Current-Sensing Semiconductor Layout for Reverse Recovery Protection
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Solution Overview
Problem
Conventional semiconductor devices face issues with destruction of the current sensing portion due to inadvertent current concentration from built-in diodes during reverse recovery operations, leading to potential damage in the active region.
Innovation Solution
The semiconductor device incorporates a non-MOS structure portion in the current sensing region, which is structurally distinct from the main semiconductor device, preventing current flow through built-in diodes by omitting n+-type source regions at trench sidewalls and utilizing p-type base layers to redirect current away from the MOS structure, thereby protecting the active region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current sensing portion is integrated into the semiconductor device, then the device can detect overcurrent and improve reliability, but current from built-in diodes concentrates in the current sensing portion during reverse recovery operations, leading to potential destruction of the active region
Solution Approach 1:
The current sensing portion is divided into multiple unit cells, each with identical configuration to the main semiconductor device. This segmentation distributes the current flow across multiple parallel paths, preventing current concentration in a single active region while maintaining overcurrent detection capability.
Solution Approach 2:
The patent introduces an n-type semiconductor layer as an intermediary structure between the p-type base layer and the n+-type substrate. This intermediary layer acts as a current distributor during reverse recovery operations, guiding the current from built-in diodes away from the sensitive active regions of the unit cells and preventing destructive current concentration.
2Measurement precision
If the current sensing portion uses the same structure as the main semiconductor device, then it can accurately detect main current, but it becomes vulnerable to damage from reverse recovery current concentration
Solution Approach 1:
While the current sensing portion uses the same basic unit cell structure as the main semiconductor device for accurate current detection, the patent applies local quality modification by introducing the n-type semiconductor layer specifically in the current sensing portion. This localized structural difference provides damage resistance exactly where needed without affecting the detection accuracy of the main current flow paths.
Data Source
AI summary
A semiconductor device includes a main semiconductor region and a current detecting region. The main semiconductor region and the current detecting region have a semiconductor substrate of a first conductivity type, a first semiconductor layer of a first conductivity type, first semiconductor regions of a second conductivity type, second semiconductor regions of the first conductivity type, trenches, first high-concentration regions of the second conductivity type, and second high-concentration regions of the second conductivity type. An active region through which a current flows when the current detecting region is in an on-state has a first cell region that operates as a transistor and second cell regions that are provided, respectively, in four corners of the first cell region and operate only as diodes and not as a transistor.