TaCN Diffusion Barrier with Ru Capping for Cu Interconnects
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Solution Overview
Problem
The use of copper (Cu) in semiconductor contact structures faces challenges due to its poor adhesion to dielectric materials and tendency to diffuse into silicon and other materials, leading to high contact resistivity and oxidation issues, which are not effectively addressed by conventional TaN/Ta diffusion barriers.
Innovation Solution
A semiconductor contact structure is formed using a TaCN diffusion barrier with a Ru film, where the TaCN barrier is treated with a plasma-excited nitrogen-containing gas to enhance its oxidation resistance and conformality, and the Ru film is deposited using thermal CVD, improving adhesion and reducing contact resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cu is used to replace W plug for vertical interconnect structures, then contact resistivity and RC-delay are improved, but Cu diffusion into dielectric materials and oxidation issues worsen
Solution Approach 1:
A TaCN diffusion barrier layer is introduced as an intermediary between Cu and dielectric materials. This barrier layer prevents Cu from diffusing into the dielectric and blocks oxygen from reaching Cu, thereby eliminating both Cu diffusion and oxidation issues while maintaining low contact resistivity
Solution Approach 2:
The patent uses a composite structure consisting of TaCN diffusion barrier combined with Ru capping layer. This composite material system provides both diffusion prevention and oxidation resistance, solving the dual problems of Cu diffusion and oxidation simultaneously
2Object-generated harmful factors
If TaN/Ta diffusion barrier is used to surround Cu, then Cu diffusion is prevented, but adhesion to dielectric materials and oxidation resistance worsen
Solution Approach 1:
The patent changes the material parameter from conventional TaN/Ta to TaCN (titanium carbonitride). This material substitution provides superior adhesion to dielectric materials and enhanced oxidation resistance while maintaining effective Cu diffusion prevention
Solution Approach 2:
The TaCN barrier layer is specifically optimized for the Cu-dielectric interface where adhesion and oxidation resistance are critical. The Ru capping layer is applied locally on top of TaCN to provide additional oxidation protection, creating localized quality improvements at critical interfaces
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
The TaCN diffusion barrier with Ru film effectively reduces oxidation and contact resistivity, providing superior adhesion and stability, thus addressing the limitations of conventional Cu metallization with TaN/Ta barriers.
Implementation Method 1
the TaCN barrier is treated with a plasma-excited nitrogen-containing gas to enhance its oxidation resistance and conformality
Implementation Method 2
the Ru film is deposited using thermal CVD, improving adhesion and reducing contact resistivity
Data Source
AI summary
The method includes providing a patterned structure in a process chamber, where the patterned structure contains a micro-feature formed in a dielectric material and a contact layer at the bottom of the micro-feature, and depositing a metal carbonitride or metal carbide film on the patterned structure, including in the micro-feature and on the contact layer. The method further includes forming an oxidation-resistant diffusion barrier by increasing the nitrogen-content of the deposited metal carbonitride or metal carbide film, depositing a Ru film on the oxidation-resistant diffusion barrier, and forming bulk Cu metal in the micro-feature. A semiconductor contact structure is described.