1. A semiconductor device comprising: a non-volatile memory transistor including an oxide-nitride-oxide (ONO) dielectric stack on a surface of a semiconductor substrate, the ONO dielectric stack comprising a multi-layer charge storage layer including a silicon-rich, oxygen-lean top silicon oxynitride layer and a silicon-rich, oxygen-rich bottom silicon oxynitride layer; and a metal oxide semiconductor (MOS) logic transistor including a gate oxide and a high work function gate electrode.