Offset Current Constriction for Stable Mounting of Narrow Semiconductor Lasers
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Solution Overview
Problem
Semiconductor laser elements with inclined substrates face challenges in mounting on sub-mounts due to narrow widths, leading to potential tilting, falling, or breaking, which affects heat dissipation and polarization performance, increasing manufacturing costs and reducing reliability.
Innovation Solution
A semiconductor laser element with a substrate having inclined and vertical side faces, featuring a current constriction part offset from the center, allowing for stable mounting with reduced force application, ensuring proper solder wetting and preventing chip instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the chip width is reduced to obtain more chips from a single wafer, then productivity increases, but the chip becomes unstable during mounting and may tilt, fall, collapse or break
Solution Approach 1:
The patent introduces asymmetry by offsetting the current constriction part from the center of the substrate in the first direction. This creates an asymmetric structure where the center of gravity is shifted, allowing the chip to be mounted stably on the sub-mount despite the narrow width. The asymmetric positioning of the current constriction part relative to the electrode enables stable mounting without requiring excessive chip width.
2Reliability
If excessive load is applied to improve solder wettability, then the joining quality improves, but the narrow chip may tilt, fall, collapse or break
Solution Approach 1:
The asymmetric offset of the current constriction part creates a configuration where the chip can be joined with appropriate load without excessive force. The offset positioning allows the joining load to be applied more effectively to the sub-mount interface rather than causing chip deformation, enabling good solder wettability while maintaining chip integrity.
Solution Approach 2:
The patent addresses the mounting stability issue by utilizing the first direction (perpendicular to the cavity direction) for offset positioning. This dimensional approach allows the current constriction part to be positioned offset from the center in the width direction while maintaining proper electrical and optical function, thereby enabling stable mounting without compromising chip strength.
3Strength
If load is reduced to prevent chip tilting and breakage, then chip stability improves, but solder wettability decreases and heat dissipation drops
Solution Approach 1:
The asymmetric offset configuration enables the chip to achieve both structural integrity and good solder wettability. The offset positioning of the current constriction part relative to the electrode creates a geometric relationship that allows moderate joining loads to effectively wet the solder while maintaining chip stability, avoiding both excessive force and insufficient bonding.
Data Source
AI summary
A semiconductor laser element includes an inclined substrate, a semiconductor layer formed on one surface of the substrate, a first electrode (n-type electrode) formed on an opposite surface of the substrate, a second electrode (p-type electrode) formed on the semiconductor layer, and a current constriction part formed in the semiconductor layer. The semiconductor layer has a multi-layer structure including at least an active layer. The current constriction part causes a current to concentrate and flow to a particular area of the active layer. The first electrode or the second electrode is joined to a sub-mount. In one embodiment, the location of the current constriction part in a chip width direction is between the center of one of the first and second electrodes, which is joined to the sub-mount, and the center of the other electrode, which is not joined to the sub-mount, when viewed in the chip width direction.