| 摘要 |
PURPOSE:To shorten one process as a whole, and to shorten a production period by writing data on a mask ROM through ion implantaion, using a protective insulating layer as a mask. CONSTITUTION:An insulating film 2 for isolating elements is formed onto a P-type semiconductor substrate 1, and an N-type impurity is diffused to shape source-drain regions 3. Gate insulating films 4 and gate electrodes 5 are formed onto the substrate 1, thus constituting a plurality of MOS transistors. Protective insulating layers 6 are shaped onto the MOS transistors. When data to be written are transmitted from a user, the transistor, which need not be operated, is determined, and ions are implanted to a gate section for the transistor to conduct the source region and the drain region. That is, an opening section 11 is formed to a section, where ions must be implanted, in the protective insulating layers 6. When data are written completely, aluminum electrodes 8 are shaped into contact holes 7, and a predetermined wiring layer 9 is formed onto the protective insulating layers 6. Lastly, separate protective insulating layer 10 is formed. |
