Stress Relaxation Layer for Through Silicon Vias
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Solution Overview
Problem
The thermal mismatch between through hole vias and the silicon substrate in semiconductor devices leads to mechanical stress and device failures due to differences in thermal expansion coefficients, limiting the reliability and performance of complex integrated circuits in three-dimensional stacked configurations.
Innovation Solution
Implementing a stress relaxation mechanism, such as a stress relaxation layer or volume expansion areas, within or near the through hole vias to accommodate thermal expansion changes, reducing mechanical stress on the substrate and enhancing the reliability of the metallization system and device level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If through hole vias are formed with high aspect ratio and small lateral dimensions to save chip area, then interconnect density is improved, but thermal mismatch stress increases due to difference in thermal expansion coefficients between via materials and substrate
Solution Approach 1:
A stress relaxation layer is introduced as an intermediary component between the through hole via and the substrate. This layer has intermediate mechanical properties that bridge the gap between the via material and substrate, allowing gradual stress transition and preventing sudden failure. The stress relaxation layer absorbs and distributes the thermal mismatch stress, thereby improving device reliability while maintaining the high aspect ratio via structure.
2Device complexity
If the number of metallization layers is increased to provide higher interconnect density, then circuit complexity is improved, but mechanical stability deteriorates due to reduced dielectric constant of sophisticated low-k dielectrics
Solution Approach 1:
The patent changes the mechanical parameters of the dielectric structure by introducing a stress relaxation layer with specific mechanical properties. This layer compensates for the reduced mechanical stability of low-k dielectric materials, allowing the use of multiple metallization layers with sophisticated low-k dielectrics without sacrificing structural integrity. The stress relaxation layer's mechanical properties are specifically tailored to counteract the weakening effect of low-k dielectrics.
3Volume of stationary object
If through hole vias are formed to enable three-dimensional stacked configurations, then volume packing density is improved, but thermally induced stress increases leading to cracks and delamination
Solution Approach 1:
The stress relaxation layer is formed beforehand in the through hole via structure, providing a cushioning effect against future thermal expansion and contraction. This pre-positioned layer absorbs the thermally induced stress before it can propagate to cause cracks or delamination in the surrounding structures. The cushioning effect is particularly important in three-dimensional stacked configurations where thermal stress accumulation is more severe.
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 stress relaxation mechanism effectively reduces thermally induced stress, minimizing the risk of cracks and delamination events, thereby improving the operational stability and reliability of semiconductor devices under varying temperature conditions.
Implementation Method 1
mismatch of coefficients of thermal expansion between the substrate and the conductive fill material of the through hole via
Implementation Method 2
a stress relaxation mechanism formed in contact with the through hole via and configured to reduce thermally induced stress
Data Source
AI summary
In a semiconductor device, through hole vias or through silicon vias (TSV) may be formed so as to include an efficient stress relaxation mechanism, for instance provided on the basis of a stress relaxation layer, in order to reduce or compensate for stress forces caused by a pronounced change in volume of the conductive fill materials of the through hole vias. In this manner, the high risk of creating cracks and delamination events in conventional semiconductor devices may be significantly reduced.