Superjunction Pillars for Power Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power semiconductor devices face challenges in balancing on-resistance and breakdown voltage, particularly in high-voltage applications, where existing technologies struggle to optimize switching speed and performance across different frequency and voltage requirements.
Innovation Solution
The development of superjunction structures with alternately arranged pillars of different conductivity types, including the formation of epitaxial layers, implant regions, and trench filling with semiconductor material, to create a charge balance that enhances breakdown voltage and reduces on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the breakdown voltage is improved by increasing the drift region thickness, then the on-resistance increases
Solution Approach 1:
The drift region is segmented into alternating pillars of first conductivity type and second conductivity type, creating a superjunction structure. This segmentation allows the electric field to be distributed across multiple junctions, enabling high breakdown voltage while maintaining low on-resistance through the combined effect of multiple parallel conduction paths.
Solution Approach 2:
Different regions of the semiconductor device are given different conductivity types and doping concentrations. The alternating pillars have locally optimized properties where pillars of one conductivity type provide charge compensation for adjacent pillars of opposite type, creating regions of high electric field for breakdown voltage and regions of low resistance for current conduction.
2Loss of energy
If the on-resistance is reduced by decreasing the drift region thickness, then the breakdown voltage decreases
Solution Approach 1:
The drift region is divided into alternating pillars of first conductivity type and second conductivity type, creating a superjunction structure. This segmentation allows the electric field to be distributed across multiple junctions, enabling high breakdown voltage while maintaining low on-resistance through the combined effect of multiple parallel conduction paths.
Solution Approach 2:
The doping concentration and thickness of alternating pillars are precisely controlled to achieve charge balance. By adjusting these parameters, the device achieves optimal breakdown voltage and on-resistance characteristics, where the product of doping concentration and thickness is optimized for each pillar type.
3Reliability
If charge balancing structures are added to the transistor drift region, then the device complexity increases
Solution Approach 1:
The drift region is segmented into alternating pillars of first conductivity type and second conductivity type, creating a superjunction structure. This segmentation allows the electric field to be distributed across multiple junctions, enabling high breakdown voltage while maintaining low on-resistance through the combined effect of multiple parallel conduction paths.
Solution Approach 2:
The charge balancing function is merged with the drift region structure itself by forming alternating pillars directly within the drift region. This integration eliminates the need for separate charge balancing structures, reducing overall device complexity while achieving both high breakdown voltage and low on-resistance.
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 improves the breakdown voltage and switching performance of power semiconductor devices, allowing for more efficient operation across a range of applications by optimizing the charge balance and reducing on-resistance, thus addressing the limitations of existing technologies.
Implementation Method 1
each of the plurality of pillars of second conductivity type further includes a plurality of implant regions of the second conductivity type arranged on top of one another along the depth of pillars of second conductivity type
Implementation Method 2
forming a plurality of epitaxial layers of a first conductivity type over a substrate
Data Source
AI summary
A power device includes a semiconductor substrate having a plurality of alternately arranged pillars of first and second conductivity types. At least one of the plurality of pillars of second conductivity type includes a first trench epitaxial layer of the second conductivity type disposed on a trench sidewall of the second trench and a trench bottom surface of the second trench, a second trench epitaxial layer of the second conductivity type disposed on the first trench epitaxial layer of the second conductivity type, and an insulating material layer disposed on the second trench epitaxial layer of the second conductivity type.