LED Epitaxial Growth Isolation Patterns for Crack Prevention
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Solution Overview
Problem
The laser lift-off process used in manufacturing semiconductor light emitting devices can cause micro-cracks in the semiconductor layer, degrading luminous efficiency and complicating the manufacturing process.
Innovation Solution
A method involving the formation of an isolation pattern on a semiconductor growth substrate to define chip unit regions, followed by the growth of semiconductor layers and the application of a reflective metal layer, allowing for stable separation from the growth substrate and simplification of the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a laser lift-off process is used to remove the growth substrate, then the semiconductor layer can be separated from the growth substrate, but micro-cracks are generated in the semiconductor layer degrading luminous efficiency
Solution Approach 1:
The patent introduces isolation patterns that divide the semiconductor layer into separate regions, preventing crack propagation across the entire layer. The isolation patterns create segmented zones that contain micro-cracks locally, protecting the overall luminous efficiency of the LED device.
Solution Approach 2:
The isolation patterns are formed before the laser lift-off process to pre-establish protective structures. This preliminary action prepares the semiconductor layer to withstand the laser irradiation by providing pre-defined isolation zones that prevent crack formation and propagation during substrate removal.
2Reliability
If an additional process is used to avoid micro-cracks during substrate removal, then luminous efficiency is maintained, but the manufacturing process becomes substantially complicated
Solution Approach 1:
The patent combines the isolation pattern formation with the existing manufacturing process flow, integrating crack prevention functionality into the standard fabrication steps. The isolation patterns are created using conventional photolithography and etching processes that are already part of the LED manufacturing sequence, avoiding the need for separate additional process equipment or methods.
Solution Approach 2:
The isolation patterns serve multiple functions simultaneously: they define chip unit regions for separation, prevent micro-crack propagation during laser lift-off, and provide structural support during manufacturing. This multi-functionality eliminates the need for dedicated crack-prevention structures or processes, simplifying the overall manufacturing workflow.
3Reliability
If the light emitting structure height is lower than the isolation pattern height, then stable separation from growth substrate is achieved, but additional etching steps are required
Solution Approach 1:
The isolation patterns are formed with greater height than the light emitting structure in advance, creating pre-established separation zones. This height difference is intentionally designed during the patterning and deposition stages to ensure that the isolation patterns extend beyond the light emitting structure, providing stable separation boundaries without requiring complex post-processing steps.
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 reliability and luminous efficiency of semiconductor light emitting devices while simplifying the manufacturing process, reducing the risk of micro-cracks and stress-related issues.
Implementation Method 1
A first conductivity-type semiconductor layer, an active layer, and a second conductivity-type semiconductor layer are sequentially grown in one chip unit region of the semiconductor single crystal growth substrate
Implementation Method 2
A reflective metal layer is formed to cover the light emitting structure and the isolation pattern
Data Source
AI summary
A method for manufacturing a semiconductor light emitting device includes forming an isolation pattern on a semiconductor single crystal growth substrate. A first conductivity-type semiconductor layer, an active layer, and a second conductivity-type semiconductor layer are sequentially grown in one chip unit region of the semiconductor single crystal growth substrate defined by the isolation pattern, and a reflective metal layer is formed to cover the light emitting structure and the isolation pattern. A support substrate is formed on the reflective metal layer, and the semiconductor single crystal growth substrate is removed from the light emitting structure. The support substrate is then cut into individual light emitting devices.