| 摘要 |
PURPOSE: A mask ROM and a fabrication method thereof are provided to improve degree of integration and reliability. CONSTITUTION: The mask ROM includes a semiconductor substrate(21) having the first and second trenches(24,30) of an oval shape, a gate insulating layer(25,31) formed on the substrate(21), the first and second gate electrodes(26,27) formed on the gate insulating layer(25) in the first trench(24), the third and fourth gate electrodes(32,33) formed on the gate insulating layer(31) in the second trench(30), and a buried impurity region(34) formed in the substrate(21) exposed between the gate electrodes(26,27,32,33). In the method, after insulating patterns are formed on the substrate(21), the first trench(24) is formed on the substrate(21) between the insulating patterns. Next, the first and second gate electrodes(26,27) are formed and then the insulating patterns are removed. Next, the second trench(30) is formed and the third and fourth gate electrodes(32,33) are formed.
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