Elimination of gate oxide weak spot in deep trench
First Claim
1. A semiconductor power device supported on a semiconductor substrate comprising:
- a trench gate of said semiconductor power device opened in said semiconductor substrate wherein a bottom surface and sidewalls of said trench gate are covered by a first and a second gate insulation layers wherein said second gate insulation layer covers entirely over said first gate insulation layer and constituting a single stop layer for covering and protecting said first gate insulation layer; and
a thick dielectric layer disposed at a bottom of said trench gate on top of and surrounded by the second gate insulation layer and said trench gate further comprises a polysilicon layer filling the trench gate on top of the thick dielectric layer wherein said second gate insulation layer covers and protects said first gate insulation layer in a wet etch process performed on said thick dielectric layer.
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Accused Products
Abstract
A MOSFET with a 0.7˜2.0 micrometers deep trench is formed by first carrying out a processing step of opening a trench in a semiconductor substrate. A thick insulator layer is then deposited in the trench such that the film at the bottom of the trench is much thicker than the sidewall of the trench. The insulator layer at the sidewall is then removed followed by the creation of composite dual layers that form the Gate Oxide. Another embodiment has the insulator layer deposited after Gate Oxide growth and stop at a thin Nitride layer which serves as stop layer during insulator pullback at trench sidewall and during Polysilicon CMP. Embodiments of the present invention eliminates weak spot at trench bottom corner encountered when Gate Oxide is grown in a 0.2 micrometers deep trench with thick bottom oxide. The present invention also maintains good control of the shape of the trench and the thickness profile of the Gate Oxide
12 Citations
12 Claims
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1. A semiconductor power device supported on a semiconductor substrate comprising:
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a trench gate of said semiconductor power device opened in said semiconductor substrate wherein a bottom surface and sidewalls of said trench gate are covered by a first and a second gate insulation layers wherein said second gate insulation layer covers entirely over said first gate insulation layer and constituting a single stop layer for covering and protecting said first gate insulation layer; and a thick dielectric layer disposed at a bottom of said trench gate on top of and surrounded by the second gate insulation layer and said trench gate further comprises a polysilicon layer filling the trench gate on top of the thick dielectric layer wherein said second gate insulation layer covers and protects said first gate insulation layer in a wet etch process performed on said thick dielectric layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification