Bond Pad Adhesion via Passivation Edge Coverage
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Solution Overview
Problem
Bond pad lift-off occurs during the bonding process due to inadequate adhesion between the aluminum interconnect and underlying layers, particularly with titanium nitride barrier layers that do not form a strong bond with the oxide layers.
Innovation Solution
A bond pad structure comprising a first passivation layer with openings for a conductive layer, and a second passivation layer covering the edges of the conductive layer, enhancing adhesion and preventing peeling by forming downward protrusions within the first passivation layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a titanium nitride barrier layer is used to prevent aluminum from spiking into underlying conductive layers, then aluminum spike prevention is improved, but adhesion to the oxide underlying the bond pad deteriorates
Solution Approach 1:
An adhesion promoter layer is introduced between the titanium nitride barrier layer and the oxide layer to serve as an intermediary that enhances adhesion. This mediator layer specifically addresses the poor bonding between TiN and oxide, allowing the barrier layer to maintain its spike prevention function while the adhesion promoter ensures strong attachment to the underlying oxide layer.
Solution Approach 2:
The bond pad structure employs a composite material approach by combining multiple layers with different functions: the titanium nitride barrier layer for spike prevention, the adhesion promoter layer for enhanced bonding, and the aluminum interconnect layer. This composite structure resolves the contradiction by allowing each layer to optimize its specific function without compromising overall performance.
2Reliability
If a large heavy bond pad is used for electrical connection, then electrical connectivity is improved, but bond pad lift off during bonding deteriorates
Solution Approach 1:
The adhesion promoter layer is applied in advance to the oxide surface before depositing the titanium nitride barrier layer and aluminum interconnect. This preliminary action prepares the surface with enhanced adhesion properties, ensuring that the subsequent layers bond strongly to prevent lift-off during the bonding process while maintaining the large bond pad area for electrical connectivity.
Solution Approach 2:
The adhesion promoter acts as a mediator between the oxide substrate and the heavy aluminum interconnect layer, enabling the large bond pad to maintain stability during bonding. Without this intermediary, the heavy aluminum layer would cause lift-off due to poor adhesion to the oxide layer.
Data Source
AI summary
An integrated circuit device having at least a bond pad for semiconductor devices and method for fabricating the same are provided. A bond pad has a first passivation layer having a plurality of openings. A conductive layer which overlies the openings and portions of the first passivation layer, having a first portion overlying the first passivation layer and a second portion overlying the openings. A second passivation layer overlies the first passivation layer and covers edges of the conductive layer.