In-Situ Metallic and Dielectric Caps for Copper Interconnects
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Solution Overview
Problem
Current copper interconnection technologies face increased electro-migration failures and corrosion due to oxygen diffusion at the metal cap/copper interface, particularly as interconnect dimensions decrease, leading to inefficiencies in both electromigration performance and corrosion resistance.
Innovation Solution
A method involving the formation of a metal cap on a copper core within a semiconductor substrate, followed by a dielectric cap that acts as an oxygen diffusion barrier, both formed in a non-oxygen atmosphere to prevent exposure and corrosion, utilizing chemical vapor deposition or atomic layer deposition techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal cap is formed on copper core to improve electromigration performance, then electromigration resistance is improved, but oxygen diffusion at the metal cap/copper interface causes copper corrosion
Solution Approach 1:
An oxygen diffusion barrier layer is introduced as an intermediary between the metal cap and copper core. This barrier layer prevents oxygen from reaching the copper core while allowing the metal cap to maintain its electromigration protection function. The barrier layer acts as a mediator that blocks the harmful oxygen diffusion path without interfering with the beneficial electromigration resistance provided by the metal cap.
Solution Approach 2:
The interconnect structure uses a composite material approach by combining multiple materials with different functions: the metal cap (for electromigration resistance), the oxygen diffusion barrier layer (for corrosion prevention), and the copper core (for electrical conductivity). This composite structure allows each material to perform its specific function optimally while mitigating the weaknesses of individual materials.
2Length of moving object
If interconnect dimensions are decreased to improve device scaling, then device density is improved, but electro-migration failures and corrosion increase
Solution Approach 1:
The solution applies local quality by providing targeted protection at specific locations and interfaces within the interconnect structure. The oxygen diffusion barrier layer is specifically placed at the metal cap/copper core interface where oxygen diffusion occurs, and the liner is applied selectively on the copper core surface. This localized approach addresses the reliability issues at critical interfaces without requiring overall dimension changes.
Solution Approach 2:
The interconnect structure is segmented into distinct functional layers: copper core, liner, metal cap, and oxygen diffusion barrier layer. Each segment performs a specific function - the copper core provides conductivity, the liner provides initial protection, the metal cap provides electromigration resistance, and the barrier layer provides corrosion protection. This segmentation allows each component to be optimized independently for its specific function while working together to solve the scaling-related reliability problems.
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 enhances electromigration performance while reducing copper corrosion by eliminating oxygen at the metal cap/copper interface, thereby improving the reliability of copper interconnects.
Implementation Method 1
configured to selectively form a metal layer on copper by chemical vapor deposition or by atomic layer deposition
Implementation Method 2
configured to selectively form a metal layer on copper by chemical vapor deposition or by atomic layer deposition
Implementation Method 3
configured to form a dielectric layer by chemical vapor deposition
Implementation Method 4
the dielectric cap is an oxygen diffusion barrier and contains no oxygen atoms
Data Source
AI summary
A structure, tool and method for forming in-situ metallic/dielectric caps for interconnects. The method includes forming wire embedded in a dielectric layer on a semiconductor substrate, the wire comprising a copper core and an electrically conductive liner on sidewalls and a bottom of the copper core, a top surface of the wire coplanar with a top surface of the dielectric layer; forming a metal cap on an entire top surface of the copper core; without exposing the substrate to oxygen, forming a dielectric cap over the metal cap, any exposed portions of the liner, and the dielectric layer; and wherein the dielectric cap is an oxygen diffusion barrier and contains no oxygen atoms.