Copper Barrier Layer Adhesion via Sputtering Parameters
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Solution Overview
Problem
Thin film transistor array panels face challenges with increased signal delay due to increased wiring lengths, resistance, and capacitance, and copper's poor contact characteristics with other layers require thick adhesive layers, which are time and cost-intensive to deposit and etch.
Innovation Solution
A method for forming a thin film transistor array panel with a copper layer and a barrier layer of titanium, tantalum, or molydenum, deposited using sputtering at specific power densities and pressures to improve adhesion without thick adhesive layers, reducing surface roughness and stress, and preventing copper diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used to reduce wire resistance, then electrical conductivity is improved, but adhesion to lower layers deteriorates
Solution Approach 1:
The patent introduces an adhesive layer comprising silicon and oxygen (forming silicon oxide or silicon sub-oxide) as an intermediary between the copper layer and the lower layer. This adhesive layer serves as a mediator that provides both good adhesion to copper and compatibility with the lower layer, resolving the adhesion problem while maintaining copper's electrical conductivity benefits
Solution Approach 2:
The patent creates a composite structure with multiple layers: copper layer, adhesive layer (silicon oxide/silicon sub-oxide), and lower layer. This composite material approach combines the advantages of each material - copper's conductivity, silicon oxide's adhesion properties - to achieve overall system performance that neither material could provide alone
2Strength
If thick adhesive layers are used to improve adhesion and prevent copper diffusion, then adhesion and barrier properties are improved, but manufacturing time and cost increase
Solution Approach 1:
The patent changes the compositional parameters of the adhesive layer by forming silicon oxide or silicon sub-oxide with controlled oxygen content. This parameter optimization allows the adhesive layer to achieve sufficient adhesion and barrier properties at reduced thickness, thereby decreasing deposition time while maintaining performance
Solution Approach 2:
The patent applies local quality by creating an adhesive layer with specific chemical composition (silicon oxide or silicon sub-oxide) that has enhanced adhesion properties localized at the copper-lower layer interface. This localized optimization allows thinner layers to achieve the same adhesion effect that would require thicker generic 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 enhances adhesion between copper and lower layers, reduces process time and expense, and maintains panel performance with a thinner barrier layer that prevents copper diffusion, lowering defect rates and improving manufacturing efficiency.
Implementation Method 1
A method for forming a thin film on a substrate through sputtering according to an exemplary embodiment of the present invention includes forming the thin film at a power density in the range of approximately 1.5 to approximately 3 W/cm2, and at a pressure of an inert gas that is in the range of approximately 0.2 to approximately 0.3 Pa.
Implementation Method 2
The thin film may have an amorphous structure, and the thin film comprise at least one of titanium, tantalum, and molybdenum. An Rms surface roughness of the thin film may be less than about 0.55 nm.
Data Source
AI summary
A method for forming a thin film according to an exemplary embodiment of the present invention includes forming the thin film at a power density in the range of approximately 1.5 to approximately 3 W/cm2 and at a pressure of an inert gas that is in the range of approximately 0.2 to approximately 0.3 Pa. This process results in an amorphous metal thin film barrier layer that prevents undesired diffusion from adjacent layers, even when this barrier layer is thinner than many conventional barrier layers.