Study of thermally grown and photo-CVD deposited silicon oxide–silicon nitride stack layers

Abstract

Silicon oxide–silicon nitride (ON) stack layers have been formed by mercury sensitized photochemical vapour deposition (photo-CVD) of silicon nitride layers over thermally grown and photo-CVD deposited silicon oxide layers on p-type Si (100) substrates. The properties of these two groups of samples were studied using Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) and capacitance–voltage measurements. Photo-CVD deposited nitrogen-rich stoichiometric silicon nitrides over thermally grown oxides give less electronic state density with an increased Si–N bond concentration, and on the other hand photo-CVD deposited oxide–nitride stacks give less fixed oxide charges. The absence of Si–H bonds in nitrides indicates that all nitrides are hydrogenated. Oxygen incorporation in the nitride layer was studied from FTIR and XPS measurements, which in turn affects the properties of these stack layers.