Nitride Semiconductor Light Emitting Device Insulating Layer
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Solution Overview
Problem
Nitride semiconductor light emitting devices manufactured using conventional methods often experience short-circuits and increased leak current at the PN junction due to metal intrusion, leading to poor reliability and yield, especially when using silver paste or similar metals.
Innovation Solution
A nitride semiconductor light emitting device with a conductive substrate and an insulating layer covering the side surfaces of the semiconductor layers and metal layers, reducing metal intrusion and contact area to minimize short-circuits and leak current, and a method involving stacking semiconductor layers, forming depression portions, and applying metal layers with controlled coverage to enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal layers (silver paste, gold, indium, tin, solder) are formed on ohmic electrodes to improve adhesiveness, then adhesion strength is improved, but metal intrusion occurs at the PN junction causing short-circuits and increased leak current
Solution Approach 1:
An insulating layer is introduced as an intermediary between the metal layers and the semiconductor structure. This insulating layer prevents metal intrusion into the PN junction while maintaining electrical connectivity through contact holes, thereby eliminating short-circuits and reducing leak current without compromising adhesion strength
Solution Approach 2:
The device structure is segmented into distinct functional regions: metal layers for adhesion, insulating layer for isolation, and contact holes for electrical connection. This segmentation allows the metal layers to provide adhesion strength while the insulating layer prevents harmful metal intrusion, resolving the contradiction between strength and reliability
2Ease of operation
If electrodes are taken out from the top and bottom of the conductive substrate, then electrical functionality is improved, but chip division becomes difficult due to non-cleavability of the substrate
Solution Approach 1:
A sacrificial insulating layer is introduced as a mediator that facilitates chip division. This layer can be selectively removed or cleaved to enable chip separation, while the underlying conductive substrate maintains its electrical functionality with top and bottom electrodes
3Stability of the object's composition
If sapphire substrate is used, then thermal stability is improved, but chip size increases and manufacturing complexity increases due to high hardness and lack of cleavability
Solution Approach 1:
The device is segmented into a sapphire substrate layer and an overlying nitride semiconductor layer stack. This segmentation allows the sapphire substrate to provide thermal stability while the nitride semiconductor layer enables easier chip division and reduced chip size through its cleavability
Data Source
AI summary
A nitride semiconductor light emitting device includes a conductive substrate, a first metal layer, a second conductivity-type semiconductor layer, an emission layer, and a first conductivity-type semiconductor layer in this order. The nitride semiconductor light emitting device additionally has an insulating layer covering at least side surfaces of the second conductivity-type semiconductor layer, the emission layer and the first conductivity-type semiconductor layer. A method of manufacturing the same is provided. The nitride semiconductor light emitting device may further include a second metal layer. Thus, a reliable nitride semiconductor light emitting device and a method of manufacturing the same are provided in which short-circuit at the PN junction portion and current leak is reduced as compared with the conventional examples.