Semiconductor Interconnect Device With Metal Nitride Capping Layer
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Solution Overview
Problem
Conventional semiconductor interconnects face challenges with copper diffusion, leading to electromigration issues and reliability concerns due to high electromigration rates and junction leakage, which conventional capping layers only partially address.
Innovation Solution
A method involving forming a semiconductor cover layer on a metal layer and dielectric layer, followed by thermal annealing to convert portions into a metal capping layer, and subsequent nitridation to create a metal nitride capping layer, which prevents copper diffusion by eliminating voids and enhancing the barrier against electromigration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper interconnects are used to reduce RC delay and improve electromigration resistance, then interconnect performance is improved, but copper diffusion into substrate and dielectric layers occurs causing junction leakage and device failure
Solution Approach 1:
A semiconductor cap layer is introduced as an intermediary between the copper interconnect and the dielectric layer. This cap layer serves as a diffusion barrier that prevents copper atoms from migrating into the dielectric and substrate, thereby eliminating the harmful copper diffusion effect while maintaining the electrical performance benefits of copper interconnects.
Solution Approach 2:
The interconnect structure is transformed from a simple copper layer into a composite structure consisting of multiple materials: copper interconnect, semiconductor cap layer, and dielectric layer. This composite structure combines the low resistivity of copper with the diffusion-blocking properties of the semiconductor cap layer, achieving both electrical performance and reliability.
2Object-generated harmful factors
If a conventional capping layer is formed on the metal layer to prevent copper diffusion, then copper diffusion is reduced to some extent, but performance and reliability of interconnects still need improvement
Solution Approach 1:
The cap layer undergoes thermal annealing treatment that changes its physical and chemical parameters. The annealing process transforms the cap layer from a simple semiconductor layer into a metallized layer with enhanced diffusion barrier properties, improving its ability to prevent copper diffusion and enhance interconnect reliability.
Solution Approach 2:
The thermal annealing process accelerates the oxidation/metallization of the semiconductor cap layer, transforming it into a metallized layer with superior diffusion barrier characteristics. This accelerated transformation enhances the cap layer's ability to prevent copper diffusion more effectively than conventional capping layers.
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 significantly improves the resistance to electromigration and electrical properties of interconnects by effectively preventing copper diffusion into undesired regions, enhancing the reliability and reducing RC delay.
Implementation Method 1
performing a thermal annealing reaction on the semiconductor cover layer to convert portions of the semiconductor cover layer that are on the metal layer into a metal capping layer
Implementation Method 2
performing a nitridation process on the metal capping layer and a remaining semiconductor cover layer to convert the metal capping layer into a metal nitride capping layer
Data Source
AI summary
A method for forming an interconnect device is provided by the present disclosure. The method includes providing a dielectric layer on a substrate, forming openings in the dielectric layer to expose a portion of a surface of the substrate at a bottom of each opening and forming a metal layer to fill up the openings. The method also includes forming a semiconductor cover layer on the metal layer and on the dielectric layer, and performing a thermal annealing reaction to convert portions of the semiconductor cover layer that are on the metal layer into a metal capping layer. The method further includes performing a nitridation process on the metal capping layer and a remaining semiconductor cover layer to convert the metal capping layer into a metal nitride capping layer and the remaining semiconductor cover layer into a semiconductor nitride layer.