| 摘要 |
PURPOSE:To establish a perfect dielectric isolation between an element and a substrate by a method wherein a silicon nitride film is formed on the side walls of a trench and then the trench is etched deeper. CONSTITUTION:A thick oxide film 102 is formed on a main surface of a substrate 101 and then the oxide film 102 is subjected to selective etching. The substrate 101 is subjected to anisotropic etching for the formation of a trench, when the oxide film 102 serves as a mask. A thin oxide film is formed on the side walls and bottom of the trench, and a nitride film 104 is attached to or allowed to grow on the thin oxide film. Another anisotropic etching is accomplished, after which the nitride film 104 is retained only on the side walls, the other portions thereof being removed from the trench bottom and main surface of the substrate 101. The thin oxide film is next removed from the trench bottom, and a third anisotropic etching process is accomplished for the selective oxidation of the trench side walls with the retained nitride film 104 serving as a mask. Finally, the element side walls are isolated by using a dielectric material. This method establishes a perfect dielectric isolation for an element.
|
