Composite Cu Interconnect Structure for Via Disconnect Prevention
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Solution Overview
Problem
Existing multi-layer line structures face issues with disconnecting at the bottom part of connection holes due to thermal expansion coefficient differences between organic resin materials and copper lines, leading to void formation and increased parasitic capacitance.
Innovation Solution
A multi-layer line structure is developed with a substrate, lower and upper Cu lines, and a via connection part in a via connection hole. The structure includes an inorganic film with silicon and an organic resin film, where the inorganic film covers the Cu lines and the via connection hole, and the organic resin film has a lower dielectric constant than the inorganic film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an organic resin material is used as an insulating layer, then the dielectric constant is low and signal delay is reduced, but the thermal expansion coefficient is high causing disconnecting at the bottom part of connection holes
Solution Approach 1:
The patent uses a composite insulating layer structure combining an inorganic resin layer (first insulating layer) and an organic resin layer (second insulating layer). The inorganic resin layer provides low thermal expansion coefficient to prevent disconnecting, while the organic resin layer provides low dielectric constant to reduce signal delay. This composite structure resolves the contradiction between thermal stability and electrical performance.
Solution Approach 2:
The patent applies different materials with different properties to different regions: the inorganic resin layer is positioned where thermal stability is critical (near connection holes), while the organic resin layer is positioned where electrical performance is critical (signal transmission areas). This local differentiation resolves the contradiction by optimizing each region for its primary function.
2Reliability
If the insulating layer thickness is increased to prevent thermal expansion damage, then connection reliability improves, but parasitic capacitance increases
Solution Approach 1:
The composite insulating layer structure allows achieving sufficient thermal protection with a thinner overall thickness by using the inorganic resin layer's superior thermal stability. This reduces the total insulating layer thickness compared to using only organic resin, thereby reducing parasitic capacitance while maintaining connection reliability.
Solution Approach 2:
The patent changes the material composition parameters of the insulating layer, specifically incorporating inorganic resin with appropriate thermal expansion coefficient and dielectric constant values. This parameter optimization allows reducing the insulating layer thickness while maintaining both thermal protection and electrical performance.
3Reliability
If copper lines are used for high conductivity, then electrical performance improves, but disconnecting occurs due to thermal expansion coefficient difference with organic resin
Solution Approach 1:
The patent combines copper lines with a composite insulating layer structure where the inorganic resin layer has a thermal expansion coefficient matched to copper. This composite structure maintains the electrical conductivity of copper while providing thermal stability to prevent disconnecting during heat cycling.
Solution Approach 2:
The inorganic resin layer is positioned adjacent to the copper lines and connection holes where thermal stress is most critical. This local placement provides thermal expansion matching where needed, while allowing copper to maintain its superior electrical conductivity in the conductive paths.
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 configuration reduces the occurrence of disconnecting at the bottom part of connection holes and suppresses the increase of parasitic capacitance, thereby enhancing the reliability and performance of the multi-layer line structure.
Implementation Method 1
an organic resin material has a thermal expansion coefficient that is higher than that of a material of lines, for example, copper or the like. Therefore, when a line structure is subjected to a heat cycle test or used in a high temperature environment, a disconnecting is likely to occur
Implementation Method 2
A material forming the organic resin film has a dielectric constant lower than a dielectric constant of a material forming the inorganic film
Data Source
AI summary
A multi-layer line structure including a substrate, a lower layer Cu line located on the substrate, an upper layer Cu line located on an insulating layer including an inorganic film located on the lower layer Cu line and an organic resin film located on the inorganic film, and a via connection part located in a via connection hole running in an up-down direction through the insulating layer in an area where the lower layer Cu line and the upper layer Cu line overlap each other is provided. The via connection part includes a barrier conductive layer located on a part of the lower layer Cu line exposed to a bottom part of the via connection hole and on an inner wall of the via connection hole.