IGZO TFT Diffraction Metal for Etching Control
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Solution Overview
Problem
The existing IGZO TFT fabrication process leads to over-etching of the IGZO layer, affecting the performance and response speed of liquid crystal display panel pixels due to repeated wet etching, resulting in defects.
Innovation Solution
Incorporating a diffraction metal layer on the IGZO layer within the channel area between the source and drain metals, which helps in light diffraction during the etching process, reducing the intensity of light exposure and preventing over-etching by modifying the etching pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If repeated wet etching is performed to remove photoresist and define patterns, then the etching process can be completed, but the IGZO layer becomes over-etched and damaged
Solution Approach 1:
A new metal layer (diffraction metal) is introduced as an intermediary element between the photoresist and the IGZO layer. This diffraction metal serves as a mediator that interacts with the etching solution and light to protect the IGZO layer from over-etching, while still allowing the etching process to proceed. The diffraction metal absorbs or deflects the harmful effects of repeated wet etching, preventing direct damage to the IGZO layer beneath it.
2Area of moving object
If the channel area is enlarged to improve pixel performance, then more light diffraction is needed, but the IGZO layer becomes more susceptible to over-etching
Solution Approach 1:
The diffraction metal is selectively positioned within the channel area rather than uniformly across the entire IGZO layer. This local placement provides targeted protection to the channel region where light diffraction occurs, while maintaining the integrity of the IGZO layer in other areas. The local quality principle allows the channel area to be enlarged for improved performance without proportionally increasing the risk of over-etching across the entire device.
3Device complexity
If multiple etching steps are used to prepare source, drain, and IGZO layers with the same mask, then fabrication complexity is reduced, but over-etching defects increase
Solution Approach 1:
The diffraction metal layer is prepared in advance, before the multiple etching steps are performed. This preliminary action establishes a protective barrier that will be in place during all subsequent etching operations. By preparing the diffraction metal layer first, the design anticipates and prevents the over-etching problem that would otherwise occur during the repeated wet etching process, rather than attempting to correct it afterward.
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
This solution effectively minimizes over-etching of the IGZO layer, enhancing the performance and response speed of the TFT device by protecting the IGZO layer from damage during the etching process.
Implementation Method 1
Incorporating a diffraction metal layer on the IGZO layer within the channel area between the source and drain metals, which helps in light diffraction during the etching process
Data Source
AI summary
A thin film transistor (TFT) device is provided with a glass substrate, a gate metal formed on a surface of the glass substrate; a gate insulating layer formed on the surface of the glass substrate, and covering the gate metal; an indium gallium zinc oxide (IGZO) layer formed on a surface of the gate insulating layer; a source metal and a drain metal formed on a surface of the IGZO layer, and a channel area is formed between the source metal and the drain metal; and a diffraction metal formed on the surface of the IGZO layer and located within the channel area.