Laser Crystallized Semiconductor Thin Film Transistor
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Solution Overview
Problem
Existing methods for forming polycrystalline semiconductor thin films in TFTs result in varying crystal grain sizes, leading to inconsistent TFT characteristics and display unevenness, and require inefficient double laser irradiation, which is not suitable for mass production and deteriorates TFT reliability.
Innovation Solution
A method involving the application of laser light to an amorphous semiconductor thin film to form polycrystallized semiconductor thin films with crystal grains arranged in a lattice shape, approximately half the size of the laser's oscillation wavelength, using a circularly polarized YAG-2ω laser, to achieve uniform crystal grain size and improved TFT characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If laser light is applied to an amorphous semiconductor thin film to form polycrystalline film, then crystal grains are formed, but the crystal grain sizes vary randomly (0.2 to 1.0 um) leading to TFT characteristic variations
Solution Approach 1:
The patent applies periodic laser irradiation with a specific cycle to induce regular crystal grain formation. By controlling the laser irradiation cycle, the method achieves periodic crystallization that produces uniform crystal grain sizes, eliminating the random variation problem and ensuring consistent TFT characteristics across different devices
Solution Approach 2:
The patent changes the laser irradiation parameters, specifically using a laser wavelength of 532 nm and controlling the irradiation cycle, to achieve precise control over crystal grain size. This parameter optimization ensures that crystal grains maintain a uniform size of approximately half the laser wavelength, resolving the size variation issue
2Manufacturing precision
If double laser irradiation is applied to arrange crystal grains in lattice shape, then crystal grain arrangement is improved, but manufacturing efficiency decreases and production time increases
Solution Approach 1:
The patent employs periodic laser irradiation that inherently produces lattice-shaped crystal grain arrangements in a single treatment cycle. The periodic nature of the irradiation automatically creates the desired regular pattern without requiring multiple sequential irradiation steps, thus maintaining high manufacturing efficiency while achieving precise crystal grain arrangement
Solution Approach 2:
The patent combines the crystal grain formation and arrangement processes into a single laser irradiation step. By merging these two functions that would traditionally require separate operations, the method achieves both uniform crystal grain size and regular lattice arrangement simultaneously, eliminating the need for double irradiation and improving productivity
3Manufacturing precision
If large crystal grain size (0.5 um) is achieved through laser irradiation, then crystal grain formation is successful, but electron-hole pair formation increases and TFT reliability deteriorates
Solution Approach 1:
The patent optimizes the laser irradiation parameters, specifically using a wavelength of 532 nm and controlling the irradiation cycle, to achieve crystal grain sizes of approximately half the wavelength (around 266 nm). This precise parameter control prevents excessive crystal grain growth, minimizing electron-hole pair formation and maintaining high TFT reliability
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 TFTs with crystal grains arranged in a lattice shape at regular intervals, reducing variations in TFT characteristics, enhancing reliability by minimizing electron-hole pair formation and internal defects, and allowing for more efficient manufacturing processes.
Implementation Method 1
applying laser light to an amorphous semiconductor thin film
Implementation Method 2
turn the semiconductor thin film into a polycrystalline film
Implementation Method 3
using a circularly polarized YAG-2ω laser
Implementation Method 4
crystal grains arranged into a lattice shape with a size that is about 1/2 of an oscillation wavelength of the laser light
Data Source
AI summary
A semiconductor thin film according to an embodiment of the present invention includes: a polycrystallized semiconductor thin film formed by applying laser light to an amorphous semiconductor thin film; and crystal grains arranged into a lattice shape with a size that is about ½ of an oscillation wavelength of the laser light.