GaN Wafer Laser Marking for Defect Leakage Path Formation
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Solution Overview
Problem
Existing laser marking methods for nitride semiconductor substrates fail to effectively create a leakage path for defect detection in the epitaxial layer, as high-energy lasers only melt the surface without forming a detectable path, while low-energy lasers transmit through and cause substrate melting and fume explosion.
Innovation Solution
A laser marking method that irradiates the defect region with a wavelength within ±10% of 365 nm, corresponding to the band gap energy of GaN, to simultaneously mark the GaN layer and single-crystal silicon substrate, forming a leakage path for electric characteristics evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser with wavelength higher energy than band gap is used, then the surface of the semiconductor can be marked, but the laser only melts the surface and cannot form a detectable leakage path in the epitaxial layer
Solution Approach 1:
The patent changes the wavelength parameter of the laser to be lower than the band gap energy of GaN (e.g., 450nm or 532nm), which fundamentally alters the laser's interaction with the semiconductor material. This parameter change enables the laser to pass through the GaN layer and mark the substrate, creating a detectable leakage path while still achieving surface marking through the combined effect on both layers.
2Reliability
If a laser with wavelength lower energy than band gap is used, then the laser can pass through the semiconductor and mark the substrate, but the laser heats and melts the substrate causing fume explosion and scattering
Solution Approach 1:
The patent applies local quality by creating different marking effects in different layers. The GaN layer experiences minimal heating and no melting due to the laser wavelength being above its band gap, while the substrate layer absorbs the laser energy and forms a leakage path. This localized differential response prevents fume generation from the GaN layer while still achieving the desired substrate marking.
Solution Approach 2:
The patent uses the substrate as a marker that copies the defect location information. By forming a leakage path in the substrate at the same location as the defect, the substrate itself becomes the marker, eliminating the need for separate marking materials and avoiding the harmful effects of excessive heating and fume generation.
3Manufacturing precision
If conventional laser marking is performed on nitride semiconductor substrate, then the surface can be marked, but the method cannot simultaneously mark both the GaN layer and substrate surfaces to form a detectable leakage path
Solution Approach 1:
The patent achieves multi-functionality by using a single laser wavelength that simultaneously performs multiple functions: it marks the GaN layer surface, passes through to mark the substrate, and creates a detectable leakage path. This universal laser parameter solution replaces the need for multiple separate marking processes or complex multi-wavelength systems.
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 method enables reliable detection and removal of defective chips by forming a leakage path at the interface, improving productivity and reducing production costs by preventing fume generation and maintaining a clean surface.
Implementation Method 1
irradiating the defect region with a laser of a wavelength within ±10% of 365 nm, having a wavelength corresponding to a band gap energy of GaN
Implementation Method 2
a laser of a wavelength within ±10% of 365 nm, having a wavelength corresponding to a band gap energy of GaN
Implementation Method 3
performing a laser marking on a defect region of a nitride semiconductor substrate
Implementation Method 4
having a wavelength corresponding to a band gap energy of GaN... preventing fume generation and maintaining a clean surface
Data Source
AI summary
A wafer marking method uses a laser for performing a laser marking on a defect region of a nitride semiconductor substrate in which a nitride semiconductor layer contains at least a GaN layer formed by epitaxial growth on a single-crystal silicon substrate. The method includes that a surface of the GaN layer and a surface of the single-crystal silicon substrate are performed laser marking simultaneously by irradiating the defect region with a laser of a wavelength within ±10% of 365 nm, having a wavelength corresponding to a band gap energy of GaN.