Recessed Barrier HEMT Gate Structure for RON, gm, and VBR
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Solution Overview
Problem
Conventional high electron mobility transistors (HEMTs) face challenges in achieving reduced on-resistance (RON), increased transconductance (gm), and improved breakdown voltage (VBR) to meet industry requirements.
Innovation Solution
The design includes a semiconductor device with a substrate, semiconductor channel layer, semiconductor barrier layer, and a gate electrode, where the semiconductor barrier layer has a recess and a gate electrode with vertical extension portions overlapping the recess, enhancing the 2-DEG region's carrier concentration and electric field distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional HEMT structure is used, then device simplicity is maintained, but on-resistance is high and transconductance is low
Solution Approach 1:
The semiconductor barrier layer is designed with different thickness regions: a first thickness in the first region and a second thickness in the second region. This local quality variation allows optimization of carrier concentration and electric field distribution in different areas, reducing on-resistance and enhancing transconductance without requiring complete structural redesign of the entire device.
Solution Approach 2:
The barrier layer is segmented into multiple regions with different thicknesses, creating distinct functional zones. The first region with greater thickness provides higher carrier concentration for reduced on-resistance, while the second region with lesser thickness maintains appropriate electric field characteristics. This segmentation enables simultaneous optimization of multiple electrical parameters.
2Reliability
If barrier layer thickness is increased uniformly, then carrier concentration increases, but breakdown voltage decreases
Solution Approach 1:
Different regions of the barrier layer are assigned different thicknesses to fulfill different functional requirements. The first region with greater thickness enhances carrier concentration for improved transconductance, while the second region with lesser thickness maintains breakdown voltage characteristics. This local differentiation resolves the contradiction between transconductance enhancement and breakdown voltage preservation.
3Reliability
If gate electrode is extended vertically, then electric field distribution is improved, but manufacturing complexity increases
Solution Approach 1:
The gate electrode is extended in the vertical dimension to overlap with the recess in the barrier layer. This vertical extension improves electric field distribution and carrier concentration control without requiring complex lateral patterning or additional processing steps. The vertical dimension provides an effective degree of freedom for optimization while maintaining manufacturing simplicity.
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, increases transconductance, and improves breakdown voltage, leading to enhanced electrical performance of the HEMT.
Implementation Method 1
A HEMT is a field effect transistor having a two dimensional electron gas (2-DEG) layer close to a junction between two materials with different band gaps (i.e., a heterojunction)
Implementation Method 2
a junction between two materials with different band gaps
Implementation Method 3
enhancing the 2-DEG region's carrier concentration and electric field distribution
Data Source
AI summary
A semiconductor device includes a substrate, a semiconductor channel layer, a semiconductor barrier layer, and a gate electrode. The semiconductor channel layer is disposed on the substrate, and the semiconductor barrier layer is disposed on the semiconductor channel layer, where the surface of the semiconductor barrier layer includes at least one recess. The gate electrode is disposed on the semiconductor barrier layer and includes a body portion and at least one vertical extension portion overlapping the recess.