Source Field Plate Air Bridge Reduces Parasitic Capacitance
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Solution Overview
Problem
High electric field peaks near the gate electrode in semiconductor devices lead to increased gate electrode leak current, material breakdown, and reduced breakdown voltage, affecting the reliability and lifetime of High Electron Mobility Transistor (HEMT) devices.
Innovation Solution
A semiconductor device design incorporating a source field plate with specific structural features, including an air bridge structure and a groove formation process, to reduce parasitic gate-source capacitance and resistance while maintaining effective modulation of the strong electric field, thereby enhancing breakdown voltage and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a source field plate is formed directly on the semiconductor layer, then the modulation effect on the strong electric field is enhanced, but the parasitic gate-source capacitance and resistance increase
Solution Approach 1:
The source field plate is divided into multiple segments with different structures: a first region directly on the semiconductor layer for strong electric field modulation, and a second region elevated on an air bridge for reduced parasitic effects. This segmentation allows each region to fulfill its specific function optimally.
Solution Approach 2:
The source field plate transitions from a two-dimensional planar structure to a three-dimensional structure by elevating part of it on an air bridge. This dimensional change reduces the overlapping area with the gate electrode, thereby reducing parasitic capacitance while maintaining the electric field modulation effect.
2Object-generated harmful factors
If the source field plate is elevated on an air bridge, then the parasitic gate-source capacitance and resistance are reduced, but the modulation effect on the strong electric field is weakened
Solution Approach 1:
Different regions of the source field plate have different local qualities: the first region is in direct contact with the semiconductor layer to provide strong electric field modulation, while the second region is elevated on an air bridge to reduce parasitic effects. This local differentiation resolves the contradiction between modulation effectiveness and parasitic reduction.
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
The design effectively reduces parasitic capacitance and resistance, improving the breakdown voltage and reliability of the semiconductor device while maintaining the modulation effect on the strong electric field, thus addressing the issues of high electric field peaks and material degradation.
Implementation Method 1
the first intermediate portion of the source field plate has an air bridge structure, in which air exists between the first intermediate portion and the semiconductor layer, which reduces parasitic gate-source capacitance and parasitic resistance
Implementation Method 2
a start portion electrically connected to the source electrode... disposed between the gate electrode and the drain electrode in a horizontal direction... the effect of modulation to the strong electric field by the source field plate
Data Source
AI summary
A semiconductor device comprises: a substrate; a semiconductor layer formed on the substrate; a source electrode, a drain electrode and a gate electrode between the source electrode and the drain electrode formed on the semiconductor layer; and a source field plate formed on the semiconductor layer. The source field plate sequentially comprises: a start portion electrically connected to the source electrode; a first intermediate portion spaced apart from the semiconductor layer with air therebetween; a second intermediate portion disposed between the gate electrode and the drain electrode in a horizontal direction, without air between the second intermediate portion and the semiconductor layer; and an end portion spaced apart from the semiconductor layer with air therebetween.