Laser Crystallization Apparatus with Vibration Device
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Solution Overview
Problem
Existing laser crystallization methods for forming polycrystalline silicon in thin film transistors suffer from display errors and nonuniformities due to inhomogeneities in the laser beam profile, particularly dot pattern defects which are difficult to remove using conventional vibration techniques.
Innovation Solution
A laser crystallization device with a vibration device that vibrates the laser beam along its long axis, with specific vibration frequency constraints calculated using equations such as F<(P*f)/(2*W), F<(P*f)/Ts, and F<(3*Tm*P*f)/(2*Ts*A), to minimize overlapping regions of multiple pulses and reduce display errors, ensuring improved uniformity of polycrystalline silicon formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a laser beam with a fixed profile is used for crystallization, then the process is simple, but linear patterns and dot pattern defects appear due to inhomogeneities in the beam profile
Solution Approach 1:
The patent applies dynamic vibration to the laser beam along its propagation direction, transforming the static beam into a dynamically oscillating one. This vibration causes the beam to sweep across multiple locations, averaging out the inhomogeneities and preventing the formation of linear patterns and dot defects in the crystallized silicon.
Solution Approach 2:
The patent specifically uses mechanical vibration of the laser beam through a vibration device that oscillates the beam along its propagation direction. This mechanical vibration approach directly addresses the inhomogeneity issue by physically moving the beam energy distribution, eliminating the need for complex optical systems while improving uniformity.
2Reliability
If excimer laser annealing is used to form polycrystalline silicon, then high electrical mobility is achieved, but the process complexity increases and manufacturing precision is affected by beam profile inhomogeneities
Solution Approach 1:
The patent extracts and isolates only the essential vibration function from complex optical beam shaping systems. By using a simple vibration device instead of elaborate optical components, it reduces system complexity while maintaining the ability to produce high-quality polycrystalline silicon with good electrical mobility.
Solution Approach 2:
The patent replaces complex optical systems (such as beam shaping optics and multiple lenses) with a simpler mechanical vibration approach. This substitution maintains the effectiveness of the crystallization process while significantly reducing system complexity and ease of manufacturing.
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 calculated vibration frequencies effectively reduce display errors and enhance the uniformity of polycrystalline silicon, leading to improved manufacturing outcomes for high-speed display devices.
Implementation Method 1
a vibration device vibrating a laser beam along the long axis of the focused beam spot
Implementation Method 2
an amorphous silicon thin film deposited on a glass substrate is irradiated by a high energy pulsed laser beam. Upon absorbing the light energy from the laser beam, the amorphous silicon thin film melts, and then re-solidifies so as to be crystallized
Implementation Method 3
Upon absorbing the light energy from the laser beam, the amorphous silicon thin film melts
Implementation Method 4
the spatial energy distribution cross-section, or profile, of the output laser beam, which typically has a Gaussian distribution, is changed by using an optical system. The output beam shape is transformed into a rectangle with a very large aspect ratio
Data Source
AI summary
A laser crystallization device is provided, which includes a vibration device vibrating a laser beam along its long axis, wherein a vibration frequency at which the laser beam vibrates is satisfied by Equation 1 below.F<(P*f)/(2*W) Equation 1where F is the mirror vibration frequency, W is the laser beam width, P is the laser scan pitch, and f is the laser pulse frequency.