Semiconductor Buffer Region Segmentation for Radiation Robustness
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Solution Overview
Problem
Semiconductor devices for automotive applications face challenges in maintaining reliability over 15 years under harsh conditions, including wide temperature ranges and cosmic radiation, while improved reliability often degrades electrical parameters or increases production costs.
Innovation Solution
A semiconductor device with a buffer region having at least three sub-regions of different doping concentrations, specifically a lower sub-region with a doping concentration of 5×10^16 to 8×10^17 cm^-3, an upper sub-region with 1×10^15 to 1×10^16 cm^-3, and a middle sub-region with 5×10^15 to 5×10^16 cm^-3, arranged between the drift and drain regions, enhancing robustness against cosmic radiation without significantly increasing specific on-state resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the buffer region is designed with multiple sub-regions of different doping concentrations to improve robustness against cosmic radiation, then reliability is improved, but device complexity increases
Solution Approach 1:
The buffer region is divided into multiple sub-regions (first, second, third sub-regions) with different doping concentrations. This segmentation allows each sub-region to handle different aspects of voltage blocking and radiation resistance, improving overall reliability while distributing the complexity across functional segments rather than a single complex structure
Solution Approach 2:
Different sub-regions of the buffer are assigned different doping concentrations tailored to their specific functional requirements. The first sub-region has higher doping for proximity to the drain, while subsequent sub-regions have progressively lower doping, creating local optimizations that collectively enhance radiation robustness without uniformly increasing device complexity
2Reliability
If the buffer region doping concentration is increased to reduce specific on-state resistance, then electrical performance is improved, but robustness against cosmic radiation deteriorates
Solution Approach 1:
The doping concentration parameter is varied across different sub-regions of the buffer rather than using a uniform value. The first sub-region uses higher doping (5×10^16 to 8×10^17 cm^-3) to maintain low on-resistance near the drain, while second and third sub-regions use progressively lower doping to enhance radiation robustness, achieving both electrical performance and reliability goals through parameter optimization
Solution Approach 2:
The buffer region functions as a composite structure with multiple doping profiles, combining regions of different electrical characteristics. This composite approach allows the device to exhibit both low on-state resistance (from higher-doped regions) and high radiation robustness (from lower-doped regions) simultaneously, resolving the contradiction between electrical performance and reliability
3Device complexity
If a single uniform buffer region is used, then device complexity is reduced, but reliability under harsh conditions deteriorates
Solution Approach 1:
The buffer region is segmented into multiple sub-regions with distinct doping concentrations, each optimized for specific functional requirements. This segmentation enables the device to handle diverse stress conditions (thermal, radiation, electrical) more effectively than a uniform buffer, improving reliability without requiring a completely different device architecture
Solution Approach 2:
The solution moves from a one-dimensional uniform doping profile to a multi-dimensional doping structure with variations in concentration across the buffer depth. This dimensional complexity in the doping profile enables enhanced reliability under harsh conditions while maintaining a relatively simple overall device structure
Data Source
AI summary
A semiconductor device include a semiconductor body with a drain region of a first conductivity type, a drift region of the first conductivity type and having a doping concentration lower than a doping concentration of the drain region, a buffer region of the first conductivity type arranged between the drift region and the drain region, a source region of the first conductivity type, a body region of a second conductivity type arranged between the source region and the drift region and forming a first pn-junction with the source region and a second pn-junction with the drift region, and a charge compensation region of the second conductivity type extending from the body region towards the buffer region. A source metallization is in ohmic contact with the source region. A drain metallization is ohmic contact with the drain region.