Trenched semiconductor devices and their manufacture
AssigneeKoninklijke Philips Electronics N.V.
InventorsErwin A. Hijzen, Michael A.A. In 't Zandt, Raymond J.E. Hueting
Life of this patent
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Abstract
In semiconductor devices which include an insulated trench electrode (11) in a trench (20), for example, trench-gate field effect power transistors and trenched Schottky diodes, a cavity (23) is provided between the bottom (25) of the trench electrode (11) and the bottom (27) of the trench (20) to reduce the dielectric coupling between the trench electrode (11) and the body portion at the bottom (27) of the trench in a compact manner. In power transistors, the reduction in dielectric coupling reduces switching power losses, and in Schottky diodes, it enables the trench width to be reduced.
Claims13
A semiconductor device including an insulated trench electrode in a trench, the trench extending in a semiconductor body portion of the device, wherein the trench electrode is dielectrically coupled to the body portion by an insulating layer at a side-wall of the trench, and there is a cavity between the bottom of the trench electrode and the bottom of the trench to reduce the dielectric coupling between the trench electrode and the body portion at the bottom of the trench.
A device of any preceding claim including a source region and a drain region of a first conductivity type, having therebetween a channel-accommodating region of an opposite, second conductivity type, wherein the trench electrode forms a gate and extends from the source region, through the channel-accommodating region to the drain region.
A device of any preceding claim wherein the body portion is a drift region contacted by a Schottky electrode which forms a Schottky barrier with the drift region.
A method of forming a semiconductor device including an insulated trench electrode in a trench, the trench extending through a semiconductor body portion of the device, and the trench electrode being dielectrically coupled to the body portion by an insulating layer at a side-wall of the trench, the method including the steps of:
- (a) etching a trench into the body portion;
- (b) providing a layer of filler material over the bottom of the trench;
- (c) providing trench electrode material in the trench with a path defined through the trench electrode material to the underlying filler material;
- (d) etching to remove filler material between the trench electrode material and the bottom of the trench;
- and
- (e) closing the path through the trench electrode material to leave a cavity between the trench electrode material and the bottom of the trench, which cavity reduces the dielectric coupling between the trench electrode and the body portion at the bottom of the trench.
Dependencies are inferred from the claim text.