Composite Bridge Interconnects for Low-Impedance IC Package Power
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Solution Overview
Problem
Integrated-circuit (IC) package power-delivery systems face issues with undesired inductance loops and impedance peak profiles due to high interconnect density between multiple IC chips, leading to power-delivery inefficiencies and reliability concerns.
Innovation Solution
The implementation of composite bridge die-to-die interconnects with passive devices such as decoupling capacitors located in the molding layer between IC dice, which reduces package inductance looping and improves power integrity by directly coupling capacitors to power rails and ground, thereby lowering power delivery network impedance and jitter behaviors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high interconnect density is implemented between multiple IC chips, then interconnect capability is improved, but inductance loops and impedance peaks increase causing power-delivery issues
Solution Approach 1:
A composite bridge interconnect structure is introduced as an intermediary component between IC chips. This bridge includes a substrate with multiple vias and conductive elements that mediate the electrical connection, replacing direct high-density interconnects that cause inductance loops. The intermediary structure provides controlled impedance pathways and reduces harmful inductance while maintaining high interconnect density.
Solution Approach 2:
The bridge interconnect employs composite construction with multiple materials including conductive elements, dielectric layers, and solder bumps. This composite structure allows optimization of electrical properties (low inductance, controlled impedance) while maintaining mechanical integrity and thermal management, resolving the power-delivery issues associated with high-density interconnects.
2Ease of manufacture
If passive devices are located far from IC dice, then manufacturing is simplified, but power integrity deteriorates due to increased inductance
Solution Approach 1:
Passive devices are positioned in the vertical dimension (z-axis) within the bridge structure itself, rather than being placed only in the horizontal plane. The bridge's multi-layer construction with vias and embedded passive devices allows compact 3D arrangement, maintaining proximity for power integrity while simplifying manufacturing through integrated assembly.
3Device complexity
If decoupling capacitors are not directly coupled to power rails, then device complexity is reduced, but power delivery network impedance increases
Solution Approach 1:
Decoupling capacitors are merged directly into the bridge interconnect structure, combining the interconnect function with power delivery and decoupling functions. This integration creates direct coupling between capacitors and power rails through the bridge's internal vias and conductive pathways, reducing PDN impedance while managing complexity through functional consolidation.
Data Source
AI summary
Disclosed embodiments include composite-bridge die-to-die interconnects that are on a die side of an integrated-circuit package substrate and that contacts two IC dice and a passive device that is in a molding material, where the molding material also contacts the two IC dice.