Integrated LED and Zener Diode Structure for ESD Protection
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Solution Overview
Problem
High voltage light emitting diode (LED) solutions face challenges with discrete LEDs and Zener diodes mounted on a PCB, where Zener diodes do not adequately protect the P-N junctions from electrostatic discharge and high breakdown voltage, leading to potential damage during fabrication and operation.
Innovation Solution
Embedding Zener diodes in the silicon substrate of the LED die, integrating protection circuits at the wafer level, and manufacturing the LED circuit and protection circuits in the same die to prevent breakdown of the silicon substrate and passivation layer, ensuring protection of the multi-junction LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discrete LEDs and Zener diodes are mounted on a PCB, then the circuit occupies PCB space and integration is challenging, but the Zener diodes do not adequately protect the P-N junctions from electrostatic discharge and high breakdown voltage
Solution Approach 1:
The patent merges the LED and Zener diode fabrication processes by forming both structures in the same semiconductor substrate using a unified manufacturing flow. The P-N junctions for both LEDs and Zener diodes are created simultaneously through coordinated doping and deposition steps, eliminating the need for separate discrete components and their associated integration challenges while providing effective ESD protection.
Solution Approach 2:
The patent implements a nested structure where Zener diode P-N junctions are formed within the same semiconductor substrate as the LED P-N junctions. The Zener diode structures are positioned and fabricated in a nested manner alongside the LED structures, allowing both functions to coexist in a compact integrated arrangement that provides protection while minimizing space occupation.
2Reliability
If Zener diodes are mounted with the LED die on a board, then the Zener diodes protect the die and package chip, but they do not protect the P-N junctions on the die from electrostatic discharge
Solution Approach 1:
The patent applies preliminary action by forming the Zener diode P-N junctions and protection structures during the initial fabrication process, before the LED die is completed or packaged. The ESD protection structures are built into the substrate beforehand, ensuring that the P-N junctions are protected from electrostatic discharge during both fabrication and operation, rather than adding protection after the fact.
Solution Approach 2:
The patent combines the fabrication of LED structures and Zener diode protection structures into a single integrated manufacturing process. Both types of P-N junctions are formed using the same doping, deposition, and processing steps, simplifying the overall fabrication process while ensuring that ESD protection is inherently built into the device structure.
3Reliability
If the junctions are exposed during fabrication or assembly, then the LED die may be damaged due to electrostatic discharge or high break down voltage, but integrating protection circuits at the wafer level increases manufacturing complexity
Solution Approach 1:
The patent segments the semiconductor substrate into distinct regions: LED active regions and Zener diode protection regions. Each region is optimized for its specific function, with the Zener diode regions strategically positioned to provide ESD protection for the LED P-N junctions. This segmentation allows for specialized design and fabrication of protection structures without compromising LED performance.
Solution Approach 2:
The patent introduces Zener diode structures as intermediary protection elements between external electrostatic discharge sources and the sensitive LED P-N junctions. These intermediary Zener diodes act as sacrificial protection structures that clamp voltage spikes and divert harmful discharge away from the LED junctions, thereby protecting them while maintaining a relatively simple integrated fabrication process.
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 effectively protects the multi-junction LEDs from electrostatic discharge and high voltage breakdown, allowing the LED chain to continue functioning even if one LED fails, with the rest of the chain continuing to produce light, enhancing reliability and operational stability.
Implementation Method 1
the junctions and thus the LED die may be damaged due to an electro static discharge (ESD)
Data Source
AI summary
A light emitting diode (LED) structure comprises a first dopant region, a dielectric layer on top of the first dopant region, a bond pad layer on top of a first portion the dielectric layer, and an LED layer having a first LED region and a second LED region. The bond pad layer is electrically connected to the first dopant region. The first LED region is electrically connected to the bond pad layer.