Warped Semiconductor Laser Chip Residual Stress Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-power optical semiconductor devices face issues with residual stress in the resonator direction, leading to variations in polarization ratios and operating current values, which affect the stability and reliability of optical semiconductor devices used in high-speed optical communications and rewritable optical discs.
Innovation Solution
The optical semiconductor device features a semiconductor laser chip warped in an upward convex shape with a solder layer that fills the gap between the chip and the submount, ensuring uniform initial characteristics and reduced residual stress, thereby stabilizing the resonator and improving device reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flat semiconductor laser chip is mounted on a substrate, then electrical connection and heat dissipation are achieved, but residual stress occurs in the active layer due to different thermal expansion coefficients, causing distortion and instability
Solution Approach 1:
The semiconductor laser chip is designed with a warped convex shape instead of being completely flat. This curvature creates a gap between the mesa portion and the substrate, preventing direct contact between the active layer and solder, thereby reducing residual stress while maintaining structural integrity and stable oscillation characteristics
Solution Approach 2:
The chip structure is divided into different regions: a mesa portion with the active layer that remains elevated, and peripheral contact portions that provide electrical connection. This segmentation allows the active layer to be isolated from stress-inducing materials while maintaining necessary electrical and thermal pathways through other regions
2Reliability
If the semiconductor laser chip is warped in upward convex shape, then residual stress is reduced and oscillation stability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention changes the geometric parameter of the chip from flat to warped convex shape. This parameter change is achieved through controlled manufacturing processes that introduce specific curvature, transforming a simple flat structure into a functional warped structure that reduces stress while maintaining manufacturability
3Stress or pressure
If a gap is formed between the mesa portion and substrate, then residual stress is reduced, but electrical connection and heat dissipation efficiency may be compromised
Solution Approach 1:
The chip is segmented into a mesa portion that is elevated and isolated from the substrate to reduce stress, and peripheral regions that maintain contact for electrical connection and heat dissipation. This segmentation allows the active layer to be protected while other functions are preserved through alternative pathways
Solution Approach 2:
The warped convex structure acts as an intermediary that creates a gap between the stress-sensitive active layer and the substrate, while still allowing electrical connection through the solder to peripheral contact portions. This intermediary structure separates the functions of stress isolation and electrical/thermal connection
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 configuration results in uniform initial characteristics and reduced variations in operating current values, enhancing the performance and reliability of high-power optical semiconductor devices by minimizing residual stress and ensuring consistent laser beam emission.
Implementation Method 1
the semiconductor laser chip and the Si substrate have different thermal expansion coefficients. Therefore, during the solidification of the solder, the active layer 2 may be distorted or residual stress may be caused in the active layer 2
Implementation Method 2
an active layer 2 for emitting a laser beam is formed in part of the mesa portion 8 near the bottom surface of the semiconductor laser chip 1
Data Source
AI summary
An optical semiconductor device includes a semiconductor laser chip, a base for mounting the semiconductor laser chip and a solder layer sandwiched between the top surface of the base and the bottom surface of the semiconductor laser chip. The semiconductor laser chip is warped in upward convex shape.