GaAs Wafer Laser Cutting via Debris Shielding Film
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Solution Overview
Problem
The existing laser processing methods for gallium arsenide wafers result in reduced transverse rupture strength of chips due to debris attachment on cut surfaces, which is exacerbated when cutting gallium arsenide wafers compared to silicon wafers.
Innovation Solution
A laser processing method involving a debris shielding film coating step, followed by laser-processed trench formation and cutting-off steps, where the laser beam is radiated through the shielding film to prevent debris from attaching to device surfaces and attach debris to the cut surface, thereby increasing transverse rupture strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser beam is radiated to a gallium arsenide wafer along streets to carry out ablation processing, then the wafer can be cut off along the streets, but heat energy is concentrated on the region to which the laser beam is radiated, thereby generating debris that attaches on surfaces of devices and reduces chip quality
Solution Approach 1:
The patent introduces a debris shielding film as an intermediary layer between the laser beam and the device surfaces. This film captures the debris generated during laser ablation, preventing it from attaching to the device surfaces. The film is applied to the rear surface of the wafer and serves as a sacrificial barrier that protects the front surface devices during the cutting process.
Solution Approach 2:
The patent extracts the harmful debris from the cutting region by using the debris shielding film to collect and remove it from the vicinity of the device surfaces. The debris is taken out of the problematic zone where it would otherwise contaminate the devices, allowing the cutting process to proceed without compromising chip quality.
2Object-affected harmful factors
If a debris shielding film is used to prevent debris attachment on device surfaces, then chip quality is improved, but the transverse rupture strength of chips is reduced when debris attaches on cut surfaces
Solution Approach 1:
The patent converts the harmful effect of debris attachment into a beneficial one by intentionally allowing debris to attach to the cut surfaces. The debris forms a filler material in the trenches, and subsequent plasma processing transforms this debris into a beneficial filling that strengthens the cut surfaces. The harmful debris becomes a strength-enhancing element.
Solution Approach 2:
The patent changes the physical and chemical parameters of the debris through plasma processing. The debris material undergoes parameter changes that transform it from a weak contaminant into a strong filling material that enhances the mechanical properties of the cut surfaces, thereby increasing transverse rupture strength.
3Object-affected harmful factors
If the laser beam is radiated through a debris shielding film to form trenches, then debris is prevented from attaching to device surfaces, but the laser processing complexity increases due to multiple steps
Solution Approach 1:
The patent merges multiple processing steps into an integrated sequence: the debris shielding film application, laser ablation trench formation, debris attachment, and plasma processing are combined into a coordinated multi-step process. This merging allows the harmful debris to be converted into a beneficial element while maintaining systematic control over the entire manufacturing process.
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 method effectively increases the transverse rupture strength of gallium arsenide chips by attaching fine debris to the cut surface, while preventing debris from adhering to device surfaces, thus enhancing the quality of the chips.
Implementation Method 1
a laser beam is radiated along the streets from the debris shielding film side to the gallium arsenide substrate having the surface coated with the debris shielding film, thereby forming laser-processed trenches
Implementation Method 2
a laser beam with a wavelength having an absorption property for the gallium arsenide substrate
Implementation Method 3
coating a surface of the gallium arsenide substrate having the rear surface stuck on the protective member with a debris shielding film
Implementation Method 4
radiating the laser beam with the wavelength having the absorption property for the gallium arsenide substrate along the laser-processed trenches to the gallium arsenide substrate having the laser-processed trenches formed therein, thereby forming cut-off trenches
Data Source
AI summary
A laser processing method for a gallium arsenide wafer of radiating a laser beam along streets formed in lattice on a surface of a gallium arsenide substrate, and cutting-off the gallium arsenide wafer along the streets includes a wafer supporting step for sticking a rear surface of the gallium arsenide substrate on a protective member, a debris shielding coating step for coating the surface of the gallium arsenide substrate with a debris shielding film, a laser-processed trench forming step for radiating a laser beam along the streets from the debris shielding film side to the gallium arsenide substrate, thereby forming laser-processed trenches each not reaching the rear surface, and a cutting-off step for radiating the laser beam along the laser-processed trenches to the gallium arsenide substrate, thereby forming cutting-off trenches each reaching the rear surface.