Segmented AlGaN Barrier Layer for Microcrack Prevention
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Solution Overview
Problem
High Al composition in AlGaN/GaN-based HEMT devices leads to tensile stress, causing microcracks in the AlGaN layer, which results in yield and reliability issues.
Innovation Solution
A method of fabricating a semiconductor structure by growing a dielectric layer, defining epitaxial and gap regions, etching to expose the substrate, and sequentially growing a gallium nitride buffer layer and an aluminum gallium nitride barrier layer, dividing the barrier layer into independent portions to prevent microcracks and increase the aluminum component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the aluminum composition in AlGaN barrier layer is increased to increase two-dimensional electron gas concentration, then device power increases, but tensile stress increases causing microcracks in the AlGaN layer
Solution Approach 1:
The AlGaN barrier layer is divided into multiple independent segments separated by gaps, rather than forming a continuous layer. This segmentation releases tensile stress that would otherwise cause microcracks, while still maintaining sufficient two-dimensional electron gas concentration at each segment interface to achieve high device power.
Solution Approach 2:
The discontinuous AlGaN structure creates local regions with different properties: the AlGaN segments provide high electron concentration for power, while the gap regions provide stress relief. This local differentiation allows simultaneous optimization of both electron concentration and stress management.
2Power
If the aluminum composition in AlGaN barrier layer is increased to increase device power, then power output improves, but yield rate decreases due to microcracks
Solution Approach 1:
By segmenting the AlGaN barrier layer into discontinuous portions with gaps between them, the structure can accommodate high aluminum composition for enhanced power output while preventing microcrack formation, thereby maintaining high yield rates during manufacturing.
3Power
If the aluminum composition in AlGaN barrier layer is increased to increase device power, then power output improves, but reliability decreases due to microcracks
Solution Approach 1:
The discontinuous AlGaN barrier layer structure segments the high-stress material into isolated regions, allowing each segment to sustain high aluminum composition for maximum power while the gaps between segments prevent stress propagation and microcrack formation, thereby maintaining device reliability.
Solution Approach 2:
The structure creates local AlGaN segments with high aluminum content for power generation, while the intervening gap regions provide local stress relief. This spatial differentiation of material properties enables simultaneous achievement of high power and high reliability.
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 yield rate and reliability of the device by reducing stress in the aluminum gallium nitride film while allowing for increased aluminum composition without microcracking.
Implementation Method 1
Performing chemical vapor deposition of metal organics on the substrate
Data Source
AI summary
A method of fabricating a semiconductor structure includes: growing a dielectric layer on a substrate; defining an epitaxial region and a gap region on the dielectric layer; etching a dielectric layer of the epitaxial region to expose the substrate; sequentially growing a gallium nitride buffer layer and an aluminum gallium nitride barrier layer on the exposed substrate. The method of fabricating a semiconductor structure provided by the present application divides the aluminum gallium nitride barrier layer into a plurality of independent portions, thus preventing the microcracks from occurring in the aluminum gallium nitrogen film while increasing the aluminum component, thereby improving the yield rate and reliability of the device.