TSV Interconnection Barrier Pad Grain Refinement
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Solution Overview
Problem
The existing technologies for creating 3D integrated circuits using through silicon vias (TSVs) face challenges in achieving a smooth surface for interconnects due to large metallic grain structures, which can lead to surface distortions and affect the conductivity and yield in package production.
Innovation Solution
The implementation of a barrier pad under the conductive pad in TSVs to reduce the size of metallic crystals and create a smoother surface, using materials like tantalum, cobalt, or titanium, which are deposited in a thin layer to prevent large-scale grain formation and surface topography issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If through silicon vias (TSVs) are used to create 3D integrated circuits, then the density of connections is substantially higher and the length of connections is shorter, but large metallic grain structures cause surface distortions and affect conductivity
Solution Approach 1:
The patent divides the TSV structure into multiple segments by introducing a barrier pad layer between the copper fill and the conductive cap. This segmentation prevents the formation of large continuous metallic grain structures, thereby reducing surface distortions while maintaining high connection density through the TSV architecture.
Solution Approach 2:
The barrier pad is deposited in advance before the conductive cap is formed. This preliminary action of creating the barrier pad layer prevents large-scale grain formation from occurring in the first place, ensuring surface smoothness is maintained throughout subsequent processing steps.
2Volume of moving object
If TSVs are used to connect chips vertically, then space is reduced and connectivity is increased, but surface topography issues affect wire bonding reliability
Solution Approach 1:
By segmenting the metallic structure with a barrier pad layer, the patent eliminates surface topography variations that would otherwise interfere with wire bonding. This allows vertical stacking for compact packaging while ensuring reliable wire bonding through smooth surfaces.
Solution Approach 2:
The barrier pad acts as an intermediary layer between the copper fill and the conductive cap, preventing direct contact that would lead to large grain formation. This intermediary structure maintains the compact vertical architecture while ensuring surface quality for reliable wire bonding.
3Reliability
If copper is deposited in TSVs to provide conductivity, then electrical performance is improved, but large metallic grain structures form causing surface distortions
Solution Approach 1:
The copper fill is segmented from the conductive cap by the barrier pad layer, preventing continuous large-scale grain formation across the entire TSV structure. This segmentation maintains electrical conductivity through the copper while ensuring surface smoothness at the cap interface.
Solution Approach 2:
The barrier pad serves as an intermediary that allows copper to provide conductivity without directly forming large grains at the surface. The intermediary layer blocks grain growth while maintaining electrical performance through the overall TSV structure.
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 results in a higher yield and improved conductivity by reducing surface distortions and topography variations, allowing for more reliable wire bonding and interconnects in semiconductor devices.
Implementation Method 1
the second layer inhibits growth of grain boundaries in the first layer
Data Source
AI summary
An interconnection structure and method disclosed for providing an interconnection structure that includes conductive features having reduced topographic variations. The interconnection structure includes a contact pad disposed over a substrate. The contact pad includes a first layer of a first conductive material and a second layer of a second conductive material over the first layer. The first conductive material and the second conductive material are made of substantially the same material and have a first average grain size and a second average grain size that is smaller than the first average grain size. The interconnection structure also includes a passivation layer covering the substrate and the contact pad, and the passivation layer has an opening exposing the contact pad.