| 摘要 |
PURPOSE:To reduce data writing steps by forming a hole in a region corresponding to a memory cell selected from a shielding layer, and emitting radioactive rays through the hole to erase writing in the selected memory cell. CONSTITUTION:A shielding layer 3 for shielding ultraviolet rays is formed on the main surface of an ultraviolet ray erasable P-ROM1, and a hole 4 is formed in the layer 3 on a memory cell to be necessarily erased of arranged memory cells 2 by a mask formed according to data to be written. Then, data at the high level (or low level) are written in all the memory cells 2, and the ultraviolet ray is emitted from above. As a result, only the cell 2 disposed under the hole 4 becomes of the low level (or high level) to erase the data. The cell 2 of the position having no hole 4 holds the level before the ultraviolet ray is emitted, and can be written with necessary data. Thus, semifabricated products may not be necessarily prepared in large quantity, an exclusive writing unit is not required, and large process can be performed in a short time. |
