Micro LED Bonded Wafer Failure Removal by Mapped Laser Sublimation
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Solution Overview
Problem
Existing methods fail to selectively remove bonding-failure and device characteristic failure portions from micro LED wafers, leading to photolithography deviations, mounting inaccuracies, and increased failure rates due to protrusion-shaped defects, which are not detectable by conventional inspections.
Innovation Solution
A method involving laser lift-off (LLO) transfer using an adhesive that absorbs laser light to optically map and irradiate failure portions, sublimating them based on map data, thereby selectively removing these defects without mechanical methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional mechanical removal methods are used to remove bonding-failure portions, then removal can be achieved, but the method cannot selectively remove only failure portions and may damage surrounding areas
Solution Approach 1:
The patent replaces mechanical removal methods with laser irradiation. The laser beam selectively removes bonding-failure portions through optical absorption and thermal effects, eliminating the need for mechanical contact and enabling precise removal without damaging surrounding areas.
Solution Approach 2:
The patent changes the physical state of the adhesive layer by irradiating it with laser light. The laser energy is absorbed by the adhesive, causing localized heating and decomposition, which transforms the adhesive from a bonded state to a removed state, enabling selective failure portion removal.
2Productivity
If batch transfer is used to transfer μ-LED dice, then transfer efficiency is improved, but failure portions cannot be selectively removed and cause transfer failures
Solution Approach 1:
The patent performs preliminary removal of bonding-failure portions before the transfer process. By eliminating protrusion-shaped failures in advance, the wafer surface becomes uniform, ensuring successful batch transfer without interference from failure portions.
Solution Approach 2:
The patent extracts and removes only the bonding-failure portions from the wafer surface while leaving the functional μ-LED dice intact. This selective extraction eliminates the source of transfer failures without affecting the overall transfer process efficiency.
3Productivity
If contact exposure photolithography is performed on wafers with protrusion-shaped failure portions, then photolithography can be completed, but mask deformation occurs and pattern accuracy deteriorates
Solution Approach 1:
The patent performs preliminary removal of protrusion-shaped failure portions before photolithography. This pre-treatment ensures a uniform wafer surface, preventing mask deformation during contact exposure and maintaining high pattern accuracy throughout the photolithography 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
Enables precise and reliable removal of bonding-failure and device characteristic defects, improving photolithography accuracy and reducing transfer failures, while maintaining the integrity of the light-emitting device structure.
Implementation Method 1
bonding a light-emitting device structure, which is to be a micro LED, to a to-be-bonded substrate transparent to laser light for LLO transfer via an adhesive that absorbs the laser light for LLO transfer
Implementation Method 2
irradiating the failure portion of the bonded wafer with the laser light for removal based on the map data for removal, and by sublimating a portion of the light-emitting device structure that is included in the failure portion, thereby removing the portion of the light-emitting device structure that is included in the failure portion
Implementation Method 3
irradiating the failure portion of the bonded wafer with the laser light for removal
Data Source
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Figure 8~10A
AI summary
The present invention is a method for producing a bonded light-emitting device wafer in which a failure portion is removed, the method includes the steps of obtaining a bonded wafer by bonding a light-emitting device structure, which is to be a micro LED, to a to-be-bonded substrate transparent to laser light for LLO transfer via an adhesive that absorbs the laser light for LLO transfer, producing map data for removal by optically investigating the failure portion of the bonded wafer, and obtaining the bonded light-emitting device wafer by irradiating the failure portion of the bonded wafer with the laser light for removal based on the map data for removal, and by sublimating a portion of the light-emitting device structure that is included in the failure portion, thereby removing the portion of the light-emitting device structure that is included in the failure portion. This provides a method for producing a bonded light-emitting device wafer capable of producing the bonded light-emitting device wafer by selectively removing a failure portion of a light-emitting device structure, which serves as a micro LED bonded to a to-be-bonded wafer via the adhesive.