Multi-Layer Cu Line Structure With Low-Stress Via Connections
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Solution Overview
Problem
Conventional multi-layer line structures using organic resin materials as insulating layers between copper lines suffer from thermal expansion coefficient mismatches, leading to disconnecting, void formation, increased parasitic capacitance, and crosstalk due to thermal stress, which are exacerbated by high integration densities and reduced line widths.
Innovation Solution
A multi-layer line structure incorporating inorganic films with a lower dielectric constant than organic resin films, combined with a barrier conductive layer, to mitigate thermal expansion differences and reduce void formation, while maintaining low parasitic capacitance and crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organic resin material is used as insulating layer, then dielectric constant is low and signal delay is reduced, but thermal expansion coefficient is high causing disconnecting and void formation
Solution Approach 1:
The patent applies composite materials by combining organic resin material with inorganic filler particles to create a hybrid insulating layer. This composite structure maintains the low dielectric constant advantage of organic materials while the inorganic filler reduces the thermal expansion coefficient, thereby resolving the contradiction between signal performance and thermal stability.
Solution Approach 2:
The patent changes the physical and chemical parameters of the insulating material by selecting specific inorganic fillers with low thermal expansion coefficients and optimizing their concentration and size distribution. This parameter adjustment allows the insulating layer to maintain dimensional stability under thermal stress while preserving the electrical performance benefits of organic resin materials.
2Productivity
If line width and interval are decreased for high density, then integration degree increases, but thermal stress concentration increases causing more disconnecting
Solution Approach 1:
The patent applies local quality by creating regions with different material compositions and filler concentrations around connection holes versus in line regions. This localized optimization ensures that areas most susceptible to thermal stress (connection holes) have enhanced mechanical stability, while maintaining high integration density in other areas through reduced line widths and intervals.
3Productivity
If stacked via structure is used for high density, then line density increases, but tensile stress on copper increases causing more connection flaws
Solution Approach 1:
The patent applies beforehand cushioning by incorporating stress-absorbing structures and compliant materials in the insulating layers between stacked vias. These pre-designed stress management features absorb and distribute tensile stresses before they can concentrate on the copper connections, thereby preventing connection flaws while maintaining the high density benefits of stacked via structures.
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
The proposed structure effectively reduces disconnecting and void formation, maintains low parasitic capacitance, and suppresses crosstalk, ensuring reliable electrical connections and signal integrity in high-density line structures.
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
Since the adhesive force between a barrier conductive layer covering the bottom part and a side surface of the connection hole, and the organic resin, is low, the barrier conductive layer is deformed and is peeled off from the organic resin
Implementation Method 3
an organic resin material such as polyimide or the like is often used as an insulating layer provided between the layers. A reason for this is an organic resin material generally has a low dielectric constant and thus is unlikely to cause delay of a signal transmitted through the lines
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.