GaN P-N Junction Formation via Pre-Regrowth Diffusion
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Solution Overview
Problem
Conventional methods for forming p-n junctions in III-nitride semiconductor devices result in structural defects and chemical contamination, leading to high leakage currents and suboptimal electrical characteristics due to etching damage and exposure to air, which are not fully annealed during regrowth processes.
Innovation Solution
The method involves displacing the p-n junction from the regrowth interface by performing an impurity diffusion before regrowth, using a dopant like zinc to shift the junction into the bulk material, thereby reducing structural defects and chemical contamination, and utilizing an in-situ etch and regrowth process to improve surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching and regrowth processes are used to form p-n junctions, then the junction can be formed at the regrowth interface, but structural defects and chemical contamination occur leading to high leakage currents
Solution Approach 1:
The patent applies preliminary action by performing impurity diffusion into the bulk material before the regrowth process occurs. This pre-positioning of dopants ensures that when regrowth happens, the p-n junction forms in pristine bulk material rather than at the defective regrowth interface, thereby preventing structural defects and chemical contamination from compromising junction quality
Solution Approach 2:
The patent uses an intermediary approach by introducing a diffusion process as a mediating step between substrate preparation and regrowth. This diffusion process serves as an intermediary mechanism that positions the p-n junction away from the regrowth interface, acting as a buffer that prevents direct formation of the junction at the contaminated interface zone
2Ease of manufacture
If the p-n junction is formed at the regrowth interface, then the formation process is simplified, but etching damage and chemical contamination are not fully annealed
Solution Approach 1:
The patent extracts the p-n junction formation location from the regrowth interface by using impurity diffusion to position the junction in the bulk material. This extraction separates the junction formation process from the problematic regrowth interface zone, allowing the junction to form in pristine material while the regrowth process continues to occur at the interface
3Reliability
If impurity diffusion is performed before regrowth to displace the p-n junction, then leakage current is reduced and junction quality is improved, but the process complexity increases
Solution Approach 1:
The patent merges the impurity diffusion process with the existing regrowth process sequence, integrating the diffusion step into the overall fabrication flow. By combining these processes in a coordinated manner within the same manufacturing sequence, the added complexity is minimized while achieving the benefit of reduced leakage current through junction displacement
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 improved p-n junction quality with reduced leakage current and enhanced current-voltage characteristics, comparable to those achieved by continuous growth processes, by forming the junction in pristine bulk material away from defective regrowth interfaces.
Implementation Method 1
diffusing an acceptor into a predetermined portion of the n-type epitaxial structure
Implementation Method 2
removing a predetermined portion of the substrate using an ex-situ etch process
Implementation Method 3
removing an additional predetermined portion of the substrate using an in-situ etch process
Implementation Method 4
regrowing a GaN-based material characterized by a second conductivity type in at least a portion of the predetermined portion and the additional predetermined portion of the substrate
Data Source
AI summary
A semiconductor device includes a III-nitride substrate having a first conductivity type and a first electrode electrically coupled to the III-nitride substrate. The semiconductor device also includes a III-nitride material having a second conductivity type coupled to the III-nitride substrate at a regrowth interface and a p-n junction disposed between the III-nitride substrate and the regrowth interface.