Cleaning Metal Contacts for Semiconductor Interconnects
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Solution Overview
Problem
As semiconductor interconnect dimensions shrink, the presence of contaminants like metal oxides, nitrides, and carbides on the underlying metal layer leads to increased contact resistance and reliability issues due to incubation delays and voids during metal gap fill processes, limiting device performance and reliability.
Innovation Solution
A method involving a process chamber that exposes substrates with contaminated metal surfaces to a process gas with an oxidizing agent to convert contaminants into metal oxides, followed by exposure to a reducing agent to achieve a substantially pure metal surface, thereby facilitating improved metal contact formation and reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If selective deposition is used to avoid liner usage, then manufacturing complexity is reduced, but contact resistance increases due to contaminants on the underlying metal layer
Solution Approach 1:
The patent applies preliminary action by performing a cleaning process on the underlying metal layer before selective deposition. The cleaning chamber exposes the metal surface to a process gas that removes contaminants such as metal oxides, carbides, and nitrides. This preliminary cleaning ensures that the subsequent selective deposition occurs on a clean surface, preventing high contact resistance while maintaining the simplified process architecture without liner usage.
Solution Approach 2:
The patent introduces an intermediary cleaning step between the feature formation and selective deposition processes. The cleaning chamber acts as an intermediary stage that mediates the transition from a contaminated metal surface to a clean surface suitable for selective deposition. This intermediary process removes harmful contaminants while preserving the underlying metal layer structure, enabling low-resistance contacts without requiring additional liner layers.
2Manufacturing precision
If CVD metal layer is deposited on contaminated surface, then gap fill is achieved, but incubation delay occurs resulting in voids or seams
Solution Approach 1:
The patent applies preliminary action by cleaning the metal surface before CVD deposition. The cleaning process removes contaminants that would otherwise cause incubation delays during the CVD gap fill process. By eliminating these contaminants in advance, the CVD metal layer can deposit uniformly across the feature without experiencing delays that would lead to voids or large seams, achieving precise and uniform gap fill.
3Length of moving object
If feature size is reduced to 10 nm level, then device scaling is improved, but contact resistance increases due to contaminant contributions
Solution Approach 1:
The patent applies local quality by targeting the cleaning process specifically at the contact region where contaminants are most problematic. The cleaning chamber exposes only the underlying metal layer surfaces that will form contacts to the process gas, removing contaminants locally at these critical interfaces. This localized cleaning ensures low contact resistance in the scaled 10 nm features without affecting other parts of the structure, maintaining device performance at advanced technology nodes.
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 approach effectively removes contaminants, reducing contact resistance and improving device reliability by ensuring a pure metal surface for subsequent metal deposition, thus enhancing the performance and reliability of semiconductor devices.
Implementation Method 1
exposing a substrate including a dielectric surface and a metal surface including metal nitride residues and metal carbide residues to a process gas including an oxidizing agent to form a substrate including a dielectric surface and a metal surface including metal oxides residues
Implementation Method 2
exposing a substrate including a dielectric surface and a metal surface including metal oxides residues to a process gas including a reducing agent to form a substrate including a dielectric surface and a substantially pure metal surface
Data Source
AI summary
Methods and apparatus for cleaning a contaminated metal surface on a substrate, including: exposing a substrate including a dielectric surface and a metal surface including metal nitride residues and metal carbide residues to a process gas including an oxidizing agent to form a substrate including a dielectric surface and a metal surface including metal oxides residues; and exposing a substrate including a dielectric surface and a metal surface including metal oxides residues to a process gas including a reducing agent to form a substrate including a dielectric surface and a substantially pure metal surface.