RC-IGBT Third Region Geometry for Thermal Homogeneity
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Solution Overview
Problem
Existing reverse-conducting semiconductor devices face issues with inhomogeneous temperature distribution and reduced safe operating area due to the arrangement of pure IGBT areas, leading to increased losses and sensitivity to snap-back effects.
Innovation Solution
The introduction of a larger third region as a pilot IGBT area in the semiconductor device, surrounded by shorted regions of alternating conductivity types, improves thermal performance and decouples the IGBT to diode area ratio, reducing snap-back effects and enhancing electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pure IGBT areas are arranged at the border of the wafer, then the device structure is simplified, but the temperature distribution becomes inhomogeneous and losses increase
Solution Approach 1:
The patent applies local quality by creating distinct regions with different functionalities: a central pilot IGBT region (third region) with specific dimensions and doping characteristics surrounded by shorted regions (first and second regions) with alternating conductivity types. This local differentiation allows the central region to generate heat that distributes more evenly across the wafer, solving the temperature inhomogeneity problem while maintaining the simplified border arrangement
2Ease of manufacture
If pure IGBT areas are arranged at the border of the wafer, then manufacturing is easier, but the safe operating area is reduced and snap-back effects increase
Solution Approach 1:
The patent changes key parameters of the pilot IGBT region: the third region has a width of 1-5 times the base layer thickness and occupies 10-30% of the active region area, with doping concentrations specifically optimized (1E16 to 1E18 atoms/cm³ for the base layer). These parameter adjustments create a pilot region that enhances the safe operating area and reduces snap-back effects while maintaining ease of manufacture through the surrounding shorted regions
Data Source
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AI summary
A reverse-conducting semiconductor device (200) with an electrically active region is provided, which comprises a freewheeling diode and an insulated gate bipolar transistor on a common wafer (100). Part of the wafer (100) forms a base layer (101) with a base layer thickness (102). A first layer (1) of a first conductivity type with at least one first region (10) and a second layer (2) of a second conductivity type with at least one second and third region (20, 22) are alternately arranged on the collector side (103). Each region has a region area with a region width (11, 21, 23) surrounded by a region border. The RC-IGBT is designed in such a way that the following geometrical rules are fulfilled: each third region area is an area, in which any two first regions (10) have a distance bigger than two times the base layer thickness (102); the at least one second region is that part of the second layer (2), which is not the at least one third region (22); the at least one third region (22) is arranged in the central part of the active region in such a way that there is a minimum distance between the third region border to the active region border of at least once the base layer thickness (102); the sum of the areas of the at least one third region (22) is between 10 and 30 % of the active region (110); and each first region width (11) is smaller than the base layer thickness (102).