| 摘要 |
An improved local oxidation of silicon (LOCOS) method using encapsulating polysilicon/silicon nitride spacer is disclosed. The method includes forming a pad oxide layer on a semiconductor substrate and forming a first silicon nitride layer on the pad oxide layer. The pad oxide layer and the first silicon nitride layer are then patterned and etched by a photoresist mask to define an active region. After removing a portion of the pad oxide layer, an undercut between the first silicon nitride layer and the substrate is formed. A silicon oxide layer is thereafter formed on the substrate, and a polysilicon layer is formed to encapsulate the first silicon nitride layer, the pad oxide layer and the silicon oxide layer. Next, a second silicon nitride layer is formed and etched back to form a silicon nitride spacer on the sidewalls of the polysilicon layer. Using the silicon nitride spacer as a mask, portions of the second silicon nitride layer, the polysilicon layer, the silicon oxide layer and the substrate are etched, and an isolation oxide is finally grown on the substrate using the spacer as a mask.
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