| 摘要 |
PURPOSE:To increase the cell ratio in the increase in densith of a static RAM by thinning the gate insultion film of a driver transistor and thickening that of a transfer gate transistor. CONSTITUTION:The static RAM (S-RAM) consists of a flip-flop composed of driver transistors T3, T4 and resistors R1, R2, and transfer gate transistors T1 and T2 that write and read out. Insulation films are formed in the gate sections of the transistors T1-T4, and the insulation films are removed only in the transistors T3 and T4. Next, when insulation films are formed to the transistors T1- T4 again, the gate insulation films of the transistors T3 and T4 become thinner, and those of the transistors T1 and T2 become thicker. This manner yields a sufficient cell-ratio without varying the width of the gate insulation film. |
