Hybrid Bond Pad Structure for Misalignment-Tolerant Die Bonding
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Solution Overview
Problem
Current wafer-to-wafer bonding methods face challenges in reducing the size and misalignment effects of bond pads, leading to increased contact resistance and package size, especially when forming hybrid bonds.
Innovation Solution
The method involves forming bond pad vias and bond pads in separate processing steps, allowing for closer spacing and smaller areas of metal pads, and forming bond pads with different areas to accommodate misalignment without affecting contact resistance, using techniques like direct bonding and hybrid bonding with specific barrier layers and conductive materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If bond pads are formed with smaller areas to reduce package size, then package size is reduced, but contact resistance increases
Solution Approach 1:
The bond pad structure is segmented into multiple layers including a first bond pad layer, a second bond pad layer, and an intermediate layer. This segmentation allows each layer to contribute to electrical connection, effectively distributing the current path and reducing contact resistance even when the overall bond pad area is minimized.
Solution Approach 2:
The bond pad structure uses composite materials with different properties in each layer. The first bond pad layer, second bond pad layer, and intermediate layer are formed with different materials optimized for their specific functions, creating a composite structure that achieves low contact resistance with smaller area.
2Area of stationary object
If metal pads are spaced closer together to reduce die size, then die size is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The solution moves from a single-plane pad configuration to a multi-layer three-dimensional configuration. By stacking bond pad layers vertically, the pads can be spaced closer in the horizontal plane without compromising electrical performance, as the vertical layering provides additional connection paths.
Solution Approach 2:
The bonding interface is segmented into multiple discrete layers formed in separate processing steps. This segmentation allows independent optimization of each layer's dimensions and materials, enabling closer horizontal spacing while maintaining manufacturing feasibility through standardized layer formation processes.
3Adaptability or versatility
If bond pads are formed with different areas to accommodate misalignment, then misalignment tolerance is improved, but device complexity increases
Solution Approach 1:
The intermediate layer acts as a cushioning layer that anticipates and compensates for potential misalignment between bond pads. By providing this intermediate layer in advance during fabrication, the structure can accommodate alignment variations without requiring complex real-time adjustment mechanisms.
Solution Approach 2:
The multi-layer bond pad structure serves multiple functions simultaneously: electrical connection, misalignment compensation, and mechanical bonding. This universal structure handles various functions through its layered architecture, reducing the need for separate components and thereby limiting the increase in overall device complexity.
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 the size of the die or package, increases routing density, and ensures improved contact resistance even with misalignment, enhancing the electrical performance of the bonded package.
Implementation Method 1
the bond layers are bonded together to form a bonded structure
Implementation Method 2
bond pad vias and bond pads in separate processing steps, allowing for closer spacing and smaller areas of metal pads
Data Source
AI summary
A package includes a first die that includes a first metallization layer, one or more first bond pad vias on the first metallization layer, wherein a first barrier layer extends across the first metallization layer between each first bond pad via and the first metallization layer, and one or more first bond pads on the one or more first bond pad vias, wherein a second barrier layer extends across each first bond pad via between a first bond pad and the first bond pad via, and a second die including one or more second bond pads, wherein a second bond pad is bonded to a first bond pad of the first die.