Self aligned metal gates on high-k dielectrics

A method for forming a transistor, comprising:

• forming a high-k gate dielectric on a substrate, the high-k gate dielectric having a dielectric constant above the dielectric constant of silicon dioxide;
• forming a sacrificial carbon gate on the gate dielectric;
• forming sacrificial carbon sidewall spacers adjacent to the sacrificial carbon gate;
• forming the source/drain regions for the transistor using the sacrificial carbon sidewall spacers to define the source/drain regions;
• removing the sacrificial carbon sidewall spacers;
• forming source/drain extensions for the transistor;
• forming non-carbon sidewall spacers adjacent to the sacrificial carbon gate;
• and
• replacing the sacrificial carbon gate with a desired metal gate material to provide the desired metal gate material on the gate dielectric.

A method for forming a transistor, comprising:

• forming a high-k gate dielectric on a substrate, including at least one of performing an atomic layer deposition process to form the high-k dielectric, performing an evaporated deposition process to form the high-k dielectric, and oxidizing a metal to form the high-k dielectric;
• forming a sacrificial carbon gate on the gate dielectric;
• forming sacrificial carbon sidewall spacers adjacent to the sacrificial carbon gate;
• forming the source/drain regions for the transistor using the sacrificial carbon sidewall spacers to define the source/drain regions;
• performing a plasma oxidation process to remove the sacrificial carbon sidewall spacers;
• forming source/drain extensions for the transistor;
• forming non-carbon sidewall spacers adjacent to the sacrificial carbon gate;
• and
• replacing the sacrificial carbon gate with a desired metal gate material to provide the desired metal gate material on the gate dielectric.

A method for forming a transistor, comprising:

• forming a high-k gate dielectric on a substrate, the high-k gate dielectric having a dielectric constant greater than the dielectric constant of silicon dioxide;
• forming a sacrificial carbon gate on the gate dielectric;
• forming sacrificial carbon sidewall spacers adjacent to the sacrificial carbon gate;
• forming the source/drain regions for the transistor using the sacrificial carbon sidewall spacers to define the source/drain regions;
• removing the sacrificial carbon sidewall spacers;
• forming source/drain extensions for the transistor;
• forming non-carbon sidewall spacers adjacent to the sacrificial carbon gate;
• filling around the sidewall spacers with silicon oxide and planarizing;
• and
• replacing the sacrificial carbon gate with a desired metal gate material to provide the desired metal gate material on the gate dielectric, including:
• removing the sacrificial carbon gate using a plasma oxidation process to form an aperture;
• filling the aperture with a desired metal gate material;
• and
• planarizing the transistor.

A method for forming a transistor, comprising:

• forming a high-k gate dielectric on a substrate;
• forming a sacrificial carbon gate on the gate dielectric;
• forming an etch barrier on the substrate and the sacrificial carbon gate;
• forming sacrificial carbon sidewall spacers over the etch barrier adjacent to the sacrificial carbon gate;
• forming the source/drain regions for the transistor;
• removing the sacrificial carbon sidewall spacers;
• removing the etch barrier;
• forming source/drain extensions for the transistor;
• forming non-carbon sidewall spacers adjacent to the sacrificial carbon gate;
• filling around the sidewall spacers with a filler material and planarizing;
• removing the sacrificial carbon gate to form an aperture;
• filling the aperture with a desired metal gate material;
• and
• planarizing the transistor.