Al Alloy Wiring Structure for Display Devices
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aluminum alloy films used in display devices face limitations in high-temperature heat resistance, electrical resistivity, and corrosion resistance, particularly when subjected to high temperatures during the production of thin-film transistor substrates, leading to issues like hillock formation and poor compatibility with increasing display sizes.
Innovation Solution
A multi-layered wiring structure comprising an Al alloy film with specific elements like Ta, Nb, Re, and rare earth metals, followed by a nitride layer of Ti, Mo, or Al, providing enhanced heat resistance and low electrical resistivity, and further improved with a third layer of Ti, Mo, or Cr to reduce contact resistance and increase resistance to hydrofluoric acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Al-based alloy thin films are used as wiring materials, then low electrical resistance is achieved, but heat resistance at high temperatures deteriorates
Solution Approach 1:
The patent employs a multi-layer composite structure consisting of an Al-based alloy thin film layer and a rare earth metal oxide layer. This composite structure combines the low electrical resistance properties of Al-based alloys with the high heat resistance and chemical stability of rare earth metal oxides, thereby simultaneously achieving both low electrical resistance and high heat resistance that cannot be obtained with single-material wiring films.
Solution Approach 2:
The rare earth metal oxide layer serves as an intermediary protective layer between the Al-based alloy wiring film and the high-temperature environment. This intermediary layer prevents direct exposure of the Al-based alloy to high temperatures, thereby protecting the wiring film from thermal degradation while allowing the wiring to maintain its low electrical resistance characteristics.
2Reliability
If Al-based alloy thin films are used as wiring materials, then low electrical resistance is achieved, but resistance to hydrofluoric acid deteriorates
Solution Approach 1:
The patent creates a composite wiring structure where the rare earth metal oxide layer provides chemical protection against hydrofluoric acid corrosion, while the Al-based alloy layer maintains low electrical resistance. This composite approach allows the wiring to resist chemical attack from hydrofluoric acid during manufacturing processes while preserving its electrical conductivity.
Solution Approach 2:
The rare earth metal oxide layer acts as an intermediary protective barrier between the Al-based alloy wiring film and hydrofluoric acid. This intermediary layer prevents direct contact between the acid and the aluminum, thereby protecting the wiring from corrosion while allowing the underlying Al-based alloy to maintain its low electrical resistance properties.
3Reliability
If conventional Al-based alloy thin films are subjected to high temperature heat treatment, then carrier mobility is improved, but hillock formation occurs
Solution Approach 1:
The rare earth metal oxide layer serves as a protective intermediary that prevents direct high-temperature exposure of the Al-based alloy wiring film. This allows the semiconductor layer to undergo high-temperature heat treatment for improving carrier mobility while the rare earth metal oxide layer prevents thermal stress and hillock formation in the wiring film.
Solution Approach 2:
The rare earth metal oxide layer is deposited beforehand on the Al-based alloy wiring film to provide thermal protection. This pre-applied protective layer cushions the wiring film against thermal stress during subsequent high-temperature heat treatment processes, preventing hillock formation while allowing the necessary heat treatment to proceed for improving carrier mobility.
4Area of stationary object
If display size is increased, then market demand is satisfied, but wiring resistance increases
Solution Approach 1:
The patent employs a composite wiring structure where the Al-based alloy layer provides low electrical resistance for large-area displays, while the rare earth metal oxide layer ensures stability and protection. This composite approach enables the wiring to maintain low resistance even as display size increases, overcoming the limitation of conventional single-material wiring films in large-scale applications.
Data Source
AI summary
Provided is a wiring structure for display device which does not generate hillocks even when exposed to high temperatures at levels around 450 to 600° C., has excellent high-temperature heat resistance, keeps electrical resistance (wiring resistance) of the entire wiring structure low, and further has excellent resistance to hydrofluoric acid. This wiring structure for a display device comprises a structure in which are laminated, in order from the substrate side, a first layer of an Al alloy that contains at least one chemical element selected from the group (group X) consisting of Ta, Nb, Re, Zr, W, Mo, V, Hf, Ti, Cr, and Pt and contains at least one rare earth element, and a second layer of an Al alloy nitride, or a nitride of at least one chemical element selected from the group Y consisted of Ti, Mo, Al, Ta, Nb, Re, Zr, W, V, Hf, and Cr.