| 摘要 |
PROBLEM TO BE SOLVED: To provide an art capable of preventing reduction of reliability caused by element isolation in a semiconductor device in which an element region in a semiconductor which is formed on an SOI substrate and composes the SOI substrate is surrounded by element isolation.SOLUTION: In a semiconductor device, by decreasing a trench width of an upper part of a deep trench 4 which composed trench isolation to be narrower than 1.2 μm, a cavity 7 produced when the inside of the deep trench 4 is filled with an insulation film 5 is prevented from being exposed on a top face of the insulation film 5. A decrease in voltage withstanding between element regions adjacent to each other, which is caused by a decrease in trench width of an upper part of the deep trench 4 is avoided by forming a LOCOS insulation film 6 linked to the insulation film 5 filled in the inside of the deep trench 4. |
