Oxide TFT Contact Structure for Faster Display Writing
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Solution Overview
Problem
Existing display devices face challenges in achieving high-speed operation for driver circuit transistors, particularly as pixel density increases, leading to longer display image writing times.
Innovation Solution
A transistor structure is introduced, where an oxide conductive layer with a crystal region is included in the source and drain regions, and a semiconductor layer is formed using an oxide semiconductor. This structure reduces contact resistance and enables high-speed operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional thin film transistor structure is used, then the device complexity is low and manufacturing is easier, but the operation speed is insufficient for high-speed driver circuits
Solution Approach 1:
The source and drain regions are segmented into multiple layers: a bottom electrode layer, an oxide conductive layer, and a top electrode layer. This segmentation allows each layer to perform specific functions - the oxide conductive layer reduces contact resistance while the electrode layers provide electrical connection, thereby achieving high-speed operation through structured complexity
Solution Approach 2:
The transistor employs composite material structures including oxide semiconductor layers combined with oxide conductive layers containing crystal regions. This composite approach combines the beneficial properties of different materials to achieve both low contact resistance and high operation speed while maintaining manageable device complexity
2Productivity
If pixel density is increased, then the display resolution is improved, but the transistor operation speed must be increased to reduce display image writing time
Solution Approach 1:
The oxide conductive layer contains crystal regions with specific orientations (c-axis or a-axis) that are controlled through formation conditions. This parameter change in crystal structure optimizes electrical properties and carrier mobility, enabling faster transistor operation that matches the increased pixel density requirements
Solution Approach 2:
The patent replaces conventional metal source/drain electrodes with an oxide-based conductive layer system. This substitution utilizes the unique electrical properties of oxide materials with crystal regions to achieve lower contact resistance and faster switching speeds, directly addressing the time loss issue in high-density displays
3Reliability
If an oxide conductive layer with crystal region is introduced, then contact resistance is reduced and operation speed increases, but the manufacturing process becomes more complex
Solution Approach 1:
The oxide conductive layer with crystal region is formed as an intermediate layer during the transistor fabrication process, before final electrode formation. This preliminary action establishes the low-resistance contact pathway early in manufacturing, ensuring reliable electrical characteristics while allowing subsequent processing steps to build upon this foundation
Solution Approach 2:
The oxide conductive layer acts as an intermediary between the metal electrode layers and the oxide semiconductor channel. This intermediate layer mediates the electrical contact, reducing resistance while its crystal structure can be controlled through standard sputtering or annealing processes, balancing manufacturing ease with electrical performance
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
The proposed transistor structure achieves high-speed operation and favorable electric characteristics, enhancing the reliability and performance of display devices by reducing contact resistance and improving switching characteristics.
Implementation Method 1
The oxide conductive layer includes a crystal region
Data Source
AI summary
It is an object to manufacture a highly reliable display device using a thin film transistor having favorable electric characteristics and high reliability as a switching element. In a bottom gate thin film transistor including an amorphous oxide semiconductor, an oxide conductive layer having a crystal region is formed between an oxide semiconductor layer which has been dehydrated or dehydrogenated by heat treatment and each of a source electrode layer and a drain electrode layer which are formed using a metal material. Accordingly, contact resistance between the oxide semiconductor layer and each of the source electrode layer and the drain electrode layer can be reduced; thus, a thin film transistor having favorable electric characteristics and a highly reliable display device using the thin film transistor can be provided.