Germanium Cap Layer for Copper Interconnect Oxidation
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Solution Overview
Problem
The semiconductor industry faces challenges with copper oxidization and diffusion into adjacent insulating materials, leading to poor resistance to oxygen and chemicals, and increased contact resistance due to the use of CoWP and CoB cap layers, which require complex processing steps and result in metal residue.
Innovation Solution
A cap layer comprising germanium, arsenic, tungsten, or gallium is formed over copper interconnects, either as a silicide or alloy, using process gases like GeH4, AsH3, GaH3, or WF6, with silane introduced before, during, or after the gas introduction to create a stable and efficient cap layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CoWP and CoB cap layers are used to reduce copper oxidation and diffusion, then copper protection is improved, but processing complexity increases and metal residue remains
Solution Approach 1:
The patent extracts and eliminates the complex CoWP and CoB cap layer processing steps, replacing them with a simpler alternative approach that achieves the same copper protection function without the harmful side effects of metal residue and processing complexity
Solution Approach 2:
The patent changes the material parameters and composition of the cap layer, transitioning from cobalt-based compounds (CoWP, CoB) to a different material system that provides equivalent or superior copper protection while simplifying the overall processing requirements
2Object-affected harmful factors
If CoWP and CoB cap layers are used to reduce copper oxidation, then oxidation resistance is improved, but contact resistance increases due to metal residue
Solution Approach 1:
The patent converts the potentially harmful effect of metal residue from the CoWP/CoB process into a benefit by eliminating the residue formation mechanism entirely, thereby maintaining oxidation resistance while improving contact resistance through a cleaner interface
Solution Approach 2:
The patent employs a cap layer material system that does not leave persistent harmful residues like the cobalt-based compounds, effectively replacing long-lived problematic materials with shorter-lived or non-residuous alternatives that achieve the same protective function without compromising contact quality
3Stability of the object's composition
If CoWP and CoB cap layers are used to prevent copper diffusion, then diffusion barrier performance is improved, but adhesive qualities deteriorate due to metal residue
Solution Approach 1:
The patent removes the source of adhesive deterioration (metal residue from CoWP/CoB processing) while preserving the essential diffusion barrier function through an alternative cap layer approach that does not generate harmful residues
Solution Approach 2:
The patent may employ composite or multi-component cap layer materials that combine the diffusion barrier properties needed to prevent copper migration with improved interfacial adhesion characteristics, eliminating the trade-off between diffusion protection and adhesive quality
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 cap layer effectively reduces copper oxidation and diffusion, improving adhesive qualities and reducing voids between layers, while being easily and efficiently formed, thus enhancing the integrity and performance of semiconductor devices.
Implementation Method 1
the cap layer effectively reduces copper oxidation
Implementation Method 2
reduces copper oxidation and diffusion
Data Source
AI summary
A method of manufacturing a semiconductor device with a cap layer for a copper interconnect structure formed in a dielectric layer is provided. In an embodiment, a conductive material is embedded within a dielectric layer, the conductive material comprising a first material and having either a recess, a convex surface, or is planar. The conductive material is silicided to form an alloy layer. The alloy layer comprises the first material and a second material of germanium, arsenic, tungsten, or gallium.