Oxide Semiconductor TFT Aperture Ratio and Cost Optimization
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Solution Overview
Problem
Current semiconductor devices face challenges in reducing manufacturing costs, improving aperture ratio, increasing display resolution, and achieving high-speed operation, particularly in the use of oxide semiconductors for both driver circuits and pixel transistors on a single substrate.
Innovation Solution
A semiconductor device design that incorporates a driver circuit and pixel portion on a single substrate, utilizing oxide semiconductors for the channel layer and conductive metal oxides for electrodes, with specific manufacturing processes including dehydration or dehydrogenation of oxide semiconductor layers to achieve high-resistance and low-resistance regions, enhancing electrical characteristics and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If oxide semiconductors are used for both driver circuit transistors and pixel transistors on a single substrate, then manufacturing cost is reduced, but device complexity increases due to the need to optimize different electrical characteristics for different circuit functions
Solution Approach 1:
The patent applies different material compositions to different regions: In-Ga-Zn-O-based oxide semiconductor for pixel transistors requiring high transparency and moderate mobility, and In-Sn-Zn-O-based oxide semiconductor for driver circuit transistors requiring high mobility. This local differentiation resolves the contradiction by enabling single-substrate integration while optimizing electrical characteristics for each specific function.
2Speed
If oxide semiconductors with high field-effect mobility are used in driver circuits, then high-speed operation is achieved, but manufacturing precision requirements increase to control electrical characteristics
Solution Approach 1:
The patent changes material composition parameters to achieve different mobility levels: In-Sn-Zn-O-based oxide semiconductor with specific atomic ratios (0.1 < Sn/(In+Sn) < 0.5) for high mobility in driver circuits, and In-Ga-Zn-O-based oxide semiconductor for pixel transistors. This parameter differentiation enables high-speed operation while controlling manufacturing precision through well-defined compositional ranges.
Solution Approach 2:
The patent performs preliminary dehydration and dehydrogenation treatments at 400-600°C before final device formation to remove water and hydrogen from oxide semiconductor layers. This preliminary action stabilizes electrical characteristics and reduces variability, thereby achieving high-speed operation with controlled manufacturing precision.
3Area of stationary object
If oxide conductors are used for pixel electrodes and wirings to improve light transmission, then aperture ratio increases, but electrical conductivity decreases compared to metal conductors
Solution Approach 1:
The patent uses composite oxide conductor structures: ITO (indium tin oxide) or IZO (indium zinc oxide) layers combined with specific thickness control (50-200 nm) to achieve both high optical transparency and sufficient electrical conductivity for pixel electrodes and wirings. This composite approach resolves the contradiction by optimizing the balance between light transmission and electrical performance.
4Reliability
If dehydration or dehydrogenation treatment is applied to oxide semiconductor layers, then electrical characteristics are improved, but manufacturing process complexity increases
Solution Approach 1:
The patent combines dehydration and dehydrogenation treatments into a single integrated thermal processing step at 400-600°C in an inert or reducing atmosphere, rather than performing them as separate sequential operations. This merging reduces manufacturing process complexity while achieving the desired improvement in electrical characteristics through simultaneous removal of water and hydrogen.
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
This approach reduces manufacturing costs, improves aperture ratio, increases display resolution, and enables high-speed operation by optimizing the electrical characteristics of thin film transistors, leading to a highly reliable semiconductor device with favorable performance.
Implementation Method 1
dehydration or dehydrogenation of oxide semiconductor layers
Implementation Method 2
dehydration or dehydrogenation of oxide semiconductor layers
Implementation Method 3
dehydration or dehydrogenation of oxide semiconductor layers to achieve high-resistance and low-resistance regions
Implementation Method 4
light-transmitting metal oxides also attract attention as materials having semiconductor properties
Implementation Method 5
TFTs including oxide semiconductors have high field-effect mobility
Implementation Method 6
oxide conductors and oxide semiconductors have light-transmitting properties
Data Source
AI summary
An aperture ratio of a semiconductor device is improved. A driver circuit and a pixel are provided over one substrate, and a first thin film transistor in the driver circuit and a second thin film transistor in the pixel each include a gate electrode layer, a gate insulating layer over the gate electrode layer, an oxide semiconductor layer over the gate insulating layer, source and drain electrode layers over the oxide semiconductor layer, and an oxide insulating layer in contact with part of the oxide semiconductor layer over the gate insulating layer, the oxide semiconductor layer, and the source and drain electrode layers. The gate electrode layer, the gate insulating layer, the oxide semiconductor layer, the source and drain electrode layers, and the oxide insulating layer of the second thin film transistor each have a light-transmitting property.