Elongated Bond Pads for IC Packaging Misalignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Metal-to-metal bonding in integrated circuit packaging faces issues with dishing problems in planarization and misalignment, leading to variations in contact resistance due to large metal pads and small bond pad sizes, which worsen performance, especially in high-density bonding.
Innovation Solution
The use of elongated bond pads with un-parallel longitudinal directions ensures a consistent contact area and resistance, even with misalignment, by designing the pads to maintain a specific contact area regardless of alignment, with lengths and widths optimized to accommodate potential misalignment during the bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If large metal pads are used for metal-to-metal bonding, then bonding area is increased, but dishing problem in planarization is worsened
Solution Approach 1:
The bonding pad is segmented into two distinct layers: a larger bottom pad layer that provides sufficient bonding area, and a smaller top pad layer that minimizes dishing during planarization. This segmentation allows each layer to serve its specific function optimally without compromising the other.
Solution Approach 2:
Different regions of the bonding structure are given different properties: the bottom pad layer has larger area for bonding coverage, while the top pad layer has smaller area to reduce dishing. This local differentiation of quality allows simultaneous optimization of bonding area and planarization quality.
2Productivity
If small bond pad sizes are used for high bond densities, then bonding density is increased, but misalignment sensitivity is worsened
Solution Approach 1:
The bonding structure is segmented into bottom and top pad layers with different dimensions. The bottom layer provides larger alignment tolerance while the top layer maintains small size for high bond density, resolving the conflict between density and alignment sensitivity.
Solution Approach 2:
The solution moves from a single-plane pad design to a multi-layer vertical structure. By utilizing the vertical dimension, the patent achieves high bond density at the top layer while maintaining alignment tolerance through the larger bottom layer footprint.
3Ease of operation
If misalignment occurs during bonding, then contact area varies, but contact resistance variation is worsened
Solution Approach 1:
The larger bottom pad layer acts as a cushioning layer that compensates for potential misalignment before it affects the actual bonding interface. This pre-positioned cushioning ensures that even if misalignment occurs, the contact area and resistance remain consistent.
Solution Approach 2:
The patent changes the geometric parameters of the bonding structure by creating a size difference between bottom and top pad layers. This parameter change provides alignment flexibility while maintaining consistent electrical contact properties.
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 design alleviates the dishing effect and improves bond quality by maintaining a constant contact area and resistance, regardless of misalignment, enhancing the reliability and performance of the bonding process.
Implementation Method 1
With the pressure and the elevated temperature, the surface portions of the metal bumps of the device die and the package substrate inter-diffuse, so that bonds are formed.
Data Source
AI summary
A package includes a package component and a second package component. A first elongated bond pad is at a surface of the first package component, wherein the first elongated bond pad has a first length in a first longitudinal direction, and a first width smaller than the first length. A second elongated bond pad is at a surface of the second package component. The second elongated bond pad is bonded to the first elongated bond pad. The second elongated bond pad has a second length in a second longitudinal direction, and a second width smaller than the second width. The second longitudinal direction is un-parallel to the first longitudinal direction.