Hybrid Micro-Bump Integration With RDL for RC Delay Reduction
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Solution Overview
Problem
High-density integrated circuits face increased parasitic capacitance and RC delay due to metal line interactions, which are not effectively mitigated by existing low-k dielectric materials, leading to limitations in conduction speed and design flexibility.
Innovation Solution
A hybrid bump scheme is introduced, allowing for the combination of micro-bumps (μ-bumps) and controlled collapse chip connection bumps (C4 bumps) in the same region, along with a dielectric layer that fills gaps between conductive pads and lines, facilitating seed layer formation and reducing the need for dummy conductive pads, thereby enhancing design flexibility and reducing parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If low-k dielectric materials are employed to form ILD layers and IMD layers, then parasitic capacitance is reduced, but conduction speed and design flexibility remain limited
Solution Approach 1:
The patent segments the bump structure into multiple types (micro-bumps and C4 bumps) that can be selectively applied to different conductive pads and lines. This segmentation allows different regions of the interconnect structure to be optimized independently, enabling design flexibility while maintaining low parasitic capacitance through the dielectric material
Solution Approach 2:
The patent applies different bump types (micro-bumps for conductive lines, C4 bumps for conductive pads) to different locations based on local requirements. This local quality approach allows optimal performance at each location while maintaining overall design flexibility and low parasitic capacitance
2Productivity
If metal lines are densely packed to increase integration density, then conduction speed decreases due to increased parasitic capacitance and RC delay
Solution Approach 1:
The patent introduces dielectric material as an intermediary between densely packed metal lines and between conductive elements. This intermediary layer reduces the parasitic capacitance that would otherwise increase with higher integration density, thereby maintaining conduction speed while enabling increased productivity
3Ease of manufacture
If conventional bump formation is used, then manufacturing process is simple, but design flexibility is reduced due to need for dummy conductive pads
Solution Approach 1:
The patent introduces a dynamic bump formation process where the decision to form micro-bumps or C4 bumps is made based on the specific conductive element being targeted. This dynamic approach eliminates the need for static dummy conductive pads while maintaining manufacturing feasibility, thereby improving design flexibility without sacrificing ease of manufacture
4Reliability
If micro-bumps and C4 bumps are used separately in different regions, then each bump type optimizes its local function, but overall design flexibility is limited
Solution Approach 1:
The patent creates a universal bump formation capability that can produce both micro-bumps and C4 bumps within the same manufacturing process. This multi-functionality allows the system to optimize local functions (micro-bumps for lines, C4 bumps for pads) while maintaining overall design flexibility through selective application, thereby achieving both reliability and adaptability
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.