| 摘要 |
<p>PURPOSE:To manufacture a semiconductor device having the output level same as the conventional product by decreasing the number of processes used before by a method wherein ions are implanted into a second and a fourth memory cell transistors, and then ions are implanted into a third and a fourth memory cell transistors. CONSTITUTION:A mask-ROM-provided semiconductor device is manufacture by forming memory cell transistors(MCTr) 5a to 5d having first to fourth output levels. In that case, data-write-in ions of the prescribed dosage are implanted with the prescribed implantation energy into the channel regions 6b and 6d of the MCTr 5b having a second output level and the MCTr 5d having a fourth output level. Then, data-write-in ions of the prescribed dosage, with which the drive current of the MCTr 5d having the fourth output level becomes zero, are implanted with the prescribed implantation energy into the MCTr 5c having a third output level and the MCTr 5d having the fourth output level.</p> |
