Size-Filtered Multimetal Interconnects for Electromigration Resistance
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Solution Overview
Problem
Interconnect level structures in semiconductor chips face challenges in integrating metal lines and vias with different widths, requiring different metallic compositions for optimal performance, leading to compromises in device performance requirements.
Innovation Solution
A size-filtered metal interconnect structure is formed by creating trenches of different widths in a dielectric layer, where a blocking material is deposited and selectively etched to allow filling with distinct metallic materials, resulting in metal structures with varying widths and compositions, including an electrically programmable fuse with different materials for the anode, cathode, and fuselink.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single metallic material is used for all metal structures in dielectric layers, then the manufacturing process is simplified, but device performance is compromised because different metal structures require different properties for optimal performance
Solution Approach 1:
The patent applies local quality by enabling different metallic compositions in different regions of the interconnect structure. Specifically, first metal structures (wider lines) use a first metallic material while second metal structures (narrower lines) use a second metallic material, allowing each region to have the optimal material properties for its specific function and width
Solution Approach 2:
The patent segments the interconnect structure into different width categories (first metal structures with width greater than critical width, and second metal structures with width less than critical width). This segmentation allows independent material selection for each segment, resolving the contradiction between manufacturing simplicity and device performance
2Device complexity
If metal structures of different widths are formed using the same material deposition process, then the manufacturing process is simpler, but the ability to optimize material selection for specific width requirements is lost
Solution Approach 1:
The patent uses preliminary action through the blocking material layer that is deposited conformally across all trenches before width-based selective removal. This preliminary blocking layer enables subsequent selective etching based on trench width, allowing different materials to be deposited in different width regions while maintaining a unified initial process step
Solution Approach 2:
The patent changes the parameter of material composition based on the width parameter of the metal structures. By correlating structure width with material type (first material for wider structures, second material for narrower structures), the patent achieves adaptability in material selection while using controlled parameter changes throughout the manufacturing process
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 approach enables the formation of metal structures with specific properties, enhancing performance by allowing for optimal material selection based on width, thereby improving electromigration resistance and device efficiency.
Implementation Method 1
A blocking material layer is conformally deposited to completely fill trenches having a width less than a threshold width
Implementation Method 2
An isotropic etch is performed to remove the blocking material layer in wide trenches, i.e., trenches having a width greater than the threshold width
Data Source
AI summary
A size-filtered metal interconnect structure allows formation of metal structures having different compositions. Trenches having different widths are formed in a dielectric material layer. A blocking material layer is conformally deposited to completely fill trenches having a width less than a threshold width. An isotropic etch is performed to remove the blocking material layer in wide trenches, i.e., trenches having a width greater than the threshold width, while narrow trenches, i.e., trenches having a width less than the threshold width, remain plugged with remaining portions of the blocking material layer. The wide trenches are filled and planarized with a first metal to form first metal structures having a width greater than the critical width. The remaining portions of the blocking material layer are removed to form cavities, which are filled with a second metal to form second metal structures having a width less than the critical width.