Semiconductor device and fabrication method

摘要

A method for forming a semiconductor device that has a fully depleted MOSFET and a partially depleted MOSFET having excellent characteristics on the same substrate without effecting control by means of the impurity concentration of the channel region. A semiconductor device is provided with a fully-depleted SOI MOSFET and a partially-depleted SOI MOSFET on the same SOI substrate through isolation by an element isolation film. The SOI substrate includes a buried oxide film and a SOI layer provided in succession on a silicon substrate.