LED Electrode Pad Adhesion via Current Blocking Gap
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Solution Overview
Problem
Conventional lateral LED chips face issues with poor adhesion of the first electrode pad to the transparent conductive layer and current blocking layer, leading to unreliable wiring and potential detachment, as well as etching risks due to the current blocking layer extending beyond the electrode pad area.
Innovation Solution
The design includes a semiconductor light-emitting stack with a transparent conductive layer and a first current blocking layer surrounded by a gap, where the first electrode pad fully covers the current blocking layer, enhancing adhesion and preventing etching by covering the current blocking layer during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current blocking layer extends beyond the covering area of the first electrode pad, then vertical current transfer is blocked, but the electrode pad has low adhesion and poor wiring reliability
Solution Approach 1:
The patent introduces a gap structure between the transparent conductive layer and current blocking layer, transforming the traditional planar layered structure into a three-dimensional configuration. This dimensional change allows the electrode pad to extend laterally and make contact with the semiconductor layer through the gap, thereby improving adhesion without compromising current blocking effectiveness.
2Reliability
If the current blocking layer extends beyond the electrode pad area, then current transfer is blocked, but etchant can easily access and etch the current blocking layer
Solution Approach 1:
The patent applies preliminary protective action by forming a gap structure that positions the current blocking layer away from the outer periphery of the electrode pad. This preliminary configuration prevents etchant from easily accessing the current blocking layer during subsequent processing steps, thereby protecting it from etching damage while maintaining its current blocking function.
3Device complexity
If the electrode pad is made smaller to reduce complexity, then manufacturing is easier, but adhesion to transparent conductive layer and current blocking layer is insufficient
Solution Approach 1:
The patent segments the electrode pad structure into multiple functional zones: a central region for electrical connection, lateral extensions for adhesion enhancement, and gap-bridging portions for mechanical support. This segmentation allows each part to serve its specific function optimally, improving overall adhesion without significantly increasing manufacturing complexity.
Data Source
AI summary
A light-emitting diode includes a semiconductor light-emitting stack, a transparent conductive layer, a first current blocking layer, and a first electrode pad. The transparent conductive layer is disposed on the semiconductor light-emitting stack, and is formed with a first opening defined by an inner edge thereof. The first current blocking layer is formed on the semiconductor light-emitting stack, and is surrounded by and spaced apart from the inner edge of the transparent conductive layer by a first gap. The first electrode pad fully covers the first current blocking layer so as to permit the first electrode pad to be in contact with the semiconductor light-emitting stack through the first gap.