Lateral GaN PN Junction via Sidewall Regrowth
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Solution Overview
Problem
Existing methods for fabricating lateral PN junctions in semiconductor devices face challenges such as dislocation generation, competitive growth issues, and difficulty in achieving conformal epitaxy on trench sidewalls, leading to defects and reduced thermal stability.
Innovation Solution
A method involving conformal regrowth of p-GaN material on exposed n-GaN sidewalls within trenches, using dielectric layers to mask horizontal surfaces and control regrowth conditions, such as low pressure and high temperature, to minimize voids and defects, and employing anisotropic and isotropic etching processes to create a lateral PN junction structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conformal epitaxy is performed on trench sidewalls to form lateral PN junctions, then the junction quality and thermal stability are improved, but dislocation generation and competitive growth issues occur leading to defects
Solution Approach 1:
A dielectric intermediary layer is deposited on the horizontal surface surrounding the trench sidewalls. This dielectric layer acts as a mediator that prevents competitive growth between horizontal and vertical directions, eliminates dislocation generation at the interface, and enables high-quality conformal epitaxy on the sidewalls without defects
Solution Approach 2:
The growth process is segmented into distinct stages: first forming the trench structure with exposed sidewalls, then depositing dielectric material on horizontal surfaces, and finally performing selective epitaxial growth only on the vertical sidewalls. This segmentation prevents competitive growth and enables controlled formation of the lateral PN junction
2Ease of manufacture
If conventional fabrication methods are used to create lateral PN junctions, then the process is simpler, but dislocation generation and competitive growth lead to reduced device performance
Solution Approach 1:
The dielectric layer is deposited on the horizontal surfaces before the epitaxial growth step. This preliminary action prevents competitive growth from occurring during the subsequent sidewall regrowth, eliminating dislocation generation and enabling high-performance devices through a systematically optimized process sequence
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 enables the fabrication of high-quality lateral PN junctions with reduced defects and improved thermal stability, facilitating the production of GaN-based devices like vertical diodes and transistors with enhanced performance and reliability.
Implementation Method 1
conformally regrowing p−GaN material on the exposed n−GaN material of the first sidewall
Data Source
AI summary
Lateral PN junctions and diodes and transistors comprising lateral PN junctions and methods used in making such devices are disclosed. A method of fabricating a lateral PN junction, can comprise: conformally growing p−GaN material on a n−GaN vertical surface extending vertically from an n−GaN horizontal surface on an n−GaN drift layer to form a first PN junction, wherein the n−GaN horizontal surface extends horizontally from the n−GaN vertical surface and the n−GaN horizontal surface has a layer of dielectric material formed on the n−GaN horizontal surface that extends from the p−GaN surface.