Amine-Based Polyether Suppressors for Void-Free Copper Plating
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Solution Overview
Problem
Current copper electroplating technologies face challenges in achieving voidless and seamless filling of small features, particularly those with convex shapes and nanometer-scale aperture sizes, due to issues like seed overhang and non-conformal copper seed deposition, which can lead to pinch-off void formation.
Innovation Solution
The use of amine-based polyoxyalkylene suppressing agents with random oxyalkylene copolymers having a molecular weight of 6000 g/mol or more, which effectively suppress sidewall copper growth and promote bottom-up fill copper growth, ensuring defect-free trench filling even in dense feature areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional suppressors are used for copper electroplating, then plating can proceed on larger features, but voids and seams form in submicron features due to inadequate sidewall suppression
Solution Approach 1:
The patent applies parameter changes by modifying the molecular weight of the polyether suppressor to 6000 g/mol or more, and adjusting the EO/PO ratio to 70:30 or higher. These parameter changes enhance the suppressor's ability to adsorb on sidewalls and prevent copper deposition, thereby eliminating voids and seams in submicron features while maintaining effective suppression.
Solution Approach 2:
The patent uses a composite suppressor system combining polyether compounds (EO/PO copolymers) with amine-based additives. This composite approach creates synergistic effects where the polyether provides base suppression and the amine components enhance sidewall adhesion and suppression efficiency, resulting in void-free filling of challenging submicron features.
2Area of moving object
If aperture size is reduced to below 100 nanometer, then device density increases, but seed overhang and non-conformal copper seed deposition cause pinch-off void formation
Solution Approach 1:
The patent applies preliminary action by ensuring complete and uniform copper seed deposition across the feature aperture before the electroplating process begins. The enhanced suppressor system prevents premature copper growth on sidewalls during seeding, creating a conformal seed layer that eliminates the root cause of pinch-off voids in sub-100nm features.
Solution Approach 2:
The patent applies local quality by creating different copper growth rates at different locations within the feature. The suppressor selectively inhibits copper deposition on sidewalls while allowing rapid growth at the bottom, creating a bottom-up filling pattern that prevents void formation even in features with initial seed overhang or non-conformal seeding.
3Manufacturing precision
If suppressor strength is increased to prevent sidewall growth, then void-free filling improves, but deposition rate decreases
Solution Approach 1:
The patent applies local quality by creating spatially differentiated copper deposition: strong suppression on sidewalls prevents void formation, while the feature bottom experiences enhanced deposition due to accelerator activity and reduced suppressor concentration. This local differentiation achieves void-free filling without uniformly reducing the overall deposition rate.
Solution Approach 2:
The patent applies dynamics by creating a time-evolving suppression profile during electroplating. As copper fills the feature from bottom to top, the suppressor concentration and adsorption dynamics change, allowing rapid initial filling while maintaining sidewall suppression. This dynamic behavior enables both high productivity and void-free filling.
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
These suppressing agents enable a flat growth front and substantially void-free filling of small features, including those with aperture sizes of 30 nanometers or below, by preventing sidewall copper growth and ensuring homogeneous bottom-up fill in neighboring features.
Implementation Method 1
suppressors are used to provide a substantially bottom-up filling of small features like vias or trenches
Implementation Method 2
Filling of small features, such as vias and trenches, by copper electroplating
Data Source
Figure 1a~1c
Figure 2a~2b
Figure 2c~3
AI summary
A composition comprising a source of metal ions and at least one suppressing agent obtainable by reacting a) an amine compound comprising active amino functional groups with b) a mixture of ethylene oxide and at least one compound selected from C3 and C4 alkylene oxides, said suppressing agent having a molecular weight Mw of 6000 g/mol or more.