Nitride Semiconductor Device ESD Tolerance
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Solution Overview
Problem
Conventional nitride semiconductor devices face challenges in achieving high electrostatic discharge (ESD) tolerance due to nonuniform electric current distribution in the p-side nitride semiconductor layer, caused by irregularities in contact resistance and Mg concentration distribution, which limits the thickness of the p-side layer and affects crystallinity and manufacturing costs.
Innovation Solution
A nitride semiconductor device with a three-layer structure is implemented, comprising a p-side wide band gap layer and a three-layer structure of p-side nitride semiconductor layers with varying p-type impurity concentrations, where the third layer has a high impurity concentration, the second layer has a lower concentration, and the first layer has a narrower band gap and lower impurity concentration near the interface, ensuring uniform electric current distribution and enhanced ESD tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the p-side nitride semiconductor layer is made thicker to improve ESD tolerance, then the ESD tolerance is improved, but the crystallinity deteriorates and manufacturing cost increases
Solution Approach 1:
The p-side nitride semiconductor layer is divided into multiple sub-layers (first p-side nitride semiconductor layer, second p-side nitride semiconductor layer, third p-side nitride semiconductor layer) with different impurity concentrations. This segmentation allows each layer to contribute differently to the overall performance, enabling thicker total structure while maintaining crystallinity in individual layers.
Solution Approach 2:
Different regions of the p-side nitride semiconductor layer are assigned different impurity concentrations: the first layer has lower impurity concentration (1×10^18 to 1×10^19 cm^-3) for good crystallinity, the second layer has intermediate concentration (1×10^19 to 1×10^20 cm^-3), and the third layer has higher concentration (1×10^20 to 1×10^21 cm^-3) for ESD tolerance. This local quality differentiation resolves the contradiction between thickness and crystallinity.
2Reliability
If the p-type impurity concentration is increased to improve ESD tolerance, then the ESD tolerance is improved, but the hole mobility decreases
Solution Approach 1:
The p-side nitride semiconductor layer is segmented into multiple layers with different impurity concentrations. The first layer with lower impurity concentration (1×10^18 to 1×10^19 cm^-3) maintains high hole mobility, while the third layer with higher impurity concentration (1×10^20 to 1×10^21 cm^-3) provides ESD tolerance. This segmentation allows both requirements to be satisfied in different regions.
Solution Approach 2:
Different impurity concentrations are assigned to different layers: the first layer has low impurity concentration for high hole mobility, the second layer has intermediate concentration for transition, and the third layer has high concentration for ESD tolerance. This local quality approach resolves the contradiction between hole mobility and ESD tolerance.
3Object-affected harmful factors
If the Mg concentration is increased to reduce contact resistance, then the contact resistance is reduced, but the electric current distribution becomes nonuniform
Solution Approach 1:
The p-side nitride semiconductor layer is segmented into multiple layers with different impurity concentrations. The third layer with higher impurity concentration (1×10^20 to 1×10^21 cm^-3) reduces contact resistance, while the first and second layers with lower concentrations ensure uniform electric current distribution. This segmentation allows both requirements to be satisfied simultaneously.
Solution Approach 2:
Different impurity concentrations are assigned to different layers: the third layer has high concentration for low contact resistance, while the first and second layers have lower concentrations for uniform current distribution. This local quality differentiation resolves the contradiction between contact resistance and current distribution uniformity.
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 three-layer structure achieves uniform in-plane electric current distribution, improving ESD tolerance and optical output by maintaining high hole mobility and preventing local current concentration, while controlling the thickness and impurity concentration to maintain crystallinity and reduce manufacturing costs.
Implementation Method 1
the third p-side nitride semiconductor layer contains a p-type impurity of 5×10^20 to 2×10^21 cm^-3, the second p-side nitride semiconductor layer contains a p-type impurity in a lower concentration than that of the third p-side nitride semiconductor layer
Data Source
AI summary
A nitride semiconductor device having excellent ESD tolerance, by preventing uneven distribution of the electric current in the p-side nitride semiconductor layer. The p-side nitride semiconductor layer (40) comprises, from the active layer (30) side, (a) a p-side wide band gap layer (12) containing a p-type impurity and (b) a three-layer structure (15) comprising a first p-side nitride semiconductor layer (16), a second p-side nitride semiconductor layer (17), and a third p-side nitride semiconductor layer (18).