Laser Processing Machine f-theta Lens Configuration
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Solution Overview
Problem
Existing laser processing machines face challenges in efficiently processing semiconductor wafers with low-k films due to laser beam debris smearing and machine upsizing, as they struggle to maintain a sufficient distance between the fθ lens and the processing point while preventing vibration from high-speed scan mirror operations.
Innovation Solution
A laser processing machine design incorporating an fθ main lens and an fθ sub-lens, where the fθ sub-lens converts the laser beam into diffused light, allowing for a larger distance between the fθ main lens and the processing point, and positioning the front focal point of the fθ main lens on the scan mirror to minimize machine size and prevent debris smearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the distance from the fθ lens to the processing point is increased to prevent debris smearing, then lens smearing is suppressed, but the machine size increases
Solution Approach 1:
A blowing unit is introduced as an intermediary component between the processing point and the fθ lens. This unit blows processed material away from the optical path, preventing debris from adhering to the lens while allowing the fθ lens to be positioned at an optimal distance without excessive machine enlargement
Solution Approach 2:
The harmful processed material (debris) is extracted and removed from the optical path by the blowing unit, eliminating the source of lens smearing and allowing for more flexible optical system design without requiring excessive distance between components
2Manufacturing precision
If the scan mirror is positioned at the front focal point of the fθ lens to ensure vertical beam incidence, then beam alignment is improved, but high-speed drive causes lens vibration
Solution Approach 1:
The optical system is segmented into distinct functional zones: the scan mirror operates at the front focal point for precise beam control, while the blowing unit is positioned downstream to remove debris. This segmentation allows the scan mirror to maintain optimal positioning for alignment without being constrained by vibration issues, as the blowing function handles debris removal separately
3Productivity
If the laser beam is scanned in Y-axis and X-axis directions to efficiently process while preventing melt backflow, then productivity is improved, but lens smearing occurs due to scattered debris
Solution Approach 1:
The blowing unit serves as a mediator that actively removes processed material from the optical path during scanning operations. This allows the laser beam to scan efficiently in both Y-axis and X-axis directions for high productivity while the blowing unit continuously clears debris that would otherwise smear the lens
Solution Approach 2:
The blowing unit operates continuously during the laser scanning process, maintaining a clear optical path throughout the entire processing cycle. This continuous action ensures that productivity is not compromised by intermittent lens cleaning stops, while simultaneously preventing lens smearing
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 vertical incidence of the laser beam on the workpiece while minimizing machine upsizing and suppressing lens smearing, improving processing efficiency and productivity.
Implementation Method 1
an fθ sub-lens that is arranged on the optical path between the laser oscillator and the scan unit and converts the laser beam from parallel light into diffused light
Implementation Method 2
an fθ main lens that focuses and applies the laser beam which has been emitted from the laser oscillator, to the workpiece held on the holding table
Implementation Method 3
a scan unit that is arranged on an optical path between the laser oscillator and the fθ main lens, scans the laser beam, and guides the resulting scanned laser beam to the fθ main lens
Data Source
AI summary
A laser beam application unit of a laser processing machine includes a laser oscillator that emits a laser beam, an fθ main lens that focuses and applies the laser beam which has been emitted from the laser oscillator, to a workpiece held on a holding table, a scan unit that is arranged on an optical path between the laser oscillator and the fθ main lens, scans the laser beam, and guides the resulting scanned laser beam to the fθ main lens, and an fθ sub-lens that is arranged on the optical path between the laser oscillator and the scan unit and converts the laser beam from parallel light into diffused light.