Multi-Layer Cu Line Structure for Thermally Stable Via Connections
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Solution Overview
Problem
Conventional multi-layer line structures experience disconnecting issues at connection holes due to thermal expansion coefficient differences between organic resin materials and copper lines, leading to void formation, increased parasitic capacitance, and signal propagation delays, especially in high-density line structures and varying temperature environments.
Innovation Solution
A multi-layer line structure incorporating an inorganic film with silicon and a barrier conductive layer made of high-melting-point metals, where the inorganic film covers the copper lines and the barrier conductive layer is in contact with the inner wall of the via connection hole, reducing thermal stress and adhesion issues, and optimizing the ratio of inorganic to organic resin film thickness to minimize void formation and capacitance.
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 at connection holes
Solution Approach 1:
The patent uses a composite insulating layer structure combining organic resin material (for low dielectric constant) with inorganic material layers (for low thermal expansion coefficient). The inorganic material layers are formed on the copper lines and extend into the connection holes, creating a composite structure that leverages the advantages of both material types to reduce thermal expansion stress while maintaining signal transmission properties.
Solution Approach 2:
The patent applies different materials to different regions: organic resin material is used in areas requiring low dielectric constant for signal transmission, while inorganic material layers are strategically placed on copper lines and in connection holes where thermal expansion stress is the primary concern. This localized material assignment optimizes both signal performance and thermal stability.
2Productivity
If connection hole size is decreased to increase line density, then more lines can be packed, but tensile stress on copper increases causing void formation
Solution Approach 1:
The patent employs inorganic material layers in connection holes to provide mechanical support and reduce tensile stress on copper lines. These inorganic layers act as a reinforcement structure that prevents void formation even when connection holes are miniaturized for higher line density.
Solution Approach 2:
The inorganic material layers are formed beforehand on copper lines and extended into connection holes to provide preventive support against tensile stress. This cushioning structure is in place before the copper lines are subjected to thermal expansion and contraction, preventing void formation proactively.
3Reliability
If inorganic material layer is added to reduce thermal expansion stress, then disconnecting is suppressed, but parasitic capacitance increases
Solution Approach 1:
The inorganic material layers are strategically placed only where thermal expansion stress is critical (on copper lines and in connection holes) rather than throughout the entire insulating structure. This localized approach minimizes the added parasitic capacitance while maintaining thermal stress resistance where it is most needed.
Solution Approach 2:
The patent creates a composite insulating layer structure that balances the thermal properties of inorganic materials with the electrical properties of organic resin materials. The inorganic layers provide thermal expansion matching, while the organic resin layers maintain low dielectric constant, achieving an optimal compromise between thermal stress resistance and parasitic capacitance reduction.
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 effectively reduces disconnecting events, suppresses void formation, and minimizes parasitic capacitance, enhancing the reliability and performance of high-density line structures by mitigating thermal expansion-related issues and maintaining signal integrity across varying temperatures.
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
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.