Patent ID: 6500727
Filing Date: 2002-12-31
Classification: H01L,Y10S

Abstract:
A method for forming a trench having upper rounded corners, comprising the steps of:providing a substrate having an oxide layer formed thereover; forming a hard mask layer over the oxide layer; forming a patterned patterning layer over the hard mask layer leaving one or more portions of the hard mask layer exposed; patterning the hard mask layer using the patterned patterning layer as a mask to form a patterned hard mask layer having one or more openings exposing one or more portions of the oxide layer; removing the patterned patterning layer; patterning the oxide layer using the patterned hard mask layer as a mask using a first trench etching process to etch through the oxide layer at the one or more exposed portions of the oxide layer and into the substrate to form one or more shallow trenches within the substrate having upper rounded corners at the respective interfaces between substrate and patterned oxide layer; and further etching the substrate at the one or more shallow trenches using a second trench etching process to form one or more completed trenches having the upper rounded corners at the respective interfaces between substrate and patterned oxide layer.