Semiconductor apparatus including semiconductor devices operated by plural power supplies

摘要

After a gate electrode of a high withstand voltage device is formed, a gate bird's beak is formed on the gate electrode by post-heat treatment. After a gate electrode of a low withstand voltage is formed, no post-heat treatment is performed and no gate bird's beak is formed. Ions are injected through a thermal oxidation film, thereby forming diffusion layers of the high withstand voltage device. Ions are directly injected in a semiconductor substrate, thereby forming diffusion layers of the low withstand voltage device. Accordingly, the impurity concentration in the diffusion layers of the low withstand voltage device is higher than that in the diffusion layers of the high withstand voltage device.