| 摘要 |
PURPOSE:To prevent the generation of crystal defects in a silicon substrate by a method wherein an N-type or P-type impurity is added to a silicon oxide film filling a trench. CONSTITUTION:Reactive ion etching (RIE) is accomplished on the entire surface of a silicon substrate 1 with a CVD oxide film 2 serving as a mask. A trench 3 is provided with a side wall standing vertical, after which the CVD oxide film 2 is removed. Next, after the formation of a first silicon oxide film 4, a polycrystalline silicon film 5 is attached by low-pressure CVD, and a boron- containing silicon oxide film 6 is attached. The trench 3 is now completely filled up with said films. Etching-back follows, whereby the boron-containing silicon oxide film 6 and polycrystalline silicon film 5 are removed, except from inside the trench 3. Further, the upper end of the polycrystalline silicon film 4 in the trench 3 is partially removed. In this way, crystal defects may be prevented which would otherwise be produced in the vicinity of the oxide fillings for the degradation of element characteristics.
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