Nitride High-Voltage Component Spatial Isolation Breakdown
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Solution Overview
Problem
Conventional high-voltage nitride devices grown on silicon substrates suffer from vertical breakdown due to the low critical electric field of silicon, limiting their breakdown voltage and increasing leakage current, and thickening the nitride epitaxial layer to enhance voltage resistance is costly and prone to defects.
Innovation Solution
Creating spatial isolation areas by removing parts of the silicon substrate below the nitride epitaxial layer between the gate and drain electrodes, filling these areas with high critical electric field materials, and oxidizing the inner sidewalls to increase breakdown voltage, thereby shifting the breakdown path to the nitride epitaxial layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the nitride epitaxial layer is increased to enhance voltage resistance, then the breakdown voltage is improved, but the manufacturing cost increases and production capacity decreases
Solution Approach 1:
The patent divides the voltage withstanding function into two parts: the nitride epitaxial layer provides horizontal voltage resistance, while the silicon substrate provides vertical voltage resistance through oxidation. This segmentation allows the epitaxial layer to remain thin (maintaining high productivity) while still achieving high breakdown voltage through the combined effect of both layers.
Solution Approach 2:
The patent creates a composite structure combining the nitride epitaxial layer with an oxidized silicon substrate layer. The silicon dioxide layer formed by oxidation acts as a high-resistance material that complements the nitride layer, together providing enhanced voltage resistance without requiring increased epitaxial layer thickness.
2Reliability
If the thickness of the nitride epitaxial layer is increased to enhance voltage resistance, then the breakdown voltage is improved, but more defects including dislocations are introduced
Solution Approach 1:
The patent segments the voltage blocking function between the thin nitride epitaxial layer and the oxidized silicon substrate. This allows the epitaxial layer to remain thin with fewer defects while the oxide layer handles part of the voltage blocking, reducing the need for thick epitaxial growth that introduces dislocations.
Solution Approach 2:
The oxidized silicon layer acts as an intermediary that provides additional voltage resistance without requiring increased epitaxial layer thickness. This mediator layer absorbs some of the voltage stress, allowing the thin epitaxial layer to operate below its defect-prone thickness threshold.
3Reliability
If the thickness of the nitride epitaxial layer is increased to enhance voltage resistance, then the breakdown voltage is improved, but material consumption and growth time increase
Solution Approach 1:
The patent segments the voltage resistance function between the nitride epitaxial layer and the oxidized silicon substrate layer. This allows the epitaxial layer to remain thin (reducing GaN material consumption) while the oxide layer provides complementary voltage blocking capability.
Solution Approach 2:
The patent changes the physical-chemical state of the silicon substrate by oxidizing it to form silicon dioxide. This parameter change (from metallic silicon to oxidized insulation) creates a high-resistance layer that provides voltage resistance without consuming additional nitride materials.
4Power
If working voltage is increased to improve device performance, then the power handling capability is improved, but leakage current increases
Solution Approach 1:
The patent creates a composite structure with the oxidized silicon substrate providing high vertical resistance that blocks leakage current paths. This allows higher working voltages to be applied without proportionally increasing leakage, improving power handling efficiency.
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 approach enhances the breakdown voltage of high-voltage nitride devices while reducing material and production costs, improving production efficiency and controllability by avoiding vertical breakdown through the silicon substrate.
Implementation Method 1
a region of a silicon substrate, which is below a nitride epitaxial layer and between a gate electrode and a drain electrode, is removed to form the spatial isolation area
Implementation Method 2
The spatial isolation area may be filled with filling material of high critical electric field, to increase the breakdown voltage of nitride devices
Implementation Method 3
the breakdown voltage of the nitride device may be further increased by oxidizing the inner sidewalls of the spatial isolation area to form silicon dioxide
Data Source
Figure 1-A~1-B
Figure 2-A~2-B
Figure 3~4
AI summary
A high-voltage nitride device which can avoid vertical breakdown and has a high breakdown voltage includes: a silicon substrate; a nitride nucleation layer prepared on the silicon substrate; a nitride buffer layer prepared on the nitride nucleation layer; a nitride channel layer prepared on the nitride buffer layer; a source electrode and a drain electrode, both of which are contacted with the nitride channel layer; a gate electrode, prepared between the source electrode and the drain electrode; and, at least one spatial isolation area, formed between the silicon substrate and the nitride epitaxial layer and below a region between the gate electrode and the drain electrode.