Liner Replacement for Interconnect Openings
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Solution Overview
Problem
In semiconductor device fabrication, conventional liners fail to adequately protect high aspect ratio openings during metal deposition, leading to damage and failures due to reactions with halogen-based reactants like tungsten hexafluoride, which form metal-fluorine complexes.
Innovation Solution
A method involving the application of a thin adhesion layer and a barrier layer on the conductive feature within the opening, where the adhesion layer is chemically bound to prevent reactions with halogen-based reactants, and the barrier layer is formed with columnar grains to reduce coverage on the sidewalls, allowing the conductive feature to be filled without forming harmful complexes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional liner is applied to protect the conductive feature during metal deposition, then the liner provides initial protection, but the liner reacts with halogen-based reactants to form metal-fluorine complexes that cause damage and failures
Solution Approach 1:
The patent removes the reactive liner material from the opening base area entirely by replacing it with a non-reactive adhesion layer. This extraction of the harmful reactive component eliminates the source of metal-fluorine complex formation while maintaining the necessary adhesion function through a different material that does not react with halogen-based reactants.
Solution Approach 2:
The patent introduces an adhesion layer as an intermediary between the conductive feature and the opening. This adhesion layer serves as a mediator that provides both adhesion functionality and chemical inertness, preventing direct contact between the conductive feature and halogen-based reactants, thereby eliminating metal-fluorine complex formation.
2Productivity
If the opening has a high aspect ratio to achieve advanced technology nodes, then the device density is improved, but the liner fails to adequately protect the surfaces during metal deposition
Solution Approach 1:
The patent applies different materials with different properties to different locations: the adhesion layer is applied specifically at the opening base where chemical reactions occur, while the barrier layer is applied on the sidewalls where mechanical protection is needed. This local differentiation allows each region to have optimized properties for its specific function, solving the protection failure in high aspect ratio openings.
Solution Approach 2:
The patent uses a composite structure consisting of an adhesion layer and a barrier layer with different functional properties. The adhesion layer provides chemical inertness and adhesion, while the barrier layer provides mechanical protection and columnar grain structure. This composite approach enables adequate protection in high aspect ratio openings that conventional single-material liners cannot provide.
3Object-generated harmful factors
If a barrier layer is formed with columnar grains to reduce coverage on sidewalls, then the harmful complex formation is prevented, but the barrier layer deposition quality requirement becomes more stringent
Solution Approach 1:
The patent changes the microstructural parameter of the barrier layer to have a columnar grain structure. This parameter change reduces the barrier layer coverage on sidewalls, preventing complex formation while allowing for more relaxed deposition quality requirements compared to a dense amorphous structure.
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 prevents the formation of halogen-containing complexes, reduces contact resistance, and enhances the reliability of the interconnect structure by minimizing corrosion and oxidation, while allowing for larger conductive feature sizes and lower quality barrier layer deposition.
Implementation Method 1
the adhesion layer is chemically bound to prevent reactions with halogen-based reactants
Implementation Method 2
the barrier layer is formed with columnar grains to reduce coverage on the sidewalls
Data Source
AI summary
Structures for a liner replacement in an interconnect structure and methods for forming a liner replacement in an interconnect structure. A metallization level is formed that includes a conductive feature. A dielectric layer is formed on the metallization level. The dielectric layer includes an opening that extends vertically through the dielectric layer to the conductive feature. An adhesion layer is formed on area of the conductive feature exposed at a base of the opening. The adhesion layer has a thickness equal to a monolayer or a fraction of a monolayer. Another layer (e.g., barrier layer) of a different composition (e.g., TiN) may be deposited on the adhesion layer before the opening is filled with metal deposited by chemical vapor deposition.