Thin Film Transistor Substrate Capping Layer Uniformity
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Solution Overview
Problem
Conventional thin film transistor substrates with crystalline silicon layers often result in non-uniform transistor characteristics, leading to display apparatuses that exhibit uneven image luminance when the same electrical signal is applied to pixels.
Innovation Solution
A thin film transistor substrate is designed with a crystalline silicon layer covered by a capping layer having varying thickness portions, where a laser beam is irradiated to selectively crystallize the amorphous silicon layer, improving mobility characteristics and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional crystalline silicon layer is formed with uniform thickness, then the manufacturing process is simple, but the transistor characteristics are non-uniform leading to uneven image luminance
Solution Approach 1:
The capping layer is designed with different thicknesses in different regions (first thickness in first region, second thickness greater than first thickness in second region). This local variation in capping layer thickness creates different heating rates during laser irradiation, resulting in controlled non-uniform crystallization of the amorphous silicon layer that improves transistor characteristic uniformity across the substrate.
2Manufacturing precision
If laser beam irradiation is applied to crystallize the amorphous silicon layer, then mobility characteristics are improved, but the crystallization uniformity is poor leading to non-uniform transistor characteristics
Solution Approach 1:
The thickness parameter of the capping layer is deliberately changed across different regions of the substrate. This parameter variation controls the heating rate and temperature distribution during laser irradiation, enabling uniform crystallization of the amorphous silicon layer into crystalline silicon with consistent mobility characteristics across the entire substrate.
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 approach results in a crystalline silicon layer with enhanced mobility and uniform off-current characteristics, enabling better control over pixel operations and higher quality image display.
Implementation Method 1
a laser beam is irradiated to selectively crystallize the amorphous silicon layer
Implementation Method 2
converting the amorphous silicon layer into a crystalline silicon layer
Data Source
AI summary
Thin film transistor substrate includes: a substrate; a crystalline silicon layer on the substrate; and a capping layer covering the crystalline silicon layer and including a first portion having a first thickness and a second portion having a second thickness that is greater than the first thickness.