Semiconductor process having dielectric layer including metal oxide and mos transistor process

A MOS transistor process, comprising:

• providing a substrate;
• forming a gate dielectric layer having a high-k dielectric constant on the substrate, wherein the gate dielectric layer has a plurality of oxygen-related vacancies;
• performing a degas process;
• performing a first oxygen-importing process after the degas process to fill the oxygen-related vacancies with oxygen;
• and
• forming a metal gate on the gate dielectric layer.

A MOS transistor process, comprising:

• providing a substrate;
• forming a sacrificed gate structure on the substrate;
• forming a spacer beside the sacrificed gate structure;
• removing the sacrificed gate structure to form a recess;
• filling a gate dielectric layer having a high-k dielectric constant in the recess, wherein the gate dielectric layer has a plurality of oxygen-related vacancies;
• performing a degas process;
• performing a first oxygen-importing process after the degas process to fill the oxygen-related vacancies with oxygen;
• and
• filling a metal gate in the recess.