Oxide TFT Contact Crystallization for Reliable Display Electrodes
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Solution Overview
Problem
Existing display devices face challenges in achieving high electrical and structural reliability due to issues with contact resistance and stability in thin film transistors, particularly in oxide semiconductor layers.
Innovation Solution
Incorporating a crystallization portion in the contact region of the active layer, which includes a mixed crystal structure of indium oxide and zinc-gallium oxide, and an intermediate layer containing tin and titanium, to reduce contact resistance and enhance adhesion between the connection electrode and the active layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oxide semiconductor layer is used as the active layer material, then leakage current is reduced and transistor reliability is improved, but contact resistance between the active layer and connection electrode increases
Solution Approach 1:
The patent applies local quality by creating a crystallization portion with a specific crystal structure only in the contact region where the connection electrode contacts the active layer, while the rest of the active layer maintains its amorphous oxide semiconductor structure. This localized crystallization reduces contact resistance at the electrode interface without affecting the overall transistor reliability benefits of the oxide semiconductor material.
Solution Approach 2:
The patent employs composite materials by forming an intermediate layer between the connection electrode and the active layer, consisting of a crystallization portion with a mixed crystal structure (e.g., bixbyite and spinel structures) containing indium, zinc, and gallium elements. This composite structure combines the low contact resistance properties of crystalline materials with the electrical characteristics of amorphous oxide semiconductors.
2Device complexity
If the connection electrode is directly connected to the active layer, then the structure is simple, but adhesion is poor and electrode lift-off occurs
Solution Approach 1:
The patent introduces an intermediate layer as a mediator between the connection electrode and the active layer. This intermediate layer, with its crystallization portion having a mixed crystal structure, serves as an adhesion promoter that strongly bonds to both the electrode and the active layer, preventing electrode lift-off while maintaining structural simplicity.
Solution Approach 2:
The patent applies preliminary action by forming the crystallization portion in advance within the active layer at the contact region before depositing the connection electrode. This pre-formed crystalline structure provides an optimal surface for electrode adhesion, ensuring strong bonding from the outset and preventing subsequent lift-off issues.
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 improves electrical conductivity and structural reliability by reducing contact resistance and preventing electrode lift-off, thereby stabilizing transistor performance and lowering operational voltage.
Implementation Method 1
a contact region that is partially crystallized and formed at opposite edges channel region
Data Source
AI summary
A display device includes a base substrate, an active layer including indium-tin-gallium-zinc oxide (ITGZO) on the base substrate and including a channel region and a contact region that is partially crystallized and formed at opposite edges of the channel region, a gate electrode on the base substrate to overlap the channel region of the active layer, a gate insulation layer between the active layer and the gate electrode, a connection electrode connected to the contact region, and a light-emitting device electrically connected to the connection electrode.