Copper Flip-Chip Bump Structure for Dense, Low-Resistance Interconnects
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Solution Overview
Problem
Existing flip-chip bumping technologies face challenges in improving electrical conductivity, manufacturing cost, and mechanical integrity of bump pads, particularly with aluminum bump pads having high resistivity and requiring additional passivation layers that can crack and increase costs.
Innovation Solution
Implementing a metallization structure with copper-based bump line structures and a polymer protection layer, replacing aluminum bond pads, which enhances conductivity and allows for smaller spacing between bumps, reducing the need for costly passivation layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If aluminum bump pads are used in flip-chip bumping, then manufacturing cost is reduced, but electrical conductivity deteriorates due to high resistivity
Solution Approach 1:
The patent employs a composite metallization structure consisting of multiple metal layers (e.g., copper, aluminum, tungsten, or cobalt) with different properties. This composite approach combines the low cost of aluminum with the high conductivity of copper or other metals, achieving both cost-effectiveness and improved electrical conductivity in the bump pads.
Solution Approach 2:
The patent changes the material parameters of the bump pad structure by transitioning from pure aluminum to multi-layer metallization with controlled thicknesses and compositions. By adjusting the parameters such as layer thickness, material composition, and structural configuration, the patent optimizes both conductivity and manufacturing cost.
2Reliability
If additional passivation layers are added to protect bump pads, then mechanical integrity is improved, but device complexity increases and manufacturing cost rises
Solution Approach 1:
The patent designs the metallization structure to serve multiple functions simultaneously: the same metal layers provide both electrical conductivity for signal transmission and mechanical strength for structural integrity. This multi-functionality eliminates the need for separate protective passivation layers, reducing device complexity while maintaining mechanical reliability.
Solution Approach 2:
The patent extracts the protective function from separate passivation layers and integrates it directly into the metallization structure itself. The metallization layers are designed with inherent mechanical strength to provide protection, thereby removing the need for additional protective layers and simplifying the overall device structure.
3Productivity
If bump spacing is reduced to increase density, then productivity is improved, but mechanical integrity deteriorates due to stress concentration
Solution Approach 1:
The patent uses composite metallization structures with strategically designed material combinations and thicknesses that provide high mechanical strength. This enables tighter bump spacing by preventing stress concentration and cracking, allowing increased bump density while maintaining mechanical integrity through the enhanced structural properties of the composite materials.
Solution Approach 2:
The patent applies local quality optimization by varying the metallization structure properties in different regions. Areas with tighter bump spacing receive reinforced metallization configurations with increased thickness or stronger materials, while other areas use standard designs. This localized adaptation allows high density without compromising mechanical integrity where stress concentration occurs.
Data Source
AI summary
Disclosed are techniques for integrated circuit device. In an aspect, an integrated circuit device includes a metallization structure that includes a top metal layer structure; a passivation layer on the metallization structure; a bump structure disposed on the first bump line structure; and a first polymer protection layer. The passivation layer may include one or more first openings. The first bump line structure may include one or more first extended portions respectively extending toward the top metal layer structure through the one or more first openings. The bump structure may be electrically coupled to the first bump line structure. The first polymer protection layer may be on the passivation layer, on a portion of the first bump line structure, and in contact with a side surface of the first bump line structure.