Copper-Capped Aluminum Pad Interconnects for Contamination-Free Bonding
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Solution Overview
Problem
The integration of aluminum pads in advanced packaging processes leads to contamination of dry etching tools and results in unreliable copper-to-aluminum interconnects, making it difficult to incorporate aluminum pads into existing hybrid bonding processes.
Innovation Solution
The formation of additional copper layers over aluminum pads, including a cap and via, to facilitate copper-to-copper interconnects by recessing the aluminum pad and forming copper layers using etching and plating processes, ensuring compatibility with existing process flows and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If aluminum pads are used in hybrid bonding processes, then cost and design flexibility are improved, but tool contamination and interconnect reliability deteriorate
Solution Approach 1:
A copper cap layer is introduced as an intermediary between the aluminum pad and the bonding interface. This cap prevents aluminum from contaminating the dry etching tools during subsequent copper-based processes while still allowing the aluminum pad to be used for hybrid bonding, thus resolving the contradiction between design flexibility and tool contamination
Solution Approach 2:
The pad structure is segmented into multiple layers: the original aluminum pad layer and an additional copper cap layer. This segmentation allows the aluminum pad to maintain its electrical and bonding functions while the copper cap protects against tool contamination during processing
2Device complexity
If aluminum pads are directly bonded to copper, then process simplicity is improved, but interconnect reliability deteriorates
Solution Approach 1:
The copper cap acts as a mediator between aluminum and copper interconnects. Instead of direct aluminum-to-copper bonding which yields unreliable interconnects, the copper cap enables copper-to-copper bonding while the aluminum remains isolated, thus improving reliability without significantly increasing process complexity
Solution Approach 2:
The copper cap is formed in advance before the hybrid bonding process. This preliminary action ensures that the bonding interface consists of copper-to-copper contact from the outset, guaranteeing reliable interconnect formation before subsequent processing steps
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 allows for the integration of aluminum pads into existing processes by preventing tool contamination and enhancing the reliability and performance of interconnects, achieving copper-to-copper bonding.
Implementation Method 1
forming copper layers using etching and plating processes
Data Source
AI summary
Embodiments disclosed herein include an apparatus that comprises a pad, and the pad comprises aluminum. In an embodiment, a liner is on a sidewall of the pad, and the liner extends past a surface of the pad. In an embodiment, a first layer is over the pad, and the first layer comprises copper. In an embodiment, a second layer is over the first layer, and the second layer is a dielectric material. In an embodiment, a via that passes through the second layer and contacts the first layer.