Laser Wafer Grooving via Segmented Shallow Passes
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Solution Overview
Problem
Laser beam machining methods for wafers with functional layers, such as nitride semiconductors on sapphire substrates, often result in melted layers that reduce chip quality and luminance, and can cause damage due to unmachined areas and rough groove surfaces.
Innovation Solution
A method involving a laser beam machining apparatus that alternately sets machining areas for forming machined grooves and shallow grooves, with the laser beam scanned from one end to the other while varying output power, ensuring the formation of continuous grooves and shallow grooves to minimize melted layers and enhance divisibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pulsed laser beam is used to machine grooves along streets on a wafer, then machining speed is improved, but the groove wall surfaces become melted and rough, causing lowered luminance in light emitting diodes
Solution Approach 1:
The patent segments the continuous groove formation process into multiple discrete laser beam irradiation passes. The laser beam is moved along the street in steps, creating a series of shallow grooves that are gradually deepened through repeated passes, rather than forming the complete groove depth in a single pass. This segmentation allows the melted material to cool and solidify between passes, preventing excessive melting and roughness while maintaining high machining speed.
2Productivity
If the laser beam is moved along streets to form machined grooves, then productivity is improved, but unmachined areas may be generated, lowering dividability and causing damage to the device layer
Solution Approach 1:
The patent applies preliminary action by first forming shallow grooves along the entire street path before deepening them. The laser beam initially creates shallow grooves at a lower power setting, ensuring complete coverage along the street. Then, in subsequent passes, the groove depth is increased to the final required depth. This preliminary shallow groove formation ensures no unmachined areas are left, guaranteeing proper wafer dividability while maintaining high productivity through the efficient multi-pass approach.
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 reduces the area of once-melted layers, minimizes luminance loss, and ensures secure groove formation for effective wafer division, maintaining chip quality and divisibility.
Implementation Method 1
a laser beam machining method for machining a transparent substrate of a wafer through ablation by irradiation with a laser beam
Data Source
AI summary
A laser beam machining method wherein machining areas in which to form machined grooves and machining start point areas in which to form shallow grooves shallower than the machined grooves are alternately set in each of streets formed on a wafer, and the machined grooves and the shallow grooves are continuously formed by scanning an irradiation point of a laser beam along each of the streets.