Buried oxide field isolation structure with composite dielectric
AssigneeGeneral Electric Company
InventorChing-Yeu Wei
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Abstract
Improved buried oxide (BOX) field isolation in a silicon structure which has a trench with a curved side wall is achieved by employing reactive ion etching or local oxidation of silicon to produce the curved side wall. Electric field enhancement which normally occurs at sharp corners in silicon structures employing conventional buried oxide field isolation is minimized by the curved side wall. The buried oxide field isolation in the silicon structure is provided by chemical vapor deposited SiO.sub.2 atop thermally produced SiO.sub.2 in the field region.
Claims6
A buried oxide field isolation structure for a silicon semiconductor device exhibiting a low radiation-induced threshold voltage shift, comprising:
- a silicon substrate layer having an active region and a trench adjacent to said active region, said trench having a side wall curved along a dimension perpendicular to said substrate layer in substantially the entire extent of said side wall so as to form no sharp corners with said active region;
- a thermal SiO.sub.2 layer in said trench along the curved side wall;
- and
- a filler of deposited SiO.sub.2 over said thermal SiO.sub.2 layer along said side wall and filling up said trench.
Dependencies are inferred from the claim text.