Laser Focal Control Using Pre-Scanned Surface Height Detection
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Solution Overview
Problem
As processing speed increases, existing laser processing devices face challenges in real-time control of the focal point of the laser beam due to delays in detecting the laser irradiation surface of the wafer, leading to inefficiencies and reduced processing quality, especially when abnormalities occur on the surface.
Innovation Solution
A laser irradiating device with a movable length measuring section that detects the height position of the laser irradiation surface ahead of the irradiation line, allowing for precise control of the focal point based on pre-acquired planned irradiation line information, and adjustable gap between the laser irradiation and length measuring sections to ensure accurate alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the scanning speed of the processing laser beam is increased to increase productivity, then productivity is improved, but a delay occurs when controlling the focal point according to displacement data, worsening manufacturing precision
Solution Approach 1:
The patent performs displacement measurement of the laser beam incident surface in advance using a separate axial distance measuring sensor before the laser processing begins. The measured displacement data is stored and then used to control the focal point position during high-speed laser processing, eliminating real-time measurement delays and enabling precise focal point control even at increased processing speeds
Solution Approach 2:
The patent introduces a separate axial distance measuring sensor as an intermediary component that measures displacement data ahead of time. This intermediary measurement system decouples the measurement process from the processing process, allowing the focal point control to use pre-acquired displacement data without being constrained by real-time measurement speed limitations
2Manufacturing precision
If a separate axial distance measuring sensor is used to measure displacement data in advance, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The separate axial distance measuring sensor serves multiple functions: it measures the displacement of the laser beam incident surface in advance, provides displacement data for focal point control, and enables correction of surface irregularities. This multi-functionality justifies the additional device complexity by delivering comprehensive measurement and control capabilities
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 enables the focal point of the laser beam to reliably follow the detection result of the laser irradiation surface, reducing delays and preventing inefficiencies in laser processing, while detecting abnormalities before they affect processing, thus enhancing processing quality and efficiency.
Implementation Method 1
detecting a height position of the laser irradiation surface by focusing a distance measuring laser beam on a planned irradiation line
Implementation Method 2
the focal point of the laser beam may deteriorate due to the difference in refractive index between the atmosphere and silicon
Data Source
AI summary
A laser irradiating method includes: detecting a height position of a laser irradiation surface of a workpiece by focusing a distance measuring laser beam onto a planned irradiation line as an irradiation line preceding an irradiation line in a sub-scanning direction from a length measuring section (24) provided to be movable in a main scanning direction together with a laser irradiation section (22) and is provided at a position preceding the laser irradiation section in the sub-scanning direction; and controlling a height position of a focal point of a laser beam irradiated from the laser irradiation section when irradiating a laser beam from the laser irradiation section with a planned irradiation line as a new planned irradiation line on the basis of planned irradiation line information acquired from a detection result of the height position of the laser irradiation surface of the workpiece detected by the length measuring section.