Reverse Blocking IGBT Field Plate Optimization
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Solution Overview
Problem
Conventional reverse blocking IGBTs face challenges in reducing the device area while maintaining high withstand voltages, as the depletion layer extension and electric field localization issues lead to increased size and reduced current capability.
Innovation Solution
The semiconductor device incorporates a breakdown withstanding region with strategically positioned electrically conductive films that suppress depletion layer expansion, allowing for improved reverse withstand voltage and reduced device area by optimizing the spacing and projection of field plates and field limiting rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the breakdown withstanding region is enlarged to improve reverse withstand voltage, then the reverse withstand voltage is improved, but the device area increases
Solution Approach 1:
The patent applies local quality by creating a breakdown withstanding region with specific local characteristics - a first region with higher impurity concentration and a second region with lower impurity concentration. This localized differentiation allows the structure to withstand reverse voltages effectively while maintaining a compact overall device area, resolving the contradiction between reliability and area.
Solution Approach 2:
The patent changes the impurity concentration parameter within the breakdown withstanding region to resolve the contradiction. By having a first region with higher impurity concentration and a second region with lower impurity concentration, the structure achieves both high reverse withstand voltage and reduced device area through optimized parameter distribution.
2Area of stationary object
If the depletion layer extension is suppressed to reduce device area, then the device area is reduced, but the electric field strength rises excessively
Solution Approach 1:
The patent uses local quality by creating regions with different impurity concentrations within the breakdown withstanding region. The first region with higher impurity concentration suppresses depletion layer extension and reduces device area, while the second region with lower impurity concentration manages electric field strength distribution, preventing excessive field concentration.
Solution Approach 2:
The patent resolves the contradiction by transitioning from a uniform one-dimensional structure to a two-dimensional impurity concentration distribution. By varying impurity concentration both laterally (first region vs second region) and vertically, the structure achieves compact area while distributing electric field stress through multi-dimensional parameter variation.
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 configuration enhances the reverse withstand voltage and reduces the reverse blocking IGBT area by preventing excessive depletion layer extension and electric field strength rise, thereby improving the overall performance and efficiency of the semiconductor device.
Implementation Method 1
the electrically conductive films, excluding at least the electrically conductive film in contact with the farthest third semiconductor region, which the depletion layer extending from the separation region toward the active region reaches
Implementation Method 2
having the second semiconductor region side edge portion projecting farther toward the separation region than the third semiconductor region side edge portion
Data Source
AI summary
A reverse blocking IGBT according to the invention can include a reverse breakdown withstanding region, p-type outer field limiting rings formed in a reverse breakdown withstanding region and an outer field plate connected to the outer field limiting rings, the outer field plate including a first outer field plate in contact with outer field limiting rings nearest to the active region and second outer field plates in contact with other outer field limiting rings. The first outer field plate having an active region side edge portion projecting toward the active region and second outer field plate having an edge area side edge portion projecting toward the edge area. The reverse blocking IGBT according to the invention can facilitate improving the withstand voltages thereof and reducing the area thereof.