Laser Beam Phase Modulation for Top-Hat Dicing Profiles
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Solution Overview
Problem
Existing laser dicing methods using masks attenuate the laser beam's energy, reducing its effectiveness in processing workpieces with desired profiles.
Innovation Solution
A laser processing machine with a phase modulation unit that adjusts the laser beam's intensity distribution from a Gaussian to an airy disk pattern, allowing it to form a top-hat profile without using a mask, thereby maintaining the beam's energy for processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mask is used to adjust the laser beam profile to a desired shape, then the processing profile precision is improved, but the laser beam energy is blocked and attenuated
Solution Approach 1:
The patent replaces the mechanical mask system with an optical phase modulation system. Instead of using a physical mask to block and shape the laser beam, the invention uses a phase modulation unit (such as a spatial light modulator or phase plate) to modulate the phase of the laser beam, which then self-organizes into the desired top-hat profile through optical field distribution. This substitution eliminates the energy loss caused by mask blocking while achieving the same profile precision.
Solution Approach 2:
The patent changes the parameter of the laser beam from intensity modulation (using masks) to phase modulation. By modulating the phase parameter of the laser beam rather than its intensity, the system achieves the desired top-hat intensity distribution at the focal point without physically blocking the beam. This parameter transformation allows energy preservation while maintaining profile precision.
2Manufacturing precision
If a mask is used to form the laser beam image, then the desired profile is achieved, but the processing energy contribution is reduced
Solution Approach 1:
The patent replaces the mechanical mask-based image formation system with an optical phase modulation system. The phase modulation unit modulates the phase of the incident laser beam, and through optical field distribution and focusing, the desired top-hat profile is formed at the focal point. This eliminates the need for masks that block energy, thereby maximizing the processing energy contribution while maintaining beam profile accuracy.
Solution Approach 2:
The patent introduces a phase modulation unit as an intermediary between the laser beam source and the workpiece. This intermediary modulates the phase of the laser beam, which then self-organizes into the desired profile through optical field distribution. The phase modulation unit acts as a mediator that transforms the beam characteristics without blocking energy, unlike masks that directly obstruct the beam path.
3Device complexity
If Gaussian distribution laser beam is used for processing, then the system is simple, but the processing uniformity across the street width is poor
Solution Approach 1:
The patent changes the intensity distribution parameter of the laser beam from Gaussian to top-hat distribution through phase modulation. The phase modulation unit modulates the phase of the incident laser beam such that, after focusing, the intensity distribution at the focal point becomes a top-hat profile with uniform intensity across the street width. This parameter change improves processing uniformity while adding only a single phase modulation component to the system.
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
Enables laser processing with a desired profile without energy attenuation, improving precision and reducing damage to devices and cutting blade wear during dicing.
Implementation Method 1
a phase modulation unit arranged between the laser oscillator and the image-forming element and configured to cause a phase difference in the laser beam such that the laser beam forms an intensity distribution along a Gaussian distribution in the X-axis direction parallel to each street set on the workpiece and forms an intensity distribution along a top-hat profile at the image-forming point in the Y-axis direction
Implementation Method 2
an image-forming element that focuses, on the workpiece, the laser beam emitted from the laser oscillator
Data Source
AI summary
A laser beam irradiation unit of a laser processing machine includes a laser oscillator, an image-forming element that focuses, on a workpiece, a laser beam emitted from the laser oscillator, and a phase modulation unit arranged between the laser oscillator and the image-forming element and configured to cause a phase difference in the laser beam such that the laser beam forms an intensity distribution along a Gaussian distribution in an X-axis direction parallel to each street set on the workpiece and forms an intensity distribution along a top-hat profile at an image-forming point in a Y-axis direction as a width direction of the each street set on the workpiece.