| 摘要 |
PROBLEM TO BE SOLVED: To provide a method by which trenches are embedded by laminating an APCVD oxide film and an HDPCVD oxide film upon the trenches through STI treatment and the isolation characteristic of a semiconductor element can be improved. SOLUTION: After a thermally oxidized film 31 has been formed on the surface of a semiconductor substrate 30 having an active region and an element isolating region which isolates the active region, a nitride film 32 is formed on the oxidized film 31 and the nitride film 32 is patterned so that only the region other than the element isolating region is left by selectively etching the nitride film 32. After the nitride layer 32 has been patterned, trenches having a fixed depth are formed by selectively etching the thermally oxidized film 31 and substrate 30 by the use of the patterned nitride layer 32 as a mask. Then another thermally oxidized film 31 is formed on the surfaces of the trenches, and an APCVD oxide film 33 is formed on the entire surface, including the thermally oxidized film 31 and patterned nitride film 32. Thereafter, an HDPCVD oxide film 34 is formed on the entire surface of the oxide film 33, heat-treated, and retained only in the trench sections by polishing the film 33 in a CMP process.
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