Epitaxial Die Structure for Pre-Bond Electrical Defect Detection

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Solution Overview

Problem

Conventional micro LED displays face challenges in detecting electrical defects of vertical chips after bonding, require high-precision bonding processes due to reduced chip size, and struggle with visible boundaries and complex issues related to chip measurement and classification, especially when reducing chip die size below 50 μm.

Innovation Solution

An epitaxial die structure with a support substrate, light-emitting part, contact electrode, and bonding pad layer is used, allowing for optical sorting and defect detection before upper wiring through high-speed photoluminescence measurement, and enabling removal of the final support substrate for repositioning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If vertical chips are used to reduce chip die size, then chip die size is reduced, but defects cannot be confirmed until after bonding and upper wiring

Engineering Contradiction:

Improvechip die sizeVSAvoiddefect detection timing

Core Design Contradiction:

Volume of moving objectVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies preliminary action by exposing the contact electrode before bonding occurs, allowing defect detection to be performed in advance. The epitaxial die is designed with the contact electrode exposed on the rear surface prior to the bonding process, enabling inspection and measurement of electrical characteristics before the chip is bonded to the substrate, thus resolving the timing issue of defect detection

Inventive Principle:

Principle #10Preliminary action

2Volume of moving object

If chip die size is reduced, then chip die size decreases, but bonding precision and bonding strength requirements increase

Engineering Contradiction:

Improvechip die sizeVSAvoidbonding precision

Core Design Contradiction:

Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent applies self-service by designing the epitaxial die with an exposed contact electrode that enables automatic or semi-automatic electrical defect detection. This self-detection capability allows the system to identify defective chips without requiring complex external inspection equipment, thereby reducing the bonding precision requirements while maintaining quality control

Inventive Principle:

Principle #25Self-service

3Volume of moving object

If sapphire final support substrate thickness is reduced to achieve smaller chip die size, then chip die size is reduced, but substrate cutting issues occur below 50 μm

Engineering Contradiction:

Improvechip die sizeVSAvoidsubstrate processing

Core Design Contradiction:

Volume of moving objectVSEase of manufacture

Solution Approach 1:

The patent applies the extraction principle by removing the sapphire final support substrate after the epitaxial growth process. The support substrate is taken out after serving its purpose during manufacturing, allowing the active area to be maximized without being constrained by substrate thickness limitations. This enables chip die size reduction below 50 μm while avoiding substrate cutting issues

Inventive Principle:

Principle #2Taking out (Extraction)

4Difficulty of detecting and measuring

If flip chips are used for micro LED displays, then defect detection is improved, but high-precision and high-speed bonding processes and specialized materials are required

Engineering Contradiction:

Improvedefect detectionVSAvoidbonding process complexity

Core Design Contradiction:

Difficulty of detecting and measuringVSDevice complexity

Solution Approach 1:

The patent applies universality by designing the epitaxial die structure to work with conventional bonding processes while enabling defect detection. The exposed contact electrode configuration allows the same bonding equipment and materials used for horizontal and vertical chips to be employed, eliminating the need for specialized flip chip bonding processes and materials while maintaining defect detection capability

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Facilitates easy detection and replacement of defective epitaxial dies, reduces chip die size, and improves light output while minimizing process costs and high-temperature treatments, suitable for mini and micro LED manufacturing processes.

Implementation Method 1

a light-emitting part that generates light

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

optical sorting and defect detection before upper wiring through high-speed photoluminescence measurement

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentUS20250294928A1Epitaxial die enabling easy detection of electrical defects, semiconductor light-emitting device using same, and manufacturing methods thereof

Publication Date: 2025.09.18 WAVELORD CO LTD

AI summary

The present invention relates to: an epitaxial die having a structure enabling easy detection of electrical defects in an epitaxial die before an upper wiring process and easy replacement of a defective epitaxial die; a semiconductor light-emitting device using same; and manufacturing methods thereof.