Segmented Power Transistor Current Filamentation
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Solution Overview
Problem
Power transistors often fail due to filamentation, where current is concentrated along a single path, leading to hot spots and early failure, as they are unable to distribute current evenly across multiple paths, limiting their current handling capability and safe operating area.
Innovation Solution
The power transistor is segmented by introducing resistive regions that divide the fingers into segments, discouraging lateral current flow and preventing hot spot formation by using higher resistance cut locations between adjacent portions of the source, drain, or tank connections, which reduces the likelihood of filamentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power transistors use multiple parallel transistor fingers to increase current handling capability, then the current handling capability is improved, but current concentration along single paths occurs leading to filamentation and hot spots
Solution Approach 1:
The source and drain regions are segmented into multiple portions using cut locations that extend through the substrate. This segmentation divides the current paths into separate segments, preventing current concentration along single continuous paths and eliminating hot spots while maintaining high current handling capability through multiple parallel transistor fingers
Solution Approach 2:
Cut locations filled with high-resistance material act as intermediaries between adjacent source and drain portions. These intermediary regions provide electrical isolation between segments, forcing current to distribute evenly across multiple paths rather than concentrating in single low-resistance paths, thereby preventing filamentation
2Reliability
If cut locations are introduced to segment source or drain regions, then filamentation is reduced, but device complexity increases
Solution Approach 1:
The substrate is segmented by cutting through it to create isolated regions for source and drain portions. This segmentation approach achieves current path separation using a relatively simple geometric modification to the standard transistor structure, adding minimal complexity while effectively preventing filamentation
Solution Approach 2:
Multiple segmentation functions are combined into a single continuous cut location that simultaneously isolates adjacent source portions and adjacent drain portions. This merging of segmentation operations reduces the total number of separate features needed, simplifying the overall device structure while achieving comprehensive filamentation prevention
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 segmentation approach reduces the likelihood of filamentation by ensuring current flows perpendicular to the fingers, thereby reducing the risk of hot spots and extending the safe operating area and current handling capability of the power transistor.
Implementation Method 1
At least one of the source or drain stripes is segmented into multiple portions, where adjacent portions are separated by a cut location having a higher electrical resistance than remaining portions of the at least one segmented source or drain stripe
Data Source
AI summary
A power transistor includes multiple substantially parallel transistor fingers, where each finger includes a conductive source stripe and a conductive drain stripe. The power transistor also includes multiple substantially parallel conductive connection lines, where each conductive connection line connects at least one source stripe to a common source connection or at least one drain stripe to a common drain connection. The conductive connection lines are disposed substantially perpendicular to the transistor fingers. At least one of the source or drain stripes is segmented into multiple portions, where adjacent portions are separated by a cut location having a higher electrical resistance than remaining portions of the at least one segmented source or drain stripe.