Stacked Oxide TFT Layout for High-Resolution Display Pixels
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Solution Overview
Problem
As the resolution of display devices increases, the number of transistors required for pixel switching increases, leading to a larger area of transistor disposition, reduced aperture ratio, and difficulty in achieving high-speed operation, which hampers the attainment of higher display resolution.
Innovation Solution
A semiconductor device with stacked transistors sharing a common gate electrode, utilizing oxide semiconductor films, particularly In-Ga-Zn-based oxide semiconductor films with aligned crystal parts, to reduce the transistor area and enhance field-effect mobility for high-speed operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of transistors is increased to achieve higher resolution, then the pixel switching capability is improved, but the area of transistor disposition is increased and aperture ratio is reduced
Solution Approach 1:
The patent applies vertical stacking to arrange transistors in the thickness direction rather than only in the planar direction. Multiple transistors are stacked above each other sharing common electrodes, which reduces the footprint area while maintaining the required number of transistors for high-resolution display switching.
Solution Approach 2:
The patent merges multiple transistor functions into a stacked configuration where transistors share common source electrodes, drain electrodes, or gate electrodes. This consolidation reduces the total area required while maintaining the functional capability of pixel switching for high-resolution displays.
2Measurement precision
If the number of transistors is increased to achieve higher resolution, then the pixel switching capability is improved, but the aperture ratio is reduced
Solution Approach 1:
By transitioning from planar arrangement to vertical stacking, the patent reduces the horizontal space occupied by transistors, thereby increasing the area available for light transmission (aperture ratio) while maintaining the transistor count needed for high-resolution pixel switching.
Solution Approach 2:
The stacked transistor configuration with shared electrodes consolidates the transistor footprint, freeing up aperture area for light passage while preserving the electrical functionality required for high-resolution display operation.
3Illumination intensity
If the transistor area is reduced to improve aperture ratio, then the aperture ratio is improved, but high-speed operation becomes difficult to achieve
Solution Approach 1:
The patent changes the semiconductor material parameter from conventional silicon-based materials to oxide semiconductor materials (such as IGZO), which provide higher field-effect mobility. This material parameter change enables high-speed transistor operation even in the reduced area of stacked configurations, resolving the trade-off between aperture ratio and switching speed.
4Ease of manufacture
If conventional semiconductor materials are used, then the manufacturing process is established, but high field-effect mobility and high-speed operation are difficult to achieve
Solution Approach 1:
The patent changes the semiconductor material composition to oxide semiconductors with specific characteristics (high electron mobility, low carrier concentration) while maintaining compatibility with existing thin-film transistor manufacturing processes. This parameter change in material properties enables high-speed operation without requiring complete process retooling.
Solution Approach 2:
The patent employs oxide semiconductor materials (such as indium gallium zinc oxide) that combine the advantages of ease of fabrication into thin films with high field-effect mobility, creating a composite material system that bridges manufacturing simplicity and high-performance operation.
Data Source
AI summary
A first transistor and a second transistor are stacked. The first transistor and the second transistor have a gate electrode in common. At least one of semiconductor films used in the first transistor and the second transistor is an oxide semiconductor film. With the use of the oxide semiconductor film as the semiconductor film in the transistor, high field-effect mobility and high-speed operation can be achieved. Since the first transistor and the second transistor are stacked and have the gate electrode in common, the area of a region where the transistors are disposed can be reduced.