Micro LED Bonded Wafer Defect Removal by Adhesive Laser Sublimation
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Solution Overview
Problem
Existing methods fail to selectively remove protrusion-shaped bonding-failure portions in micro LED wafers, leading to photolithography deviations, mounting inaccuracies, and transfer failures, which are difficult to detect and costly to rectify.
Innovation Solution
A method involving bonding a micro LED structure with a substrate via an adhesive that absorbs laser light, optically mapping failure portions, and using laser irradiation to sublimate the adhesive in these areas, thereby removing the failure portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If bonding is performed using BCB to create a bonded wafer, then the micro LED structure is firmly attached to the substrate, but bonding-failure portions generate protrusion-shaped defects that degrade photolithography precision and cause transfer failures
Solution Approach 1:
The patent performs optical inspection to map failure portions before photolithography processing. By identifying and marking defective areas in advance, the system can selectively remove only the protrusion-shaped failure portions without affecting good dice, thereby preserving bonding strength while eliminating sources of photolithography deviation
Solution Approach 2:
The patent applies selective laser irradiation to remove adhesive only in failure portions rather than uniformly across the entire wafer. This localized approach maintains the bonding integrity of good dice while eliminating protrusion defects in specific failure areas, resolving the contradiction between overall bonding strength and local photolithography precision
2Reliability
If conventional mechanical removal methods are used to eliminate failure portions, then some defects can be removed, but the methods cannot selectively remove only failure portions without affecting good dice, and batch transfer methods cannot handle uneven die heights
Solution Approach 1:
The patent replaces mechanical removal methods with optical detection and laser-based selective removal. The optical inspection system maps failure portions non-contactly, and selective laser irradiation removes adhesive in defective areas without mechanical contact, enabling precise selective removal that preserves good dice while eliminating failure portions
Solution Approach 2:
The patent introduces map data as an intermediary between detection and removal processes. The optical inspection generates a spatial map of failure portions, which guides the selective laser irradiation process to remove only mapped defective areas, achieving selective removal without affecting good dice
3Productivity
If protrusion-shaped failure portions are not removed before transfer, then the transfer process becomes simpler, but the protrusion portions generate non-uniform pressure distribution that causes transfer failures
Solution Approach 1:
The patent performs selective removal of failure portions before the transfer process. By eliminating protrusion-shaped defects in advance, the system ensures uniform pressure distribution during subsequent transfer operations, preventing transfer failures while maintaining high transfer efficiency
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 method enables precise and selective removal of bonding and device characteristics failures, improving photolithography accuracy and preventing transfer failures, reducing mounting costs and enhancing overall device quality.
Implementation Method 1
irradiating the failure portion of the bonded wafer with laser light for removal from the to-be-bonded substrate, a portion of adhesive which is included in the failure portion absorbs the laser light for removal
Implementation Method 2
a portion of adhesive which is included in the failure portion absorbs the laser light for removal and sublimates
Data Source
AI summary
The present invention is a method for producing a bonded light-emitting device wafer, in which a light-emitting device structure, to be a micro LED, and a to-be-bonded substrate are bonded with each other via an adhesive, the method includes the steps of bonding the light-emitting device structure to the to-be-bonded substrate via the adhesive to obtain a bonded wafer, producing a map data for removal by optically investigating a failure portion of the bonded wafer, and irradiating the failure portion of the bonded wafer with the laser light for removal from the to-be-bonded substrate based on the map data for removal, causing a portion of the adhesive which is included in the failure portion to absorb the laser light for removal and causing the portion of the adhesive which is included in the failure portion to sublimate, thereby removing the portion of the light-emitting device structure which is included in the failure portion to obtain the bonded light-emitting device wafer. This can provide the method for producing a bonded light-emitting device wafer capable of selectively removing the failure portion of the light-emitting device structure and producing the bonded light-emitting device wafer.