Coaxial Feedthroughs for 3D IC Signal Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing 3D IC technologies face significant electrical and magnetic cross talk issues between densely packed through silicon vias due to the nature of signal transfer and density of feedthroughs, which current technologies fail to adequately address.
Innovation Solution
The development of coaxial feedthroughs using a process that involves etching a recess in a silicon wafer, depositing oxide and copper layers, and forming a coaxial conductor with a copper ground shield and inner conductor, which are embedded in a plastic layer to act as insulators, effectively shielding each via from others and the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If through silicon vias are densely packed to accommodate more signals, then signal transfer capacity is improved, but electrical and magnetic cross talk between vias increases
Solution Approach 1:
The via structure is segmented into multiple functional components: inner conductor, outer conductor, and dielectric material between them. This segmentation creates isolated electromagnetic fields within each coaxial via, preventing cross-talk between adjacent vias while maintaining high density signal transfer capacity
Solution Approach 2:
A dielectric material is introduced as an intermediary between the inner and outer conductors, and between adjacent vias. This dielectric layer acts as an electromagnetic shield that reduces capacitive and inductive coupling between neighboring vias, thereby reducing cross-talk while allowing dense packing
2Ease of manufacture
If conventional TSV structures are used, then manufacturing simplicity is maintained, but signal integrity at high frequencies deteriorates due to cross talk
Solution Approach 1:
The coaxial via structure employs a nested configuration where the inner conductor is surrounded by the dielectric material, which is in turn surrounded by the outer conductor. This nested structure provides electromagnetic shielding that maintains signal integrity at high frequencies while using standard semiconductor manufacturing processes
Solution Approach 2:
The via structure uses composite materials comprising conductive materials (inner and outer conductors) and dielectric material. This composite structure provides both electrical conductivity for signal transfer and electromagnetic shielding for cross-talk reduction, maintaining reliability while being manufacturable with existing processes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution substantially reduces cross talk between through silicon vias, preserving signal integrity and allowing for high-frequency operations without the fear of electrical crosstalk, while being easily integratable and manufacturable with minimal additional processing steps.
Implementation Method 1
forming a coaxial conductor with a copper ground shield and inner conductor, which are embedded in a plastic layer to act as insulators, effectively shielding each via from others and the substrate
Data Source
AI summary
Methods of forming coaxial feedthroughs for 3d integrated circuits that provide excellent isolation of signal paths from the substrate and from adjacent feedthroughs. One method is to form a recess in a substrate and deposit alternate layers of insulation and conductive layers and then thin the substrate to make the layers available from both sides of the substrate, with the first metal layer forming the coaxial conductor and the second metal layer forming the central conductor. Alternatively the coaxial feedthroughs may be formed using a modified pillar process to form the coaxial conductor at the same time as the center conductor is formed so that the coaxial feedthrough is formed without requiring extra steps. Both processes are low temperature processes.