Self-Aligned Dielectric Caps for Copper Interconnects
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Solution Overview
Problem
Conventional dielectric caps used in copper interconnects have high dielectric constants, leading to RC delay and compromising electromigration performance, necessitating a self-aligned dielectric cap solution for capacitance reduction and performance improvement.
Innovation Solution
The use of plasma-enhanced chemical vapor deposition (PECVD) silicon carbon nitride (SiCN) with selective deposition properties, which deposits only on copper metallization and not on the metal liner, allowing for a self-aligned dielectric cap formation, and subsequent etching and recess formation to ensure uniform thickness and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dielectric caps (SiC, SiCN) are used to protect copper interconnects, then copper diffusion barrier and oxidation protection are improved, but RC delay increases due to high dielectric constant
Solution Approach 1:
The patent changes the dielectric constant parameter by transitioning from conventional high-k materials (SiC, SiCN with k=5-7) to low-k materials (carbon-doped silicon oxide with k<4.0), directly reducing RC delay while maintaining protective functions
Solution Approach 2:
The patent uses composite material structures including carbon-doped silicon oxide combined with porous low-k materials, achieving both low dielectric constant for reduced RC delay and adequate barrier properties for copper diffusion and oxidation protection
2Reliability
If dielectric cap thickness is increased to improve barrier performance, then copper diffusion protection is improved, but manufacturing precision decreases due to non-uniform deposition on varying line widths
Solution Approach 1:
The patent employs self-aligned deposition where the dielectric cap automatically conforms to the copper interconnect geometry through selective deposition processes, ensuring uniform thickness without requiring manual thickness control adjustments
Solution Approach 2:
The patent implements selective dielectric deposition that adapts to local variations in interconnect geometry, providing appropriate coverage and thickness at different locations based on the underlying copper structure characteristics
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 reduces capacitance, enhances performance by minimizing RC delay, and ensures increased interconnect reliability through uniform dielectric cap thickness across varying line widths, while maintaining the protective barrier against copper diffusion and oxidation.
Implementation Method 1
The use of plasma-enhanced chemical vapor deposition (PECVD) silicon carbon nitride (SiCN) with selective deposition properties
Data Source
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AI summary
Interconnect structures having self-aligned dielectric caps are provided. At least one metallization level is formed on a substrate. A dielectric cap is selectively deposited on the metallization level.