TFT Gate Electrode Thickness Optimization for LCD ON/OFF Ratio
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Solution Overview
Problem
The challenge in LCD units is to achieve a higher ON/OFF ratio of drain current without increasing the OFF current, which is hindered by the limitations of gate insulating film thickness, leading to poor image quality due to non-uniformity and point defects.
Innovation Solution
The active-matrix-drive display unit incorporates a thin film transistor with a gate electrode layer, a gate insulating film thinner than the gate electrode layer, and a patterned semiconductor layer on an insulating substrate, preventing etching residues and leakage current paths by ensuring the gate insulating film is thinner than the gate electrode layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the thickness of the gate insulating film is reduced to increase the ON current, then the ON/OFF ratio improves, but the OFF current increases significantly causing poor image quality
Solution Approach 1:
The invention changes the thickness parameter of the gate insulating film to be equal to or less than the thickness of the gate electrode layer, which optimizes the electric field distribution and prevents excessive OFF current while maintaining high ON current, thus improving the ON/OFF ratio
Solution Approach 2:
The invention uses a composite structure combining the gate electrode layer and gate insulating film with matched thicknesses, creating an integrated system that controls both ON and OFF current characteristics effectively
2Power
If the thickness of the gate insulating film is reduced further to improve ON current, then the ON/OFF ratio increases, but etching residues and leakage current paths are generated
Solution Approach 1:
The invention sets the gate insulating film thickness parameter to be equal to or less than the gate electrode layer thickness, which prevents the formation of etching residues and leakage current paths while maintaining high ON current
Solution Approach 2:
The invention preemptively controls the gate insulating film thickness to prevent the generation of etching residues and leakage current paths before they can occur during manufacturing or operation
Data Source
AI summary
An active-matrix-drive LCD includes a TFT substrate, on which a TFT is formed. The TFT includes a gate electrode layer, a gate insulating film, a patterned semiconductor layer, and a source/drain electrode layer, which are consecutively formed on an insulating substrate of the TFT substrate. The gate electrode layer has a thickness smaller than a thickness of the gate insulating film.