Plated Protection Layers for Oxidation-Resistant Redistribution Lines
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Solution Overview
Problem
In the formation of integrated circuits, existing technologies face challenges in protecting redistribution lines from oxidation and improving adhesion between conductive features and dielectric layers, which can lead to reliability issues and performance degradation.
Innovation Solution
A method is developed to form a conductive protection layer on redistribution lines by patterning a photo resist, plating a conductive feature, and then depositing a protection layer using electrochemical or electroless plating processes, which also helps in reducing oxidation and enhancing adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal pad is exposed through openings in passivation and polymer layers, then electrical connection is achieved, but the metal pad is susceptible to oxidation
Solution Approach 1:
A conductive protection layer is formed over the metal pad before subsequent processing steps. This preliminary protective measure prevents oxidation of the metal pad during manufacturing and operation, while the protection layer is later removed only in the specific area where electrical connection is needed, maintaining both reliability and controlled complexity
Solution Approach 2:
The conductive protection layer acts as an intermediary between the metal pad and the environment. It provides oxidation protection while allowing the metal pad to remain exposed through patterned openings where electrical connection is required, thus resolving the contradiction between protection and connectivity
2Strength
If redistribution lines are formed without protection layers, then manufacturing process is simpler, but adhesion between conductive features and dielectric layers deteriorates
Solution Approach 1:
The conductive protection layer is formed as a preliminary step before dielectric layer deposition. This layer serves dual purposes: it prevents oxidation of the redistribution line and provides an optimal surface for adhesion to the dielectric layer, ensuring strong bonding without requiring additional adhesion promotion steps
Solution Approach 2:
The structure employs a composite approach by forming a conductive protection layer with specific material properties that combine oxidation resistance and adhesion promotion. This composite structure integrates multiple functions into a single layer, improving adhesion strength while managing process complexity
3Reliability
If conductive materials are exposed to environment, then electrical connectivity is maintained, but oxidation occurs leading to performance degradation
Solution Approach 1:
The conductive protection layer is applied in advance to cover conductive materials before they are exposed to the environment during subsequent manufacturing steps. This preliminary protection prevents oxidation while maintaining electrical connectivity through patterned openings, ensuring performance stability without significantly complicating the manufacturing process
Solution Approach 2:
The protection strategy applies local quality by having the conductive protection layer present in specific areas where oxidation prevention is needed, while allowing exposure in areas where electrical connection is required. This localized approach maintains manufacturing simplicity while ensuring performance stability where critical
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 layers effectively reduce oxidation of conductive materials and improve the adhesion of redistribution lines to dielectric layers, enhancing the reliability and performance of integrated circuit packages.
Implementation Method 1
The wafer is then heated, so that the photo resist shrinks, resulting in a gap between the patterned photo resist and the conductive feature
Implementation Method 2
plating a conductive feature, and then depositing a protection layer using electrochemical or electroless plating processes
Implementation Method 3
plating a conductive feature, and then depositing a protection layer using electrochemical or electroless plating processes
Data Source
AI summary
A method includes forming a metal seed layer over a first conductive feature of a wafer, forming a patterned photo resist on the metal seed layer, forming a second conductive feature in an opening in the patterned photo resist, and heating the wafer to generate a gap between the second conductive feature and the patterned photo resist. A protection layer is plated on the second conductive feature. The method further includes removing the patterned photo resist, and etching the metal seed layer.