Semiconductor Cavity Displacement for Thermal Stress Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Heterojunction bipolar transistors (HBTs) in semiconductor apparatuses experience thermal stress and reliability issues due to temperature variations among parallel-connected unit transistors, leading to reduced radio-frequency characteristics and shortened lifespan.
Innovation Solution
A semiconductor apparatus design featuring a plurality of unit transistors with strategically positioned cavities in the insulating film, where the centroid of the cavity is displaced from the operating region, optimizing heat dissipation and thermal stress distribution by varying the area of overlapping regions, thereby equalizing temperatures across the transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the cavity is positioned directly over the emitter layer to reduce thermal resistance, then heat dissipation is improved, but thermal stress increases due to coefficient of thermal expansion mismatch
Solution Approach 1:
The patent applies asymmetry by deliberately displacing the cavity from the symmetric position directly over the emitter layer. The cavity is positioned offset in the longitudinal direction, creating an asymmetric thermal management structure that reduces thermal stress while maintaining effective heat dissipation from the operating region.
Solution Approach 2:
The patent applies local quality by creating different thermal management conditions for different regions. The cavity is strategically positioned to provide optimized thermal stress reduction for the emitter layer while maintaining adequate heat dissipation, rather than using a uniform approach throughout the device structure.
2Productivity
If multiple unit transistors are operated in parallel to increase power output, then productivity is improved, but temperature variations increase leading to degraded reliability
Solution Approach 1:
The patent applies local quality by implementing position-dependent cavity displacement for different unit transistors. Unit transistors at different locations (center vs. ends) have their cavities displaced by different amounts, creating localized thermal management that equalizes temperatures across all parallel-operated transistors, thereby maintaining reliability while enabling high power output.
Solution Approach 2:
The patent applies parameter changes by varying the displacement parameter of the cavity position based on the location of each unit transistor. The displacement amount is changed systematically from center to end positions, allowing dynamic thermal management across the multi-transistor array to achieve uniform temperature distribution.
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
The design effectively reduces thermal stress and temperature variations among unit transistors, enhancing the reliability and radio-frequency performance of the semiconductor apparatus by optimizing heat dissipation and thermal management.
Implementation Method 1
the metal member is disposed on the insulating film and is electrically connected to the first wiring via the at least one cavity... effectively reduces thermal stress and temperature variations among unit transistors, enhancing the reliability and radio-frequency performance by optimizing heat dissipation
Data Source
AI summary
A wiring is disposed above operating regions of plural unit transistors arranged on a substrate in a first direction. An insulating film is disposed on the wiring. A cavity entirely overlapping with the wiring as viewed from above is formed in the insulating film. A metal member electrically connected to the wiring via the cavity is disposed on the insulating film. The centroid of the cavity is displaced from that of the operating region of the corresponding unit transistor in the first direction. When the cavity having a centroid the closest to the operating region of a unit transistor is defined as the closest proximity cavity, the amount of deviation of the centroid of the closest proximity cavity from that of the operating region of the corresponding unit transistor in the first direction becomes greater from the center to the ends of the arrangement direction of the unit transistors.