Bond Pads with Differently Sized Passivation Openings
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Solution Overview
Problem
Asymmetrically distributed bond pads in integrated circuits can lead to unbalanced stresses during bonding processes, potentially causing damage to the IC and altering its electrical performance.
Innovation Solution
Creating a die passivation layer with differently sized openings to expose bond pads, allowing for more even stress distribution during bonding by varying the contact area between bumps and bond pads, thereby alleviating stress gradients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bond pads are asymmetrically distributed to meet functional requirements, then the IC can achieve desired electrical connectivity, but unbalanced stresses are created during bonding that can damage the IC and alter electrical performance
Solution Approach 1:
The patent applies local quality by creating differently sized openings in the passivation layer corresponding to different bond pad locations. The opening sizes are specifically tailored to local stress conditions - larger openings for bond pads in high-stress regions and smaller openings for bond pads in low-stress regions. This local differentiation of opening sizes balances the stress distribution across the IC during bonding while maintaining the required asymmetric bond pad configuration for electrical connectivity.
2Ease of manufacture
If uniformly sized openings are used in the passivation layer, then manufacturing is simplified, but stress concentrations occur during bonding when bond pads are asymmetrically distributed
Solution Approach 1:
The patent applies asymmetry by intentionally creating non-uniform opening sizes in the passivation layer. Instead of using identical openings for all bond pads, the invention introduces asymmetric opening dimensions that correspond to the asymmetric bond pad distribution. This asymmetric opening pattern compensates for the uneven stress distribution caused by asymmetric bond pad placement, balancing the overall stress during bonding while remaining compatible with standard semiconductor manufacturing processes.
3Stress or pressure
If larger openings are created to expose more bond pad surface area, then stress distribution improves, but the contact area between bumps and bond pads increases which may affect bonding precision
Solution Approach 1:
The patent applies parameter changes by systematically varying the opening sizes as a controlled parameter. The opening dimensions are adjusted within specific ranges - larger than minimum requirements to improve stress distribution, but constrained to maintain adequate bonding precision. The parameter optimization balances stress relief needs against bonding accuracy requirements, with opening sizes selected to provide sufficient stress distribution while preserving precise bump-to-bond-pad alignment.
Data Source
AI summary
Integrated circuit dies are provide with a passivation layer having a plurality of differently sized openings exposing bond pads for bonding. The sizes of the bond pads vary in a manner that at least partially compensates for stresses during bonding, such as flip chip thermocompression bonding, due to asymmetric distribution of bond pads.