Tapered Junction Termination in GaN Devices for Higher Breakdown Voltage
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Solution Overview
Problem
Current power electronics face challenges in achieving improved breakdown voltage and manufacturing efficiency, particularly in the formation of junction termination structures for semiconductor devices, where edge effects and conductivity modulation remain unresolved.
Innovation Solution
The development of tapered junction termination elements using ion implantation processes in III-nitride semiconductor materials, specifically in gallium nitride (GaN) based epitaxial layers, to modulate conductivity and alleviate edge effects, allowing for improved breakdown voltage and reduced manufacturing costs through a single masking process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional junction termination structures are used, then manufacturing process is simpler, but breakdown voltage is lower and edge effects are not alleviated
Solution Approach 1:
The patent applies local quality by creating a tapered junction termination extension (JTE) structure with spatially varying dopant concentration. The JTE region has a gradient from higher dopant concentration near the contact region to lower dopant concentration at the terminal region, providing locally optimized electrical properties that alleviate edge effects and enhance breakdown voltage without requiring complete structural redesign.
Solution Approach 2:
The patent utilizes parameter changes by varying the dopant concentration as a function of position within the JTE structure. The tapered profile creates a continuous transition in electrical parameters (conductivity, depletion width) from the contact region to the terminal region, which modifies the electric field distribution to reduce peak fields at corners and improve breakdown characteristics.
2Manufacturing precision
If multiple masking processes are used for precise JTE formation, then manufacturing precision is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent merges the formation of the tapered JTE structure with the existing contact region definition process. By using the same mask layer that defines the contact region to also define the JTE tapered region, the patent combines two patterning operations into one, reducing manufacturing steps and costs while maintaining the required precision for the tapered profile.
Solution Approach 2:
The mask layer serves multiple functions: it defines the contact region boundaries, defines the JTE tapered region boundaries, and provides the template for the tapered profile. This multi-functionality of the mask layer eliminates the need for separate masking processes that would otherwise be required to create the tapered JTE structure with the desired precision.
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 tapered junction termination elements effectively alleviate edge effects, enhance breakdown voltage, and reduce manufacturing costs by modulating conductivity and adapting to varying semiconductor layer thicknesses and dopant concentrations, while being independent of doping levels.
Implementation Method 1
forming a mask layer on the second semiconductor layer, wherein the mask layer is patterned with a planar region aligned with the contact region and a tapered region aligned with the terminal region of the second semiconductor layer; implanting ions into the terminal region of the second semiconductor layer using the mask layer to form a tapered junction termination element
Data Source
AI summary
A method for manufacturing a semiconductor device includes: providing a semiconductor substrate; epitaxially growing a first semiconductor layer coupled to the semiconductor substrate; epitaxially growing a second semiconductor layer coupled to the first semiconductor layer, wherein the second semiconductor layer comprises a contact region and a terminal region surrounding the contact region; forming a mask layer on the second semiconductor layer, wherein the mask layer is patterned with a tapered region aligned with the terminal region of the second semiconductor layer; implanting ions into the terminal region of the second semiconductor layer using the mask layer to form a tapered junction termination element in the terminal region of the second semiconductor layer; and forming a contact structure in the contact region of the second semiconductor layer.