Shallow trench isolation process for high aspect ratio trenches
AssigneeDigital Equipment Corporation
InventorsAmitava Bose, Marion M. Garver, Andre I. Nasr, Steven S. Cooperman
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Abstract
Disclosed is a method of planarizing the surface of a silicon wafer in integrated circuit manufacture where shallow trench isolation techniques are employed. The etched trenches are first coated with a silicon nitride protective liner before the trenches and active area mesas are conformally coated with a layer of silicon oxide. The conformal oxide then is steam annealed to densify the conformal oxide, and then the surface of the silicon wafer is etched and polished back down to the tops of the active area mesas, to form a substantially planar surface.
Claims12
A method of planarizing a face of a semiconductor substrate comprising:
- etching said face to form trenches between flat active area mesas;
- depositing a liner of silicon nitride on the walls and base of the trenches;
- depositing a conformal coating of an undoped dielectric material over said face;
- annealing the conformal undoped dielectric material in a steam atmosphere to densify the undoped dielectric material;
- and
- planarizing the undoped densified dielectric conforming coating down to the level of the tops of the flat active area mesas to form a substantially planar surface.
A method of planarizing a face of a silicon substrate comprising:
- etching said face to form flat active area mesas and trenches including a plurality of high aspect ratio trenches;
- depositing a liner of silicon nitride on the walls and base of the trenches, said liner having a thickness of about 0.010 to about 0.015 .mu.m;
- depositing a conformal coating of undoped silicon oxide over said face, in a thickness such that the level of the top of the undoped conformal oxide in the trenches is at least about the same level as the top of the active area mesas;
- annealing the undoped conformal oxide material in a steam atmosphere;
- and,
- etching and polishing the undoped conformal oxide coating down to the level of the tops of the active area mesas, to form a substantially planar surface.
Dependencies are inferred from the claim text.