LTPS Thin Film Transistor with Segmented Polysilicon
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Solution Overview
Problem
Low Temperature Poly-silicon Thin Film Transistors (LTPS TFTs) face challenges in achieving high electron mobility while maintaining low leakage current, as existing designs either increase on-state current at the expense of higher leakage current or fail to optimize both simultaneously.
Innovation Solution
A thin film transistor design featuring a semiconductor active layer composed of an amorphous silicon layer with polysilicon portions, arranged in strip-shaped structures to enhance electron mobility and reduce leakage current, where the polysilicon portions are strategically distributed to form conduction paths and reduce heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polysilicon portions are increased to enhance electron mobility, then on-state current is improved, but leakage current increases
Solution Approach 1:
The patent applies local quality by creating a composite semiconductor active layer where polysilicon portions are strategically distributed within an amorphous silicon matrix. The polysilicon regions provide high electron mobility for improved on-state current, while the surrounding amorphous silicon regions maintain low leakage current. This spatial differentiation of material properties allows simultaneous optimization of both contradictory parameters.
Solution Approach 2:
The patent employs composite materials by combining polysilicon and amorphous silicon in a single semiconductor active layer. The polysilicon portions (5-20 nm in size) are embedded within the amorphous silicon layer, creating a composite structure that leverages the high carrier mobility of polysilicon while utilizing the low leakage characteristics of amorphous silicon. This composite approach resolves the contradiction between achieving high on-state current and maintaining low leakage current.
2Speed
If polysilicon portions are concentrated to form conduction paths, then electron mobility is enhanced, but heat generation increases
Solution Approach 1:
The patent applies segmentation by dividing the polysilicon content into multiple discrete portions (5-20 nm each) distributed throughout the semiconductor active layer, rather than forming a single large polysilicon region. This segmentation creates multiple localized conduction paths that enhance electron mobility while distributing heat generation across multiple small regions, preventing excessive temperature concentration in any single area.
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 design achieves a high on-state current with reduced leakage current by leveraging the high mobility of polysilicon and low mobility of amorphous silicon, while minimizing heat generation through the distribution of polysilicon portions, thereby improving overall transistor performance.
Implementation Method 1
leveraging the high mobility of polysilicon
Implementation Method 2
low mobility of amorphous silicon
Implementation Method 3
minimizing heat generation through the distribution of polysilicon portions
Data Source
AI summary
A thin film transistor, an array substrate, a display device and a method for manufacturing a thin film transistor are provided. The thin film transistor is formed on a base substrate and includes a source; a drain; and a semiconductor active layer having an amorphous silicon layer and one polysilicon portion or a plurality of polysilicon portions, the amorphous silicon layer being contacted with the one polysilicon portion or the plurality of polysilicon portions. The method includes a process of forming a source, a drain, and a semiconductor active layer: wherein forming a semiconductor active layer comprises: forming a first amorphous silicon thin film on a base substrate; and performing a crystallization treatment to the first amorphous silicon thin film to convert a part of the amorphous silicon in the first amorphous silicon thin film into polysilicon, such that a semiconductor active layer comprising one polysilicon portion or a plurality of polysilicon portions are formed.