| 摘要 |
PROBLEM TO BE SOLVED: To recover a defective device having no refreshing capacity by a method wherein the leakage in a dummy memory cell is detected to emit output signal corresponding to the leakage amount in the dummy memory cell so as to control the substrate voltage VBB of a semiconductor substrate to decrease the leakage amount in the memory cell. SOLUTION: Within a memory cell leak monitor 100, if a leakage occurs in the drain 3 of a transistor N10 of a dummy memory cell A10, a current runs in the transistor N10 to lower the level in an output signal MC. On the other hand, if the level in the input signal MC is lowered in the substrate voltage generating circuit, the period of a ring oscillator 21 is extended thereby lowering the level of the substrate VBB to be an output. That is, the negative potential is made shallow-by its slight shift in the positive direction. Through these procedures, the level of the substrate potential VBB can be controlled corresponding to the refreshing capacity of the memory cell. |
