CMP Slurry for Cu Damascene Wiring with Low Friction
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Solution Overview
Problem
Conventional CMP slurries face challenges in suppressing dishing and corrosion of Cu and insulating films during the formation of Cu damascene wiring in semiconductor devices, particularly due to high polishing friction and instability, which are exacerbated when using Low-k materials.
Innovation Solution
A CMP slurry comprising water, polyvinylpyrrolidone (PVP) with a weight average molecular weight of 20,000 or more, an oxidizing agent, a protective film-forming agent with both water-insoluble and water-soluble complexing agents, and colloidal silica with a primary particle diameter between 5 to 50 nm, is used to reduce polishing friction and enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional CMP slurry is used, then polishing friction is large, but this causes dishing of Cu and peeling/fracture of Low-k insulating film
Solution Approach 1:
The patent changes the chemical composition parameters of the slurry by incorporating specific additives including polyvinyl alcohol, polyacrylic acid, and colloidal silica with controlled particle sizes (5-50 nm). These parameter changes modify the slurry's friction characteristics and chemical reactivity, enabling effective Cu polishing while protecting Low-k films from damage.
Solution Approach 2:
The patent creates a composite slurry system combining multiple functional components: polyvinyl alcohol as a protective agent, polyacrylic acid as a dispersant, colloidal silica as an abrasive, and specific pH adjusters. This composite formulation achieves synergistic effects that reduce friction and prevent film damage while maintaining polishing efficiency.
2Productivity
If conventional silicone-based surfactant is used, then polishing is enhanced, but coarse silica particles are generated causing scratch and unstable polishing rate
Solution Approach 1:
The patent replaces conventional silicone-based surfactants with polyvinyl alcohol, which forms a protective layer that is continuously refreshed during polishing. This approach uses a consumable protective layer that prevents scratch while maintaining stable polishing conditions, eliminating the problem of coarse particle generation associated with silicone surfactants.
Solution Approach 2:
The patent controls the particle size parameter of colloidal silica to be in the range of 5-50 nm, which is significantly smaller than conventional silica particles. This parameter change prevents the generation of coarse particles that cause scratch, while still maintaining effective polishing action and stable polishing rate.
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 described slurry effectively minimizes dishing and corrosion of Cu and insulating films, achieving stable and uniform polishing with low friction, thereby meeting the performance demands for next-generation LSI manufacturing.
Implementation Method 1
a first polishing where the abrasion of Cu is mainly performed
Implementation Method 2
an oxidizing agent
Data Source
AI summary
A CMP slurry for metallic film is provided, which includes water, 0.01 to 0.3 wt %, based on a total quantity of the slurry, of polyvinylpyrrolidone having a weight average molecular weight of not less than 20,000, an oxidizing agent, a protective film-forming agent containing a first complexing agent for forming a water-insoluble complex and a second complexing agent for forming a water-soluble complex, and colloidal silica having a primary particle diameter ranging from 5 to 50 nm.