Semiconductor device and manufacturing method thereof

摘要

In a method for manufacturing an FET having a gate insulation film with an SiO₂ equivalent thickness of 2 nm or more and capable of suppressing the leak current to 1/100 or less compared with existent SiO₂ films, an SiO₂ film of 0.5 nm or more is formed at a boundary between an Si substrate (polycrystalline silicon gate) and a high dielectric insulation film, and the temperature for forming the SiO₂ film is made higher than the source-drain activating heat treatment temperature in the subsequent steps. As such, a shifting threshold voltage by the generation of static charges or lowering of a drain current caused by degradation of mobility can be prevented so as to reduce electric power consumption and increase current in a field effect transistor of a smaller size.