Built-In Resistor Insulation Layout for IGBT Dielectric Breakdown
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Solution Overview
Problem
The existing IGBT designs face dielectric breakdown issues due to thin insulating films between the built-in resistor and the semiconductor substrate, especially under high electric fields during switching operations, and thickening the trench gate insulating film affects the device's operation.
Innovation Solution
The insulating film under the built-in resistor is made thicker than the trench gate insulating film, while maintaining the trench gate insulating film's thickness, thereby relaxing the electric field and preventing dielectric breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the insulating film under the built-in resistor is made thicker to prevent dielectric breakdown, then the reliability improves, but the trench gate insulating film thickness must also increase which prevents proper electric field application to the p type channel region
Solution Approach 1:
The patent applies different thickness specifications to different insulating film regions: the first insulating film under the built-in resistor is made thicker (50-200 nm) for dielectric breakdown prevention, while the second insulating film in the trench gate is kept thinner (5-50 nm) for proper electric field application. This local differentiation resolves the contradiction by optimizing each region for its specific functional requirement.
2Ease of operation
If the insulating film under the built-in resistor is made thinner to maintain trench gate insulating film thickness, then the IGBT operation is maintained, but dielectric breakdown occurs between the built-in resistor and the semiconductor substrate
Solution Approach 1:
The patent implements local quality differentiation by specifying that the first insulating film under the built-in resistor has a greater thickness than the second insulating film in the trench gate. This allows the trench gate region to maintain thin film characteristics for proper operation while the built-in resistor region has thick film characteristics for dielectric breakdown prevention.
Data Source
AI summary
A built-in resistor electrically connecting a trench gate electrode and a gate pad is formed of a conductive film formed on a semiconductor substrate via an insulating film. Here, a film thickness of the insulating film is larger than a film thickness of an insulating film in a trench and is smaller than an insulating film which is a field oxide film.