Single Damascene Interconnect with Self-Forming Barrier
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Solution Overview
Problem
Conventional dual damascene processes require refractory barrier layers on both via and trench sidewalls and bottoms, leading to high line and via resistance due to thick barrier layer deposition, which is not optimal for integrated circuit performance.
Innovation Solution
The process forms single damascene interconnect structures where only one of the via or trench has a refractory barrier layer, while the other uses a self-forming barrier layer of Mn, Si, and O, reducing the need for refractory metals like Ta, TaN, and increasing the flexibility in barrier layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refractory barrier layers are deposited on both via and trench sidewalls and bottoms in dual damascene process, then diffusion protection is improved, but line and via resistance increase due to thick barrier layer deposition
Solution Approach 1:
The patent applies different barrier layer configurations to different structures: trenches receive refractory barrier layers (Ta/TaN) for diffusion protection, while vias use self-forming barrier layers (Mn, Ti, or Al compounds) that react with the dielectric to form protective barriers. This local differentiation allows each structure to have the appropriate barrier type, reducing overall resistance while maintaining diffusion protection where most needed.
Solution Approach 2:
The patent replaces expensive refractory barrier materials (Ta, TaN) with cheaper self-forming barrier materials (Mn, Ti, Al) in the via structures. These simpler barrier layers form through reaction with the dielectric material, eliminating the need for complex refractory barrier deposition in vias and reducing overall interconnect resistance.
2Reliability
If thick refractory barrier layers are deposited on via sidewalls and bottoms, then diffusion inhibition is improved, but electromigration issues worsen due to increased barrier thickness
Solution Approach 1:
The patent implements local quality by applying refractory barrier layers selectively to trench structures where they provide optimal diffusion protection, while using self-forming barrier layers in via structures. This differentiation ensures that electromigration-prone via regions do not suffer from the harmful effects of thick refractory barriers, while trenches still receive adequate diffusion protection.
3Reliability
If refractory barrier layers are used in both via and trench structures, then diffusion protection is improved, but manufacturing flexibility decreases due to fixed barrier thickness requirements
Solution Approach 1:
The patent enables manufacturing flexibility by allowing different barrier layer thicknesses and types in different locations: trenches can have thicker refractory barriers where diffusion protection is critical, while vias use thinner self-forming barriers that adapt to via dimensions. This local customization improves both diffusion protection and manufacturing adaptability.
Solution Approach 2:
The patent changes the barrier layer formation mechanism from fixed refractory deposition to variable self-forming reactions. The self-forming barriers (Mn, Ti, Al compounds) develop thickness based on reaction conditions and dielectric composition, providing natural parameter adjustment and flexibility that fixed refractory barrier deposition cannot achieve.
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 line and via resistance and alleviates electromigration issues, allowing for more precise tuning of refractory metal barrier thickness for improved integrated circuit performance.
Implementation Method 1
reacting the Cu(metal) alloy with the first dielectric layer to form a barrier layer comprising metal, O, and Si
Data Source
AI summary
A single damascene interconnect structure which includes a first layer of a first dielectric material having a first filled opening that has a sidewall layer which includes a compound of a metal, O, and Si such that the metal is Mn, Ti and Al, and with Cu filling the first filled opening. The compound is in direct contact with the first dielectric material. Also included is a second layer that includes a second dielectric material having a second filled opening that has a barrier layer of a refractory material with Cu filling the second filled opening. The first layer is adjacent to the second layer and the first filled opening is aligned with the second filled opening so that one of the first and second filled openings is a via and the other of the first and second filled openings is a trench.