BEOL Metallization Using SiC Dielectric Without Nitride Liner
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Solution Overview
Problem
Conventional semiconductor integrated circuit back end of line (BEOL) metallization structures rely on silicon oxide dielectric layers with metal nitride liners, which can lead to interdiffusion issues during annealing processes, affecting the reliability of metal conductors like copper.
Innovation Solution
The use of patterned dielectric layers made from silicon carbide (SiC), silicon nitride (SiN), or nitrogen-doped silicon carbide (SiC(N,H) without a metal nitride liner, allowing for the deposition of a pure metal conductive liner/seed layer and subsequent metal conductor deposition, eliminating interdiffusion issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal nitride liner layer is used in conventional BEOL metallization structures, then the dielectric layer provides barrier properties, but interdiffusion issues occur during annealing processes affecting metal conductor reliability
Solution Approach 1:
The patent removes the metal nitride liner layer from the conventional BEOL metallization structure, eliminating the source of interdiffusion problems. The dielectric layer itself is engineered to provide the necessary barrier properties without requiring a separate metal nitride liner, thus resolving the interdiffusion issue while maintaining reliability.
Solution Approach 2:
The patent employs a composite dielectric layer structure comprising multiple layers with different compositions (e.g., silicon oxide, silicon nitride, silicon carbide) to achieve the necessary barrier properties. This composite structure provides effective protection against interdiffusion during annealing processes without requiring a metal nitride liner layer.
2Device complexity
If a metal nitride liner layer is present, then the structure follows conventional design, but the liner layer complicates the metallization structure and deposition process
Solution Approach 1:
By removing the metal nitride liner layer entirely, the patent simplifies the metallization structure and reduces the number of deposition steps required. The dielectric layer is directly patterned and etched to form openings, followed by straightforward metal conductor deposition, eliminating the complex multi-layer liner structure.
3Manufacturing precision
If silicon oxide dielectric layers with metal nitride liners are used, then the conventional structure is maintained, but coplanar surface finish is difficult to achieve
Solution Approach 1:
Removing the metal nitride liner layer eliminates the interface complexity between different liner and dielectric materials, making it easier to achieve a coplanar surface finish. The simplified structure allows for better control over surface topology during the planarization 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 enhances the reliability and integrity of metal conductors by preventing interdiffusion, ensuring a coplanar surface finish and improving the overall performance of BEOL metallization structures.
Implementation Method 1
A bulk metal is disposed in the one or more openings, wherein the bulk metal has an upper surface coplanar to an upper surface of the dielectric layer, wherein the bulk metal is free of a metal nitride liner layer
Data Source
AI summary
Back end of line metallization structures and processes of fabricating the metallization structures generally patterning a dielectric layer formed of SiC, SiN or SiC (N, H) and filled the openings in the patterned dielectric layer with a metal conductor. Optionally, the surfaces defining the openings of the dielectric layer are subjected to a nitridation process to form a nitride layer at the surface. Still further, the metallization structures can include a pure metal liner on the surfaces defining the openings of the dielectric layer.