Semiconductor Pad Structure With Segmented Probing and Bonding Regions
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Solution Overview
Problem
Existing semiconductor pad structures face challenges in withstanding combined probing and bonding forces, leading to potential damage and reduced die area due to the use of metal layers as buffer layers, which limits routing area and product reliability.
Innovation Solution
A pad structure with a first metal-containing layer and a passivation layer, where the probing region contacts the metal layer through an opening and the bonding region overlies a portion of the passivation layer, allowing for separate handling of probing and bonding forces without the need for additional metal buffer layers, thus maintaining routing area and enhancing reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal layers are used as buffer layers under the pad layer to withstand probing and bonding forces, then the mechanical strength is improved, but the routing area is reduced
Solution Approach 1:
The pad layer is segmented into a probing region and a bonding region, with each region having dedicated support structures. The probing region is supported by a first buffer layer, while the bonding region is supported by a second buffer layer, allowing independent optimization of each region without requiring a single comprehensive metal buffer layer underneath the entire pad.
Solution Approach 2:
Different buffer layer configurations are applied to different regions of the pad structure. The first buffer layer is positioned under the probing region with specific mechanical properties to withstand probing forces, while the second buffer layer is positioned under the bonding region with properties optimized for bonding forces. This localized approach provides appropriate mechanical support only where needed, preserving routing area in other regions.
2Area of stationary object
If the pad dimension is reduced to achieve high-integration goals, then the die size is reduced, but the pad may not tolerate the combined forces of probing and bonding
Solution Approach 1:
The pad layer is divided into separate probing and bonding regions with dedicated buffer layer support for each. This segmentation allows the pad to be smaller overall while maintaining adequate force tolerance in each specific region, as each buffer layer is optimized for its particular function rather than requiring a single large buffer structure.
Solution Approach 2:
Buffer layers are introduced as intermediary structures between the pad layer and the substrate. These buffer layers act as force-distributing intermediaries that protect the underlying circuit patterns from the concentrated probing and bonding forces, enabling smaller pad dimensions without compromising force tolerance.
3Area of stationary object
If the passivation layer is used as a buffer layer under the probing region, then the routing area is increased, but the passivation layer may crack under probing force
Solution Approach 1:
The buffer layer configuration is made region-specific: a first buffer layer with appropriate mechanical properties is placed under the probing region to withstand probing forces, while the passivation layer is extended under the bonding region where it serves as a buffer. This local differentiation ensures that each region has the appropriate material properties for its function, preventing cracking in the probing region while maintaining routing area.
Solution Approach 2:
The structure uses composite material arrangement where different buffer layer types (metal buffer layer vs. extended passivation layer) are strategically positioned in different regions. The first buffer layer under the probing region provides crack-resistant support, while the extended passivation layer under the bonding region provides adequate buffering, creating a composite structure that optimizes both reliability and routing area.
Data Source
AI summary
A pad structure includes a first metal-containing layer formed over a substrate. A first passivation layer is formed over the first metal-containing layer. The first passivation layer has a first opening partially exposing the first metal-containing layer. A pad layer is formed over the first passivation layer, covering the first opening. The pad layer includes a probing region configured to be contacted by a probe and a bonding region configured to have a wired bonded to it. The probing region contacts the first metal-containing layer through the first opening, and the bonding region overlies a portion of the first passivation layer.