Active Matrix TFT Electrode Patterning with Etch-Protective Covering
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Solution Overview
Problem
In the manufacturing of active matrix displays, such as LCDs and OLEDs, the patterning of metal layers for source and drain electrodes using photoresist films can lead to erosion of additional areas and contamination of semiconductor layers, affecting the characteristics and reliability of thin-film transistors due to etching by-products.
Innovation Solution
The solution involves forming a gate line on a substrate, followed by a gate insulating layer, a semiconductor layer, and a metal layer, with a photoresist film pattern used to etch the insulator and metal layers using dry etching, and forming a passivation layer to protect the semiconductor substrate, employing materials like MoW for the metal layer and silicon nitride or oxide for the covering member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photoresist film is used as etching mask for metal layer patterning, then source and drain electrodes can be formed, but photoresist film erosion causes additional area erosion and semiconductor layer contamination
Solution Approach 1:
An insulator layer is introduced as an intermediary between the metal layer and the photoresist film. This insulator layer serves as a protective barrier that prevents etching by-products from contaminating the semiconductor layer while still allowing the photoresist film to function as an effective etching mask for precise patterning of source and drain electrodes.
Solution Approach 2:
The insulator layer is formed in advance before the photoresist film patterning process. This preliminary action ensures that the protective barrier is already in place to prevent contamination during the subsequent etching process, rather than attempting to prevent contamination after it occurs.
2Ease of manufacture
If conventional lithography and etching are used for conductive layer patterning, then TFTs can be manufactured, but etching by-products adversely affect TFT characteristics and reliability
Solution Approach 1:
The insulator layer acts as a mediator that allows the conventional lithography and etching processes to continue unchanged for ease of manufacture, while simultaneously protecting the semiconductor layer from etching by-products to maintain TFT reliability.
Solution Approach 2:
The structure is segmented into distinct functional layers: the insulator layer is separated from both the metal layer and the semiconductor layer, creating a protective barrier that isolates the semiconductor layer from contamination while allowing the metal layer to be patterned using standard processes.
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 method reduces unwanted etching effects, enhances the precision of source and drain region patterning, and improves the reliability of thin-film transistors by minimizing contamination and erosion, thereby improving the overall performance and stability of the display device.
Implementation Method 1
etching the insulator layer and the metal layer using the photoresist film pattern insulator layer to form a covering member, a data line and a drain electrode
Data Source
AI summary
The display device according to an exemplary embodiment of the present invention includes an insulation substrate, a first signal line formed on the insulation substrate, a second signal line intersecting and insulated from the first signal line, an covering member formed on the second signal line, and a switching element having a first terminal, a second terminal, and a third terminal, wherein the first terminal is connected to the first signal line and the second terminal is connected to the second signal line, and a pixel electrode is connected to the third terminal of the switching element. The covering member according to an embodiment of the present invention reduces the etching error in forming a fine pattern.