Cobalt Interconnect Surface Protection Against Etch Damage
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Solution Overview
Problem
Cobalt interconnect structures in semiconductor manufacturing are prone to damage during etching and wet cleaning processes due to surface modification by reactive ion etching and subsequent chemical attacks, leading to reliability and yield issues.
Innovation Solution
A cobalt metallization structure with a modified surface treated using trisilylamine or deposition of resistant metals like Ru or Co, followed by a silicide process, to protect against etching and wet cleaning damage, ensuring the integrity of the interconnect structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cobalt is used as interconnect material to reduce resistivity at small dimensions, then device performance is improved, but the cobalt surface is damaged during etching and wet cleaning processes
Solution Approach 1:
The patent applies preliminary action by forming a protective layer of ruthenium or other resistant metal on the cobalt surface before the harmful etching and wet cleaning processes occur. This pre-established protection prevents the subsequent damage that would otherwise occur to the cobalt interconnect structure during manufacturing processes.
Solution Approach 2:
The patent uses an intermediary substance (protective layer of ruthenium or resistant metal) that acts as a mediator between the cobalt interconnect and the harmful etching/wet cleaning processes. This intermediary layer absorbs the chemical attack, protecting the underlying cobalt from direct exposure to damaging chemicals while allowing the necessary manufacturing processes to proceed.
2Ease of manufacture
If reactive ion etching is used to etch trenches, then trench formation is achieved, but the cobalt surface is modified and subsequently dissolved by wet cleaning processes
Solution Approach 1:
The protective layer is formed on the cobalt surface before the trench etching and subsequent wet cleaning processes. This preliminary protection ensures that when the trenches are etched and the structure is cleaned, the cobalt surface remains intact and undissolved, maintaining manufacturing precision throughout the fabrication sequence.
Solution Approach 2:
The resistant metal layer serves as an intermediary that protects the cobalt surface during the trench formation process. It allows the reactive ion etching to proceed effectively while mediating the subsequent wet cleaning process, preventing direct contact between the cleaning chemicals and the cobalt surface, thus preserving surface integrity.
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 proposed solution effectively prevents damage to cobalt interconnect structures during etching and wet cleaning, enhancing interconnect reliability and yield by forming protective layers that resist chemical attacks.
Implementation Method 1
A cobalt metallization structure with a modified surface of etch chemistries; a layer of material on the modified surface
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to interconnect structures and methods of manufacture. The structure includes: a cobalt metallization structure with a modified surface of etch chemistries; a layer of material on the modified surface; and an interconnect structure in direct contact with the material.