Polysilicon TFT on Polymer Substrate with Heat-Absorbing TCO
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Solution Overview
Problem
The challenge lies in manufacturing polysilicon-based thin film transistors on flexible polymer substrates, where high temperature dehydrogenation processes damage the substrate due to outgassing and low heat resistance, and existing low-temperature processes compromise transistor reliability and charge mobility.
Innovation Solution
Incorporating an oxide transparent electrode layer to absorb heat and light during the dehydrogenation process, combined with a barrier layer to prevent substrate damage, allows for the use of a polymer substrate that can withstand the high temperatures required for polysilicon formation, using a method that includes depositing a polymer substrate, an oxide transparent electrode layer, a barrier layer, and forming amorphous silicon, followed by dehydrogenation treatment and laser radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature dehydrogenation process is used to manufacture polysilicon-based thin film transistors, then charge mobility and transistor reliability are improved, but polymer substrate is damaged due to outgassing and low heat resistance
Solution Approach 1:
A heat resistance improvement layer is inserted between the polymer substrate and the amorphous silicon layer to serve as a protective intermediary. This layer has higher heat resistance than the polymer substrate, allowing it to withstand the dehydrogenation temperature (420-550°C) and prevent direct thermal damage to the substrate during high-temperature polysilicon manufacturing processes.
Solution Approach 2:
The invention changes the thermal parameter profile by introducing a layer with intermediate heat resistance properties. The heat resistance improvement layer has a glass transition temperature higher than the polymer substrate's decomposition temperature, creating a thermal buffer zone that enables high-temperature processing without substrate damage.
2Object-affected harmful factors
If low temperature process is used to avoid substrate damage, then polymer substrate integrity is maintained, but transistor reliability and charge mobility deteriorate
Solution Approach 1:
The heat resistance improvement layer acts as a thermal mediator that decouples the substrate temperature from the processing temperature. This intermediary layer allows the polymer substrate to remain at lower temperatures while the dehydrogenation and crystallization processes occur at higher temperatures (420-550°C) in the semiconductor layer.
3Reliability
If dehydrogenation treatment is performed at high temperature (420-550°C) to form polysilicon, then charge mobility is improved, but polymer substrate undergoes outgassing and damage
Solution Approach 1:
The heat resistance improvement layer serves as a protective barrier between the polymer substrate and the high-temperature dehydrogenation process. This intermediary layer prevents outgassing from reaching and damaging the substrate while allowing the necessary thermal energy to pass through for polysilicon formation in the semiconductor layer.
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 enables the production of polysilicon thin film transistors with high charge mobility and reliability while preventing substrate damage, allowing for the successful integration of flexible organic light emitting diode displays.
Implementation Method 1
Incorporating an oxide transparent electrode layer to absorb heat and light during the dehydrogenation process
Implementation Method 2
performing dehydrogenation treatment of the amorphous silicon and radiating a laser beam thereon
Data Source
AI summary
A thin film transistor substrate includes: a polymer substrate, an oxide transparent electrode layer (TCO) formed on the polymer substrate, a barrier layer formed on the oxide transparent electrode layer, and a semiconductor layer formed on the barrier layer, in which the semiconductor layer is polysilicon. The polysilicon thin film transistor provides an oxide transparent electrode layer (TCO) which absorbs heat energy and light generated during a process of manufacturing the polysilicon thin film transistor to prevent a damage of the substrate using a polymer material.