GaN Semiconductor Trench Electrode Reduces Current Density
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Solution Overview
Problem
Conventional GaN-based semiconductor devices face challenges with high current density leading to electro-migration and disconnection issues, and difficulties in forming via holes and insulating films due to substrate distortion and thermal stress, which complicates manufacturing and increases on-resistance.
Innovation Solution
A GaN-based semiconductor device with a trench structure where the source electrode is formed on the internal wall of the trench, extending from the top surface to the silicon substrate, and is in ohmic contact with both the substrate and active layer, reducing current density and eliminating the need for additional bonding pads, while an insulating layer prevents electrical contact and avalanche breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode thickness is increased to reduce current density, then electro-migration resistance is improved, but electrode height increases causing breakage upon resin molding
Solution Approach 1:
The source electrode is configured to extend vertically into a trench structure, changing the current flow path from a horizontal planar direction to a vertical three-dimensional direction. This dimensional change allows current to flow through the depth of the trench rather than across the surface, reducing current density without requiring increased electrode height that would cause breakage during resin molding.
2Reliability
If the via hole depth is increased to connect electrodes through the substrate, then electrical connection is improved, but manufacturing difficulty increases due to substrate distortion
Solution Approach 1:
The trench structure is formed preliminarily in the semiconductor layer before electrode formation. This preliminary structuring creates a predefined pathway that guides subsequent electrode deposition and ensures proper electrical connection without requiring deep via hole formation through the distorted substrate, thereby simplifying the manufacturing process.
3Reliability
If the electrode width is increased to reduce current density, then electro-migration resistance is improved, but device area increases
Solution Approach 1:
The invention transitions from two-dimensional planar electrode expansion to three-dimensional vertical trench utilization. By extending the electrode vertically into the trench depth rather than expanding horizontally, the current density is reduced without increasing the device footprint area, maintaining compact device dimensions while improving electro-migration resistance.
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 current density, prevents electro-migration, and improves reliability by lowering on-resistance and eliminating the need for additional bonding pads, while maintaining the advantages of low on-resistance and preventing avalanche breakdown.
Implementation Method 1
the first electrode being formed of the metal in direct ohmic contact with both the silicon substrate and the active layer
Implementation Method 2
a portion of the source electrode is covered with an insulating film so as not to be in electrical contact with the active layer
Data Source
AI summary
In a GaN-based semiconductor device, an active layer of a GaN-based semiconductor is formed on a silicon substrate. A trench is formed in the active layer and extends from a top surface of the active layer to a depth reaching the silicon substrate. A first electrode is formed on an internal wall surface of the trench and extends from the top surface of the active layer to the silicon substrate. A second electrode is formed on the active layer to define a current path between the first electrode and the second electrode via the active layer in an on-state of the device. A bottom electrode is formed on a bottom surface of the silicon substrate and defines a bonding pad for the first electrode. The first electrode is formed of metal in direct ohmic contact with both the silicon substrate and the active layer.