Power Device Circuit Segmentation Under Repetitive Thermal Stress
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Solution Overview
Problem
Power devices face reliability issues due to thermo-migration induced stress, which can lead to failure under repetitive thermal stress, especially during high power transient events, and increasing the device size is not desirable for compact applications.
Innovation Solution
The method involves dynamically deactivating subsets of power device components during high stress conditions to redistribute thermo-migration induced stress, using control circuits and sensors to select which components to deactivate based on stress readings, thereby modifying temperature gradients and extending the device's lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the size of the power device's active area is increased to reduce peak temperature during high power pulse events, then thermo-migration induced stress is reduced, but the device size increases which is undesirable for compact applications
Solution Approach 1:
The power device components are divided into multiple subsets (first subset, second subset, third subset, etc.) that can be independently activated or deactivated. During high stress conditions, only certain subsets are activated while others are deactivated, effectively segmenting the active area to reduce thermal stress without increasing the overall device footprint.
Solution Approach 2:
The invention dynamically controls the activation state of different power device component subsets based on real-time stress conditions. Control circuits sense high stress conditions and dynamically switch between different subsets of components, allowing the device to adapt its effective active area during operation to manage thermal stress while maintaining compact size.
2Power
If all power device components are activated during high stress conditions, then the device can handle high power loads, but thermo-migration induced stress increases leading to metallization degradation and failure
Solution Approach 1:
During high stress conditions, the invention activates only a partial subset of power device components rather than all components. This partial action approach provides sufficient power handling capability through the activated subsets while avoiding the excessive thermal stress that would result from activating all components, thereby preventing metallization degradation and improving reliability.
Solution Approach 2:
Different subsets of power device components are selectively activated based on local stress conditions. The control system identifies which subsets are experiencing high stress and deactivates those specific subsets while keeping other subsets active, applying local quality control to manage stress distribution across different regions of the device.
3Reliability
If subsets of power device components are deactivated during high stress conditions, then thermo-migration induced stress is reduced, but the number of components that can be deactivated is limited to maintain performance
Solution Approach 1:
The power device components are segmented into multiple subsets with sufficient redundancy. This segmentation allows the system to deactivate certain subsets during high stress conditions without compromising overall performance, as other subsets remain active to maintain the required power handling capability.
Solution Approach 2:
The invention changes the operational parameters by dynamically adjusting which subsets of components are active versus inactive based on stress conditions. This parameter change allows the system to optimize between reliability and performance by selecting appropriate subsets to deactivate during high stress while maintaining sufficient power handling capability.
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 approach reduces thermo-migration induced stress, increases the lifetime of power devices, and maintains performance without significantly affecting on-state resistance, even when peak temperatures are increased, by bifurcating the active area and shifting stress points to different portions.
Implementation Method 1
high transient local temperatures and high temperature gradients, which may cause metal/thermo migration
Implementation Method 2
high power transient events, like inductive clamping, may generate high transient local temperatures and high temperature gradients, which may cause metal/thermo migration (thermal driven migration of the metals) in chip components
Data Source
AI summary
Thermo-migration induced stress in power devices can be mitigated by deactivating a subset of power device components (e.g., transistors, etc.) when the power device experiences a high stress condition. Deactivating the subset of power device components serves to bifurcate the active area of the power switching device into smaller active regions, which advantageously changes the temperature gradients in the active area/regions. In some embodiments, a control circuit dynamically deactivates different subsets of power device components to shift the thermo-migration induced stress points to different portions of the active region over the lifetime of the power switching device.