Substrate Conveyance Layout for Uniform Single-Pass Laser Irradiation
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Solution Overview
Problem
Existing conveyance systems for laser irradiation processes, such as those used in laser anneal apparatuses, face challenges in stabilizing and efficiently conveying substrates to ensure high-speed and uniform laser irradiation, particularly in forming polycrystalline silicon thin films.
Innovation Solution
A conveyance apparatus with a levitation unit, a holding mechanism, and a moving mechanism that tilts the substrate conveyance direction relative to the laser beam path, combined with pusher pins and a rotary mechanism, allows for precise control and rotation of substrates to ensure comprehensive laser irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the substrate is conveyed in a state levitated by the levitation unit with the loading position and unloading position at the same location, then the substrate can circulate over the levitation unit twice to ensure comprehensive laser beam irradiation, but the conveyance stability and high-speed processing are compromised
Solution Approach 1:
The conveyance path is divided into two separate positions: a loading position for substrate insertion and an unloading position for substrate removal. This segmentation allows the substrate to be conveyed once through the laser irradiation region while maintaining stable levitation, eliminating the need for double circulation and thereby improving conveyance speed and processing efficiency.
Solution Approach 2:
The laser beam is configured to irradiate the substrate in a tilted direction relative to the conveyance direction, rather than perpendicular to it. This dimensional change in irradiation angle allows the entire substrate surface to be uniformly irradiated during a single pass, resolving the contradiction between comprehensive irradiation and high-speed conveyance.
2Device complexity
If the laser beam irradiates the substrate perpendicular to the conveyance direction, then the irradiation path is simplified, but the entire substrate surface cannot be uniformly irradiated at high speed
Solution Approach 1:
The laser beam irradiation direction is tilted relative to the substrate conveyance direction, creating a diagonal irradiation path. This angular adjustment ensures that the entire substrate surface receives uniform laser energy during a single pass, achieving complete crystallization without requiring complex multi-pass irradiation paths.
3Device complexity
If conventional conveyance mechanisms are used without pusher pins and rotary mechanism, then the device structure is simpler, but the substrate cannot be properly received from the transfer machine and rotated for comprehensive irradiation
Solution Approach 1:
Pusher pins are introduced as intermediary elements between the transfer machine and the levitation unit. These pins receive the substrate from the transfer machine and transfer it to the levitation unit, enabling proper substrate loading without requiring complex direct coupling mechanisms.
Solution Approach 2:
A rotary mechanism is incorporated to rotate the substrate to a predetermined orientation before it enters the laser irradiation region. This preliminary rotation ensures that the entire substrate surface is properly positioned for uniform laser irradiation, simplifying the overall process by eliminating the need for multiple passes or complex positioning adjustments during irradiation.
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 configuration enables stable and high-speed substrate conveyance, preventing moiré generation and improving display quality by ensuring uniform crystallization of amorphous silicon films into polycrystalline silicon films.
Implementation Method 1
a levitation unit configured to levitate a substrate over an upper surface of the levitation unit by ejecting gas
Implementation Method 2
a laser beam source configured to irradiate the substrate with a laser beam
Implementation Method 3
an amorphous silicon film is crystallized into a poly-silicon film
Data Source
AI summary
A conveyance apparatus according to the present embodiment is a conveyance apparatus configured to convey a substrate to irradiate the substrate with a linear laser beam and includes: a levitation unit including a loading region into which the substrate is loaded; a first holding mechanism configured to hold the substrate over the levitation unit; a first moving mechanism configured to move the first holding mechanism in a first conveyance direction; a plurality of pusher pins disposed in the loading region of the levitation unit and provided to be movable upward and downward to receive the substrate from a transfer machine transferring the substrate; and a rotary mechanism disposed among the plurality of pusher pins in the loading region of the levitation unit and configured to rotate the substrate.