| 摘要 |
PROBLEM TO BE SOLVED: To improve the originally low yield of RAMs to enable the stable production by enhancing the back bias dependent of each MOS in a memory cell to control the potential thereof. SOLUTION: A common drain is separated, using the trench isolation such as U-trench and DMOS and TMOS drains are fed at separate wells to suppress the memory cell area expansion. In the memory cell, to increase the back bias dependent of TMOS in view of the process, it is structured such that the back bias potential can be switched over by a fuse or external signal. When the stability of the memory cell is not ensured or read time is long due to lowering of the read current, the back bias potential of TMOS is switched to control so as to ensure the stability of the cell or reduce the read time. |
