Multilayer Flex Interconnect for Semiconductor Chip Reliability
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Solution Overview
Problem
Wire bonding in semiconductor devices leads to large inductance effects and uncontrolled impedance variations due to manufacturing variability, resulting in reduced manufacturing tolerance and increased physical movement during packaging.
Innovation Solution
The use of multilayer flex interconnect structures, comprising a first and second conductive layer with a dielectric layer in between, provides mechanical support and reduces inductance effects by allowing multiple signals or buses between chips, thereby minimizing physical movement and impedance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonding is used to connect chips to substrate, then electrical connections can be established, but large inductance effects and uncontrolled impedance variations occur due to manufacturing variability
Solution Approach 1:
The patent transitions from traditional wire bonding (1D linear connection) to a multilayer flex interconnect structure (2D/3D planar network). The interconnect structure includes multiple conductive layers stacked vertically and connected through vias, creating a planar transmission line network that reduces inductance by providing multiple parallel current paths and better impedance control through controlled layer spacing and geometry.
Solution Approach 2:
The interconnect structure uses composite construction with alternating conductive layers (copper or aluminum) and dielectric layers (polyimide or other flexible insulators). This composite structure provides both electrical connectivity and mechanical flexibility while maintaining controlled impedance through the precise arrangement of different materials with complementary properties.
2Reliability
If wire bonding is used for chip interconnection, then electrical connections are achieved, but physical movement occurs during packaging due to lack of mechanical support
Solution Approach 1:
The patent merges the electrical interconnection function with the mechanical support function into a single integrated structure. The multilayer flex interconnect structure serves both as the electrical pathway between chips and as the mechanical framework that maintains positional stability during packaging and operation, eliminating the need for separate support structures.
Solution Approach 2:
The patent employs flexible dielectric films (such as polyimide) as the base material for the interconnect structure. These thin flexible films provide mechanical support and positional stability while allowing the overall structure to accommodate thermal expansion and manufacturing tolerances, preventing physical movement during packaging.
3Manufacturing precision
If multilayer flex interconnect structure is used, then inductance effects are reduced and manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the interconnect structure into multiple discrete conductive layers separated by dielectric layers. Each layer can be independently patterned and controlled, allowing precise impedance management for each signal path. The segmentation into layers connected by vias creates modular units that can be designed and manufactured using standard PCB fabrication techniques.
Data Source
AI summary
Semiconductor devices with multilayer flex interconnect structures. In some embodiments, a semiconductor device may include a semiconductor chip coupled to a planar substrate and a multilayer flex interconnect structure coupled to the semiconductor chip, the multilayer flex interconnect structure including at least: a first conductive layer, a second conductive layer, and a dielectric layer disposed between the first and second conductive layers. The semiconductor device may also include another semiconductor chip coupled to the planar substrate and placed in a side-by-side configuration with respect to the semiconductor chip, where the multilayer flex interconnect structure provides electrical connections between at least two terminals of the semiconductor chip and at least two terminals of the other semiconductor chip.