Self-Assembled Etch Stop Layer for Misalignment-Tolerant Interconnects
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Solution Overview
Problem
The semiconductor industry faces challenges in overlay control as geometry sizes decrease, leading to misalignment issues and reliability problems such as time-dependent dielectric breakdown and excessive parasitic capacitance in semiconductor devices.
Innovation Solution
A self-assembly layer is selectively formed on conductive components to prevent the deposition of a dielectric layer, which serves as an etching stop layer during the fabrication process, ensuring precise alignment and reducing parasitic capacitance by forming a stack of dielectric layers with varying dielectric constants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional deposition processes are used to form dielectric layers, then manufacturing simplicity is maintained, but overlay misalignment occurs leading to reliability degradation
Solution Approach 1:
A self-assembled monolayer (SAM) is formed on the conductive component surface before the dielectric layer deposition. This preliminary action creates a selective surface that prevents dielectric material deposition on the conductive component while allowing deposition on the ILD, thereby achieving self-aligned formation of the etching stop layer and preventing overlay misalignment issues
Solution Approach 2:
The self-assembled monolayer acts as an intermediary substance between the conductive component and the dielectric layer. This intermediary layer selectively blocks the dielectric precursor from depositing on the conductive component surface, enabling precise spatial control of the etching stop layer formation without requiring complex alignment processes
2Productivity
If geometry sizes are decreased to increase functional density, then device integration is improved, but overlay control becomes more difficult
Solution Approach 1:
The self-assembled monolayer performs the alignment function automatically through its inherent surface selectivity. The SAM spontaneously forms on the conductive component surface and self-regulates the dielectric deposition process, eliminating the need for external alignment control mechanisms that become increasingly difficult as geometry sizes decrease
3Device complexity
If a single dielectric layer is used, then process complexity is reduced, but parasitic capacitance becomes excessive
Solution Approach 1:
The dielectric structure is segmented into multiple layers with different dielectric constants. The first dielectric layer (etched stop layer) is formed selectively on the ILD with a first dielectric constant, while a second dielectric layer is formed on the conductive component with a second dielectric constant. This segmentation allows optimization of parasitic capacitance by using lower dielectric constant materials in critical regions
Solution Approach 2:
Different dielectric materials with different dielectric constants are applied to different locations. The region over the conductive component uses a dielectric material optimized for minimizing parasitic capacitance, while the region over the ILD uses a dielectric material optimized for etching selectivity and mechanical properties
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 enhances the reliability and performance of semiconductor devices by preventing over-etching and minimizing parasitic capacitance, while maintaining compatibility with existing fabrication processes.
Implementation Method 1
selectively forming a self-assembly layer on the first conductive component
Implementation Method 2
A self-assembly layer is selectively formed on conductive components to prevent the deposition of a dielectric layer
Data Source
AI summary
A structure is provided that includes a first conductive component and a first interlayer dielectric (ILD) that surrounds the first conductive component. A self-assembly layer is formed on the first conductive component but not on the first ILD. A first dielectric layer is formed over the first ILD but not over the first conductive component. A second ILD is formed over the first conductive component and over the first ILD. An opening is etched in the second ILD. The opening is at least partially aligned with the first conductive component. The first dielectric layer protects portions of the first ILD located therebelow from being etched. The opening is filled with a conductive material to form a second conductive component in the opening.