Oxide TFT Capping Layer Work Function
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Solution Overview
Problem
Conventional amorphous silicon TFTs face limitations in mobility and cost-effectiveness for large-sized, high-image-quality displays, while polycrystalline silicon TFTs are costly and difficult to manufacture on large substrates, necessitating a new TFT technology that combines the advantages of both.
Innovation Solution
An oxide thin film transistor with a capping layer having a higher work function than the channel, formed using materials like In-Zn oxide doped with Ni or Ga-In-Zn oxide, enhances electrical characteristics and facilitates manufacturing on large substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If amorphous silicon TFTs are used, then manufacturing cost is reduced and ease of manufacture is improved, but mobility and electrical performance deteriorate
Solution Approach 1:
The patent uses a composite structure consisting of an amorphous In-Ga-Zn-O semiconductor layer combined with a crystalline In-Ga-Zn-O semiconductor layer. This composite approach allows the device to benefit from the ease of manufacture of amorphous materials while achieving the high mobility characteristics of crystalline materials, thereby resolving the contradiction between manufacturing ease and electrical performance.
2Reliability
If polycrystalline silicon TFTs are used, then mobility and electrical performance are improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent divides the semiconductor layer into two distinct segments: an amorphous In-Ga-Zn-O layer and a crystalline In-Ga-Zn-O layer. Each segment serves a specific function - the amorphous layer provides ease of formation and coverage, while the crystalline layer provides high mobility. This segmentation allows the device to achieve high performance without requiring entirely crystalline structures, thereby reducing manufacturing complexity.
3Reliability
If oxide semiconductor materials are used, then mobility is improved and electrical characteristics are enhanced, but manufacturing process complexity increases
Solution Approach 1:
The patent utilizes parameter changes in the semiconductor material structure - specifically transitioning from entirely amorphous to a combination of amorphous and crystalline phases of In-Ga-Zn-O. By controlling the crystallization process and material composition ratios, the patent achieves enhanced electrical characteristics while managing manufacturing process complexity through controlled phase transitions rather than requiring entirely new material systems.
Data Source
AI summary
An oxide thin film transistor and a method of manufacturing the oxide TFT are provided. The oxide thin film transistor (TFT) including: a gate; a channel formed to correspond to the gate, and a capping layer having a higher work function than the channel; a gate insulator disposed between the gate and the channel; and a source and drain respectively contacting either side of the capping layer and the channel and partially on a top surface of the capping layer.