Light-Transmissive Electrode Segmentation for LED Light Extraction
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Solution Overview
Problem
Current manufacturing methods for semiconductor light emitting elements require numerous steps and suffer from light absorption issues due to pad electrodes, which hampers productivity and light extraction efficiency.
Innovation Solution
A method involving the formation of a light-transmissive electrode with intermittent openings covered by a light-reflecting layer and a protective layer, where the protective layer is etched using a mask to prevent etching solution from entering the openings, allowing for the formation of pad electrodes without eroding the insulating layer, thereby reducing light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a light-transmissive electrode is formed on the entire upper surface of the p-type semiconductor layer, then current diffusion to the p-type semiconductor layer is improved, but optical absorption by the electrode increases
Solution Approach 1:
The light-transmissive electrode is divided into multiple segments by forming openings (through-holes) in the electrode layer. This segmentation allows light to pass through the openings while the electrode segments still provide current diffusion to the p-type semiconductor layer through the regions between the openings.
Solution Approach 2:
Different regions of the electrode structure are assigned different functions: the electrode material regions provide electrical conduction and current diffusion, while the openings provide optical transmission. This local differentiation allows simultaneous optimization of both electrical and optical performance.
2Reliability
If pad electrodes are formed directly on the light-transmissive electrode, then electrical connection is achieved, but light absorption by the pad electrodes increases
Solution Approach 1:
A reflective layer is introduced as an intermediary between the pad electrode and the light-transmissive electrode. This reflective layer serves as a mediator that redirects light away from the pad electrode while maintaining electrical connection through the conductive structure.
Solution Approach 2:
The reflective layer converts the harmful effect of light absorption by the pad electrode into a beneficial effect by reflecting light back towards the light-emitting region, thereby improving light extraction efficiency while maintaining electrical functionality.
3Ease of manufacture
If the protective layer is etched to form openings for pad electrodes, then pad electrode formation is enabled, but etching solution may enter and erode the insulating layer
Solution Approach 1:
The openings in the protective layer are formed in advance before the etching process that creates the pad electrode recesses. This preliminary action allows the openings to serve as defined pathways that control etching solution flow, preventing it from reaching and eroding the insulating layer underneath.
Solution Approach 2:
The openings in the protective layer act as intermediaries that control the flow of etching solution. By pre-defining these openings, the etching solution is guided through controlled paths that allow pad electrode formation while preventing uncontrolled erosion of the insulating layer.
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 simplifies the manufacturing process and reduces light absorption by pad electrodes, enhancing the productivity and light extraction efficiency of semiconductor light emitting elements.
Implementation Method 1
a light-reflecting layer made of a metal material, having high light-reflecting properties
Implementation Method 2
etching the protective layer to remove the protective layer exposed in the opening of the mask by way of wet etching
Data Source
AI summary
A method of manufacturing a semiconductor light emitting element includes providing a semiconductor stacked layer body; forming an insulating layer on a portion of the semiconductor stacked layer body; forming a light-transmissive electrode covering an upper surface of the semiconductor stacked layer body and an upper surface of the insulating layer, and on a region at least partially overlapping a region for disposing an extending portion in a plan view; forming a light reflecting layer in each of the openings of the light-transmissive electrode; forming a protective layer on a main surface side of the semiconductor stacked layer body; forming a mask on an upper surface of the protective layer except for the region for forming the pad electrode; etching the protective layer to form an opening in the protective layer; and forming a pad electrode in the opening of the protective layer.