| 摘要 |
PURPOSE:To enable a masked ROM to program memory and be shortened enough in manufacturing time and to enable a defective masked ROM to be remedied by a method wherein a surface protective film is formed in a final process, and an impurity diffusion layer is selectively formed by implanting N-type impurities from above. CONSTITUTION:A bit line 10 is previously set at a potential higher than a ground potential such as a power supply potential or the like by pre-charging, an N-type transistor formed of a word line 4 selected corresponding to the inputted address is put in an ON state when a source side impurity diffusion layer 7 is connected to an N-type impurity diffusion layer 5 kept at a ground potential through a selectively formed N-type impurity diffusion layer 12, the bit line 10 formed on a drain side impurity diffusion layer 6 discharges electricity to the source side impurity diffusion layer 5 through a contact hole 8 and is of a ground potential. If an N-type impurity diffusion layer 12 is not provided, the bit line 10 is prevented from discharging, so that it is kept at a pre-charge potential. Data of one bit is stored through this two states. |
