Copper Metallization Filling by Oxidation-Reduction Migration
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Solution Overview
Problem
Current methods for forming metal structures in integrated circuits, such as ALD, PVD, and CVD, require high temperatures and diffusion barrier layers, leading to voids and inefficiencies, especially in high aspect ratio openings and low-κ dielectric layers.
Innovation Solution
A method involving the introduction of a gas that alternately oxidizes and reduces metal material from a first metal structure, allowing it to migrate and fill openings without the need for a diffusion barrier layer, using oxidation and reduction reactions to create a second metal structure with varying oxygen concentrations and potentially lower density, which can be planarized using CMP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods (ALD, PVD, CVD) are used to form metal structures, then metal deposition can be achieved, but high temperatures and diffusion barrier layers are required, leading to voids and inefficiencies
Solution Approach 1:
The patent changes the chemical parameters of the deposition process by using a gas mixture that alternately oxidizes and reduces metal material in situ, eliminating the need for separate diffusion barrier layers and enabling void-free filling at lower temperatures
Solution Approach 2:
The patent extracts and eliminates the diffusion barrier layer from the conventional metal deposition process by using gas-phase oxidation and reduction reactions that prevent void formation without requiring additional barrier layers
2Manufacturing precision
If high temperatures are used for metal deposition, then complete filling can be achieved, but damage to low-κ dielectric layers and existing structures occurs
Solution Approach 1:
The patent changes the temperature parameter by using a chemical reaction-based filling mechanism (oxidation-reduction cycles) that operates at lower temperatures, avoiding thermal damage to low-κ dielectric layers while still achieving complete opening filling
3Reliability
If diffusion barrier layers are added to prevent voids, then void formation is reduced, but process complexity and manufacturing steps increase
Solution Approach 1:
The patent removes the diffusion barrier layer from the process stack by using in situ gas-phase oxidation and reduction reactions that inherently prevent void formation during metal deposition, simplifying the overall device structure
Solution Approach 2:
The patent introduces a gas mixture as an intermediary that mediates the metal deposition process through alternating oxidation and reduction reactions, preventing void formation without requiring physical barrier layers
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 method allows for the formation of metal structures without voids and at lower temperatures, reducing the need for diffusion barrier layers, resulting in more efficient filling of high aspect ratio openings and improved integration with memory cells and logic regions in integrated circuits.
Implementation Method 1
A gas is provided that alternately oxidizes and reduces metal material from the first metal structure
Implementation Method 2
A gas is provided that alternately oxidizes and reduces metal material from the first metal structure
Implementation Method 3
metal material from the first metal structure to migrate into the opening
Data Source
AI summary
A second metal structure such as a metal plug is formed over a first metal structure, such as a metal line, by causing metal material from the first metal structure to migrate into an opening in a dielectric layer over the first metal structure. The metal material, which may be copper, is of a type that undergoes a reduction in density as it oxidizes. Migration is induced using gases that alternately oxidize and reduce the metal material. Over many cycles, the metal material migrates into the opening. In some embodiments, the migrated metal material partially fills the opening. In some embodiments, the migrated metal material completely fills the opening.