Trench Schottky barrier diode
AssigneeInternational Rectifier Corporation
InventorsKohji Andoh, Davide Chiola
Life of this patent
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Abstract
A fabrication process for a Schottky barrier structure includes forming a nitride layer directly on a surface of an epitaxial (“epi”) layer and subsequently forming a plurality of trenches in the epi layer. The interior walls of the trenches are then deposited with a final oxide layer without forming a sacrificial oxide layer to avoid formation of a beak bird at the tops of the interior trench walls. A termination trench is etched in the same process step for forming the plurality of trenches in the active area.
Claims15
A method for fabricating a trench Schottky barrier semiconductor device, comprising the steps of:
- forming a nitride layer directly on a face of a silicon substrate having a first conductivity type;
- patterning the nitride layer to define spaced windows and then etching through the windows to form spaced trenches extending downward from the face into the silicon substrate;
- and lining the interior walls of the trenches with a final oxide layer without forming and etching a sacrificial oxide layer to prevent formation of bird beaks at tops of the interior walls of the trenches.
A method of forming a trench Schottky barrier device, the method comprising the steps of:
- forming a nitride layer on one of the opposite faces of a semiconductor substrate having a first conductivity;
- patterning the nitride layer to define spaced windows on the nitride layer;
- opening windows in said nitride layer by etching through said windows and through regions of the one face of the semiconductor substrate opposing the windows to form alternating trenches and mesas in the semiconductor substrate;
- forming an oxide layer on a bottom surface and sidewalls of the trenches without forming a sacrificial oxide layer to avoid bird beak formations at spaced interfaces between the nitride layer and the semiconductor substrate along the mesa;
- depositing a continuous layer of un-doped polysilicon over the nitride layer to fill the trenches with the un-doped polysilicon layer;
- implanting a second type conductivity impurities into the non-doped polysilicon layer to provide the polysilicon layer with the second type conductivity;
- stripping the nitride layer overlaying the mesas to expose the semiconductor substrate;
- applying a continuous barrier layer over the one face to form a Schottky between the exposed portion of the semiconductor substrate of the mesas and the barrier layer;
- and
- applying metal on the opposite faces of the semiconductor substrate to form anode and cathode electrodes of the semiconductor device.
Dependencies are inferred from the claim text.