Super Junction Trench Liner With Diffusion Barrier Interfaces
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Solution Overview
Problem
Conventional methods struggle to produce high-quality super junction semiconductor devices with high aspect ratios due to challenges in uniformly etching and filling trenches, leading to defects such as seams and voids, which affect the device's performance and breakdown voltage.
Innovation Solution
The formation of a thin P-type liner with diffusion barriers on the sidewalls of trenches in super junction devices, using epitaxial growth to prevent dopant diffusion and create an abrupt transition between N-type and P-type regions, allowing for higher aspect ratios and improved uniformity in filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional etching and filling methods are used to create high aspect ratio trenches, then device breakdown voltage is limited, but manufacturing defects such as seams and voids increase
Solution Approach 1:
A diffusion barrier layer is introduced as an intermediary between the P-type liner and N-type regions. This barrier layer prevents dopant diffusion while maintaining the high aspect ratio structure, enabling both high breakdown voltage and manufacturing precision. The barrier acts as a mediator that resolves the conflict between achieving high aspect ratios and preventing defects.
Solution Approach 2:
The structure employs composite materials including P-type liner, diffusion barrier layer, and N-type regions in combination. This multi-material approach allows each layer to perform its specific function: the P-type liner provides charge balance, the diffusion barrier prevents dopant contamination, and the N-type regions provide electrical conductivity, collectively achieving high breakdown voltage without manufacturing defects.
2Reliability
If P-type dopant concentration is increased to maintain charge balance, then device performance improves, but dopant diffusion into N-type regions increases
Solution Approach 1:
The diffusion barrier layer serves as an intermediary that blocks P-type dopants from diffusing into N-type regions. This allows the P-type liner to maintain high dopant concentration for charge balance while the barrier prevents the harmful diffusion effect, resolving the contradiction between performance and contamination.
Solution Approach 2:
The harmful dopant diffusion is extracted or removed from the system by introducing the diffusion barrier layer. This barrier selectively blocks the unwanted dopant migration while allowing the beneficial charge balance function to continue, effectively separating the harmful effect from the useful function.
3Reliability
If trench width is reduced to increase aspect ratio, then device breakdown voltage increases, but etching and filling uniformity deteriorates
Solution Approach 1:
The diffusion barrier layer acts as an intermediary that enables the use of narrower trenches for high breakdown voltage while compensating for the manufacturing difficulties. By preventing dopant diffusion, the barrier allows process engineers to achieve narrow trench dimensions without sacrificing filling uniformity, as the barrier ensures clean interfaces even when trench geometry is challenging.
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 production of asymmetric super junction devices with doubled breakdown voltage and reduced defects by maintaining charge balance and preventing dopant diffusion, even at high temperatures, thus enhancing device performance.
Implementation Method 1
a diffusion barrier between the P-type region and the N-type region
Implementation Method 2
using epitaxial growth to prevent dopant diffusion and create an abrupt transition between N-type and P-type regions
Data Source
AI summary
A super junction device with an increased voltage rating may be formed by creating a P liner on the sidewalls of a trench etched into N material, then filling the trench with additional N-type material. This thin P liner may be doped at a significantly higher concentration than the surrounding N material to maintain a charge balance. However, these relatively thin dimensions and the high doping concentration differential may cause P dopants to diffuse into the N material during subsequent high-temperature manufacturing processes. Diffusion barriers on either side of the P liner prevent diffusion of the dopants into the surrounding N material. The diffusion barriers create an abrupt interface between the N and P materials that prevents diffusion and improves the performance of the super junction devices.