Bonding Pads With Recessed Metallic Liners
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Solution Overview
Problem
Bonding pads in semiconductor devices are prone to recesses near metallic diffusion barrier layers, leading to copper migration and void formation, which affects the quality of bonding between dies.
Innovation Solution
The formation of self-aligned diffusion barrier layers with vertically recessed metallic liners in the pad-level dielectric layer reduces recess formation and prevents copper migration, enhancing bonding quality by integrating metallic fill material portions with recessed liners within the pad-level dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bonding pads are formed with metallic diffusion barrier layers, then copper migration is prevented, but recesses and voids form near the barrier layers
Solution Approach 1:
The patent applies different materials and structures to different regions of the bonding pad. The metallic liner is vertically recessed in the center region while the pad-level dielectric layer remains intact at the periphery, creating local quality variations that prevent both copper migration and recess formation. This localized structural differentiation resolves the contradiction between preventing copper migration and maintaining bonding pad flatness.
Solution Approach 2:
The patent transitions from a planar bonding pad structure to a three-dimensional structure with vertical recessing of the metallic liner. By introducing vertical dimensionality and creating a stepped profile where the liner is recessed below the dielectric surface, the patent eliminates copper migration pathways while maintaining surface flatness for bonding, thus resolving the contradiction between reliability and manufacturing precision.
2Reliability
If metallic liners are formed to prevent copper migration, then reliability improves, but recess formation occurs affecting bonding quality
Solution Approach 1:
The metallic liner is selectively recessed in the central region where copper migration is most problematic, while the peripheral regions maintain full dielectric coverage. This localized quality differentiation prevents copper migration in critical areas without creating harmful recesses that would affect bonding quality, thus resolving the contradiction between reliability improvement and harmful factor reduction.
Solution Approach 2:
The patent converts the potential harm of recess formation into a benefit by intentionally designing the metallic liner to be vertically recessed only in specific regions. This controlled recessing prevents copper migration (the benefit) while the dielectric material fills or covers the recessed areas to prevent void formation (converting the potential harm into a beneficial 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 reduces or prevents recesses and voids in the bonding pads, improving the bonding quality between semiconductor dies and minimizing electromigration and stress-induced voids.
Implementation Method 1
a first pad-level dielectric layer which is a diffusion barrier overlying the at least one first semiconductor device
Implementation Method 2
a metallic liner laterally surrounding the metallic fill material portion and vertically spaced from the horizontal plane by a vertical recess distance
Data Source
AI summary
A semiconductor die includes at least one first semiconductor device located on a first substrate, a first pad-level dielectric layer which is a diffusion barrier overlying the at least one first semiconductor device, and first bonding structures including a respective first metallic bonding pad embedded in the first pad-level dielectric layer. Each of the first bonding structures includes a metallic fill material portion having a horizontal distal surface that is located within a horizontal plane including a horizontal distal surface of the first pad-level dielectric layer, and a metallic liner laterally surrounding the metallic fill material portion and vertically spaced from the horizontal plane by a vertical recess distance.