| 摘要 |
PROBLEM TO BE SOLVED: To solve the matter of a technology for performing heat treatment of STI (shallow trench isolation employing a silicon oxide layer) in nitrogen atmosphere that occurrence of a silicon nitride layer 501 on the interface of a first gate layer 301 and a silicon substrate 101 during heat treatment cannot be suppressed, and although a second gate layer 401 is formed with no problem in a flat part because the silicon nitride layer 501 has a small thickness, oxidation rate lowers under impact of the silicon nitride layer 501 in the vicinity of an unflat STI region 202, and reliability of the second gate layer 401 lowers because a region of thin gate layer is generated partially in the second gate layer 401. SOLUTION: Heat treatment of STI is performed in nitrogen atmosphere having oxygen concentration of 0.1-1%. Since the occurrence of the silicon nitride layer 501 during heat treatment can be suppressed on the interface of the first gate layer 301 and the silicon substrate 101, uniformity in thickness of the second gate layer 401 is enhanced and reliability of the second gate layer 401 can be ensured. COPYRIGHT: (C)2007,JPO&INPIT
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