Dynamic Beam Stop Adjusts Laser Line for Non-Planar Film Surfaces
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Solution Overview
Problem
Existing laser crystallization systems face challenges in maintaining uniform energy density and steep sidewalls for amorphous silicon films due to surface variations and limited depth of focus, leading to undesirable crystal quality and surface profiles.
Innovation Solution
A system with adjustable beam stops and sensors measures surface variations to dynamically adjust the focused line beam, ensuring uniform energy distribution and steep sidewalls by moving beam stop segments to conform to the film's surface profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a focused line beam with shallow depth of focus is used to achieve steep sidewalls and high resolution, then manufacturing precision is improved, but the system becomes sensitive to surface variations causing non-uniform energy density
Solution Approach 1:
The patent implements dynamic focusing by making the focal plane adjustable along the optical axis. The focal position can be changed in real-time to match surface height variations, allowing the system to maintain both shallow depth of focus for steep sidewalls and adaptability for uniform energy density across non-planar surfaces
Solution Approach 2:
The system changes the focal plane parameter dynamically to compensate for surface variations. By adjusting the focal position z-coordinate based on measured surface topography, the system maintains optimal focus conditions despite surface height differences, ensuring uniform energy density while preserving the shallow depth of focus needed for steep sidewalls
2Reliability
If a larger depth of focus is used to accommodate surface variations, then energy density uniformity is improved, but sidewall steepness and manufacturing precision deteriorate
Solution Approach 1:
Rather than using a large static depth of focus, the system uses dynamic refocusing to maintain a shallow depth of focus at the correct plane. The focal position is adjusted in real-time to match surface variations, achieving both uniform energy density and steep sidewalls by keeping the beam tightly focused at the actual surface location
3Device complexity
If fixed beam stops are used to define the beam profile, then device complexity is reduced, but the system cannot adapt to surface variations causing poor manufacturing precision
Solution Approach 1:
The beam stops are made movable along the optical axis, allowing their positions to be adjusted dynamically. This enables the beam stops to maintain proper alignment with the focused beam and surface, adapting to surface height variations while defining the beam profile, thus achieving both adaptability and manufacturing precision without excessive complexity
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 achieves a more uniform energy density and steep sidewalls, improving crystal quality and surface flatness, making the crystallized films suitable for applications like LCDs and OLEDs.
Implementation Method 1
a sensor that measures a distance between a selected point on a surface of the film and a reference plane and generates a signal representative of the measured distance
Implementation Method 2
An actuator may be coupled to the beam stop and responsive to the signal to move a portion of beam stop edge
Implementation Method 3
An optic may then be used to produce an image of the short-axis stop at the film
Implementation Method 4
the melting of an amorphous silicon film to induce crystallization of the film upon resolidification of the melted segment
Implementation Method 5
melting of an amorphous silicon film to induce crystallization of the film upon resolidification
Data Source
AI summary
Systems and methods are disclosed for shaping laser light as a line beam for interaction with a film that may have an imperfect, non-planar surface. The system may include a beam stop that defines an edge; a sensor that measures a distance between a selected point on a surface of the film and a reference plane and generates a signal representative of the measured distance; and an actuator coupled to the beam stop and responsive to the signal to move a portion of beam stop edge. Movement of the beam stop edge portion shifts a corresponding portion of the focused line beam in a direction normal to the reference plane to produce a line beam that more closely conforms to the surface profile of the film.