Characterisation of Step Coverage by Pulsed-Pressure Metalorganic Chemical Vapour Deposition: Titanium Dioxide Thin Films on 3-D Micro- and Nano-Scale Structures [article]

Vilailuck Siriwongrungson, University Of Canterbury
An examination of the possibility of applying pulse pressure metalorganic chemical vapour deposition (PP-MOCVD) to conformal coating and an investigation of PP-MOCVD processing parameters were undertaken using the deposition of thin, conformal titanium dioxide (TiO₂) on 3-D featured and non-featured substrates. The characterisation of the conformality and wettability analysis of thin TiO₂ was carried out using titanium tetraisopropoxide (TTIP) dissolved in toluene as a precursor and featured
more » ... sor and featured silicon (Si) and silicon nitride (Si₃N₄) as substrates. The features on the substrates were in micro- and nano-scale with the aspect ratio up to 2:1. The processing parameters investigated were temperatures between 400 and 600°C, reactor base pressures from 50 to 200 Pa, injection volumes between 50 and 250 µl, precursor concentrations in the range of 0.15 to 0.50 mol% and pulsing times from 10 to 20 sec. The surface morphology and thickness were examined using a scanning electron microscope (SEM). The composition of the films was qualitatively identified by energy dispersive X-ray spectroscopy (EDS). X-ray diffraction (XRD) and Raman spectroscopy were used to analyse the phase and grain size. The surface roughness and grain size were evaluated using atomic force microscopy (AFM). The optical properties were characterised using UV-VIS light spectroscopy. The anti-sticking characteristic was examined by wettability analysis, measuring the contact angle of the film with water. The research examined the relationships between processing parameters and growth rate, conformality, surface roughness, grain size, phase and water contact angle. A new measurement for thin film conformality was derived based on a statistical analysis of a large number of film thickness measurements on a fracture surface over the lithographed features. The best conformality of 0.95 was obtained for micro-scale features at the lowest temperature in the range of investigation, 400℃, with pulse exposure characterised by a base pressure of 100 Pa, TTIP concen [...]
doi:10.26021/1534 fatcat:cgnvtw3gqnc4jl5wiaddlyvqbu