| 摘要 |
A structure for a read-only-memory (ROM) having both bipolar and channel transistors as memory cells to achieve efficient space utilization and higher density of ROM elements. The channel transistors include bit lines and word lines, with a threshold voltage at about 0.7 V. By implanting impurities into predetermined channel regions, memory cells become conductive or non-conductive. Bipolar transistors are formed in predetermined intersections of bit lines and word lines with a threshold voltage of about 3 V to 5 V, which can be treated as conductive memory cells that conduct current under 5 V operating voltage. Intersections of bit lines and word lines without bipolar transistors formed therein can be treated as non-conductive memory cells.
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