Trench-gate transistors and their manufacture
First Claim
1. A transistor circuit comprising:
- a semiconductor body;
a plurality of transistor cells in the body, each cell having a channel region in the body and, underlying the channel region, a drain drift region;
an array of trenches extending from an upper surface of the semiconductor body, each trench extending through one of the channel regions and into an underlying drain drift region; and
in each trench,a gate dielectric insulating layer extending from an upper surface of the semiconductor body, over a top corner of the trench and along a sidewall of the trench adjacent to both the channel region and the drain drift region;
a layer of silicon nitride laterally adjacent a portion of the gate dielectric insulating layer that is adjacent the drain drift region;
a layer of silicon dioxide laterally adjacent a portion of the gate dielectric insulating layer that is adjacent the drain drift region;
a gate immediately laterally adjacent a portion of the gate dielectric insulating layer that is adjacent the channel region; and
a field plate below the gate and separated from a portion of the gate dielectric insulating layer that is adjacent the drain drift region by the respective layers of silicon nitride and silicon dioxide.
11 Assignments
0 Petitions
Accused Products
Abstract
A trench-gate transistor has an integral first layer of silicon dioxide extending from the upper surface of the semiconductor body over top corners of each cell array trench. The integral first layer also provides a thin gate dielectric insulating layer for a thick gate electrode and the integral first layer also provides a first part of a stack of materials which constitute a thick trench sidewall insulating layer for a thin field plate. Consistent with an example embodiment, there is a method of manufacture. A hardmask used to etch the trenches is removed before providing the silicon dioxide layer. The layer is then protected by successive selective etching of the oxide layer and the nitride layer in the upper parts of the trenches. After the gate electrodes are provided, layers for the channel accommodating regions and source regions may be formed through the oxide layer on the upper surface.
-
Citations
7 Claims
-
1. A transistor circuit comprising:
-
a semiconductor body; a plurality of transistor cells in the body, each cell having a channel region in the body and, underlying the channel region, a drain drift region; an array of trenches extending from an upper surface of the semiconductor body, each trench extending through one of the channel regions and into an underlying drain drift region; and in each trench, a gate dielectric insulating layer extending from an upper surface of the semiconductor body, over a top corner of the trench and along a sidewall of the trench adjacent to both the channel region and the drain drift region; a layer of silicon nitride laterally adjacent a portion of the gate dielectric insulating layer that is adjacent the drain drift region; a layer of silicon dioxide laterally adjacent a portion of the gate dielectric insulating layer that is adjacent the drain drift region; a gate immediately laterally adjacent a portion of the gate dielectric insulating layer that is adjacent the channel region; and a field plate below the gate and separated from a portion of the gate dielectric insulating layer that is adjacent the drain drift region by the respective layers of silicon nitride and silicon dioxide. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
Specification