Vertical Light Emitting Device Passivation Layer Formation
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Solution Overview
Problem
Conventional methods for manufacturing vertical light emitting devices face issues such as crack formation during the laser lift off process, non-uniform passivation layer deposition, and connection defects due to heat generation, which affect the device's performance and reliability.
Innovation Solution
The method involves forming inclined trenches using ICP-RIE, depositing a passivation layer of insulating materials like SiO2 or Si3N4 before forming electrodes, and using a laser lift off method with a stronger material to separate the substrate, ensuring the passivation layer is not damaged and reducing the likelihood of cracks. Additionally, the passivation layer is formed to have a thickness less than the remaining emissive layer, allowing for easier and reliable deposition and preventing connection defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passivation layer is formed on the sidewalls of the vertical light emitting device to prevent current leakage, then the reliability of the device is improved, but the manufacturing complexity increases due to additional deposition steps and process control requirements
Solution Approach 1:
The passivation layer is formed on the sidewalls before the metal supporting layer is deposited, allowing the passivation function to be established early in the manufacturing process. This preliminary action simplifies subsequent steps by eliminating the need for later passivation deposition and reduces the overall manufacturing complexity while maintaining reliability
2Ease of manufacture
If the passivation layer is formed after the metal supporting layer, then the manufacturing process is simplified, but the passivation layer may be damaged during substrate separation causing cracks
Solution Approach 1:
The passivation layer is formed on the sidewalls before the metal supporting layer is deposited, allowing the passivation function to be established early in the manufacturing process. This preliminary action simplifies subsequent steps by eliminating the need for later passivation deposition and reduces the overall manufacturing complexity while maintaining reliability
3Reliability
If the passivation layer is formed thick to ensure complete coverage, then the current leakage prevention is improved, but connection defects occur due to heat generation during deposition
Solution Approach 1:
Instead of forming a thick passivation layer that causes heat-related connection defects, the invention forms a thin passivation layer (50-200 nm) that provides sufficient passivation function. This partial action approach achieves the necessary current leakage prevention without excessive thickness that would generate harmful heat during deposition, thereby avoiding connection defects
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 reduces the occurrence of cracks, enhances the reliability of the passivation layer deposition, and maintains the integrity of the passivation layer, leading to improved device performance and reduced manufacturing costs.
Implementation Method 1
the trenches 92 are formed by etching the emissive layers 30 using the inductively coupled plasma-reactive ion etching (ICP-RIE) method
Implementation Method 2
when the sapphire substrate 20 is separated and the post 94 is removed using a laser lift off (LLO) method
Implementation Method 3
a passivation layer 70 is formed by depositing an insulating material, for example, SiO2, in the trenches 92 formed between the emissive layers 30 using a plasma enhanced chemical vapor deposition (PECVD) method
Data Source
AI summary
Provided is a method of manufacturing a vertical light emitting device. The method of manufacturing the vertical light emitting device may include forming an emissive layer including a n-type semiconductor layer, an active layer, and a p-type semiconductor layer on a substrate, forming a first trench dividing the emissive layer into light emitting device units in which the emissive layer remains on the lower part of the first trench to a desired, or alternatively, a predetermined thickness, forming a passivation layer on the emissive layer, forming a p-type electrode on the p-type semiconductor layer of the emissive layer, forming a metal supporting layer on the passivation layer and the p-type electrode, removing the substrate, removing a remaining portion of the emissive layer when the surface of the emissive layer is exposed by removing the substrate, forming a n-type electrode on the n-type semiconductor layer of the emissive layer, and cutting the metal supporting layer to divide the emissive layer into the light emitting device units.