| 摘要 |
PURPOSE: A formation method of an isolation layer of semiconductor devices is provided to restrain a hump phenomenon and an INWE(Inverse Narrow Width Effect) by preventing an exposure of an edge portion of an active region due to a following wet cleaning. CONSTITUTION: A gate oxide(23) and a first polysilicon(24) are deposited on a semiconductor substrate(21). At this time, the first polysilicon(24) has a half thickness of a desirable thickness because another half thickness is formed at a following polysilicon deposition. After forming and patterning a nitride, a trench is formed by sequentially etching the first polysilicon(24) and the gate oxide(23) until the semiconductor substrate(21) is etched. Then, a sidewall oxide(26) is formed by an oxidation of the inner surface of the trench and a field oxide is filled into the trench by depositing and polishing an USG(Undoped Silicon Glass). A wet cleaning using an HF solution is performed to remove a remaining oxide on the first polysilicon(24). At this time, the field oxide is etched to reduce a step coverage. Then, a second polysilicon(28) having the same thickness with the first polysilicon(24) is formed on the resultant structure, thereby overlapping an edge portion of an active region.
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