Laser Processing Apparatus with Real-Time Groove Inspection
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Solution Overview
Problem
Existing laser processing methods for semiconductor wafers struggle to form proper through-grooves along all division lines due to abrupt thickness variations in molding resin, leading to blind holes and increased processing time, with current methods requiring manual inspection and discard of defective chips.
Innovation Solution
A laser processing apparatus featuring a chuck table with a transparent holding member, a laser processing unit, and an examination unit with a line sensor and determination section to assess and correct processing results in real-time, ensuring thorough groove formation without prolonging processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ablation by pulsed laser beam is used to form narrow grooves, then the cutting allowance can be minimized and division lines can be made thin, but processing time is prolonged when multiple scans are required to deepen grooves
Solution Approach 1:
The patent implements an examination unit with a line sensor that detects light transmitted through the workpiece to determine whether through-grooves are properly formed. This feedback mechanism allows the system to identify regions where grooves are incomplete and automatically re-process those areas, ensuring complete through-groove formation without requiring excessive initial scanning passes.
Solution Approach 2:
The examination unit performs preliminary detection of through-groove formation status before final processing completion. By detecting light transmission through the workpiece, the system can identify which regions require additional processing, allowing targeted re-processing rather than blanket multiple scans across the entire workpiece.
2Productivity
If minimum number of laser beam scans are used to shorten processing time, then productivity increases, but through-grooves cannot be properly formed in regions with abrupt thickness variations, resulting in blind holes
Solution Approach 1:
The line sensor in the examination unit provides real-time feedback on through-groove formation quality by detecting light transmission. When the sensor detects insufficient light transmission, indicating a blind hole or incomplete groove, the system automatically re-processes that specific region with additional laser scans, ensuring complete through-groove formation without requiring excessive initial scanning passes across the entire workpiece.
Solution Approach 2:
The system applies different processing strategies to different regions of the workpiece based on local characteristics. Regions with abrupt thickness variations that show incomplete groove formation receive additional localized processing passes, while regions that are already properly processed continue without further treatment, optimizing both quality and efficiency.
3Measurement precision
If manual inspection of wafers is performed after ablation, then defective regions can be identified, but all defective chips must be discarded, increasing loss of time and material
Solution Approach 1:
The examination unit with the line sensor enables the processing system to automatically inspect and identify defective regions without requiring manual inspection. The system self-diagnoses incomplete through-groove formation by detecting light transmission patterns, automatically marks defective regions, and triggers re-processing, eliminating the need for time-consuming manual inspection and subsequent discarding of all defective chips.
Solution Approach 2:
The line sensor provides automatic feedback on processing quality, allowing the system to identify and correct defective regions in real-time. This automated feedback loop replaces manual inspection, reducing inspection time and enabling selective re-processing of only the defective areas rather than requiring discarding of entire chips.
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 enables proper formation of through-grooves along all division lines, reducing defective chips and optimizing processing efficiency by allowing for immediate re-processing of substandard regions.
Implementation Method 1
a laser processing unit that applies a laser beam of such a wavelength as to be absorbed in the workpiece to the workpiece held by the chuck table, to form a through-groove along each of division lines
Implementation Method 2
a light emitting body that illuminates the workpiece through the holding member on the side of a surface opposite to the holding surface of the holding member
Implementation Method 3
an examination unit that examines the through-grooves of the workpiece held by the chuck table. The examination unit includes a line sensor that extends along a surface direction of the holding surface in a direction orthogonal to the processing feed direction, faces the holding surface and receives light from the light emitting body
Data Source
AI summary
A laser processing apparatus includes: a chuck table that holds a packaged wafer by a holding surface; a laser processing unit that applies a laser beam to the packaged wafer to form a through-groove along each division line; an X-axis moving unit that moves the chuck table in an X-axis direction; and an examination unit. The chuck table includes: a holding member that forms the holding surface; and a light emitting body. The examination unit includes: a line sensor that extends in a Y-axis direction; and a control unit that determines the result of processing through reception by the line sensor of light from the light emitting body through the through-groove. The line sensor images the whole surface of the packaged wafer being held by the chuck table.