Oxide Semiconductor TFT Wiring and Electrode Structure
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Solution Overview
Problem
The productivity of thin film transistors using oxide semiconductors is lower compared to those using amorphous silicon, which hinders their application in display devices such as liquid crystal displays and electronic paper.
Innovation Solution
A display device structure is developed with a gate electrode, gate insulating film, wiring, and electrode layers, including low-resistance and high-resistance oxide semiconductor layers, where the low-resistance oxide semiconductor layers are used to improve conductivity and the high-resistance layers enhance semiconductor properties, allowing for efficient pixel formation and improved manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductor is used for thin film transistor channel formation region, then field-effect mobility is improved, but productivity deteriorates
Solution Approach 1:
The oxide semiconductor layer is divided into two distinct regions: a first oxide semiconductor layer with lower resistance and a second oxide semiconductor layer with higher resistance. This segmentation allows each region to perform its specific function optimally - the first layer ensures good electrical contact and conductivity, while the second layer provides the necessary semiconductor characteristics for transistor operation, thereby resolving the contradiction between mobility and productivity
Solution Approach 2:
Different regions of the oxide semiconductor layer are assigned different resistance characteristics to fulfill different functional requirements. The first oxide semiconductor layer (closer to source/drain electrodes) has lower resistance to improve carrier injection and reduce contact resistance, while the second oxide semiconductor layer (channel region) has higher resistance to maintain proper semiconductor behavior and threshold voltage control, thus achieving both high mobility and manufacturability
Data Source
AI summary
A display device includes a first wiring functioning as a gate electrode formed over a substrate, a gate insulating film formed over the first wiring, a second wiring and an electrode layer provided over the gate insulating film, and a high-resistance oxide semiconductor layer formed between the second wiring and the electrode layer are included. In the structure, the second wiring is formed using a stack of a low-resistance oxide semiconductor layer and a conductive layer over the low-resistance oxide semiconductor layer, and the electrode layer is formed using a stack of the low-resistance oxide semiconductor layer and the conductive layer which is stacked so that a region functioning as a pixel electrode of the low-resistance oxide semiconductor layer is exposed.