P-GaN HEMT Gate Surface Conditioning for Low Leakage
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Solution Overview
Problem
The challenge in preparing high-quality P-type GaN material for enhancement mode HEMT devices leads to issues such as surface damage, defects, and reliability degradation due to high-temperature annealing, resulting in electric leakage and pre-breakdown.
Innovation Solution
A method involving sequential stacking of layers, etching and growing sacrificial layers to reduce magnesium ion concentration on the P-type semiconductor layer surface, forming a high-resistance region through repeated processes, and using a protection layer to minimize surface damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-temperature annealing is used to prepare P-type GaN material, then magnesium ion concentration is increased, but surface damage and defects occur leading to reliability degradation
Solution Approach 1:
A protection layer is formed on the P-type GaN layer before magnesium ion implantation or annealing processes. This protection layer prevents surface damage and defect formation during high-temperature processing, allowing adequate magnesium ion concentration to be achieved without compromising device reliability
Solution Approach 2:
The protection layer acts as an intermediary between the P-type GaN layer and the harsh processing environment. It mediates the conflict between achieving high magnesium ion concentration through high-temperature annealing and preventing surface damage, by providing a protective barrier that can be removed or integrated after processing
2Reliability
If high-temperature annealing is performed to activate magnesium ions, then P-type conductivity is improved, but surface damage causes electric leakage and pre-breakdown
Solution Approach 1:
The protection layer is applied beforehand to cushion and absorb the harmful effects of high-temperature annealing on the P-type GaN layer surface. This allows the necessary thermal processing to occur for activating magnesium ions and achieving proper P-type conductivity without causing surface damage that would lead to electric leakage and pre-breakdown
3Adaptability or versatility
If conventional P-GaN gate method is used, then enhancement mode HEMT device is achieved, but high-quality P-type GaN material is difficult to obtain
Solution Approach 1:
The protection layer is formed in advance before P-type GaN layer fabrication and processing. This preliminary protective measure enables achievement of high-quality P-type GaN material with proper conductivity and minimal defects, while maintaining the enhancement mode functionality of the HEMT device
Solution Approach 2:
The protection layer serves as an intermediary that facilitates the conventional P-GaN gate method by protecting against the very processing steps that normally degrade material quality. This allows standard enhancement mode HEMT fabrication to proceed while achieving superior P-type GaN material quality
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 results in an enhancement mode HEMT device with low gate leakage current, high breakdown voltage, and stable threshold voltage, improving device reliability.
Implementation Method 1
magnesium ions on a surface of the P-type semiconductor layer diffusing into the sacrificial layer
Data Source
AI summary
A method for manufacturing a semiconductor structure includes: sequentially stacking a substrate, a heterojunction structure layer, and a P-type semiconductor layer; remaining the P-type semiconductor layer in a gate region and etching the P-type semiconductor layer in a non-gate region; growing a sacrificial layer on the P-type semiconductor layer, and magnesium ions on a surface of the P-type semiconductor layer diffusing into the sacrificial layer; etching the sacrificial layer; and repeating N times processes of growing the sacrificial layer first and then etching the sacrificial layer until a concentration of the magnesium ions on the surface of the P-type semiconductor layer is less than a preset value, so that the magnesium ions on the surface is reduced to form a high-resistance region on the surface of the P-type semiconductor layer, obtaining an enhancement mode HEMT device with low gate leakage current, high breakdown voltage, and stable threshold voltage.