Top Via Protective Liner for IC Interconnects
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Solution Overview
Problem
During top via formation in integrated circuit fabrication, the removal of the dielectric scaffold can cause degradation and damage to tall metal lines due to poor etch selectivity, leading to significant over-etching of the top via portion.
Innovation Solution
A selective metal or dielectric liner is grown on the exposed portions of the top via before removal of the interlayer dielectric layer to protect the metal lines from damage during the etch process, using techniques such as in situ radical assisted deposition to form a conformal and dense liner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a dielectric scaffold is used to support tall metal lines during processing, then the metal lines can be formed to required heights, but the removal of the scaffold causes over-etching and damage to the top via portion due to poor etch selectivity
Solution Approach 1:
A liner is deposited on the top via portion before the scaffold removal etch process. This preliminary protective layer prevents the etchant from attacking the metal line during scaffold removal, thereby maintaining the top via dimensional accuracy while still allowing the metal lines to be formed to the required heights
Solution Approach 2:
The liner acts as an intermediary protective layer between the etchant and the metal line. It provides etch selectivity by being resistant to the removal etch, allowing the dielectric scaffold to be removed without damaging the top via portion of the metal lines
2Ease of manufacture
If the dielectric scaffold is removed to complete the top via formation, then the interconnect structure is finalized, but significant over-etching occurs damaging the metal lines
Solution Approach 1:
The liner is deposited in advance before the scaffold removal process, preparing the metal line surface to resist etching. This preliminary protection enables complete scaffold removal while maintaining metal line integrity and preventing over-etching damage
Solution Approach 2:
The liner provides a protective cushioning layer that absorbs the harmful effect of the etchant during scaffold removal. This beforehand protection ensures that the metal lines are shielded from over-etching damage while allowing the interconnect structure to be finalized
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
The protective liner prevents damage to the top via portion of the metal lines during the etch process, ensuring accurate and reliable formation of interconnect structures in integrated circuits.
Implementation Method 1
using techniques such as in situ radical assisted deposition to form a conformal and dense liner
Data Source
AI summary
An interconnect structure and a method of forming the interconnect structure are provided. The interconnect structure includes one or more metal lines and one or more top vias in direct contact with a top surface of the one or more metal lines. The interconnect structure also includes a liner formed on sidewalls of the one or more top vias and top portions of the one or more metal lines.