Nitrogen Plasma Treatment for CESL Copper Interface
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Solution Overview
Problem
The integration circuit (IC) industry faces challenges in reducing resistance-capacitance (RC) delay due to increased capacitance from decreased distances between interconnects, leading to stress-induced void formation and degradation of IC performance, particularly at the copper etch stop layer (CESL)/copper interface.
Innovation Solution
A nitrogen plasma treatment is applied to the CESL to increase nitrogen concentration and bonding, preventing copper diffusion and reducing void formation by enhancing the diffusion blocking ability at the CESL/copper interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If geometry size is decreased to reduce RC delay, then signal transmission speed is improved, but capacitance between interconnects increases
Solution Approach 1:
The patent applies nitrogen plasma treatment specifically to the CESL material at the interface region, creating a localized nitrogen-enriched zone with enhanced diffusion blocking properties. This local modification allows the interface to prevent copper diffusion without requiring changes to the entire interconnect structure, thus maintaining the reduced geometry sizes while addressing the diffusion problem.
Solution Approach 2:
The patent changes the chemical composition parameter of the CESL by introducing nitrogen through plasma treatment. This parameter change (increasing nitrogen concentration) fundamentally alters the diffusion blocking capability of the CESL, enabling it to prevent copper diffusion even at reduced thicknesses and geometry sizes required for high-speed signaling.
2Reliability
If interconnect structures are improved to reduce RC delay, then performance is enhanced, but metal diffusion into dielectric materials increases causing void formation
Solution Approach 1:
The nitrogen plasma treatment is applied to the CESL before copper deposition, creating a pre-conditioned interface that is resistant to copper diffusion. This preliminary anti-action establishes a diffusion barrier in advance, preventing the harmful effect of copper diffusion and subsequent void formation during subsequent processing steps.
Solution Approach 2:
Nitrogen acts as an intermediary substance between the CESL and copper interconnect. The nitrogen-enriched CESL interface serves as a mediating layer that prevents direct interaction and diffusion between copper atoms and the CESL, thereby eliminating void formation while maintaining electrical performance.
3Length of moving object
If CESL thickness is reduced to enable further scaling, then geometry scaling is achieved, but diffusion blocking ability is insufficient leading to voids
Solution Approach 1:
The patent changes the chemical composition parameter of the CESL by introducing nitrogen through plasma treatment. This parameter change (increasing nitrogen concentration) fundamentally alters the diffusion blocking capability of the CESL, enabling it to prevent copper diffusion even at reduced thicknesses and geometry sizes required for high-speed signaling.
Solution Approach 2:
The patent creates a composite structure by combining the CESL material (e.g., aluminum nitride) with additional nitrogen from plasma treatment. This composite approach enhances the diffusion blocking properties of the CESL beyond what would be achievable with the base material alone, enabling effective barrier performance at reduced thicknesses.
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 nitrogen plasma treatment effectively limits copper diffusion and void formation, improving the reliability and performance of IC devices by reducing resistance and maintaining interconnect integrity.
Implementation Method 1
A nitrogen plasma treatment is applied to the CESL to increase nitrogen concentration and bonding
Implementation Method 2
preventing copper diffusion and reducing void formation by enhancing the diffusion blocking ability at the CESL/copper interface
Data Source
AI summary
Interconnect structures exhibiting reduced accumulation of copper vacancies along interfaces between contact etch stop layers (CESLs) and interconnects, along with methods for fabrication, are disclosed herein. A method includes forming a copper interconnect in a dielectric layer and depositing a metal nitride CESL over the copper interconnect and the dielectric layer. An interface between the metal nitride CESL and the copper interconnect has a first surface nitrogen concentration, a first nitrogen concentration and/or a first number of nitrogen-nitrogen bonds. A nitrogen plasma treatment is performed to modify the interface between the metal nitride CESL and the copper interconnect. The nitrogen plasma treatment increases the first surface nitrogen concentration to a second surface nitrogen concentration, the first nitrogen concentration to a second nitrogen concentration, and/or the first number of nitrogen-nitrogen bonds to a second number of nitrogen-nitrogen bonds, each of which minimizes accumulation of copper vacancies at the interface.