Selective Deposition on Non-Metallic Surfaces via Blocking Layer
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Solution Overview
Problem
Current methods for reducing via resistance in middle of the line (MOL) and back end of the line (BEOL) structures, particularly due to high resistivity of barrier films, have not effectively addressed the issue of increased via resistance despite efforts to decrease barrier film thickness or find lower resistivity films.
Innovation Solution
A method involving selective deposition using unsaturated hydrocarbons to form a blocking layer on metallic surfaces over non-metallic surfaces, followed by sequential exposure to metal precursors and reactants to deposit films on non-metallic surfaces, thereby reducing the resistance of metal vias by forming low-resistance metal vias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If barrier film thickness is decreased to reduce via resistance, then via resistance decreases, but barrier protection capability deteriorates
Solution Approach 1:
The patent applies local quality by creating different barrier film thicknesses at different locations: a first thickness on the dielectric sidewall and a second, smaller thickness on the metal surface. This allows the barrier film to provide adequate protection on the dielectric while minimizing resistance on the metal contact surface, thus resolving the contradiction between barrier protection and via resistance.
Solution Approach 2:
The patent uses preliminary action by first depositing a conformal barrier film of uniform thickness, then selectively removing portions of the barrier film from the metal surface through etch-selective processes. This preliminary deposition ensures complete barrier coverage, while subsequent selective removal reduces resistance without compromising the barrier function on dielectric surfaces.
2Reliability
If barrier film thickness is decreased to reduce via resistance, then via resistance decreases, but diffusion barrier function deteriorates
Solution Approach 1:
The patent implements local quality by varying the barrier film thickness according to location: maintaining sufficient thickness on dielectric surfaces to prevent diffusion, while reducing thickness on metal surfaces to minimize resistance. The etch-selective process enables precise control of local thickness, ensuring diffusion barrier function is preserved where needed while reducing via resistance where appropriate.
3Manufacturing precision
If selective deposition is performed on metal surfaces, then film deposition on metal is improved, but deposition on non-metallic surfaces deteriorates
Solution Approach 1:
The patent applies inversion by reversing the conventional selective deposition approach. Instead of depositing film selectively on metal surfaces while excluding non-metallic surfaces, the process deposits conformal film on all surfaces and then uses etch-selectivity to remove film from metal surfaces. This inverted approach enables precise control of film presence on different surface types, improving manufacturing precision for both metal and non-metallic surfaces.
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 reduces via resistance by selectively forming a blocking layer on metallic surfaces, allowing for the deposition of low-resistance films on non-metallic surfaces, resulting in a significant reduction in metal via resistance, typically less than 80% of the resistance without the blocking layer, and providing a via resistance reduction of greater than 20%.
Implementation Method 1
exposing a substrate to an unsaturated hydrocarbon to selectively form a blocking layer on a first surface over a second surface. The substrate comprises a metallic material having the first surface and a non-metallic material having the second surface
Implementation Method 2
The substrate is sequentially exposed to a metal precursor and a reactant to form a film on the second surface over the blocking layer on the first surface
Data Source
AI summary
Methods for selectively depositing on non-metallic surfaces are disclosed. Some embodiments of the disclosure utilize an unsaturated hydrocarbon to form a blocking layer on metallic surfaces. Deposition is performed to selectively deposit on the unblocked non-metallic surfaces. Some embodiments of the disclosure relate to methods of forming metallic vias with decreased resistance.