Surface passivation by Al2O3 and a-SiNx: H films deposited on wet-chemically conditioned Si surfaces

S. Bordihn, V. Mertens, P. Engelhart, K. Kersten, M.M. Mandoc, J.W. Müller, W.M.M. Kessels

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Abstract

The surface passivation of p- and n-type silicon by different chemically grown SiO2 films (prepared by HNO3, H2SO4/H2O2 and HCl/H2O2 treatments) was investigated after PECVD of a-SiNx:H and ALD of Al2O3 capping films. The wet chemically grown SiO2 films were compared to thermally grown SiO2 and the surface passivation was benchmarked against single-layer a-SiNx:H and Al2O3 films deposited on HF-last Si surfaces. Directly after PECVD and ALD the surface passivation was found to be similar for all chemically grown SiO2 stacks and higher than for the single-layer films. After annealing at 400°C the level of surface passivation improved but remained similar for the chemically grown SiO2 stacks. Corona charging experiments on the annealed chemically grown SiO2/Al2O3 stacks revealed that the fixed charge density, i.e. the field-effect passivation, was lower compared to single-layer Al2O3 films whereas the chemical passivation was found to be higher. The surface passivation was also investigated as a function of the annealing time. Chemically grown SiO2 stacks achieved the maximum level of surface passivation after annealing for half a minute which is different from the stacks with a-SiNx:H and Al2O3 films deposited on thermally grown SiO2 or HF-last Si surfaces which required considerably longer annealing times.
Original languageEnglish
Pages (from-to)P320-P325
JournalECS Journal of Solid State Science and Technology
Volume1
Issue number6
DOIs
Publication statusPublished - 2012

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