Bond Pad Structure with Dual Passivation Layers for Corrosion Resistance
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Solution Overview
Problem
Existing bond pad structures in semiconductor manufacturing face issues with corrosion and process limitations, particularly due to the vulnerability of aluminum materials and residue-related corrosion issues during the patterning process, which affect reliability and increase costs.
Innovation Solution
A novel bond pad structure is developed with a protection layer that covers the pad material layer before etching, using a photoresist as a mask to pattern the protection and pad material layers, and is easily removable by wet etching, providing a larger process window and reducing damage and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thick photoresist layer is used for patterning the aluminum pad, then the patterning process can be completed, but residues are left on the aluminum layer surface due to PR hardening, significantly increasing the possibility of Al corrosion
Solution Approach 1:
A silicon nitride protection layer is introduced as an intermediary between the photoresist and the aluminum pad layer. This protection layer prevents direct contact between the photoresist residues and the aluminum, thereby eliminating the corrosion issue while allowing the patterning process to proceed with thick photoresist layers.
Solution Approach 2:
The silicon nitride protection layer is formed on the aluminum pad layer before the photoresist patterning process. This preliminary action ensures that the aluminum surface is already protected against corrosion before any photoresist residues can form, preventing the reliability issue from occurring in the first place.
2Reliability
If copper wiring is used instead of aluminum, then chip performance and reliability are improved, but copper reacts with ball-soldering materials and is susceptible to environmental damage and corrosion
Solution Approach 1:
The invention uses a composite structure combining copper interconnection with an aluminum pad layer and silicon nitride protection layer. The copper provides excellent electrical performance, while the aluminum and silicon nitride layers provide corrosion protection, creating a multi-material system that leverages the advantages of each material.
Solution Approach 2:
The aluminum pad layer and silicon nitride protection layer serve as intermediary layers between the copper interconnection and the external environment. These intermediaries prevent direct exposure of copper to corrosive elements, solving the copper corrosion issue while maintaining copper's superior electrical properties.
3Object-affected harmful factors
If an aluminum pad structure is used to protect copper interconnection, then copper deterioration issues are solved, but aluminum materials are vulnerable to corrosion and require additional protection
Solution Approach 1:
The invention creates a composite protection structure with aluminum pad layer combined with silicon nitride protection layer. This composite structure provides superior corrosion protection compared to aluminum alone, as the silicon nitride layer adds an additional barrier against environmental factors.
Solution Approach 2:
The silicon nitride protection layer is formed on the aluminum pad layer before the aluminum is exposed to environmental factors. This preliminary protective action ensures that the aluminum layer is already shielded from corrosion sources, enhancing its reliability from the outset.
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
The protection layer effectively prevents corrosion and pad discoloration, enhances the process window, and simplifies the etching process, reducing the risk of damage and manufacturing costs while ensuring reliable electrical connections.
Implementation Method 1
a protection layer is used in present invention to cover the pad material layer before the pad material layer is etched and patterned into a bond pad. The protection layer is suitable for protecting the underlying pad material layer from corrosion or pad discoloration issue
Implementation Method 2
using a photoresist as a mask to perform an etching process for patterning the protection layer and the pad material layer into a bond pad structure
Implementation Method 3
the protection layer may be easily removed from the underlying bond pad structure by a simple strip or wet etching process after forming the bond pad
Data Source
AI summary
A bond pad structure with dual passivation layers is disclosed. The bond pad structure includes: a pad material layer on a first passivation layer; a protection layer on the top surface of the pad material layer; a second passivation layer covering on the first passivation layer and the protection layer; and an opening formed through the second passivation layer and the protection layer to expose the pad material layer.