HEMT Drain Cavity Etching for High Breakdown Voltage
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Solution Overview
Problem
High electron mobility transistors (HEMTs) face challenges with low breakdown voltage, leading to potential device destruction under high voltage applications due to silicon's low electron mobility and high source resistance, necessitating the use of gallium nitride-based compounds but requiring innovative manufacturing techniques to enhance structural integrity.
Innovation Solution
The manufacturing of HEMTs involves forming a cavity in the substrate below the drain by etching, using anisotropic or isotropic techniques, with specific etchants and doping to create an etching stop region, allowing for the formation of semiconductor layers with group III-V compounds and insulation layers, thereby increasing the breakdown voltage and preventing device destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon substrate is used for HEMT manufacturing, then ease of manufacture is improved, but breakdown voltage is reduced leading to device destruction under high voltage applications
Solution Approach 1:
The patent removes a portion of the silicon substrate beneath the drain electrode to create a cavity structure. This extraction eliminates the weak silicon region that causes low breakdown voltage, allowing the HEMT to withstand high voltage applications while maintaining manufacturing feasibility through selective substrate removal processes
Solution Approach 2:
The patent creates a cavity structure where the substrate is selectively removed only in specific regions (beneath the drain) rather than uniformly. This local modification provides high breakdown voltage in critical areas while maintaining the overall silicon substrate structure for ease of manufacture, achieving both contradictory requirements through spatially differentiated properties
2Reliability
If gallium nitride-based compounds are used instead of silicon, then breakdown voltage is improved, but manufacturing complexity increases
Solution Approach 1:
The patent employs a composite structure combining silicon substrate with gallium nitride-based semiconductor layers (such as AlGaN/GaN heterostructure). The silicon substrate provides mechanical support and ease of manufacture, while the gallium nitride layers provide high breakdown voltage and high electron mobility, achieving both requirements through material composition rather than process complexity
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 HEMTs, preventing device destruction and enabling high power and high frequency operations by creating a structural integrity that withstands high electric fields.
Implementation Method 1
forming a cavity in the substrate by etching the substrate via the hole
Data Source
AI summary
High electron mobility transistors (HEMTs) including a cavity below a drain and methods of manufacturing HEMTS including removing a portion of a substrate below a drain.