| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device and manufacturing method thereof which enables two or more different desired threshold voltages by applying the back bias of different potentials to two or more MOSFETs on a SOI substrate from a Si semiconductor substrate beneath a SOI film. SOLUTION: Impurity-diffused regions 61, 62 are electrically separately formed on a surface region of a semiconductor substrate beneath MOSFETs T1, T2 having two or more different threshold voltages on a SOI substrate. To these regions different voltages are applied to control the threshold voltages of the MOSFETs T1, T2 by the back bias effect. The diffused regions 61, 62 of the substrate beneath the MOSFETs formed on an SOI film 3 are formed by implanting ions of conductive impurities as deep as piercing the film 3, using an ion implanting apparatus allowing a high accelerating applied voltage. Using this semiconductor device for a semiconductor memory, the read/write thereof can be made at high speed and stabilized. |
