| 摘要 |
PURPOSE:To complete a mask ROM in a short time after information is given, by a method wherein information writing is made by radiating a laser beam at almost the final time or in a final process after wiring formation. CONSTITUTION:A drain electrode drawing out hole 12a is made for all memory cells. Accordingly, a wiring 13a as a bit line is connected to a drain diffusion layer 10a in all memory cells. After wirings 13 and 13a are formed, a connection part between the wiring 13a an the drain diffusion layer 10a (the drain electrode drawing out hole 12a) is irradiated by a laser beam, in the only memory cell in which information '1' is written. Thereby, silicon 15 in the wiring 13a is deposited on the boundary surface between the wiring 13a and the drain diffusion layer 10a, and the wiring 13a and the drain diffusion layer 10a are made nonconductive, so that writing the information '1' is finished. In the memory cell which is not irradiated by the laser beam, writing the information '0' is finished. |
