Thin Film Transistor Gate Structure for Light Blocking
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Solution Overview
Problem
Thin film transistors used in display devices face performance deterioration due to external light and temperature, particularly in optical touch screen applications where direct light incidence affects the channel layer's performance.
Innovation Solution
A thin film transistor structure is designed with a larger cross-sectional area of the gate compared to the channel, source, and drain, utilizing transparent conductive oxides and metal materials to minimize light incidence on the channel layer, and incorporating transparent electrode layers and conductive vias to direct light obliquely around the source and drain areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional thin film transistor structure is used, then the device can be manufactured with standard processes, but the channel layer performance deteriorates due to light incidence from the backlight
Solution Approach 1:
The patent introduces a new spatial dimension by extending the gate electrode in the vertical direction to overlap with the channel layer. This dimensional change creates a shadow effect that blocks light from reaching the channel layer, resolving the contradiction between maintaining standard manufacturing processes and protecting against light-induced performance deterioration.
Solution Approach 2:
The extended gate electrode acts as an intermediary element that blocks light between the backlight and the channel layer. By positioning the gate electrode to overlap the channel layer vertically, it serves as a protective mediator that prevents harmful light incidence while allowing the transistor to function normally.
2Object-affected harmful factors
If the gate cross-sectional area is increased to block more light, then light protection improves, but the device area and complexity increase
Solution Approach 1:
The gate electrode is designed with dynamic dimensions - extending in the vertical direction to provide light blocking coverage while maintaining appropriate width and length parameters. This dynamic structural design allows the gate to perform both switching function and light protection function without excessive complexity.
Solution Approach 2:
The gate electrode is designed to perform multiple functions simultaneously: it serves as the control electrode for switching operations and as a light-blocking structure to protect the channel layer. This multi-functionality reduces the need for additional components, thereby limiting the increase in device complexity while improving light protection.
Data Source
AI summary
A thin film transistor is provided. The transistor includes a gate; a first passivation layer covering the gate; a channel layer disposed on the first passivation layer; a source and a drain that are disposed on the first passivation layer and contact two sides of the channel layer; a second passivation layer covering the channel layer, the source, and the drain; first and second transparent electrode layers that are disposed on the second passivation layer and spaced apart from each other; a first transparent conductive via that penetrates the second passivation layer and connects the source and the first transparent electrode layer; and a second transparent conductive via that penetrates the second passivation layer and connects the drain and the second transparent electrode layer. A cross-sectional area of the gate is larger than a cross-sectional area of the channel layer, the source, and the drain combined.