Vertical Wiring Structure for Contact Alignment in Semiconductor Devices
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Solution Overview
Problem
As semiconductor devices miniaturize, the tapered profile of wiring structures can lead to misalignment with lower contact structures, deteriorating the functional characteristics and reliability of the devices.
Innovation Solution
A wiring structure is developed with an etch stop film and insulating film configuration, where the first wiring layer has a sidewall inclination angle of about 88 to 90 degrees, and the surfaces in contact have a carbon concentration of 3% or less, and a second wiring layer with a different inclination angle, to prevent unloading and improve alignment with contact structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the wiring structure size is decreased to achieve miniaturization, then the device integration is improved, but the wiring structure forms a tapered profile causing misalignment with lower contact structures
Solution Approach 1:
The patent changes the etching parameters and process conditions to transform the wiring structure profile from tapered to substantially vertical. By adjusting etch selectivity, plasma power, and gas flow rates, the etching process achieves a vertical sidewall angle of 85-90 degrees, eliminating the tapered profile that causes misalignment while maintaining miniaturization benefits
Solution Approach 2:
The patent employs a composite etching approach using multiple etching gases with different chemistries (e.g., CF4/O2/Ar mixture) to achieve vertical profiles. The composite material strategy also extends to the wiring structure itself, using layered compositions of barrier metals and conductive materials to maintain structural integrity at vertical profiles with reduced dimensions
2Volume of moving object
If the wiring structure has a tapered profile, then the miniaturization is achieved, but the functional characteristics and reliability of the semiconductor device deteriorate
Solution Approach 1:
By changing the etching parameters to achieve vertical profiles, the patent eliminates the fundamental cause of poor connections and misalignment. The vertical sidewall angle of 85-90 degrees ensures proper alignment with lower contact structures, thereby maintaining functional reliability while preserving the miniaturized form factor
Solution Approach 2:
The patent applies preliminary surface treatment and etch stop layers before the main etching process to prepare the substrate for vertical profile formation. This preliminary action prevents tapered profile formation from the outset, ensuring both alignment precision and functional reliability are maintained throughout the miniaturized structure
Data Source
AI summary
A wiring structure includes an etch stop film disposed on a substrate. A first insulating film is disposed on the etch stop film. A first wiring layer extends in a vertical direction perpendicular to an upper surface of the substrate and extends through the first insulating film and the etch stop film. A sidewall of the first wiring layer forms a first inclination angle of about 88 degrees to about 90 degrees with respect to a first horizontal direction parallel to the upper surface of the substrate. A surface of the first insulating film and a surface of the etch stop film in direct contact with the first wiring layer have a carbon (C) concentration less than or equal to about 3 at %.