Nitride Semiconductor Laser Chip Automatic Inspection
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Solution Overview
Problem
Nitride semiconductor laser devices with reduced widths face challenges in automatic chip inspection and mounting due to variations in ridge-like stripe positions and electrode pad areas, leading to incorrect defect determination and alignment issues.
Innovation Solution
Implementing a method that uses automatic image recognition to differentiate between chip types based on the position of stripe-like waveguide structures and electrode pad areas, with specific area ratios and reflectance differences to optimize chip selection and mounting processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the width of nitride semiconductor laser device is reduced to 50-250 μm to increase yield rate and reduce cost, then productivity is improved, but automatic chip inspection and mounting become difficult due to variations in ridge-like stripe positions and electrode pad areas
Solution Approach 1:
The patent applies the principle of optical property changes by forming a light-absorbing layer in specific regions to create reflectance differences. The light-absorbing layer is formed in the electrode pad region but not in the ridge-like stripe region, creating a visual contrast that enables automatic image recognition systems to distinguish between these features and accurately identify chip positions and orientations during automated inspection and mounting processes.
2Ease of operation
If automatic image recognition is implemented to differentiate chip types based on ridge-like stripe positions and electrode pad areas, then ease of operation is improved, but device complexity increases due to additional light-absorbing layer formation
Solution Approach 1:
The patent merges the light-absorbing layer formation process with the existing electrode pad formation process. The same photolithography and metal deposition steps used to create the electrode pad are utilized to form the light-absorbing layer in the electrode pad region, eliminating the need for separate processing steps and reducing overall device complexity despite adding functional capability for automatic recognition.
3Manufacturing precision
If ridge-like stripe position variations occur due to trenched region processing, then manufacturing precision is maintained for crack suppression, but measurement precision deteriorates for automatic image recognition
Solution Approach 1:
The patent introduces a light-absorbing layer as an intermediary element that mediates between the variable ridge-like stripe position and the automatic image recognition system. This light-absorbing layer provides a consistent, recognizable reference feature with distinct optical properties that the automatic recognition system can reliably detect regardless of ridge-like stripe position variations, thereby maintaining measurement precision while preserving the manufacturing precision benefits of trenched region processing.
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
Enables accurate and automatic selection of nitride semiconductor laser devices during inspection and mounting, reducing defective chip determination and improving process efficiency by optimizing chip and electrode pad configurations.
Implementation Method 1
an area not having the electrode pad for the second conductivity type is lower by more than 10% in reflectance with respect to almost the entire wavelength range of incident illumination light vertical to the chip during the automatic image recognition
Data Source
AI summary
A method of producing a nitride semiconductor laser device includes: forming a wafer including a nitride semiconductor layer of a first conductivity type, an active layer of a nitride semiconductor, a nitride semiconductor layer of a second conductivity type, and an electrode pad for the second conductivity type stacked in this order on a main surface of a conductive substrate and also including stripe-like waveguide structures parallel to the active layer; cutting the wafer to obtain a first type and a second type of laser device chips; and distinguishing between the first type and the second type of chips by automatic image recognition. The first type and the second type of chips are different from each other in position of the stripe-like waveguide structure with respect to a width direction of each chip and also in area ratio of the electrode pad to the main surface of the substrate.