METHOD FOR MANUFACTURING A TRENCH ISOLATION AND STRUCTURE THEREOF

摘要

PURPOSE: A fabrication method of a trench isolation and structure thereof are provided to prevent a variation of a threshold voltage of selected cell according to a potential of storage node of non-selected cell. CONSTITUTION: The trench isolation method comprises the steps of: forming a trench etching mask layer(208) on a semiconductor substrate(200); forming a trench(210) by etching the semiconductor substrate(200) using the trench etching mask layer(208); forming a thermal oxide(212) at bottom and both sidewalls of the trench(210); forming a conductive layer on the thermal oxide(212) to entirely fill the trench; fattening the conductive layer to expose the upper surface of the trench etching mask layer(208); selective etching a portion of the conductive layer, wherein the upper surface of the conductive layer is lower than that of the semiconductor substrate(200) formed at both sides of the trench; and depositing a trench isolation layer(216) on the resultant structure to entirely fill the step coverage region between the surface of the conductive layer and the surface of the trench etching mask layer.