Laser Diode Mesa Stripe Cleavage via Trench Geometry
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Solution Overview
Problem
Existing methods for manufacturing laser diode devices often result in reduced yield due to cracks and chipping in cleaved surfaces, especially when cleaving semiconductor laser bars without scribed grooves in edge portions, leading to faulty cleavage and decreased efficiency.
Innovation Solution
The method involves forming separation trenches with wide portions in the edge and narrow portions in the central area of the semiconductor laser bar, and scribing grooves that terminate short of the edge portions to facilitate crack propagation, ensuring cleaved surfaces do not extend into mesa stripes, thereby preventing faulty cleavage and increasing yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If scribing is performed by means of a pointed tool such as a diamond needle, then grooves can be formed in the semiconductor laser bar, but the tool cannot be stabbed into the edge portions resulting in unscribed edge areas
Solution Approach 1:
The separation trenches are designed with different widths at different locations: wide portions at the edge portions and a narrow portion at the longitudinal central portion. This local variation in geometry allows the scribing tool to successfully complete grooves in the central area while the wide edge portions prevent crack propagation into mesa stripes, compensating for the tool's inability to scribe edge areas.
2Productivity
If the semiconductor laser bar is cleaved without scribed grooves in the edge portions, then the cleavage process can be completed, but the resulting cleaved surfaces have cracks or chippings resulting in reduced yield
Solution Approach 1:
Wide portions are formed in the separation trenches at the edge portions before the cleavage process. These wide portions act as preventive structures that stop crack propagation before cracks can reach the mesa stripes, thereby preventing the harmful effect of cracks and chippings on the cleaved surfaces.
Solution Approach 2:
The narrow portion in the longitudinal central area of the separation trenches is designed to facilitate crack propagation in a controlled manner, while the wide portions at the edges convert the potential harm of uncontrolled cracking into a benefit by guiding and limiting crack paths to prevent them from reaching the mesa stripes.
3Manufacturing precision
If crack propagation is caused from grooves, then the semiconductor laser bar can be split along the grooves, but cracks may extend to the mesa stripe resulting in reduced yield
Solution Approach 1:
The separation trenches have a non-uniform width profile with narrow portions in the central area that facilitate crack propagation and wide portions at the edges that prevent cracks from reaching the mesa stripes. This local differentiation in trench geometry simultaneously achieves precise cleavage paths and high manufacturing yield.
Solution Approach 2:
The separation trenches are segmented into different functional zones: wide portions at the edge portions that act as crack stoppers and a narrow portion in the longitudinal central portion that facilitates controlled crack propagation. This segmentation allows different regions to perform different functions in the cleavage 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
This approach enhances the manufacturing yield of laser diode devices by preventing cracks and slanted cleaved surfaces from reaching the mesa stripes, resulting in higher quality and more reliable cleavage processes.
Implementation Method 1
by causing crack propagation from the grooves, splitting the semiconductor laser bar along the grooves so as to form cleaved surfaces
Implementation Method 2
by causing crack propagation from the V-shaped trenches, splitting the semiconductor laser bar along the V-shaped trenches so as to form cleaved surfaces
Data Source
AI summary
A method of manufacturing a laser diode device includes: forming, in a semiconductor laser bar, separation trenches extending across all of a transverse dimension of the semiconductor laser bar and defining a mesa stripe, each of the separation trenches having wide portions located at longitudinal edge portions of the semiconductor laser bar and a narrow portion located in a longitudinal central portion of the semiconductor laser bar; scribing, in the semiconductor laser bar, grooves extending parallel to the separation trenches and terminating before reaching longitudinal edge portions of the semiconductor laser bar; and splitting the semiconductor laser bar along the grooves to form cleaved surfaces extending from a bottom surface of the semiconductor laser bar to bottom surfaces of the separation trenches.