Integrated circuit structure having thin gate dielectric device and thick gate dielectric device

A method of forming an integrated circuit structure including a thin gate dielectric device region over a set of fins within a substrate and a thick gate dielectric device region over the set of fins within the substrate, the method comprising:

• forming a nitrided oxide layer over each fin in the set of fins within the thin gate dielectric device region and the thick gate dielectric device region;
• forming a conformal carbon hard mask over nitrided oxide layer within the thin gate dielectric device region and the thick gate dielectric device region;
• patterning a photoresist stack over the conformal carbon hard mask within the thin gate dielectric device region and the thick gate dielectric device region to expose the conformal carbon hard mask within the thin gate dielectric region such that a remaining portion of the photoresist stack remains within the thick gate dielectric device region;
• removing the exposed conformal carbon hard mask from the thin gate dielectric device region such that a remaining portion of the conformal carbon hard mask remains within the thick gate dielectric device region covered by the remaining portion of the photoresist stack;
• wet etching to remove the remaining portion of the photoresist stack from over the remaining conformal carbon hard mask within the thick gate dielectric device region;
• removing the nitrided oxide layer from the thin gate dielectric device region such that a remaining portion of the nitrided oxide layer remains within the thick gate dielectric device region covered by the remaining portion of the conformal carbon hardmask;
• ashing the remaining portion of the conformal carbon hard mask to remove the remaining portion of the conformal carbon hard mask from the thick gate dielectric device region to expose the nitrided oxide layer within the thick gate dielectric device region;
• and
• forming an interfacial layer within the thin gate dielectric device region.