| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of forming an element isolation region wherein a trench can be formed deep to improve electrical isolation without deteriorating the insulator embedding performance. SOLUTION: The method of forming an element isolation region comprises processes of laminating a first SiO2 film 2 and an Si3 N4 film 3 on a silicon substrate 1 in this order, forming a hole in the first SiO2 film 2 and the Si3 N4 film 3 and then forming a first trench 101 in the silicon substrate 1, forming a second SiO2 film 102 on the inner wall of the first trench 101, forming a hole in the bottom of the first trench 101 and then forming a second trench 103 in the silicon substrate 1, and forming a third SiO2 film 104 on the inner wall of the second trench 103.
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