Semiconductor Die Backside Trenches Filled With Elastic Conductive Material
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current power semiconductor die packages face limitations in heat dissipation and thermal stress management, leading to increased risk of cracking and reduced lifespan due to the generation of heat from high power switching and the use of complex designs to mitigate this.
Innovation Solution
The solution involves forming trenches on the backside of the semiconductor die with mesa regions and applying an elastic conductive material to fill voids created by these trenches, which reduces the effective length of the electron drift region and enhances thermal management by minimizing stress and strain through the use of a more elastic conductive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the die is thinned to reduce heat generation, then the heat generated by the die is reduced, but the die's ability to handle thermal stresses is weakened resulting in cracking
Solution Approach 1:
The patent applies local quality by creating trenches at specific locations on the backside of the die where thermal stresses concentrate. These trenches are filled with elastic material only in the high-stress regions, rather than uniformly treating the entire die structure. This localized approach reduces thermal stress in critical areas while maintaining the overall structural integrity and heat dissipation characteristics of the die.
Solution Approach 2:
The patent uses composite materials by combining the semiconductor die material with elastic filling material in the trenches. The elastic material has different mechanical properties (higher elasticity, lower thermal conductivity) than the semiconductor material, creating a composite structure that manages both thermal and mechanical stresses. This composite approach allows the die to handle thermal cycling without cracking while still dissipating heat effectively.
2Reliability
If trenches are formed in the backside of the die to reduce drift region length, then on-state resistance is reduced, but voids are created that cause hot spots and failure points
Solution Approach 1:
The patent converts the harmful effect of voids into a beneficial structure by intentionally creating trenches and filling them with elastic material. The voids that would normally cause hot spots are replaced with a material that provides both mechanical compliance and controlled thermal management. The trenches themselves become beneficial features that reduce the drift region length and on-state resistance, while the elastic filling material eliminates the harmful hot spot effect.
Solution Approach 2:
The patent changes the physical parameters of the trench regions by filling them with material that has specific properties (elastic modulus, thermal conductivity). This parameter change transforms the trenches from potential defect sites into functional elements that simultaneously reduce electrical resistance and eliminate thermal hot spots. The elastic material's parameters are specifically chosen to match or complement the semiconductor material's thermal and mechanical properties.
3Temperature
If complex package designs are used to improve heat dissipation, then heat dissipation capability is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the backside of the die into multiple regions: active device areas, trench regions, and mesa regions. The trenches are segmented into discrete locations rather than being continuous, allowing selective stress management in high-stress areas. This segmented approach to thermal and mechanical management achieves effective heat dissipation and stress relief without requiring a completely complex package design.
Solution Approach 2:
The patent addresses thermal and mechanical management by moving to another dimension - creating features on the backside of the die rather than modifying the top surface or requiring complex external packaging. The trenches and elastic material filling create a third-dimensional structure that manages thermal stresses and heat flow without increasing planar complexity or requiring additional external heat sink components.
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 effectively reduces on-state resistance, minimizes warping and cracking, and provides improved thermal cycling performance by reducing thermal stress and strain, while also eliminating air pockets that cause hot spots and failure points.
Implementation Method 1
filling the trench voids with an elastic conductive material that is more elastic than the die's semiconductor substrate
Implementation Method 2
an elastic conductive layer disposed over the trench's surface and a portion of the substrate's second surface
Implementation Method 3
provides improved thermal cycling performance by reducing thermal stress and strain
Data Source
AI summary
Disclosed are semiconductor dice with backside trenches filled with elastic conductive material. The trenches reduce the on-state resistances of the devices incorporated on the dice. The elastic conductive material provides a conductive path to the backsides of the die with little induced stress on the semiconductor die caused by thermal cycling. Also disclosed are packages using the dice, and methods of making the dice.