Bulk Cobalt Contact With Replacement Metal Cap
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Solution Overview
Problem
Conventional metal interconnection wires, such as Copper, face challenges in meeting the demands of miniaturized semiconductor chip designs due to limitations in wire width and pitch, leading to reliability issues and increased resistance, which hinders further miniaturization in semiconductor fabrication.
Innovation Solution
The use of bulk cobalt contacts with a non-cobalt metal cap, formed through a chemical exchange reaction, in the back-end-of-line (BEOL) metallization layers, where the non-cobalt metal cap is integral to the cobalt contact, enhances the reliability and performance of metal interconnections by reducing electro-migration resistance and oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional metal interconnection wires (Copper or Aluminum) are used, then manufacturing process is simple, but wire width and pitch cannot be reduced further due to fabrication processing problems and reliability issues
Solution Approach 1:
The patent changes the material parameter from conventional Copper/Aluminum to Cobalt, enabling smaller wire widths and pitch values. Cobalt's superior material properties allow fabrication at dimensions where conventional metals fail, resolving the contradiction between miniaturization and reliability.
Solution Approach 2:
The patent uses a composite structure with Cobalt as the core material and an additional metal layer (such as Ruthenium, Rhodium, or Platinum) deposited on the Cobalt surface. This composite approach combines Cobalt's excellent electrical conductivity with the protective properties of the outer metal layer, achieving both miniaturization and reliability.
2Productivity
If metal interconnection wires are miniaturized to meet chip design requirements, then feature density increases, but barriers between wires reach design limits and resistance increases
Solution Approach 1:
Changing the material from Copper to Cobalt fundamentally alters the electrical and physical parameters. Cobalt maintains lower resistance and better electro-migration resistance at smaller dimensions, enabling continued feature density improvement without hitting the limitations that constrain conventional metals.
3Manufacturing precision
If Cobalt is used instead of Copper, then wire width and pitch can be reduced for miniaturization, but Cobalt is more reactive and prone to oxidation
Solution Approach 1:
The patent introduces an intermediary metal layer (such as Ruthenium, Rhodium, or Platinum) that deposits on the Cobalt surface. This intermediate layer acts as a protective barrier, preventing direct contact between Cobalt and oxidizing environments, thus eliminating Cobalt's reactivity and oxidation problems while preserving its excellent electrical properties.
Solution Approach 2:
The patent creates a composite material system where Cobalt provides excellent electrical conductivity and enables miniaturization, while the outer metal layer (Ruthenium, Rhodium, or Platinum) provides oxidation resistance. This composite structure resolves the contradiction between Cobalt's miniaturization benefits and its reactivity drawbacks.
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 improves the reliability and performance of metal wiring in semiconductor products by using cobalt instead of copper, allowing for smaller wire widths and increased miniaturization while mitigating reactivity and oxidation issues, thus enabling continued advancements in semiconductor design.
Implementation Method 1
perform selective deposition, by a chemical exchange reaction of metal between a non-cobalt metal and Cobalt in the bulk cobalt contact, of a replacement non-cobalt metal cap integrally formed in a top surface region of the bulk cobalt contact
Data Source
AI summary
Various methods and structures for fabricating BEOL metallization layer including at least one bulk cobalt contact, the at least one bulk cobalt contact including a replacement non-cobalt metal cap integral to the at least one bulk cobalt contact. The method includes performing selective deposition, by a chemical exchange reaction of metal between a non-cobalt metal and Cobalt in the at least one bulk cobalt contact, of the replacement non-cobalt metal cap integrally formed in a top surface region of the bulk cobalt contact.