Nitride Semiconductor Trench Structure for Normally-Off Operation
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Solution Overview
Problem
Semiconductor devices with nitride semiconductors face challenges in optimizing ON resistance and threshold voltage, particularly in maintaining normally-off operation and high gate breakdown voltage due to limitations in the design of the barrier layer and trench structure.
Innovation Solution
The semiconductor device incorporates a specific trench structure with shallow and deep bottom portions in the barrier and channel layers, allowing for the adjustment of two-dimensional electron gas concentration and polarization charge effects, achieved through a multilayered barrier structure and precise etching techniques to optimize Al concentration and layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trench structure is formed to control two-dimensional electron gas concentration, then device performance is improved, but manufacturing complexity increases
Solution Approach 1:
The trench structure is segmented into different depth regions: a first trench portion extending through the insulating layer to a first depth, and a second trench portion extending to a second depth greater than the first. This segmentation allows precise control of two-dimensional electron gas concentration at different locations, improving device performance while managing manufacturing complexity through systematic structure design.
Solution Approach 2:
The trench structure introduces a vertical dimension for controlling electron gas concentration, with different trench depths creating distinct regions for electron gas management. This dimensional approach enables precise performance optimization without proportionally increasing manufacturing complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces ON resistance, maintains high gate breakdown voltage, and ensures normally-off operation by controlling the two-dimensional electron gas concentration and polarization charge effects, thereby improving the overall performance of the semiconductor device.
Implementation Method 1
a concentration of two-dimensional electron gas in a first region on a side close to a first electrode is lower than a concentration of two-dimensional electron gas in a second region between an end of the first region on the side close to the first electrode and the first electrode
Data Source
AI summary
A semiconductor device includes a buffer layer, a channel layer, a barrier layer, and agate electrode over a substrate, the gate electrode being disposed in a first opening with agate insulating film in between, the first opening running up to the middle of the channel layer through the barrier layer. The concentration of two-dimensional electron gas in a first region on either side of a second opening that will have a channel is controlled to be lower than the concentration of two-dimensional electron gas in a second region between an end of the first region and a source or drain electrode. The concentration of the two-dimensional electron gas in the first region is thus decreased, thereby the conduction band-raising effect of polarization charge is prevented from being reduced. This prevents a decrease in threshold potential, and thus improves normally-off operability.