Laser Machining Apparatus with Separate Detection Beam Wavelength
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Solution Overview
Problem
Existing laser beam machining apparatuses struggle to accurately detect the height position of wavy or thick semiconductor wafers due to the coincidence of detection and machining laser beam condensing points, leading to reduced light intensity and inaccurate machining.
Innovation Solution
A laser beam machining apparatus with a detection laser beam of different wavelength, separate condensing point displacement means for the detection and machining laser beams, and chromatic aberration lenses to adjust the condensing points, ensuring accurate height detection and machining depth even on wavy surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the condensing point of the detection laser beam coincides with the condensing point of the machining laser beam, then the detection system can be simplified, but the spot area becomes very large when the condensing point is positioned deep, reducing light intensity and detection accuracy
Solution Approach 1:
The patent divides the laser beam system into two separate wavelength systems: a detection laser beam (first wavelength) and a machining laser beam (second wavelength). This segmentation allows independent optimization of each beam's condensing point position, enabling the detection beam to maintain a small spot size for accurate height detection while the machining beam can be focused deep into the workpiece for effective processing.
Solution Approach 2:
The patent changes the wavelength parameter of the laser beam used for detection, distinguishing it from the machining laser beam. By using different wavelengths, the system can apply different optical paths and condensing conditions to each beam, resolving the contradiction between simplified system design and detection accuracy.
2Manufacturing precision
If the condensing point of the machining laser beam is positioned deep into the workpiece, then effective machining at predetermined depth is achieved, but the detection laser beam spot area becomes very large, reducing light intensity per unit area
Solution Approach 1:
The patent segments the laser processing system into detection and machining functions with separate wavelength beams. The detection laser beam operates at a wavelength optimized for surface reflection and height detection, while the machining laser beam operates at a different wavelength optimized for deep penetration and material processing, allowing each to optimize its condensing point independently.
Solution Approach 2:
The patent utilizes wavelength as a key parameter to differentiate between detection and machining laser beams. By selecting appropriate wavelengths for each function, the system can control the optical properties of each beam, including penetration depth, spot size, and intensity distribution, to simultaneously achieve accurate detection and effective deep machining.
3Device complexity
If the detection laser beam spot area is large, then the system configuration is simplified, but the quantity of light per unit area is reduced, making accurate height position detection impossible
Solution Approach 1:
The patent implements functional segmentation by using separate laser beams for detection and machining. The detection laser beam is optimized with appropriate condensing conditions to produce a small spot size on the workpiece surface, ensuring sufficient light intensity for accurate height detection, while the machining beam handles the processing function.
Solution Approach 2:
The patent applies parameter optimization by selecting specific wavelengths and condensing conditions for the detection laser beam that maximize light intensity at the surface. This allows the detection system to achieve high measurement precision without requiring complex optical configurations, as the wavelength and focus parameters are optimized for surface reflection detection.
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 apparatus achieves precise height position detection and machining depth control, enabling accurate machining of wafers with waviness or thickness variations by maintaining a smaller detection laser beam spot and increasing light intensity per unit area.
Implementation Method 1
detection laser beam oscillating means for oscillating a detection laser beam different in wavelength from the machining pulsed laser beam
Implementation Method 2
the condensing point position displacing means includes a chromatic aberration lens for displacing a condensing point position into which the detection laser beam is condensed by the condenser lens
Implementation Method 3
condenser for condensing the machining pulsed laser beam oscillated by the machining laser beam oscillating means
Implementation Method 4
a reflected beam generated upon reflection by the workpiece held on the chuck table of a laser beam radiated through the detection laser beam irradiation path and the condenser
Data Source
AI summary
A laser beam machining apparatus includes a height position detecting unit configured to detect the height position of an upper surface of a workpiece to be machined which is held on a chuck table, and a controller configured to control a condensing point position adjusting unit on the basis of a detection signal from the height position detecting unit. The height position detecting unit includes a detection laser beam oscillating unit configured to oscillate a detection laser beam having a wavelength different from the wavelength of the machining laser beam, and a reflected beam analyzing unit which analyzes a reflected beam generated upon reflection of the detection laser beam on the upper surface of the workpiece and which sends an analytical results to the controller. The laser beam machining apparatus further includes a condensing point position displacing unit configured to displace the condensing point position of the detection laser beam and the condensing point position of the machining laser beam.