| 摘要 |
PURPOSE:To upgrade integrity twice and to make a photomask needless, by forming a plurality of first gate electrodes at appropriate intervals on a semiconductor substrate and forming second gate electrodes among the first gate electrodes and introducing impurities selectively onto the semiconductor substrate from the upper parts of the first and second gate electrodes. CONSTITUTION:A semiconductor substrate 1 is partitioned into active regions, and a gate insulating film 2 is formed on the substrate 1, and a polycrystalline silicon layer 3 and insulating films 4, 5 are formed on the film 2. Said insulating films 4, 5, and the polycrystalline silicon layer 3 are formed into desired patterns, and a plurality of first gate electrodes 7 are formed at appropriate intervals on the substrate 1. Next, an insulating film 8 is formed on a surface of the first gate electrode 7, and a polycrystalline silicon 9 is made to grow over the whole film 8 and then it is etched, so that second gate electrodes 10 are formed among said first gate electrodes 7. In succession, impurities are introduced selectively onto the semiconductor substrate 1 from the upper parts of said first and second gate electrodes 7, 10. In the case of the introduction of said impurities, for example, a photoresist 14 formed on the desired pattern is used as a mask to perform a writing operation of ROM codes by ion implantation.
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