Copper Wiring Doping for Back-End-of-Line Adhesion
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Solution Overview
Problem
Copper wiring in semiconductor devices experiences diffusion through insulators during high-temperature processes, leading to circuit malfunctions, and the use of low dielectric constant materials complicates integration, increasing susceptibility to plasma damage and reducing reliability.
Innovation Solution
Directly doping the top surface of copper lines with a copper alloy material, such as manganese, to enhance adhesion between copper lines and dielectric layers, using a high concentration CuMn seed layer and thermal diffusion to create a doped region for improved adhesion and reduced line resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper wiring is used in semiconductor devices, then electrical performance is improved, but copper diffuses through insulators during high temperature processes causing circuit malfunctions
Solution Approach 1:
A barrier layer is introduced as an intermediary between the copper wiring and the insulator to prevent copper diffusion. The barrier layer acts as a mediator that blocks copper atoms from migrating into the insulator during high temperature processes, thereby maintaining electrical performance while preventing circuit malfunctions.
Solution Approach 2:
The patent employs composite material structures combining copper with alloying elements or protective coatings. By creating a composite wiring structure, the copper maintains its excellent electrical conductivity while the additional materials provide diffusion resistance, resolving the contradiction between electrical performance and diffusion prevention.
2Quantity of substance
If low dielectric constant materials are used to increase circuit density, then circuit density is improved, but the materials become more susceptible to plasma damage and have lower reliability
Solution Approach 1:
The patent applies local quality enhancement by providing targeted protection to vulnerable low-K dielectric regions. Through selective barrier layer placement or localized reinforcement at critical areas, the low dielectric constant materials maintain their density-increasing benefit while gaining plasma damage resistance where most needed.
Solution Approach 2:
Protective barrier layers are deposited beforehand on low-K dielectric materials before plasma processing steps. This prior cushioning prevents plasma damage from occurring in the first place, allowing the use of low dielectric constant materials for increased circuit density without compromising reliability.
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 method enhances adhesion between copper lines and dielectric layers, reducing delamination and line resistance variability, while maintaining device reliability and circuit density without degrading electrical performance.
Implementation Method 1
directly doping a top surface of the copper line with a copper alloy material
Data Source
AI summary
A method of forming a metal interconnect structure includes forming a copper line within an interlevel dielectric (ILD) layer; directly doping a top surface of the copper line with a copper alloy material; and forming a dielectric layer over the ILD layer and the copper alloy material; wherein the copper alloy material serves an adhesion interface layer between the copper line and the dielectric layer.