Elastomeric Interface Layer for Micro-LED Pick and Place
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Solution Overview
Problem
The challenge in LED display fabrication is the difficulty in picking and placing smaller light emitting diode (LED) dies without damaging them, due to their decreasing form factor, which complicates adhesive attachment and transfer from one substrate to another.
Innovation Solution
An elastomeric layer is formed over the epitaxial structure of LED dies, etched into individual interface layers, and then used to facilitate adhesion with a pick-up head during the manufacturing process, allowing for precise attachment and transfer to a display substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional picking and placing methods are used for smaller LED dies, then the form factor of LEDs can be reduced, but the difficulty of picking and placing without damage increases
Solution Approach 1:
An elastomeric layer is introduced as an intermediary between the LED dies and the pick-up head. This layer provides a compliant adhesive interface that enables reliable attachment of micro-LEDs to the pick-up head, solving the handling difficulty caused by reduced LED size. The elastomeric material deforms to conform to the LED surface, ensuring complete contact and adhesion even for very small dies that would be difficult to handle with rigid picking methods.
Solution Approach 2:
The invention changes the physical parameters of the interface between LED and pick-up head by using a soft, elastomeric material instead of rigid adhesive or mechanical grippers. The elastomeric layer's compliance and deformability allow it to adapt to the small LED geometry, providing sufficient contact area and adhesive force for reliable picking and placing of miniaturized LED dies.
2Productivity
If LEDs are transferred from carrier substrate to display substrate, then display fabrication can be completed, but adhesive attachment becomes increasingly difficult with smaller LEDs
Solution Approach 1:
The elastomeric layer serves as a mediator between the LED dies and both the carrier substrate and display substrate during transfer operations. It provides a consistent adhesive interface that works reliably for attachment and release, enabling automated pick-and-place manufacturing of displays with miniaturized LEDs without increasing process complexity.
Solution Approach 2:
The elastomeric layer is a flexible thin film that can deform during the picking and placing process. This flexibility allows the layer to conform to the small LED geometry and maintain adhesive contact during transfer, solving the manufacturing difficulty posed by smaller LED sizes while enabling complete display fabrication.
3Ease of operation
If an elastomeric layer is formed over the epitaxial structure, then adhesion facilitation is improved, but the process complexity increases
Solution Approach 1:
The elastomeric layer is formed on the epitaxial structure before LED singulation and transfer operations. This preliminary action ensures that the adhesive interface is already in place when LEDs are picked up, eliminating the need for separate adhesive application steps and simplifying the overall process despite the additional material layer.
Solution Approach 2:
The elastomeric layer performs multiple functions: it provides adhesion for pick-up head attachment, protects the LED surface during handling, and can serve as a release layer during transfer to the display substrate. This multi-functionality justifies the added process step by consolidating several operations into a single material layer.
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 efficient and damage-free picking and placement of LED dies by providing a conformable adhesive interface, improving the handling and alignment of micro-LEDs or VCSELs during electronic display manufacturing.
Implementation Method 1
The elayers facilitate adhesion of the LED dies with a pick-up head for pick and place operations during the manufacturing of an electronic display
Implementation Method 2
The etching of the portions of the elastomeric layer and the second portions of epitaxial structure is performed by anisotropic dry etching. In some embodiments, the anisotropic dry etching includes inductively coupled plasma (ICP) etching
Implementation Method 3
the metallic layer is formed by electron beam deposition
Data Source
AI summary
Embodiments relate to an integrated process for forming an elastomeric layer over an epitaxial structure of multiple light emitting diode (LED) dies, and then etching the elastomeric layer into individual elastomeric interface layers (elayers) on each of the LED dies and etching the epitaxial structure to singulate the LED dies. The elayer allows each LED die to be picked up by a pick-up head (or pick and place head (PPH)), and placed onto a display substrate including control circuits for sub-pixels of an electronic display. In some embodiments, the LED dies are micro-LED (uLED) dies.