VCSEL Array Second Separation Trench Moisture Protection
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Solution Overview
Problem
Vertical-cavity surface-emitting laser (VCSEL) arrays are susceptible to oxidation due to moisture, leading to performance issues, as the semiconducting multilayer films can separate and be affected by physical shocks during manufacturing, causing microcracks that allow moisture intrusion.
Innovation Solution
The implementation of a surface-emitting laser array design that includes a second separation trench surrounding the light-emitting units, which reaches the substrate and is filled with a dielectric film, such as silicon nitride, to prevent moisture intrusion and enhance shock resistance, combined with selective oxidation of the upper semiconductor DBR to create an oxidized and non-oxidized area for current control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If circumferential trenches are formed at outer edges of pad-forming area to isolate chips, then moisture intrusion is prevented and semiconducting multilayer film oxidation is reduced, but outermost edges become susceptible to physical shock causing microcracks that allow moisture intrusion
Solution Approach 1:
The invention divides the protection structure into multiple segments: the circumferential trench for chemical isolation and a second separation trench for mechanical protection. This segmentation allows each structure to specialize in one function, resolving the contradiction between oxidation resistance and shock susceptibility.
Solution Approach 2:
The second separation trench acts as an intermediary structure between the chip edge and the circumferential trench. It provides mechanical buffering against physical shocks while maintaining the chemical isolation function of the circumferential trench, thus protecting against both oxidation and physical damage.
2Reliability
If semiconducting multilayer film is used for VCSEL arrays, then laser emission performance is achieved, but the film is susceptible to oxidization due to high aluminum content
Solution Approach 1:
The invention extracts the protective function from the semiconducting multilayer film itself and implements it through separate structural elements (circumferential trench and second separation trench). This allows the film to maintain its laser-emitting function while the trenches provide oxidation protection.
Solution Approach 2:
The invention creates a composite protection system combining the circumferential trench (for chemical isolation) and the second separation trench (for mechanical protection). This composite structure addresses both oxidation resistance and physical shock resistance simultaneously.
3Reliability
If interlayer insulator film covers exposed surfaces of semiconducting multilayer film, then oxidation is prevented, but microcracks develop on the film surface due to physical shock during manufacturing
Solution Approach 1:
The second separation trench is formed beforehand to provide mechanical protection before the interlayer insulator film is applied. This preliminary structural reinforcement prevents microcrack development during subsequent manufacturing processes, ensuring film integrity while maintaining oxidation protection.
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 effectively prevents moisture intrusion and enhances the reliability and longevity of the VCSEL arrays by providing a barrier against environmental moisture and physical shocks, ensuring consistent performance.
Implementation Method 1
a second separation trench 13 which surrounds the light-emitting units 1, reaches the substrate 100 and is filled with a dielectric film 109
Implementation Method 2
selective oxidation of the upper semiconductor DBR to create an oxidized and non-oxidized area for current control
Data Source
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AI summary
A surface-emitting laser array (10, 10A, 10B, 10C) and a laser device (300) including the surface-emitting laser array (10, 10A, 10B, 10C). The surface-emitting laser array (10, 10A, 10B, 10C) includes a layered product including a lower reflecting mirror (102) having two layers with different refractive indexes, an upper reflecting mirror (106), and an active layer (104) disposed between the lower reflecting mirror (102) and the upper reflecting mirror (106), a first separation trench (11) from which the upper reflecting mirror (106), the active layer (104), and the lower reflecting mirror (102) are removed, the first separation trench (11) separating the surface-emitting laser array (10, 10A, 10B, 10C) from an adjacent chip (10, 10A, 10B, 10C), and a second separation trench (13) disposed between the first separation trench (11) and a light-emitting unit (1) that emits a laser beam, the second separation trench (13) having a prescribed depth.