Hybrid Micro-Bump RDL Layout for Lower Parasitic Capacitance
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Solution Overview
Problem
High-density integrated circuits face issues with parasitic capacitance and RC delay due to increasing integration levels, which are not adequately addressed by existing low-k dielectric materials in interconnect structures.
Innovation Solution
The formation of conductive pads and lines with a conformal passivation layer, followed by the creation of conductive bumps and dummy bumps over conductive lines, allowing for a hybrid bump scheme that includes mixing C4 and μ-bumps, and the use of a dielectric layer to facilitate seed layer formation and improve bump placement flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If low-k dielectric materials are employed to reduce parasitic capacitance, then conduction speed is improved, but manufacturing complexity increases due to additional process steps
Solution Approach 1:
The patent combines the formation of conductive bumps and dummy bumps into a single integrated process step. The conformal passivation layer is formed over both conductive features and interconnect structures simultaneously, and both bump types are created using the same seed layer deposition and electroplating processes, thereby reducing manufacturing complexity while maintaining the parasitic capacitance reduction benefits of low-k dielectric materials
Solution Approach 2:
The conformal passivation layer serves multiple functions: it provides electrical isolation for the hybrid bump structure, protects the underlying low-k dielectric material, and enables the formation of both C4 bumps and micro-bumps using identical process steps. This multi-functionality reduces the number of separate manufacturing steps required
2Productivity
If hybrid bump scheme is implemented to improve layout flexibility, then manufacturing yield is improved, but process complexity increases due to additional conformal passivation layer
Solution Approach 1:
The conformal passivation layer is formed in advance before bump formation, creating a prepared surface that enables subsequent electroplating of both C4 bumps and micro-bumps. This preliminary action of forming the passivation layer with integrated via openings simplifies the overall process by pre-establishing the structural framework needed for hybrid bump fabrication
Solution Approach 2:
The patent segments the bump formation process into distinct phases: conformal passivation layer deposition, seed layer formation in via openings, and electroplating. This segmentation allows for precise control of each step while maintaining overall process efficiency and improving manufacturing yield through better process monitoring
3Adaptability or versatility
If conformal passivation layer is formed to enable hybrid bump structure, then bump placement flexibility is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes parameter changes in the electroplating process, specifically adjusting current density and plating time, to achieve precise control over bump dimensions and placement. This allows for flexible bump placement while maintaining manufacturing precision through process parameter optimization rather than relying solely on conformal layer thickness control
Data Source
AI summary
A semiconductor device includes a substrate; an interconnect structure over the substrate; a first passivation layer over the interconnect structure; a first conductive pad, a second conductive pad, and a conductive line disposed over the first passivation layer and electrically coupled to conductive features of the interconnect structure; a conformal second passivation layer over and extending along upper surfaces and sidewalls of the first conductive pad, the second conductive pad, and the conductive line; a first conductive bump and a second conductive bump over the first conductive pad and the second conductive pad, respectively, where the first conductive bump and the second conductive bump extend through the conformal second passivation layer and are electrically coupled to the first conductive pad and the second conductive pad, respectively; and a dummy bump over the conductive line, where the dummy bump is separated from the conductive line by the conformal second passivation layer.