Metal Oxide Diffusion Barriers for BEOL Interconnects
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Solution Overview
Problem
As semiconductor device dimensions shrink, existing processes struggle to form desired materials and structures within acceptable tolerances, particularly in forming interconnects, due to issues with adhesion, diffusion, and conformal step coverage of barrier layers in back-end-of-line (BEOL) interconnects.
Innovation Solution
A method involving plasma pre-treatment of dielectric substrates to modify their surface, followed by the deposition of metal oxide barrier layers using atomic layer deposition (ALD) or chemical vapor deposition (CVD), which improves adhesion and nucleation, and the use of in-situ metal liners to enhance the integration of subsequent layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional barrier layer formation processes are used, then existing processes can be maintained, but adhesion and conformal step coverage are insufficient for shrinking device dimensions
Solution Approach 1:
The patent changes the chemical composition parameters of the barrier layer by forming metal oxide barrier layers (such as tungsten oxide, molybdenum oxide, tantalum oxide) instead of conventional metal layers. This parameter change enables conformal step coverage and improved adhesion to low-k dielectric materials, solving the manufacturing precision issue while maintaining process compatibility through ALD or CVD deposition methods.
Solution Approach 2:
The patent employs composite material structures by combining metal oxide barrier layers with underlying dielectric materials and overlying conductive layers. The metal oxide composite structure provides both the diffusion barrier function and the adhesion promotion function, replacing the need for separate adhesion layers and simplifying the overall process despite the sophisticated material composition.
2Length of moving object
If barrier layer thickness is reduced to meet smaller device dimensions, then space is saved, but adhesion to dielectric material deteriorates
Solution Approach 1:
The patent changes the material parameter from conventional metals to metal oxides, which inherently provide better adhesion to dielectric materials. This parameter change allows the barrier layer to maintain strong adhesion even at reduced thicknesses of 50-200 nm, simultaneously achieving space savings and adhesion requirements through the unique properties of metal oxide materials.
3Reliability
If metal oxide barrier layers are formed, then metal diffusion is prevented, but deposition process complexity increases
Solution Approach 1:
The patent replaces the mechanical/physical vapor deposition processes with chemical vapor deposition or atomic layer deposition processes that form metal oxide barrier layers through chemical reactions. This substitution provides superior diffusion prevention through the oxide material structure while the automated ALD/CVD processes actually simplify process control and uniformity compared to conventional methods, resolving the apparent complexity issue.
4Strength
If plasma pre-treatment is applied to dielectric surface, then adhesion is improved, but dielectric material may be damaged
Solution Approach 1:
The patent changes the surface chemistry parameters of the dielectric material through plasma pre-treatment, introducing reactive groups and increasing surface energy to improve adhesion. By carefully controlling plasma parameters (power, pressure, gas composition, treatment time), the treatment enhances adhesion while minimizing damage to the dielectric bulk material, achieving both improved bonding and material integrity.
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 enables the formation of high-quality, thin, and conformal metal oxide barrier layers that prevent metal diffusion, improve adhesion, and facilitate the integration of subsequent layers, addressing the challenges of adhesion, diffusion, and conformal step coverage in BEOL interconnects.
Implementation Method 1
exposing the substrate to plasma to thereby modify a top surface of the dielectric material
Implementation Method 2
forming a metal oxide barrier layer on the modified top surface of the dielectric material, where the metal oxide barrier layer is formed, at least in part, through atomic layer deposition
Implementation Method 3
forming a metal oxide barrier layer on the modified top surface of the dielectric material, where the metal oxide barrier layer is formed, at least in part, through atomic layer deposition and/or chemical vapor deposition
Implementation Method 4
forming high-quality, thin, and conformal metal oxide barrier layers that prevent metal diffusion
Data Source
AI summary
Various embodiments herein relate to methods, apparatus, and systems for forming an interconnect structure, or a portion thereof, on a substrate. In one example, the method includes receiving the substrate in a processing chamber, the substrate having dielectric material exposed within recessed features formed therein; exposing the substrate to plasma to thereby modify a top surface of the dielectric material; forming a metal oxide barrier layer on the modified top surface of the dielectric material, wherein the metal oxide barrier layer is formed through atomic layer deposition and/or chemical vapor deposition. In certain implementations, one or more additional step may be taken to improve processing results, for example to promote nucleation and/or adhesion of relevant layers.