Nitride Semiconductor Groove Depth Control for Clean Laser Separation
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Solution Overview
Problem
The existing methods for separating nitride semiconductor devices using sapphire or GaN substrates result in uncleaved and cleaved surfaces, making automatic assembly difficult and increasing processing residue, while increasing laser power for separation leads to debris formation, compromising the reliability of semiconductor light emitting apparatuses.
Innovation Solution
A compound semiconductor device with a laminated body featuring cleaved and uncleaved surfaces, where a groove with varying depth is formed on the uncleaved surface using YAG laser irradiation, allowing for separation without reaching the cleaved surfaces, and a method involving laser irradiation to create grooves that do not penetrate the cleaved surfaces, reducing debris and enhancing separation yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a scribe groove is formed using a diamond needle to separate devices, then separation is achieved, but uncleaved and cleaved surfaces are created making automatic assembly difficult and increasing processing residue
Solution Approach 1:
The patent replaces the mechanical scribing method (diamond needle) with a laser-based method. The laser beam forms grooves by melting and evaporating material, eliminating mechanical contact. This substitution removes the tool wear and mechanical stress issues that caused mixed cleaved/uncleaved surfaces, enabling fully automated processing without compromising separation quality.
Solution Approach 2:
The patent changes the separation method from mechanical to optical/thermal by using laser parameters (wavelength, power, pulse duration, scanning speed) instead of mechanical parameters (needle hardness, applied force, scanning speed). This allows precise control over groove formation to create clean separation surfaces that are suitable for automatic assembly while reducing processing residue.
2Productivity
If laser power is increased to improve separation yield, then separation efficiency is improved, but debris and processing residue increase compromising device reliability
Solution Approach 1:
The patent employs pulsed laser irradiation instead of continuous laser power. By using periodic pulses with optimized duration and frequency, the material is removed in controlled increments, allowing heat to dissipate between pulses and prevent excessive melting and debris generation. This periodic action maintains high separation yield while minimizing harmful residue.
Solution Approach 2:
The patent uses high peak power laser pulses that rapidly vaporize material before heat can diffuse to surrounding areas. This 'rushing through' approach completes the separation action quickly, preventing the formation of excessive debris while maintaining high separation efficiency. The brief interaction time reduces the opportunity for harmful residue generation.
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 enables efficient separation of nitride semiconductor devices with reduced debris and improved surface cleanliness, facilitating stable operation of semiconductor laser apparatuses by minimizing attachment of processing residue to critical mirror surfaces, thus enhancing the reliability and longevity of the devices.
Implementation Method 1
forming a groove on a major surface of the bar by laser irradiation
Implementation Method 2
the groove having a depth from the major surface varied with position
Data Source
AI summary
A compound semiconductor device includes a laminated body including a crystal substrate and a compound semiconductor multilayer film. The laminated body has a major surface, a first side face, a second side face, a third side face, and a fourth side face. The first and the second side faces are opposed to each other, substantially perpendicular to the major surface of the laminated body, made of cleaved surfaces. The third and the fourth side faces are perpendicular to the major surface and to the first and the second side faces, opposed to each other, and made of uncleaved surfaces. A groove is provided on the third side face, and the groove has a depth varied with position as viewed from the major surface, and has ends not reaching the first and second side face.