Flexible Display Active Layer Laser Annealing Doping
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Solution Overview
Problem
Flexible display devices with polymer films as substrates face performance deterioration due to limitations in processing temperature during the formation of circuit layers, leading to reliability issues in transistor performance.
Innovation Solution
A display panel with a circuit layer containing polycrystalline silicon, featuring an active layer with boron and fluorine doping, where the concentration of fluorine is higher in surface layers than in the core layer, and boron is higher in ion doping regions, along with a control electrode and insulation layer, is manufactured using a method involving preliminary doping, laser annealing, and heat treatment to improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature semiconductor processes are performed to form transistors on a polymer base substrate, then transistor performance is improved, but the base substrate is damaged due to excessive temperature
Solution Approach 1:
The patent applies laser annealing to change the thermal processing parameters from high-temperature conventional annealing to localized, controlled laser heating. This allows the active layer to be crystallized and doped at temperatures that do not damage the polymer base substrate, while still achieving the desired transistor performance through precise control of laser power, scanning speed, and multiple passes
Solution Approach 2:
The patent replaces the conventional thermal field (heating chamber, hot plates) with a laser beam system for annealing and doping processes. The laser provides localized, high-energy density heating that can crystallize the active layer and activate dopants without heating the entire substrate to damaging temperatures, thus substituting mechanical/thermal processing with optical processing
2Reliability
If conventional doping processes are used to form active layers, then transistor functionality is achieved, but interface properties are poor and threshold voltage hysteresis occurs
Solution Approach 1:
The patent performs preliminary doping of the active layer before laser annealing, incorporating dopant materials (such as BCP, TPBi, or Alq3) into the amorphous active layer. The subsequent laser annealing then activates these pre-introduced dopants and improves the crystalline structure, achieving better interface properties and reduced threshold voltage hysteresis compared to post-annealing doping methods
Solution Approach 2:
The patent uses composite material systems combining organic semiconductor materials (such as Alq3, BCP, TPBi) with the active layer, where the dopant materials serve dual functions: introducing charge carriers for transistor functionality and improving interfacial properties through favorable energy level alignment and reduced defect states at interfaces
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 enhances the reliability and performance of transistors by minimizing damage to the substrate, improving interface properties, and reducing threshold voltage hysteresis and afterimage retention time, thus addressing the temperature limitations and reliability challenges in flexible display manufacturing.
Implementation Method 1
providing laser light to the secondarily doped preliminary active layer, thereby forming an active layer
Implementation Method 2
providing a preliminary active layer containing amorphous silicon on a base substrate, primarily doping the preliminary active layer with first ions, secondarily doping the primarily doped preliminary active layer with second ions
Data Source
AI summary
A display panel includes: a base substrate; a circuit layer on the base substrate; and a display element layer on the circuit layer, wherein the circuit layer includes an active layer on the base substrate and containing boron and fluorine; a control electrode on the active layer; and a control electrode insulation layer between the active layer and the control electrode, wherein the active layer includes: a core layer in which a concentration of the boron is greater than a concentration of the fluorine; and a surface layer on the core layer and in which a concentration of the fluorine is greater than a concentration of the boron.