Copper Display Wiring with Metal Oxide Barrier for Adhesion
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Solution Overview
Problem
In display substrates, the use of copper wiring leads to poor adhesive strength with the substrate, causing defects and increased resistance due to copper diffusion into titanium layers during high-temperature processing, which affects the transmission speed and reliability of the wiring.
Innovation Solution
A display substrate with a metal oxide layer of tantalum, niobium, or titanium, and a copper metal layer, where the metal oxide layer is formed by natural oxidation, and an optional intermetallic compound layer is created to enhance adhesion and prevent copper diffusion, maintaining low resistance and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used as the material of the wiring to achieve low resistance, then the resistance is reduced, but the adhesive strength between the copper layer and substrate becomes poor causing peeling defects
Solution Approach 1:
The patent uses a composite wiring structure consisting of a copper layer combined with a titanium nitride layer. The copper layer provides low resistance while the titanium nitride layer provides strong adhesion to the substrate. This composite structure resolves the contradiction by combining materials with complementary properties - the copper ensures low resistance for high-speed signal transmission while the titanium nitride ensures strong adhesive strength to prevent peeling defects.
2Strength
If a titanium layer is formed between the copper layer and substrate to increase adhesive strength, then the adhesive strength is improved, but copper diffuses into the titanium layer during high-temperature processing causing resistance increase
Solution Approach 1:
The patent changes the material parameter from pure titanium to titanium nitride for the adhesion layer. Titanium nitride has higher thermal stability and forms a diffusion barrier that prevents copper diffusion during high-temperature processing. This parameter change maintains the adhesive strength benefit while eliminating the copper diffusion problem that occurs with pure titanium layers.
3Area of stationary object
If the display substrate area is increased to accommodate larger display, then the display area is improved, but the wiring length increases requiring lower resistance materials
Solution Approach 1:
The patent employs a composite wiring structure with copper as the primary conductive material. Copper has inherently low resistance which allows for longer wiring lengths without significant resistance increase. This enables the display substrate area to be expanded while maintaining acceptable signal transmission characteristics through the longer wirings required for larger displays.
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 solution effectively prevents resistance increases and defects in the wiring, ensuring reliable and efficient signal transmission by maintaining low resistance and improved adhesive strength between the copper layer and the substrate.
Implementation Method 1
converting the first metal layer into a metal oxide layer by oxidation
Implementation Method 2
a metal layer on the metal oxide layer and including copper (Cu)
Data Source
AI summary
A display substrate may include a substrate and a wiring on the substrate. The wiring may include a metal oxide layer including at least one oxide selected from tantalum (Ta), niobium (Nb), and titanium (Ti), and a metal layer on the metal oxide layer and including copper (Cu), and a thickness of the metal oxide layer may be in a range of about 30 angstroms (Å) to about 50 Å.