Carbon Liner at Metal Interfaces for Lower Contact Resistance
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Solution Overview
Problem
In electronic devices, copper's high diffusion rate and asymmetric deposition at metal interfaces lead to increased contact resistance, reducing electrical performance and causing semiconductor device failures, while barrier layers intended to prevent diffusion also increase contact resistance.
Innovation Solution
A layer of graphite or graphene is introduced at metal interfaces to reduce contact resistance by preventing heat transfer and ensuring symmetric deposition, with the option to etch the carbon-based layer before deposition of subsequent metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If barrier layers are used to prevent copper diffusion, then copper ion diffusion is reduced, but contact resistance increases
Solution Approach 1:
A carbon-based liner layer is introduced as an intermediary between the copper contact plug and the surrounding dielectric material. This liner acts as a diffusion barrier to prevent copper ion migration while simultaneously maintaining low contact resistance at the metal interface, resolving the contradiction between preventing copper diffusion and maintaining electrical conductivity.
2Ease of manufacture
If asymmetric deposition occurs at metal interfaces, then manufacturing simplicity is maintained, but contact resistance increases and device reliability decreases
Solution Approach 1:
The carbon-based liner is selectively deposited only at the critical metal interface regions where contact resistance is a concern. This localized application ensures symmetric deposition characteristics at the interface while maintaining simplicity in the overall manufacturing process, preventing asymmetric deposition effects that would increase contact resistance.
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 use of graphite or graphene layers effectively decreases contact resistance, enhancing electrical performance and preventing semiconductor device failures by ensuring symmetric metal deposition and reducing copper ion diffusion.
Implementation Method 1
A layer of carbon (e.g., graphite or graphene) at a metal interface (e.g., between an MEOL interconnect and a gate contact or a source or drain region contact, between an MEOL contact plug and a BEOL metallization layer, and/or between BEOL conductive structures) reduces contact resistance at the metal interface
Data Source
AI summary
A layer of carbon (e.g., graphite or graphene) at a metal interface (e.g., between an MEOL interconnect and a gate contact or a source or drain region contact, between an MEOL contact plug and a BEOL metallization layer, and/or between BEOL conductive structures) is used to reduce contact resistance at the metal interface, which increases electrical performance of an electronic device. Additionally, in some implementations, the layer of carbon may help prevent heat transfer from a second metal to a first metal when the second metal is deposited over the first metal. This results in more symmetric deposition of the second metal, which reduces surface roughness and contact resistance at the metal interface. As an alternative, in some implementations, the layer of carbon is etched before deposition of the second metal in order to reduce contact resistance at the metal interface.