in a semi-anechoic chamber and operated at various system conditions and various rotational pump speeds. Pump operational data, noise data and time dependent pressure data are recorded. Fast Fourier Transform spectra of noise and pressure data are compared. Coherence spectrum between sound pressure level and hydraulic pressures ...
Synthesis and photoluminescence of ultra-pure germanium nanoparticles Chivas, R.; Yerci, Selçuk; Li, R.; Dal Negro, L.; Morse, T. F. (2011-09-01) We have used aerosol deposition to synthesize defect and micro-strain free, ultra-pure germanium nanoparticles. Transmission electron microscopy images show a core-shell configuration with highly crystalline core material. Powder X-ray diffraction measurements verify the presence of highly pure, nano-scale germanium with average crystallite size of 30 nm and micro-strain of 0.058%. X-ray photoelectron spectroscopy demonstrates that GeOx (x <= 2) shells cover the surfaces of the nanoparticles. Under optical ...
Processing and characterization of carbon nanotube based conductive polymer composites Yeşil, Sertan; Bayram, Göknur; Department of Chemical Engineering (2010) The aim of this study was to improve the mechanical and electrical properties of conductive polymer composites. For this purpose, different studies were performed in this dissertation. In order to investigate the effects of the carbon nanotube (CNT) surface treatment on the morphology, electrical and mechanical properties of the composites, poly(ethylene terephthalate) (PET) based conductive polymer composites were prepared by using as-received, purified and modified carbon nanotubes in a twin screw extrude...

Citation Formats

G. Aygün Özyüzer, “Growth and characterization of thin sio2 and ta2o5 dielectric layers nd : yag laser oxidation,” Ph.D. - Doctoral Program, Middle East Technical University, 2005.