Patent ID: 6110793
Filing Date: 2000-08-29
Classification: H01L

Abstract:
A method for forming a trench isolation having a conformal trench liner oxide with rounded top and bottom corners for integrated circuits comprising the steps of:providing a silicon substrate;forming a pad oxide layer on said substrate;depositing an oxidation barrier layer on said pad oxide;patterning by photoresist masking and anisotropic etching said oxidation barrier layer and said pad oxide layer leaving portions over device areas while providing openings in said oxidation barrier layer for said trench isolation;etching trenches in said silicon substrate exposed in said openings of said oxidation barrier layer;thermally oxidizing said silicon substrate in said trenches thereby forming said liner oxide, wherein said thermal oxidation is carried out in a first and second thermal oxidation step done consecutively at two different temperatures to provide said conformal trench liner oxide having said rounded top and bottom corners in said trenches, wherein said first thermal oxidation step provides said bottom rounded corners in said trenches, and said second thermal oxidation step provides said top rounded corners in said trenches;depositing an insulating layer sufficiently thick to fill said trenches;planarizing said insulating layer to said oxidation barrier layer and completing said trench isolation.