Resistive Edge Termination for Power Device Avalanche Current
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Solution Overview
Problem
Conventional charge balance power devices face challenges in achieving high breakdown voltage and low on-resistance, particularly at the edge termination region, which limits their ability to handle high avalanche currents during switching events, leading to increased power losses and reduced safe operating area (SOA).
Innovation Solution
A resistive element is coupled to the termination region of a field effect transistor, which redirects a portion of the avalanche current from the termination region to the active region during high current events, using a resistive voltage division technique to minimize power dissipation and improve SOA performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If charge balance structures are implemented in the drift region, then breakdown voltage is improved, but on-resistance increases due to lighter doping requirements
Solution Approach 1:
The patent applies different doping concentrations to different regions: the drift region is lightly doped to achieve high breakdown voltage, while the termination region uses heavier doping to reduce on-resistance. This local differentiation allows each region to be optimized for its specific function without compromising the other.
Solution Approach 2:
The device is divided into distinct functional regions with different charge balance structures: the drift region contains buried electrodes and floating regions for voltage support, while the termination region uses opposite polarity pillars for field control. This segmentation allows independent optimization of each region's electrical characteristics.
2Area of stationary object
If the termination region area is reduced, then device integration is improved, but current handling capability deteriorates during high current avalanche events
Solution Approach 1:
The patent changes the doping parameters in the termination region, using heavier doping concentrations to reduce resistance and improve current handling capability. This parameter optimization allows the termination region to sustain high avalanche currents despite its reduced area, maintaining reliability while enabling better device integration.
3Loss of energy
If the drift region is heavily doped, then on-resistance is reduced, but breakdown voltage decreases
Solution Approach 1:
The patent implements local quality by assigning different doping concentrations to different regions: the drift region maintains light doping for high breakdown voltage, while the termination region uses heavy doping for low on-resistance. This spatial differentiation resolves the contradiction by allowing each region to be optimized for its primary function.
Solution Approach 2:
The device structure is segmented into functionally distinct regions with independently optimized doping profiles. The drift region is optimized for voltage blocking with light doping, while the termination region is optimized for current conduction with heavy doping, eliminating the need to compromise between these conflicting requirements.
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 effectively reduces current flow in the termination region during high avalanche events, minimizing power losses and enhancing the safe operating area by shifting a significant portion of the avalanche current to the active region, thereby improving the device's blocking capability and current handling.
Implementation Method 1
upon occurrence of avalanche breakdown in the termination region an avalanche current starts to flow in the termination region
Implementation Method 2
the resistive element is configured to induce a portion of the avalanche current to flow through the termination region and a remaining portion of the avalanche current to flow through the active region
Data Source
AI summary
A field effect transistor includes an active region and a termination region surrounding the active region. A resistive element is coupled to the termination region, wherein upon occurrence of avalanche breakdown in the termination region an avalanche current starts to flow in the termination region, and the resistive element is configured to induce a portion of the avalanche current to flow through the termination region and a remaining portion of the avalanche current to flow through the active region.