Wafer Laser Cutting with Transparent Chuck and Optical Inspection
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Solution Overview
Problem
Existing wafer cutting methods, such as laser processing, face challenges in confirming complete cutting along streets without detaching the wafer, especially when there are variations in wafer thickness or test element groups, leading to difficulties in reprocessing incomplete cuts.
Innovation Solution
A wafer processing method and apparatus that uses a chuck table with a transparent holding member and a light emitting body, allowing for real-time imaging and confirmation of complete cuts during processing, enabling reprocessing without removing the wafer, and adjusting processing conditions based on incomplete cutting proportions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser processing is used to cut the wafer along the streets, then cutting speed and flexibility are improved, but complete cutting cannot be confirmed without detaching the wafer, leading to reprocessing difficulties
Solution Approach 1:
The patent implements a feedback mechanism by using an imaging means to capture images of the wafer during laser processing and automatically determine whether cutting is complete based on the captured images. This allows real-time confirmation of cutting completeness without detaching the wafer, resolving the contradiction between high-speed laser cutting and reliable cutting confirmation.
Solution Approach 2:
The patent introduces an intermediary system consisting of the imaging means and determination means that acts as a mediator between the laser processing and the quality confirmation. This intermediary enables non-contact, real-time detection of cutting completeness, eliminating the need to detach the wafer for inspection.
2Measurement precision
If the wafer is detached after processing to check cutting completeness, then inspection accuracy is improved, but device movement occurs causing reprocessing alignment errors
Solution Approach 1:
The patent enables the wafer to self-inspect its own cutting completeness through the imaging means while remaining on the chuck table. The determination means analyzes images of the same wafer position that was just processed, eliminating the need for detachment and subsequent repositioning, thus preventing alignment errors.
Solution Approach 2:
The patent replaces the mechanical detachment and manual inspection system with an optical imaging and automatic determination system. This substitution allows inspection to be performed in-situ without physical handling, eliminating the source of alignment errors caused by wafer movement during detachment and repositioning.
3Reliability
If laser processing parameters are adjusted to ensure complete cutting through variations in wafer thickness, then cutting reliability is improved, but processing time increases
Solution Approach 1:
The patent employs partial action by using the imaging means to inspect only the specific regions where cutting completeness needs to be confirmed, rather than inspecting the entire wafer or using overly conservative processing parameters for all areas. This allows optimized processing time while ensuring reliability where needed.
Solution Approach 2:
The patent performs preliminary determination of cutting completeness immediately after laser processing while the wafer is still on the chuck table. This preliminary action allows immediate identification of incomplete cuts and enables prompt reprocessing without waiting for post-processing inspection, thereby minimizing total processing time.
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
Enables accurate confirmation and reprocessing of incomplete cuts without wafer detachment, ensuring precise cutting and allowing for adjustments in processing conditions to improve cutting efficiency.
Implementation Method 1
a light emitting body disposed laterally of a side of the holding member opposite to the holding surface
Implementation Method 2
determining acceptance or rejection of the penetration based on whether or not light has passed through the processing region
Data Source
AI summary
In a wafer processing method for penetrating a wafer by use of a laser processing apparatus including a chuck table for holding the wafer, laser beam irradiation means for irradiating the wafer held on the chuck table with a laser beam, and imaging means for imaging the wafer held on the chuck table, the chuck table includes a chuck table main body, a holding member disposed on an upper surface of the chuck table main body and having a holding surface for holding an entire surface of the wafer, the holding member comprising a transparent or translucent member, and a light emitting body disposed laterally of a side of the holding member opposite to the holding surface. The wafer processing method comprises irradiating a predetermined processing region of the wafer held on the chuck table with the laser beam to perform the penetration in a predetermined manner, then lighting the light emitting body, with the wafer being held on the chuck table, imaging the processing region by the imaging means, and determining acceptance or rejection of the penetration based on whether or not light has passed through the processing region.