Patent ID: 6548373
Filing Date: 2003-04-15
Classification: H01L

Abstract:
A method for forming shallow trench isolation structure, comprising the steps of:providing a substrate; forming a pad oxide layer over the substrate; forming a sacrificial layer over the pad oxide layer; forming a mask layer over the sacrificial layer; patterning the mask layer, the sacrificial layer, the pad oxide layer and the substrate to form a trench and an active region; performing an oxidation step to form a liner oxide layer on exposed sidewalls of the patterned sacrificial layer and an exposed substrate surface inside the trench; depositing an insulation material into the trench and over the substrate to form an insulation layer; performing chemical-mechanical polishing to remove a portion of the insulation layer and a portion of the mask layer and retaining an insulation plug inside the trench such that a top surface of the insulation plug and a top surface of the mask layer are at the same level; patterning the patterned mask layer after the oxidation step to expose a portion of the patterned sacrificial layer between two neighboring insulation plugs; performing an ion implantation; and removing the patterned mask layer and the remaining patterned sacrificial layer not oxidized in the oxidation step such that the liner oxide layer remain covering a portion of a sidewall of the insulation plug at a top corner of the trench.