Transparent Conductive Layer Overlap in Thin-Film Transistors
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Solution Overview
Problem
Conventional bottom gate thin-film transistors with etch stop layers suffer from larger device sizes and longer channel lengths, making them unsuitable for high-resolution, high-aperture ratio, and narrow border display panels, due to potential damage to the active layer during electrode formation.
Innovation Solution
A display panel design featuring a thin-film transistor structure with a gate electrode, gate insulating layer, source electrode, transparent conductive layer, pixel electrode, and active layer, where the transparent conductive layer overlaps and electrically connects the source electrode, reducing channel length and eliminating the need for a separate drain electrode, thus avoiding the issues associated with etch stop layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an etch stop layer is formed on the active layer to protect it during electrode formation, then the active layer is protected from damage, but the device size and channel length increase
Solution Approach 1:
The invention removes the etch stop layer from the transistor structure, extracting the problematic layer that caused increased device size and channel length. The active layer is protected through alternative means during the electrode formation process, allowing for smaller device dimensions while maintaining protection functionality.
Solution Approach 2:
The invention segments the electrode formation process into controlled steps where the active layer is protected through process sequencing rather than additional protective layers. The source and drain electrodes are formed in a manner that avoids direct damage to the active layer without requiring an etch stop layer.
2Reliability
If an etch stop layer is formed on the active layer to protect it during electrode formation, then the active layer is protected from damage, but the device area increases
Solution Approach 1:
The invention removes the etch stop layer from the transistor structure, extracting the problematic layer that caused increased device area. This extraction enables smaller device footprints while maintaining active layer protection through alternative process control methods.
Solution Approach 2:
The invention segments the manufacturing process to protect the active layer through process sequencing rather than additional protective layers, thereby reducing the overall device area while maintaining protection functionality.
3Ease of manufacture
If the source electrode and drain electrode are formed directly on the active layer, then the manufacturing process is simplified, but the active layer is damaged
Solution Approach 1:
The invention applies preliminary protective measures to the active layer before electrode formation, such as forming a protective coating or using controlled deposition techniques that prevent damage during the subsequent electrode formation process, thereby maintaining both simplicity and integrity.
Solution Approach 2:
The invention introduces an intermediary protective layer or process step between the active layer and electrode formation that prevents direct damage while maintaining process simplicity. This intermediary mechanism protects the active layer without significantly complicating the manufacturing flow.
Data Source
AI summary
An embodiment of the present invention provides a display panel including a first substrate; a device layer disposed on the first substrate, wherein the device layer includes a plurality of thin-film transistors and the thin-film transistor includes a gate electrode; a gate insulating layer disposed on the first substrate and covering the gate electrode; a source electrode disposed on the gate insulating layer; a transparent conductive layer disposed on the gate insulating layer and overlapping and electrically connecting the source electrode; a pixel electrode; an active layer electrically connecting the transparent conductive layer and the pixel electrode; a second substrate disposed on the first substrate; and a display medium between the first substrate and the second substrate.