| 摘要 |
<p>A method of producing a NAND-type ROM in which are alternatingly arranged first and second gate electrodes (5, 7) that are formed through two different steps (Fig. 6B, Fig. 6E). The data is written by introducing impurity into the surface of an impurity layer (1) just under each gate electrode. The conductivity type of this impurity is opposite to that of the layer (1). The region of the first gate electrode (5) is doped after the electrode (5) has been formed (Fig. 6B) and the dopant (4) is energized to penetrate the electrode (Fig. 6C). On the other hand, the region of the second gate electrode (7) is doped before the electrode (7) is formed and the dopant (9) is less energized so that it will not penetrate the first gate electrode (Fig. 6D). When the data is written (11) through the first gate electrode (5), the impurity is introduced (10) to that region of the substrate (1) where the second gate electrode (7) is to be formed (Fig. 6C). To cancel this (Fig. 7), the impurity (1B) is introduced (1A) in advance into the substrate in a step (Fig. 6A).</p> |
