Laser Processing Apparatus Scanner Frequency Control
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Solution Overview
Problem
The existing laser processing technologies face challenges in maintaining consistent intervals of pulsed laser beam spots on a circular stacked wafer, leading to potential failure in destroying the buffer layer or damaging the light-emitting layer, and result in uneven laser processing during grinding due to scanner frequency limitations.
Innovation Solution
A laser processing apparatus with a control unit that adjusts the operation frequency of a scanner and decimator to maintain pulsed laser beam spots at predetermined intervals, using an fθ lens for focusing and an acoustooptical device for pulse energy adjustment, ensuring the scanner operates within a safe frequency range and uniformly applies the laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the scanner operation frequency is increased to maintain constant laser beam spot intervals when scanning from outer circumferential side radially inwardly, then the spot interval consistency is improved, but the scanner may exceed its maximum allowable operation frequency, causing actual frequency to deviate from expected frequency
Solution Approach 1:
The patent applies dynamics by making the laser beam applying unit frequency-adjustable. The control unit dynamically changes the repetitive frequency of the pulsed laser beam based on the radial position during spiral scanning. As the scan moves from outer circumferential side toward the center, the required scanner frequency increases to maintain constant spot intervals, but the laser repetitive frequency is adjusted to compensate, ensuring the scanner operates within its safe frequency range while maintaining spot interval consistency.
2Manufacturing precision
If the scanner operation frequency is increased to maintain constant laser beam spot intervals, then the spot interval consistency is improved, but the intervals between laser beam spots may be disturbed, failing to destroy the buffer layer reliably
Solution Approach 1:
The patent applies parameter changes by adjusting the repetitive frequency parameter of the pulsed laser beam. The control unit changes the laser repetitive frequency in response to the radial position during spiral scanning. This parameter adjustment ensures that even as the scanner frequency varies to maintain constant spot intervals, the laser processing parameters remain optimized for reliable buffer layer destruction without damaging the light-emitting layer.
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 solution ensures uniform destruction of the buffer layer and smooth grinding by maintaining consistent laser beam spot intervals, preventing damage to the light-emitting layer and ensuring precise processing within the scanner's operational limits.
Implementation Method 1
a decimator for decimating pulses of the pulsed laser beam to adjust a repetitive frequency thereof
Data Source
AI summary
A laser processing apparatus includes a chuck table for holding a workpiece, a laser beam applying unit for applying a pulsed laser beam to the workpiece held by the chuck table while positioning spots of the pulsed laser beam on the workpiece, thereby processing the workpiece with the pulsed laser beam, and a control unit for controlling operation of the laser beam applying unit. The laser beam applying unit includes a laser oscillator for oscillating pulsed laser to emit a pulsed laser beam, a decimator for decimating pulses of the pulsed laser beam to adjust a repetitive frequency thereof, a scanner for scanning the spots of the pulsed laser beam over the workpiece at predetermined intervals, and an fθ lens for focusing the pulsed laser beam.