VUV Excimer Laser Machining 3D Structures
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Solution Overview
Problem
Existing laser machining systems face challenges in creating high-resolution three-dimensional structures on sensitive materials and curved surfaces due to thermal effects and limited processing speed, especially when using 248 nm lasers, which result in melting and deformation of materials like PMMA and other thermally sensitive polymers.
Innovation Solution
A laser machining system that employs a vacuum ultraviolet (VUV) excimer laser with a wavelength of 193 nm, a sealed beam delivery system, and coordinated opposing motion (COMO) between the workpiece and mask to control laser beam intensity and scanning, allowing for precise imaging and material removal on rotating workpieces, enabling the creation of complex 3-D structures with reduced thermal damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a 248 nm laser is used to machine sensitive materials, then processing speed can be improved, but thermal effects cause melting and deformation of the material
Solution Approach 1:
The patent changes the laser wavelength parameter from 248 nm to 193 nm. This parameter change results in higher optical absorption by sensitive materials, enabling faster processing speeds while reducing thermal penetration depth and minimizing melting and deformation effects.
Solution Approach 2:
The patent replaces the conventional 248 nm laser system with a 193 nm vacuum ultraviolet excimer laser system. This substitution fundamentally changes the interaction mechanism between laser and material, achieving high-speed processing with reduced thermal damage through the different absorption characteristics at the shorter wavelength.
2Productivity
If laser energy density is increased to improve material removal rate, then productivity increases, but residual heat penetration increases causing loss of precision
Solution Approach 1:
The patent utilizes the wavelength parameter change to 193 nm, which increases optical absorption in sensitive materials. This allows achieving high material removal rates at lower fluence levels, thereby maintaining high precision features without excessive residual heat penetration that would occur at higher energy densities with longer wavelengths.
3Productivity
If high fluence is used to increase etch rate, then productivity improves, but excess energy is converted to heat causing thermal damage to adjacent material
Solution Approach 1:
By changing the laser wavelength to 193 nm, the patent achieves higher optical absorption in the material. This parameter change enables high etch rates to be achieved at lower fluence levels, significantly reducing the conversion of excess energy to heat and thereby minimizing thermal damage to adjacent material while maintaining high productivity.
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 effectively processes sensitive materials with high resolution and precision, minimizing thermal effects and achieving efficient machining of 3-D structures on both sensitive and non-sensitive materials, including polymers and biomedical devices, while maintaining cost-effectiveness and high processing speed.
Implementation Method 1
A structure may be machined by using the laser to selectively remove material according to the desired pattern
Implementation Method 2
laser ablation is the removal of thin layers (usually sub micron) of material at low fluence levels, where the ablated material carries at least some of the residual heat away from the remaining workpiece
Implementation Method 3
Sensitive materials generally have an optical absorption at the 248 nm wavelength that is low compared to the optical absorption at the 222 nm, 193 nm or 157 nm wavelengths
Data Source
AI summary
A system and method of laser machining rotates a workpiece about an axis of rotation, and translates the workpiece in a first direction along the axis of rotation. A mask defining a shape is translated in a second direction opposite the first direction, and a laser beam is directed at the mask such that the laser beam is scanned across the mask and at least a portion of the laser beam passes through the mask and toward the workpiece. The mask and the workpiece are translated with coordinating opposing motion to cause the laser beam to be imaged onto the workpiece with a shape or pattern corresponding to a shape or pattern defined by the mask. Rotation of the workpiece and the shape of the image on the workpiece produce different vectorial intensities such that material of the workpiece is removed to different respective depths to form a three-dimensional structure.