Group III Nitride Semiconductor Device On-State Resistance Reduction
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Solution Overview
Problem
Group III nitride semiconductor devices, such as HEMTs, face challenges with high on-state resistance due to impurity incorporation and interface degradation during selective re-growth processes, which affects the mobility of the 2DEG layer and increases on-state resistance.
Innovation Solution
The solution involves forming a second carrier transport layer through selective re-growth on a first carrier transport layer, followed by a carrier supply layer with a larger bandgap energy, which reduces impurity incorporation and improves interface flatness, thereby reducing on-state resistance. This structure includes a control electrode and insulating film to enhance electron accumulation and mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If selective re-growth is used to form carrier supply layer directly on carrier transport layer, then normally-off characteristic is achieved, but impurities are incorporated at the interface and flatness is degraded, resulting in reduced mobility and increased on-state resistance
Solution Approach 1:
The patent divides the carrier transport layer into multiple sub-layers (first carrier transport layer, second carrier transport layer, third carrier transport layer) with different doping concentrations. This segmentation allows the interface directly below the gate electrode to have zero or low doping concentration, preventing 2DEG formation in that region while maintaining normally-off characteristic, and avoiding impurity incorporation issues at critical interfaces.
Solution Approach 2:
The patent applies different doping concentrations to different regions of the carrier transport layer. The region directly below the gate electrode has zero or low doping concentration to prevent 2DEG formation and ensure normally-off operation, while other regions have appropriate doping concentrations for optimal device performance. This local quality variation resolves the contradiction between achieving normally-off characteristic and maintaining interface quality.
2Reliability
If selective re-growth is used to form carrier supply layer directly on carrier transport layer, then normally-off characteristic is achieved, but mobility of 2DEG is reduced and on-state resistance increases
Solution Approach 1:
By segmenting the carrier transport layer into multiple sub-layers with different doping concentrations, the patent ensures that the interface directly below the gate electrode has zero or low doping concentration, preventing 2DEG formation there. This allows the 2DEG to form only in regions with appropriate doping concentrations, maintaining high mobility and low on-state resistance while achieving normally-off characteristic.
Solution Approach 2:
The patent implements local quality variation by assigning different doping concentrations to different regions of the carrier transport layer. The region below the gate electrode has zero or low doping to prevent unwanted 2DEG formation and maintain normally-off operation, while other regions have optimized doping concentrations for high 2DEG mobility, thus resolving the contradiction between reliability and mobility.
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
The approach results in a semiconductor device with reduced on-state resistance, improved mobility of the 2DEG layer, and enhanced breakdown voltage, suitable for power converters with low loss and high performance.
Implementation Method 1
a carrier supply layer formed through selective growth of a Group III nitride semiconductor having a bandgap energy (hereinafter may be referred to simply as 'bandgap') larger than that of the Group III nitride semiconductor of the second carrier transport layer
Data Source
AI summary
A method for producing a semiconductor device, includes forming a first carrier transport layer including a Group III nitride semiconductor, forming a mask on a region of the first carrier transport layer, selectively re-growing a second carrier transport layer on an unmasked region of the first carrier transport layer, the second carrier transport layer including a Group III nitride semiconductor, and selectively growing a carrier supply layer on the second carrier transport layer, the carrier supply layer including a Group III nitride semiconductor having a bandgap different from that of the Group III nitride semiconductor of the second carrier transport layer.