Slanted Convex Lens for Linear Laser Beam Formation
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Solution Overview
Problem
Conventional laser irradiation systems for semiconductor manufacturing are complex, difficult to adjust, and prone to return beams, which can interfere with output and frequency stability, and require larger footprints and additional components like isolators to manage reflectance issues.
Innovation Solution
A simplified laser irradiation system using a convex lens slantly set with respect to the laser beam to form a linear beam on the irradiation surface, with the beam incident at an angle greater than or equal to arctan(w/(2×d)), where w is the beam width and d is the substrate thickness, allowing for efficient annealing and crystallization of semiconductor films without the need for isolators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional optical system with cylindrical lens arrays is used to form linear laser beam, then the energy density distribution can be homogenized, but the device complexity increases and the footprint becomes larger
Solution Approach 1:
The patent extracts and eliminates the complex cylindrical lens arrays and beam homogenizer from the optical system. Instead of using multiple lens arrays to divide and synthesize laser beams, the invention uses a single convex lens with slanted incidence to directly form the linear beam with uniform energy density distribution, removing unnecessary optical components
Solution Approach 2:
The patent inverts the conventional approach by making the laser beam incident at a slant angle to the convex lens rather than perpendicularly. This slanted incidence (at an angle of 30° or more) creates astigmatism that naturally forms the linear beam shape and homogenizes energy density without requiring additional optical components
2Shape
If conventional optical systems are used, then linear beam can be formed, but return beams are generated that interfere with laser output stability
Solution Approach 1:
The patent converts the harmful return beam reflection into a beneficial effect by deliberately setting the laser beam to incident at a slant angle of 30° or more to the convex lens. This slanted incidence causes the return beam to be reflected away from the optical path at a different angle, preventing interference with the laser output while still achieving the desired linear beam formation on the substrate
3Shape
If conventional optical systems with multiple lens arrays are used, then beam shaping is achieved, but optical adjustment becomes difficult
Solution Approach 1:
The patent removes the complex multi-component optical system including cylindrical lens arrays and beam homogenizers, replacing them with a single convex lens used in an unconventional slanted incidence configuration. This drastic simplification makes optical alignment and adjustment significantly easier while maintaining the ability to form linear beams
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 system enables compact, efficient, and uniform annealing of semiconductor films, reducing electrical property variations and enhancing the reliability of TFTs, while simplifying optical adjustments and reducing costs by eliminating the need for isolators and minimizing return beams.
Implementation Method 1
a convex lens slantly set with respect to the traveling direction of the laser beam emitted from the laser and making the shape of the laser beam linear on an irradiation surface
Implementation Method 2
an astigmatism or the like is generated by laser beam being slantly incident with respect to the convex lens
Implementation Method 3
laser annealing is performed for a semiconductor film formed on an insulating substrate made of glass or the like, to crystallize the film
Implementation Method 4
to crystallize the film, to improve its crystallinity so that a crystalline semiconductor film is obtained
Data Source
AI summary
The present invention is characterized in that by laser beam being slantly incident to the convex lens, an aberration such as astigmatism or the like is occurred, and the shape of the laser beam is made linear on the irradiation surface or in its neighborhood. Since the present invention has a very simple configuration, the optical adjustment is easier, and the device becomes compact in size. Furthermore, since the beam is slantly incident with respect to the irradiated body, the return beam can be prevented.