| 摘要 |
PROBLEM TO BE SOLVED: To realize reduction of threshold voltage using a metal gate, without requiring complicated manufacturing steps. SOLUTION: A silicon oxide film 15 is formed as an insulation film on a silicon substrate 11, and a tungsten film is formed on the formed film 15 by a PVD method. Then, a PMOS region is covered with a photoresist 17, and thorium is introduced into the film 16 on the NMOS region through ion implantation. In this way, the metal gate of the PMOS is formed of a tungsten, and the metal gate of the NMOS is formed of a thorium-doped tungsten, and thus the metal gates having different work functions can be formed easily on the PMOS and the NMOS.
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