Oxide TFT Channel Protection via Metallic Layer Oxidation
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Solution Overview
Problem
Oxide thin film transistors (Oxide TFTs) face challenges in preventing channel damage during the patterning process, particularly in BCE-type TFTs, where the channel is susceptible to damage during etching, and in ESL-type TFTs, where additional patterning processes are required due to alignment issues, leading to increased manufacturing costs and electrical property degradation.
Innovation Solution
Incorporating a channel protection layer formed by oxidizing a part of the first metallic layer between the source and drain electrodes, using materials like aluminum and copper, which reduces the need for additional patterning processes and prevents ion diffusion, thereby protecting the channel and improving electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional patterning processes are used to protect the channel in ESL-type TFTs, then channel protection is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent combines the channel protection layer formation with the source/drain electrode patterning process by using the same etching step to both define the electrode positions and create the protection layer openings, thereby eliminating the need for separate patterning steps while maintaining channel protection
Solution Approach 2:
The patent segments the first metallic layer into different functional regions: a patterned portion forming the source/drain electrodes and an unpatterned portion forming the channel protection layer, allowing both functions to be achieved from a single metallic layer structure
2Ease of manufacture
If the channel is exposed during etching in BCE-type TFTs, then manufacturing simplicity is maintained, but channel damage occurs
Solution Approach 1:
The patent introduces an intermediary channel protection layer made of metal oxide that acts as a barrier between the etching process and the channel, protecting the channel from ion bombardment and damage while allowing the etching process to proceed without additional complexity
Solution Approach 2:
The channel protection layer is formed preliminarily during the electrode patterning process itself, rather than requiring pre-formation or post-formation steps, ensuring channel protection is in place before the channel could be damaged
3Reliability
If multiple metallic layers are added to protect the channel, then channel protection is improved, but device structure complexity increases
Solution Approach 1:
The patent makes the first metallic layer multi-functional by having it serve both as the source/drain electrode material and as the channel protection layer material, eliminating the need for separate protective metallic layers while maintaining both functions
Solution Approach 2:
The patent applies local quality by having different portions of the first metallic layer exhibit different properties: the patterned portions conduct electricity as electrodes while the unpatterned portions form insulating oxide protection layers
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 effectively protects the channel from damage, reduces the number of patterning processes, and enhances the electrical properties of the Oxide TFT by forming a compact, insulating metal oxide layer without the need for additional metallic layers or plasma treatments, thus lowering manufacturing costs and avoiding issues like eave and chamfer.
Implementation Method 1
performing an oxidation treatment to a part of the first metallic layer located between the source electrode and the drain electrode, so as to form a channel protection layer
Data Source
AI summary
Embodiments of the present application provide an Oxide TFT, a manufacturing method thereof, an array substrate and a display device. The Oxide TFT includes a base substrate; a gate electrode, a gate insulating layer and an active layer which are located on the base substrate; a source electrode and a drain electrode, the active layer is at least partly covered with the source electrode and the drain electrode; and a channel protection layer located between the source electrode and the drain electrode, each of the source electrode and the drain electrode includes at least part of a first metallic layer and at least part of a second metallic layer, the first metallic and the second metallic layer are stacked one on another, the channel protection layer is of a metal oxide.