Post-annealed silicon nanocrystal formation on substoichiometric SiO_xN_y (x < 2, y < 1) layers deposited in SiH₄-N₂O radiofrequency discharges

¹ LGET, 118 route de Narbonne, 31062 Toulouse, France
² CEMES, 29 rue J. Marvig, 31055 Toulouse, France

Corresponding author: bedjaoui@lget.ups-tlse.fr

Received: 7 October 2005
Revised: 18 January 2006
Accepted: 24 February 2006
Published online: 25 May 2006

Abstract

In this work is presented a detailed physicochemical, structural and optical characterization of SiO_xN_y thin films. The films deposited using PECVD in SiH₄-N₂O-He discharges were thermally annealed at 1273 K for 1 hour in ambient nitrogen. The film stochiometry was measured by Rutherford Backscattering Spectroscopy. The chemical composition was dominated by silicon suboxide containing some Si-N and Si-H bonds. Raman scattering measurements suggest the formation of nanocrystallite silicon in the annealed films. The Raman observation is strongly supported by Transmission Electron Microscopy analysis which shows a high density of silicon nanocrystals, having a mean radius ranging between 3 and 6 nm. Using Spectroscopic Ellipsometry, we discussed the dielectric function evolution as a function of the deposition parameters.