Thin Film Transistor Contact Regions with Variable Thickness
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Solution Overview
Problem
High contact resistance between the active layer and source/drain electrodes in thin film transistors (TFTs) degrades their performance, particularly in display devices like OLEDs and LCDs, by reducing power generation and efficiency.
Innovation Solution
A thin film transistor design with contact regions thinner than the remaining active layer regions, using an oxide semiconductor and an interface stabilizing layer with a band gap equal to or greater than the active layer, and an etch stop layer to reduce contact resistance, along with a method of fabricating the TFTs using a half-tone mask and over etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the active layer is made uniformly thick, then the structural simplicity is maintained, but the contact resistance between source/drain electrodes and active layer increases
Solution Approach 1:
The active layer is designed with different thicknesses in different regions: a first thickness in the channel region and a second thickness (greater than the first) in the contact regions. This local variation in thickness reduces contact resistance at the source/drain electrodes while maintaining the necessary channel properties, directly resolving the contradiction between contact resistance and structural simplicity.
2Reliability
If additional crystallization processes are introduced to improve electrical characteristics, then the TFT performance improves, but the manufacturing process complexity and time increase
Solution Approach 1:
The invention changes the physical parameter of the active layer from uniform thickness to non-uniform thickness with thicker contact regions. This parameter change improves electrical characteristics and reduces contact resistance without requiring additional crystallization processes, thereby maintaining high productivity while improving reliability.
Data Source
AI summary
A thin film transistor (TFT) including a gate electrode, an active layer, and source and drain electrodes. The active layer includes contact regions that contact the source and drain electrodes, which are thinner than a remaining region of the active layer. The contact regions reduce the contact resistance between the active material layer and the source and drain electrodes.