Thin Film Transistor Gate Electrode Adhesion via Bonding Layer
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Solution Overview
Problem
Conventional thin film transistor substrates for liquid crystal displays face issues with weak adhesion between metallic gate electrodes and silicon dioxide-based base substrates, leading to desquamation during significant shocks, and existing solutions like using molybdenum as a bonding layer provide limited adhesion strength.
Innovation Solution
A thin film transistor substrate is fabricated with a bonding layer of aluminum oxide or zirconium dioxide on a silicon dioxide base substrate, combined with a conductive copper layer and a titanium nitride or tantalum nitride barrier layer, forming strong ionic and covalent bonds to enhance adhesion, and optionally featuring micro-grooves on the bonding layer for increased contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper is used as the gate electrode material to minimize RC delay, then electrical performance is improved, but adhesion strength to the base substrate deteriorates
Solution Approach 1:
The patent introduces a bonding layer made of aluminum oxide or zirconium dioxide as an intermediary between the copper gate electrode and the silicon dioxide base substrate. This bonding layer forms strong ionic and covalent bonds with both the copper layer and the base substrate, acting as a mediator that resolves the adhesion problem while allowing the copper layer to maintain its excellent electrical conductivity for minimizing RC delay.
Solution Approach 2:
The gate electrode structure is designed as a composite material system consisting of multiple layers: the copper conductive layer combined with the aluminum oxide or zirconium dioxide bonding layer. This composite structure integrates the electrical conductivity of copper with the strong adhesion properties of the bonding layer, achieving both improved electrical performance and enhanced adhesion strength.
2Strength
If molybdenum is used as the bonding layer to increase adhesion strength, then adhesion between gate electrode and base substrate is improved, but the adhesion strength remains limited and desquamation occurs under significant shock
Solution Approach 1:
The patent changes the material parameter of the bonding layer from molybdenum to aluminum oxide or zirconium dioxide. This material substitution fundamentally changes the bonding mechanism from weak metallic adhesion to strong ionic and covalent bonding, increasing adhesion strength from 0.5-2 J/sq.m to 48-79 J/sq.m and preventing desquamation under significant shock conditions.
3Strength
If a bonding layer is added to improve adhesion, then adhesion strength is improved, but device complexity increases
Solution Approach 1:
The bonding layer is applied locally only at the critical interface between the gate electrode and the base substrate where adhesion is needed. This localized approach improves adhesion strength at the specific problem area without unnecessarily complicating the entire device structure, maintaining simplicity in non-critical regions.
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 achieves a significantly higher adhesion strength between the gate electrode and the base substrate, preventing desquamation and ensuring the gate electrode remains tightly attached, even under shock conditions, with adhesion strengths up to 48-79 joules per square meter.
Implementation Method 1
forming strong ionic and covalent bonds to enhance adhesion
Implementation Method 2
forming strong ionic and covalent bonds to enhance adhesion
Implementation Method 3
The bonding layer is formed on the base substrate and is made of aluminum oxide or zirconium dioxide... achieving a significantly higher adhesion strength between the gate electrode and the base substrate
Data Source
AI summary
An exemplary thin film transistor substrate (30) includes a base substrate (31) and a gate electrode (32) formed on the base substrate. The gate electrode includes a bonding layer (321) formed on the base substrate and an electrically conductive layer (322) formed on the bonding layer. The bonding layer includes one of aluminum oxide and zirconium dioxide.