Micro LED Rod Inspection on Growth Substrates Before Transfer
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Solution Overview
Problem
Conventional lighting inspection methods for micro light emitting elements in display devices are inefficient, leading to decreased process efficiency and productivity due to the difficulty in replacing defective elements after the display device process is completed.
Innovation Solution
A method and device for inspecting light emitting elements on a growth substrate by forming light emitting element rods, applying a protective layer, a metal layer, and a contact pad, and conducting a test power inspection to identify defects before integration into the display device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional lighting inspection method is used after display device process completion, then defect detection is performed, but process efficiency and productivity decrease due to difficulty in replacing defective elements
Solution Approach 1:
The patent performs lighting inspection on light emitting elements while they are still on the growth substrate, before the elements are transferred to the display device. This preliminary inspection allows defective elements to be identified and replaced early in the manufacturing process, avoiding the need to disassemble and rework completed display devices, thereby maintaining both high defect detection capability and productivity
2Measurement precision
If inspection is performed after display device assembly, then defect detection is achieved, but replacement of defective elements becomes difficult
Solution Approach 1:
The inspection is conducted at an early stage when light emitting elements are still mounted on the growth substrate, before integration into the display device structure. This timing allows easy access to defective elements for replacement without requiring disassembly of the display device, thus maintaining both defect detection capability and ease of repair
3Productivity
If early inspection on growth substrate is implemented, then productivity improves through easy replacement, but additional process steps are required
Solution Approach 1:
The patent combines the lighting inspection process with the existing manufacturing flow at the growth substrate stage. By integrating inspection and replacement operations into the current process sequence before element transfer, the method improves productivity without requiring separate inspection equipment or complex additional process steps
Data Source
AI summary
A light emitting element inspection method including: forming a plurality of light emitting element rods by etching a plurality of semiconductor material layers stacked on a growth substrate; forming a protective layer covering a portion of a top surface and a portion of side surfaces of the plurality of light emitting element rods and a contact electrode on the protective layer; forming a metal layer on the side surfaces of the plurality of light emitting element rods and on a portion of the growth substrate on which none of the plurality of light emitting elements rods is located; forming a contact pad connected to the metal layer on the growth substrate; and applying a test power to the contact electrode and the contact pad.