Low thermal budget SiO 2 ∕ Si 3 N 4 ∕ SiO 2 stacks for advancedSONOS memories

SiO 2 ∕ Si 3 N 4 ∕ SiO 2 (ONO) stacks are used as trapping media in industrial semiconductor memories. This memory device uses deep traps in the silicon oxynitride interlayer between the silicon nitride layer and the top oxide. In this research, low-thermal budget (low temperature) ONO layers were designed suitable for integration into advanced scaled down semiconductor technologies. The alternative growing procedure included oxidation of silicon nitride surface in oxygen plasma. Low temperature oxidation of the silicon nitride layer in oxygen plasma allows incorporation of oxygen into the silicon nitride layer, thus forming a silicon oxynitride layer. The chemical composition of the silicon oxynitride interlayer was similar to the oxynitride of thermally grown ONO. The plasma procedure did not cause any surface roughening. The memory devices with the low-temperature-oxygen-plasma ONO stack showed similar performance to memories with standard high temperature ONO. ONO structures were characterized chemically and structurally by the time of flight secondary ion mass spectrometry (TOF-SIMS), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM).