Method of fabricating a flash memory

A method fabricating a hardened conformal oxide layer covering a gate structure of a split gate flash memory cell, comprising:

• providing the gate structure on a semiconductor substrate;
• forming a conformal oxide layer containing silicon atoms over the semiconductor substrate to cover the gate;
• performing a nitrogen ion implantation to introduce nitrogen ions into the conformal oxide layer;
• and
• performing a high temperature process to make the nitrogen ions bond with the silicon atoms or oxygen atoms to form Si--N and Si--O--N chemical bonds in the conformal oxide layer.

A method of fabricating an integrated circuit, comprising the steps of:

• providing a semiconductor substrate;
• forming a gate structure on the semiconductor substrate;
• forming a conformal oxide layer over the semiconductor substrate to cover the gate structure;
• performing a nitrogen ion implantation to introduce nitrogen ions into a surface of the conformal oxide layer;
• forming silicon nitride spacers on sidewalls of the gate structure, wherein the nitride spacers are formed by a high temperature deposition process such that Si--N and Si--O--N chemical bonds are formed in the conformal oxide layer;
• and
• performing a wet etching process to remove the conformal oxide layer exposed by the spacers.