IGBT Peripheral Structure for Avalanche Current Recovery
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Solution Overview
Problem
The existing semiconductor devices face challenges in maintaining stable control of IGBTs due to avalanche current issues, leading to potential latch-up and decreased reliability, particularly in regions outside the element forming area.
Innovation Solution
The semiconductor device incorporates an avalanche current recovery structure, including an emitter terminal electrode with specific routing and connecting portions, and a RESURF layer to manage and recover avalanche currents, thereby preventing unwanted switching of the parasitic bipolar transistor and enhancing control stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional IGBT structures are used without avalanche current recovery mechanisms, then device simplicity is maintained, but reliability deteriorates due to avalanche current-induced latch-up and unstable control
Solution Approach 1:
The patent introduces an intermediary avalanche current recovery path consisting of the emitter terminal electrode, connecting portion, and drift region. This intermediary structure safely channels avalanche currents away from the parasitic bipolar transistor, preventing latch-up while maintaining overall device simplicity. The connecting portion acts as a dedicated corridor for current diversion, resolving the contradiction between reliability improvement and structural complexity.
Solution Approach 2:
The emitter terminal electrode is segmented into distinct functional portions: a first portion for normal operation and a second portion (connecting portion) specifically for avalanche current recovery. This segmentation allows the structure to handle both normal switching and avalanche conditions through dedicated pathways, improving reliability without requiring a completely new complex architecture.
2Manufacturing precision
If the drain electrode peripheral edge is positioned away from the end surface, then manufacturing precision is improved, but the area available for avalanche current management is reduced
Solution Approach 1:
The patent extends avalanche current management into the vertical dimension by having the connecting portion of the emitter terminal electrode extend downward to connect with the drift region. This vertical extension compensates for the reduced lateral area caused by positioning the drain electrode peripheral edge away from the end surface, maintaining adequate avalanche current management capability while preserving manufacturing precision.
Solution Approach 2:
The connecting portion is strategically positioned in the outer region of the semiconductor chip, creating a localized avalanche current recovery path. This local quality approach concentrates current management functionality in a specific area, ensuring adequate avalanche handling capability even when the overall lateral area is constrained by precise drain electrode positioning.
3Reliability
If the connecting portion extends to the drift region, then avalanche current recovery effectiveness is improved, but device complexity increases
Solution Approach 1:
The patent merges the avalanche current recovery function with the existing emitter terminal electrode structure. By forming the connecting portion as an extension of the emitter terminal electrode rather than as a separate component, the design achieves effective avalanche current recovery while minimizing additional structural complexity. The merging approach integrates multiple functions into a unified structure.
Solution Approach 2:
The emitter terminal electrode is designed with multi-functionality: the first portion handles normal IGBT operation while the second portion (connecting portion) handles avalanche current recovery. This universal structure performs multiple critical functions through a single integrated component, improving avalanche current recovery effectiveness without proportionally increasing device complexity.
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 effectively suppresses parasitic bipolar transistor activation and maintains IGBT control stability by recovering avalanche currents, reducing the risk of latch-up and improving overall device performance.
Implementation Method 1
avalanche current recovery structure, including an emitter terminal electrode with specific routing and connecting portions, and a RESURF layer to manage and recover avalanche currents
Data Source
AI summary
The semiconductor device includes a semiconductor chip that has a first principal surface, a withstand-voltage holding structure in a peripheral region in the first principal surface, a plurality of first conductive layers that are formed in the first principal surface, a second conductive layer overlaps with a space between the plurality of mutually adjacent first conductive layers in a plan view, and a protective layer that covers the plurality of first conductive layers and the second conductive layer.