Patent ID: 8741784

Claim:
A process for fabricating a semiconductor device, comprising: forming a silicon oxide layer, wherein forming the silicon oxide layer comprises an in-situ steam generation (ISSG) oxidation process or a decoupled plasma oxidation process; and performing a nitridation process including at least two steps to nitridate the silicon oxide layer into a silicon oxynitride (SiON) layer, wherein the nitridation process comprises a first nitridation step and a second nitridation step, and the first nitridation step and the second nitridation step are different in setting of at least one parameter, wherein the first nitridation step and the second nitridation step each comprises remote plasma nitridation, or NH 3 thermal nitridation; the electric power of the first nitridation step is higher than the electric power of the second nitridation step, so that a peak of the resulting nitrogen concentration profile from the first nitridation step is farther away from a top surface of the silicon oxide layer, and nitrogen atoms provided by the second nitridation step are closer to the top surface of the silicon oxide layer; and a time period of the second nitridation step is longer than a time period of the first nitridation step, so that nitrogen penetration through the silicon oxide layer is prevented or reduced during the first nitridation step.