Light Emitting Element with Light-Transmissive Electrode
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Solution Overview
Problem
Existing light emitting elements, such as LEDs, face reduced light extraction efficiency due to protective films and complex manufacturing processes, particularly because resist films used for electrodes and protective films hinder light propagation and complicate manufacturing.
Innovation Solution
A light emitting element design where a protective film continuously covers semiconductor layers, exposing light-transmissive electrodes, allowing for improved light extraction efficiency and simplifying manufacturing by using the same resist layer for both electrode and protective film formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective film is formed on light-transmissive electrodes, then the semiconductor layers are protected, but light extraction efficiency is reduced due to interface hindrance
Solution Approach 1:
The protective film is selectively removed from the light-transmissive electrode regions through etching processes, extracting only the necessary portions of the protective film that would hinder light extraction. This allows the protective film to remain on semiconductor layers for protection while being absent from electrode areas to maximize light extraction efficiency.
2Manufacturing precision
If separate resist films are used for forming light-transmissive electrodes and protective films, then precise patterning is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the functions of multiple resist films into a single resist film structure. The first resist film is used for patterning light-transmissive electrodes, and the same resist film structure (after selective removal) serves as the basis for forming the protective film pattern. This consolidation reduces the number of separate resist application and removal steps, simplifying manufacturing while maintaining patterning precision.
Solution Approach 2:
The first resist film serves multiple functions: it acts as a patterning mask for light-transmissive electrodes, and subsequently as a template for forming the protective film pattern. This multi-functional use of a single resist film structure eliminates the need for separate dedicated resist films for each patterning step.
3Reliability
If protective film interfaces are present on light-transmissive electrodes, then semiconductor layers are protected, but light propagation is hindered
Solution Approach 1:
The protective film is applied with spatially varying presence: it is present on semiconductor layer surfaces where protection is needed, but intentionally absent from light-transmissive electrode surfaces where light propagation is critical. This local differentiation of protective film presence optimizes both protection and light extraction performance in different regions of the device.
Data Source
AI summary
A light emitting element includes an n-type semiconductor layer having an upper surface; a p-type semiconductor layer over a portion of the upper surface of the n-type semiconductor layer, the p-type semiconductor layer having an upper surface; a protective film continuously covering the n-type semiconductor layer and the p-type semiconductor layer, the protective film defining an n-side opening at the upper surface of the n-type semiconductor layer and a p-side opening at an upper surface of the p-type semiconductor layer; a p-side electrode on the upper surface of the p-type semiconductor layer that is exposed in the p-side opening; an n-side electrode on the upper surface of the n-type semiconductor layer that is exposed at the n-side opening, n-side electrode having an n-side light-transmissive electrode; and an n-side pad electrode on the upper surface of the n-side light-transmissive electrode.