Wafer Laser Street Processing Inversion
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Solution Overview
Problem
Laser processing of wafers along streets leads to cumulative deviation in the position relationship between the focal point and the streets due to wafer expansion, necessitating alignment compensation, which reduces productivity.
Innovation Solution
A method using a rotatable chuck table and a laser beam processing machine that applies a laser beam along the streets in a specific sequence, with the outermost street on one side processed first, followed by adjacent streets, ensuring that the largest center area is processed last, minimizing cumulative displacement and eliminating the need for alignment compensation during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser beam is applied along the streets formed on the wafer, then the wafer is divided along the streets, but the wafer expands in a direction perpendicular to the streets, causing cumulative deviation in the position relationship between the focal point and the streets
Solution Approach 1:
The patent inverts the conventional processing sequence by processing streets from both outer edges toward the center, rather than from one side to the other. This reversal of the processing direction ensures that the cumulative expansion effect does not cause progressive misalignment, as each newly processed street serves as a reference for the next, maintaining consistent alignment throughout the wafer.
Solution Approach 2:
The patent segments the laser processing into two independent sequences: one starting from the first outermost street and proceeding toward the center, and another starting from the second outermost street and proceeding toward the center. This segmentation allows simultaneous or sequential processing from both edges, reducing total processing time while maintaining alignment precision through the inverted approach.
2Manufacturing precision
If alignment work for compensating for deviation is carried out during laser processing, then the position relationship between focal point and streets is maintained, but productivity is reduced due to additional alignment operations
Solution Approach 1:
The patent performs preliminary alignment work before laser processing begins, establishing the initial position relationship between the focal point and the streets. By conducting this alignment operation once before processing rather than continuously during processing, the patent eliminates repeated alignment interventions while maintaining precision throughout the entire processing sequence.
Solution Approach 2:
The inverted processing sequence from outer edges toward the center inherently compensates for thermal expansion effects without requiring additional alignment operations. The processing order itself becomes the compensation mechanism, eliminating the need for time-consuming intermediate alignment work.
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 approach maintains the position relationship between the focal point and the streets, eliminating the need for alignment compensation during laser processing, thereby enhancing productivity by maintaining consistent alignment and reducing processing deviations.
Implementation Method 1
a pulse laser beam of a wavelength (for example, 1,064 nm) having permeability for the workpiece... which continuously forms deteriorated layers in the workpiece along the streets
Implementation Method 2
forms deteriorated layers in the workpiece along the streets... whose strength has been reduced by the formation of the deteriorated layers
Implementation Method 3
a pulse laser beam of a wavelength (for example, 355 nm) having absorptivity for the wafer is applied along the streets formed on the wafer to form laser processed grooves
Data Source
AI summary
A method of carrying out laser processing on a wafer having a plurality of parallel streets on the front surface along the streets, comprising the steps of:carrying out a first laser processing step of carrying out laser processing along streets formed in one half area of the wafer by carrying out a laser beam application step for applying a laser beam along the streets by positioning the outermost street on one side in the indexing-feed direction of the wafer right below a condenser and an indexing-feed step for positioning a street adjacent to the street which has undergone the laser beam application step on the wafer right below the condenser sequentially; andcarrying out a second laser processing step of carrying out laser processing along streets formed in the other half area of the wafer by carrying out a laser beam application step for applying a laser beam along the streets by positioning the outermost street on the other side in the indexing-feed direction of the wafer which has undergone the first laser processing step right below the condenser and an indexing-feed step for positioning a street adjacent to the street which has undergone the laser beam application step on the wafer right below the condenser sequentially.