Polysilicon Grain Uniformity via Laser Energy Density Control
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Solution Overview
Problem
The existing methods for manufacturing polysilicon films for liquid crystal displays, such as those used in high-performance televisions, face challenges in achieving large grain sizes while maintaining productivity and uniformity, as applying a laser beam with low energy density multiple times can lead to varying grain sizes and reduced productivity.
Innovation Solution
A method is developed to derive the relationship between laser beam energy density and grain size, select a predetermined energy density range, and apply a laser beam within this range to polycrystallize amorphous silicon films, forming polysilicon films with a uniform grain size of 50 nm or less, which improves productivity and uniformity by allowing a single irradiation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser beam with low energy density is applied multiple times to increase grain size, then the grain size of the polysilicon film increases, but the productivity decreases and grain size uniformity deteriorates
Solution Approach 1:
The patent changes the energy density parameter of the laser beam from low to high values, and adjusts the number of irradiations from multiple to single or limited times. This parameter optimization allows achieving large uniform grain sizes (50 nm or less) while maintaining high productivity, resolving the contradiction between manufacturing precision and productivity
Solution Approach 2:
The patent employs periodic laser irradiation with optimized intervals and timing. By controlling the irradiation schedule (single shot or limited number of shots with specific intervals), the method achieves complete polycrystallization in each irradiation cycle, ensuring uniform grain size without requiring multiple repeated applications, thus maintaining both precision and productivity
2Manufacturing precision
If a laser beam with low energy density is applied multiple times to increase grain size, then the grain size of the polysilicon film increases, but the manufacturing complexity increases
Solution Approach 1:
The patent simplifies the manufacturing process by changing the laser irradiation parameters to high energy density with single or limited applications. This eliminates the need for complex multi-step irradiation sequences, reducing process complexity while maintaining precise grain size control through optimized energy density selection
Solution Approach 2:
The patent performs preliminary optimization of the laser irradiation parameters (energy density, irradiation time, number of shots) before actual production. By establishing the optimal parameter set in advance, the method enables straightforward single-shot or limited-shot irradiation processes, reducing manufacturing complexity while ensuring consistent grain size outcomes
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 enhances the mobility of electrons and achieves a stable, uniform grain size, improving the manufacturing efficiency and reducing production costs, particularly beneficial for large-sized displays like 8K televisions.
Implementation Method 1
irradiating a first area including the amorphous silicon film with a laser beam at energy density in the selected range of the energy density to thereby polycrystallize the amorphous silicon film
Implementation Method 2
polycrystallize the amorphous silicon film and form the polysilicon film
Data Source
AI summary
Provided is a method of manufacturing a display, a display, and a liquid crystal television that can improve productivity and make a grain size uniform. A method of manufacturing a display includes: (A) deriving, when a laser beam is applied to an aSi film 18 provided on a substrate 11 to thereby polycrystallize the aSi film 18 and form a pSi film 14, a relationship between energy density of the laser beam and a grain size of the pSi film 14; (B) selecting a predetermined range of the energy density in the derived relationship; and (C) irradiating a first area including the aSi film 18 with a laser beam at energy density in the selected range of the energy density to thereby polycrystallize the aSi film 18 and form the pSi film 14.