Interconnect Protective Stack for Reliable Fine-Pitch IC Wiring
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Solution Overview
Problem
The downscaling of integrated circuit (IC) devices has led to a need for improved electrical reliability of metal wiring layers, as they are reduced in terms of linewidth and pitch.
Innovation Solution
The IC device incorporates a structure with a lower insulating film on a substrate, lower metal wiring layers passing through the insulating film, an insulating protective structure covering the metal wiring layers, an upper insulating film, and upper metal wiring layers, where the insulating protective structure includes alternating layers of SiCN films and oxide thin films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If metal wiring layers are downscaled in linewidth and pitch, then device integration density is improved, but electrical reliability of the metal wiring layers deteriorates
Solution Approach 1:
An insulating protective structure is formed on the metal wiring layers before subsequent etching processes. This protective structure includes a lower insulating protective structure covering the metal wiring layers and an upper insulating protective structure formed thereon, providing preliminary protection against etching damage before the actual etching of contact holes or vias is performed.
Solution Approach 2:
The insulating protective structure acts as a cushioning layer that prevents direct contact between etching chemicals and the metal wiring layers. The structure includes multiple insulating layers (such as silicon oxide, silicon nitride, or silicon carbonitride) that absorb or mitigate the harmful effects of etching processes, thereby protecting the scaled-down metal wiring layers from damage.
2Device complexity
If conventional single-layer insulating protective structure is used, then manufacturing process is simple, but protection effectiveness during etching is insufficient
Solution Approach 1:
The insulating protective structure is divided into multiple segments: a lower insulating protective structure formed directly on the metal wiring layers, and an upper insulating protective structure formed on the lower insulating protective structure. This segmentation allows each layer to perform specific protective functions and enables better control over etching selectivity and protection effectiveness.
Solution Approach 2:
The insulating protective structure comprises multiple different insulating materials stacked together, such as silicon oxide layers, silicon nitride layers, and silicon carbonitride layers. Each material has different etching selectivity and protective properties, and their combination creates a composite structure that provides superior protection during various etching processes compared to a single-material structure.
Data Source
AI summary
An integrated circuit device includes a lower insulating film on a substrate, a lower metal wiring layer extending through the lower insulating film, an insulating protective structure on a top surface of each of the lower metal wiring layer and the lower insulating film, an upper insulating film on the insulating protective structure, an upper metal wiring layer on the upper insulating film, and a conductive contact plug extending through the upper insulating film and the insulating protective structure in a vertical direction and contacting each of the lower metal wiring layer and the upper metal wiring layer. The insulating protective structure includes a plurality of first silicon carbonitride (SiCN) films and at least one first oxide thin film. Each first oxide thin film is between two adjacent ones of the plurality of first SiCN films.