Thin-Film Transistor Nitrided Diffusion Barrier
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Solution Overview
Problem
The thickness of thin-film transistors (TFTs) in liquid crystal displays (LCDs) affects manufacturing productivity, as thick films reduce productivity and make it difficult to pattern and secure process uniformity and margins, due to the diffusion of metal atoms into the active layer.
Innovation Solution
A method is introduced to reduce the thickness of source and drain electrodes by using a thin diffusion-preventing layer with higher nitrogen content, formed through surface nitriding, to prevent metal atom diffusion and maintain ohmic contact characteristics, thereby reducing the overall thickness of the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the thickness of source and drain electrodes is reduced to improve productivity and patternability, then manufacturing productivity and process uniformity are improved, but metal atom diffusion into the active layer increases causing deterioration of TFT characteristics
Solution Approach 1:
A nitrogen-containing diffusion-preventing layer is introduced as an intermediary between the source/drain electrodes and the active layer. This layer acts as a mediator that blocks metal atom diffusion while maintaining electrical contact, allowing thin electrode structures to be used without compromising TFT characteristics.
Solution Approach 2:
The surface of the diffusion-preventing layer is nitrided to increase nitrogen content at the surface, creating a concentration gradient that enhances diffusion prevention. This parameter change in nitrogen concentration allows the layer to effectively block metal atoms while maintaining appropriate thickness for productivity.
2Reliability
If a thick diffusion-preventing layer is used to prevent metal atom diffusion, then TFT characteristics are maintained, but the overall thickness of source and drain electrodes increases reducing productivity
Solution Approach 1:
The diffusion-preventing layer exhibits local quality variation through nitrogen concentration gradient, with higher nitrogen content at the surface and lower content deeper in the layer. This localized nitrogen distribution provides effective diffusion prevention at the interface while keeping the overall layer thickness minimal for productivity.
Solution Approach 2:
By changing the nitrogen concentration parameter through surface nitriding, the layer achieves optimal diffusion prevention with minimal thickness. The surface nitriding process creates a high nitrogen concentration region exactly where diffusion blocking is most needed, eliminating the need for thick uniform layers.
3Manufacturing precision
If the thickness of thin film is increased to ensure process uniformity and margins, then process uniformity is improved, but patternability and productivity are reduced
Solution Approach 1:
The patent utilizes thin film structures with controlled nitrogen distribution to achieve both process uniformity and productivity. The diffusion-preventing layer, particularly with surface nitriding, provides sufficient functional performance in a thin configuration that maintains patternability while ensuring uniform processing.
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 approach improves productivity and secures process uniformity and margins by maintaining optimal current characteristics without deteriorating TFT performance, as evidenced by reduced ON and OFF current values within optimal ranges.
Implementation Method 1
nitriding a surface of the first material layer
Implementation Method 2
a thin diffusion-preventing layer with higher nitrogen content, formed through surface nitriding, to prevent metal atom diffusion
Data Source
AI summary
A thin-film transistor (TFT) and a method of manufacturing the same are disclosed herein. The TFT may include a gate electrode disposed on an insulating substrate, an insulating layer disposed on the insulating substrate and the gate electrode, an active layer pattern disposed on the insulating layer to overlap the gate electrode, a source electrode disposed on the insulating layer and at least part of which overlaps the active layer pattern, and a drain electrode which is separated from the source electrode and at least part of which overlaps the active layer pattern. A first ohmic contact layer pattern may be disposed between the active layer pattern and the source electrode and between the active layer pattern and the drain electrode. The first ohmic contact layer may have higher nitrogen content on its surface than in other portions of the first ohmic contact layer.