| 摘要 |
PURPOSE: A method for forming a metal contact of a semiconductor device is provided to prevent that an insulating layer tail occurs in a metal contact bottom by making an insulating layer of a metal contact forming area as a double insulating layer structure, and etching the insulating layer at two-stages. CONSTITUTION: The first polysilicon layer and the second polysilicon layer are formed on a cell area of a semiconductor substrate(10). The first interfacial insulating layer(13) is formed on the total structure, and the first photoresist layer is formed on the total structure. In the first photoresist layer, the third polysilicon layer contact and a metal contact area are determined. By a photolithography using the first photoresist layer as a mask, the third polysilicon layer contact and the metal contact are formed at the same time. PSG layer is formed on the total structure, so that the third polysilicon layer contact and the metal contact are buried, and then the PSG layer is smoothened. The second photoresist layer for the third polysilicon layer contact is deposited on the total structure, and PSG layer inside of the third polysilicon layer contact is removed. The second photoresist layer is removed, the third polysilicon layer contact spacer(20) is formed on a sidewall of the third polysilicon layer contact, and then the third polysilicon layer is formed on the total structure in order to bury the third polysilicon layer contact. The second interfacial insulating layer(16) is formed on the total structure, the third photoresist layer(24) for forming a metal contact is formed, and then the second interfacial insulating layer is etched by using a photolithography using the third photoresist layer as a mask. The third photoresist layer is removed, and then the PSG layer remaining in the metal contact is removed. The exposed semiconductor substrate is cleaned.
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