Copper Interconnection Barrier with Silicon Interface Layer
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Solution Overview
Problem
Semiconductor devices with copper interconnections and low dielectric constant insulation films face challenges in achieving both good electro-migration resistance and stress migration resistance, as existing techniques either degrade interconnection resistance or fail to maintain both resistances effectively.
Innovation Solution
The use of titanium (Ti) and tantalum (Ta) based barrier metal films, along with a silicon-containing interface layer formed by thermal processing and silylation, improves adhesion and suppresses Ti diffusion in copper interconnections, thereby enhancing electro-migration and stress migration resistance without increasing interconnection resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium (Ti) based barrier metal films are used to improve adhesion and suppress diffusion, then electro-migration and stress migration resistance are enhanced, but Ti diffusion into copper interconnections increases interconnection resistance
Solution Approach 1:
A silicon-containing interface layer is introduced as an intermediary between the titanium barrier metal film and the copper interconnection. This interface layer suppresses titanium diffusion into the copper, thereby maintaining low interconnection resistance while preserving the electro-migration and stress migration resistance provided by the titanium barrier film.
Solution Approach 2:
The barrier structure is formed as a composite system consisting of a titanium-based barrier metal film combined with a silicon-containing interface layer. This composite structure leverages the adhesion and diffusion suppression properties of titanium while using the silicon-containing layer to prevent harmful Ti diffusion into copper, achieving both reliability improvement and resistance control.
2Reliability
If titanium (Ti) based barrier metal films are used to improve adhesion and suppress diffusion, then stress migration resistance is enhanced, but Ti diffusion into copper interconnections increases interconnection resistance
Solution Approach 1:
A silicon-containing interface layer is introduced as an intermediary between the titanium barrier metal film and the copper interconnection. This interface layer suppresses titanium diffusion into the copper, thereby maintaining low interconnection resistance while preserving the stress migration resistance provided by the titanium barrier film.
Solution Approach 2:
The barrier structure is formed as a composite system consisting of a titanium-based barrier metal film combined with a silicon-containing interface layer. This composite structure leverages the adhesion and diffusion suppression properties of titanium while using the silicon-containing layer to prevent harmful Ti diffusion into copper, achieving both reliability improvement and resistance control.
3Object-generated harmful factors
If copper is used as interconnection material, then low resistance is achieved, but electro-migration and stress migration resistance are degraded
Solution Approach 1:
The interconnection structure is formed as a composite system with copper interconnections combined with a titanium-based barrier metal film and a silicon-containing interface layer. This composite structure maintains the low resistance advantage of copper while using the titanium barrier film and silicon-containing interface layer to suppress Ti diffusion and improve electro-migration and stress migration resistance.
4Object-generated harmful factors
If copper is used as interconnection material, then low resistance is achieved, but stress migration resistance is degraded
Solution Approach 1:
The interconnection structure is formed as a composite system with copper interconnections combined with a titanium-based barrier metal film and a silicon-containing interface layer. This composite structure maintains the low resistance advantage of copper while using the titanium barrier film and silicon-containing interface layer to suppress Ti diffusion and improve stress migration resistance.
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 effectively maintains low interconnection resistance while significantly improving electro-migration and stress migration resistance, as demonstrated by comparative tests showing improved electro-migration life and reduced stress migration defect rates.
Implementation Method 1
suppresses Ti diffusion in copper interconnections
Implementation Method 2
formed by thermal processing and silylation
Implementation Method 3
titanium (Ti) and tantalum (Ta) based barrier metal films... suppresses Ti diffusion
Implementation Method 4
formed by thermal processing and silylation
Data Source
AI summary
A semiconductor device includes an insulation film formed above a semiconductor substrate, a conductor containing Cu formed in the insulation film, and a layer film formed between the insulation film and the conductor and formed of a first metal film containing Ti and a second metal film different from the first metal film, a layer containing Ti and Si is formed on the surface of the conductor.