Laser Processing Apparatus with Chromatic Aberration Height Detection
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Solution Overview
Problem
Existing laser processing methods for semiconductor workpieces face challenges in accurately measuring surface height due to undulations, leading to inconsistent laser processing and handling issues with white light sources, which affects the efficiency and stability of wavelength component focusing.
Innovation Solution
A laser processing apparatus with a configuration that includes a white light source, a second focusing lens, optical fibers, and a detector system with diffraction gratings and light intensity sensors to stabilize the focusing of white light on the workpiece, allowing for precise detection of surface height and edge position, and control of the laser processing based on this information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a pinhole is used to guide reflected light to a photodetector, then the apparatus structure is simple, but multiple wavelength components (both focused and unfocused) are guided to the photodetector, reducing measurement precision
Solution Approach 1:
The patent introduces a monochromator as an intermediary device between the pinhole and photodetector. This monochromator selectively transmits only the focused wavelength component while blocking unfocused wavelength components, thereby improving measurement precision without significantly complicating the overall apparatus structure
Solution Approach 2:
The patent changes the optical parameter (wavelength selection) by using a monochromator to filter light based on its wavelength. This allows the system to distinguish between focused and unfocused light components by their different wavelengths, thereby improving measurement precision while maintaining relatively simple apparatus structure
2Ease of operation
If white light is emitted without limitation to the workpiece, then the white light source is easy to use, but the white light is hard to handle and focus efficiently
Solution Approach 1:
The patent changes the wavelength parameter of white light by using a monochromator to select and transmit only specific focused wavelength components. This transformation converts broad-spectrum white light into a more controllable, focused wavelength component, improving focusing stability while maintaining ease of operation through automated wavelength selection
3Productivity
If the focal position is not corrected according to surface height variations, then the laser processing is simple and fast, but the laser processed groove or modified layer is not uniform, reducing manufacturing precision
Solution Approach 1:
The patent performs preliminary measurement of surface height variations using the improved detection apparatus before laser processing. This preliminary action provides advance information about surface undulations, allowing the laser processing system to pre-calculate and prepare the necessary focal position corrections, thereby maintaining high processing speed while ensuring uniform laser processed grooves
Solution Approach 2:
The patent implements a feedback mechanism where the detection apparatus continuously measures surface height variations and feeds this information back to the laser processing system. This feedback loop enables real-time adjustment of focal position based on actual surface conditions, ensuring uniform laser processed grooves while maintaining high processing speed through automated control
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 configuration improves the measurement performance of surface height by ensuring only the focused wavelength component is propagated, enabling more accurate and stable laser processing even with varying workpiece surface heights, thus enhancing the quality of semiconductor chip division.
Implementation Method 1
This detecting apparatus utilizes the fact that the white light passed through a chromatic aberration lens has different focal lengths according to the wavelengths of the white light
Implementation Method 2
a second optical fiber for guiding the reflected light to the detector
Implementation Method 3
a detecting apparatus for detecting the surface height of a workpiece by using white light
Data Source
AI summary
A laser processing apparatus including a detecting unit. The detecting unit includes a white light source for emitting white light, a focusing lens for focusing the white light to the workpiece, a first optical fiber for guiding the white light emitted from the white light source to the focusing lens, a detector for detecting the intensity of reflected light from the workpiece, and a second optical fiber for guiding the reflected light to the detector. Accordingly, the white light to be focused to the workpiece can be easily handled and only a wavelength component focused on the workpiece can be stably propagated.