Method of manufacturing a shallow trench isolation structure

Abstract

A method of manufacturing a shallow trench isolation structure that utilizes the early formation of a strong oxide spacers so that for any subsequent pad oxide layer or sacrificial oxide layer removal using a wet etching method, the oxide layer adjacent to the substrate will not be over-etched to form recesses, thereby preventing the lowering of threshold voltage and the induction of a kink effect. The method includes the steps of forming a mask over a substrate and then patterning the mask to form a protective layer for subsequent etching operation. An oxide space is farmed on the sidewalls of the mask over the surface of the substrate. Subsequently, a trench is formed in the substrate along the side edges of the oxide spacers. A liner oxide box is formed on the sidewall of the trend and the liner oxide layer does not fill the trench. This is followed by filling the trench with a second oxide layer. After planarizing the upper surface with a chemical-mechanical polishing action, the mask is removed.