Patent ID: 6107159
Filing Date: 2000-08-22
Classification: H01L

Abstract:
A method for forming a shallow trench isolation (STI) structure, which is separately formed at a dense patter region and at a loose patter region in a substrate, the method comprising:forming a first trench in the substrate at the dense pattern region, and a second trench in the substrate at the loose pattern region, in which the first trench is narrower than the second trench;forming a first insulating layer to fill the first trench, and forming a spacer on each sidewall of the second trench;forming a conformal first polysilicon layer over the substrate;forming a second insulating layer on the first polysilicon layer to fill the second trench;removing an exposed portion of the first polysilicon layer other than under the second insulating layer;forming a second polysilicon layer on each sidewall of the first polysilicon layer for compensation; andoxidizing the second polysilicon layer and a portion of the first polysilicon layer abutting the second polysilicon layer to form an oxide object, which allows the spacer and the second insulating layer to be merged together to cover the first polysilicon layer, wherein the portion of the first polysilicon layer is not absolutely necessary to be oxidized.