Micro LED Inspection Using Pulsed Laser RF Defect Signals

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Solution Overview

Problem

Existing micro LED inspection methods are inefficient and prone to missing defects due to the small size of micro LEDs, with contact-based electroluminescence tests risking chip damage and contactless photoluminescence tests having low detection efficiency.

Innovation Solution

A system using a pulsed laser beam to generate a photovoltaic radio frequency signal from micro LEDs, which is received by an antenna and processed to determine defectiveness, allowing contactless and high-efficiency inspection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electroluminescence (EL) tests are used to identify more defects, then detection efficiency is improved, but chip damage risk increases due to contact-based electric current application

Engineering Contradiction:

Improvedefect detection efficiencyVSAvoidchip damage risk

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces contact-based electrical testing with contactless optical detection. A pulsed laser beam illuminates the LED chip, and the resulting photoluminescence signal is detected by a sensor, eliminating the need for physical contact with the chip terminals and thus preventing chip damage while maintaining defect detection capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces light as an intermediary medium for testing. Instead of applying electric current directly to the chip, the laser beam serves as an intermediary that interacts with the LED material to generate detectable photoluminescence signals, enabling indirect testing without harmful contact

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If photoluminescence (PL) tests are used for contactless inspection, then chip damage is avoided, but defect detection efficiency decreases

Engineering Contradiction:

Improvechip damage avoidanceVSAvoiddefect detection efficiency

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent modifies the parameters of conventional photoluminescence testing by using pulsed laser excitation instead of continuous illumination and by optimizing the detection of specific photoluminescence signal characteristics. These parameter changes enhance the sensitivity and resolution of defect detection while maintaining contactless operation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs periodic pulsed laser excitation to stimulate the LED chip. The pulsed nature of the excitation allows for time-resolved detection of photoluminescence signals, improving the ability to distinguish defective from functional LEDs through analysis of signal timing and intensity characteristics

Inventive Principle:

Principle #19Periodic action

3Ease of manufacture

If conventional testing equipment is used for micro LED inspection, then existing infrastructure is utilized, but testing becomes difficult and slow due to small chip size

Engineering Contradiction:

Improveuse of existing equipmentVSAvoidtesting speed

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent replaces mechanical contact-based testing equipment with optical testing systems. The contactless optical measurement approach eliminates the physical handling and positioning requirements that slow down conventional testing of microscopic LED chips, enabling faster inspection throughput

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from two-dimensional planar testing approaches to three-dimensional optical field interactions. By using focused laser beams and spatially resolved photoluminescence detection, the system can rapidly characterize micro LED chips without the mechanical constraints of conventional contact probes

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

Enables efficient and reliable identification of defective micro LEDs without physical contact, facilitating rapid sorting and assembly of functional LEDs into display panels.

Implementation Method 1

The LED may generate a photovoltaic radio frequency signal when radiated by the pulsed laser beam

Methodology Applied

Scientific EffectPhotovoltaic effect: Photovoltaic Effect

Data Source

PatentUS12566208B2Pulsed laser micro LED inspection

Publication Date: 2026.03.03 ORBOTECH LTD

AI summary

The system includes a laser generator, an antenna, and a processor to distinguish the photovoltaic radio frequency signals emitted by defective LEDs and functioning LEDs in a contactless manner. The laser generator emits a pulsed laser beam toward an LED. The LED generates a photovoltaic radio frequency signal when radiated by the pulsed laser beam. The antenna receives the photovoltaic radio frequency signal generated by the LED. The processor is in electronic communication with the antenna and is configured to read the photovoltaic radio frequency signal and determine whether the LED is a defective LED or a functioning LED based on the photovoltaic radio frequency signal, such as by using the frequency, amplitude, or phase shift of the radio frequency signal.