Metal Oxide Transistor Structure for Stray-Light-Stable Displays
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Solution Overview
Problem
Transistors in display devices experience characteristic degradation due to stray light, leading to adverse effects on image quality and pixel operation, with existing solutions failing to adequately address this issue.
Innovation Solution
A transistor design incorporating a metal oxide with a bandgap greater than or equal to 3.3 eV, specifically an In-Ga-Zn oxide, is used in the channel formation region, along with a gate insulator with low nitrogen concentration to minimize defect states and oxygen vacancies, reducing the impact of stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional transistor structure is used in display devices, then manufacturing is simpler, but stray light causes degradation of transistor characteristics
Solution Approach 1:
The transistor is divided into multiple functional regions: a channel formation region with metal oxide semiconductor, source and drain regions, and a light-blocking region. This segmentation allows the light-blocking function to be separated from the channel function, preventing stray light from reaching the channel while maintaining simple manufacturing processes.
Solution Approach 2:
A light-blocking region is introduced as an intermediary structure between the light-emitting element and the transistor channel. This light-blocking region absorbs or blocks stray light before it can reach the channel formation region, protecting the transistor characteristics without requiring complex shielding structures.
2Reliability
If the transistor structure is designed to block stray light, then characteristic degradation is reduced, but device complexity increases
Solution Approach 1:
The light-blocking region is localized to specific areas where stray light would otherwise reach the channel, rather than implementing a comprehensive shielding structure. The metal oxide semiconductor is also used locally in the channel formation region to provide inherent light resistance. This localized approach reduces overall device complexity while maintaining pixel operation stability.
3Reliability
If metal oxide with high bandgap is used in channel formation region, then stray light resistance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a bandgap parameter of 3.3 eV or higher for the metal oxide semiconductor, which provides sufficient stray light resistance while allowing for standard manufacturing tolerances. This parameter selection balances the need for light resistance with the practical constraints of manufacturing precision in existing semiconductor fabrication processes.
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 solution effectively reduces stray-light-induced degradation of transistor characteristics, ensuring stable pixel operation and improved electrical performance with reduced power consumption.
Implementation Method 1
The metal oxide has a bandgap greater than or equal to 3.3 eV
Data Source
AI summary
A transistor whose characteristic degradation due to stray light is small is provided. The transistor includes a first insulator, a second insulator over the first insulator, a metal oxide over the second insulator, a first and a second conductor over the metal oxide, a third insulator over the first insulator, the second insulator, the metal oxide, the first conductor, and the second conductor, a fourth insulator over the metal oxide, a fifth insulator over the fourth insulator, and a third conductor over the fifth insulator. The third insulator has an opening to overlap with a region between the first conductor and the second conductor. The fourth insulator, the fifth insulator, and the third conductor are positioned in the opening. The metal oxide has a bandgap greater than or equal to 3.3 eV. The transistor has Vsh higher than or equal to −0.3 V.