Tungsten Interconnect Liners for IGZO Copper Diffusion Barriers
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Solution Overview
Problem
Copper interconnects in integrated circuits (ICs) tend to diffuse into surrounding materials, leading to degradation of performance when used with channel materials like indium gallium zinc oxide (IGZO), necessitating the use of traditional barrier materials such as tantalum or tantalum nitride, which also degrade performance.
Innovation Solution
Employing tungsten as a barrier material for IC interconnects, optionally combined with additional layers like tantalum or tantalum nitride, to shield the inner barrier layer from the channel material, thereby maintaining conductivity and preventing degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper interconnects are used in IC devices, then electrical conductivity is improved, but copper diffuses into surrounding materials causing performance degradation
Solution Approach 1:
A tungsten liner layer is introduced as an intermediary barrier between the copper interconnect and the IGZO channel material. This tungsten layer prevents direct contact and diffusion of copper into the channel material, while maintaining electrical conductivity through the interconnect structure.
Solution Approach 2:
The interconnect structure uses a composite approach by combining copper (for conductivity) with a tungsten barrier layer (for diffusion prevention). This multi-material structure resolves the contradiction by assigning different materials to different functional requirements within the same interconnect system.
2Object-generated harmful factors
If traditional barrier materials like tantalum or tantalum nitride are used, then copper diffusion is prevented, but performance degradation occurs due to interaction with channel materials
Solution Approach 1:
The patent changes the material parameter of the barrier layer from traditional tantalum or tantalum nitride to tungsten. This material substitution alters the interaction properties with IGZO channel materials, preventing both copper diffusion and performance degradation that occurs with traditional barrier materials.
3Object-generated harmful factors
If barrier materials are added around copper interconnects, then copper diffusion is reduced, but device complexity increases
Solution Approach 1:
Instead of applying a complex multi-layer barrier structure throughout the entire interconnect system, the tungsten liner is selectively applied only where copper diffusion into IGZO channel materials is a concern. This localized approach provides necessary protection while minimizing overall device complexity.
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 tungsten barrier materials enhances the performance and reliability of ICs by reducing interaction with IGZO-based channel materials, preserving electrical properties and manufacturing integrity.
Implementation Method 1
Copper tends to diffuse into surrounding materials, so copper interconnects are typically surrounded by a barrier material
Data Source
AI summary
Described herein are integrated circuit devices with semiconductor devices and interconnects coupled to contacts of the semiconductor devices, where the interconnects have tungsten liners between a fill material of the interconnect and the contacts. Interconnect liners can help maintain conductivity between semiconductor devices (e.g., transistors) and the interconnects that conduct current to and from the semiconductor devices. Tungsten liners may be in combination with semiconductor devices that use certain channel materials, such as indium gallium zinc oxide.