Micro Device Stabilization Posts for Reliable Transfer
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Solution Overview
Problem
Integration and packaging issues, such as delamination and adhesion challenges, hinder the commercialization of micro devices like RF MEMS microswitches, LED display systems, and quartz-based oscillators in traditional transfer printing technologies.
Innovation Solution
A structure and method involving an array of micro devices supported by stabilization posts made of thermoset materials like epoxy or benzocyclobutene, with a sacrificial layer and adhesion promoter layers, allowing for low volume shrinkage and enhanced adhesion, enabling efficient pick-up and transfer of micro devices to a carrier substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional transfer printing technologies are used, then device transfer can be achieved, but delamination and adhesion challenges occur
Solution Approach 1:
The patent changes the material parameter of the stabilization layer from traditional photoresist to thermoset materials (epoxy, BCB) with specific volume shrinkage characteristics (10% or less, preferably 6% or less). This parameter change enables the stabilization layer to maintain dimensional stability during curing while providing sufficient adhesion to prevent delamination during the transfer process.
Solution Approach 2:
The patent employs a composite structure consisting of multiple layers with distinct functions: the thermoset stabilization layer provides structural support and adhesion, the sacrificial layer (oxide or nitride) enables selective removal, and adhesion promoter layers enhance interfacial bonding. This composite material approach resolves the adhesion-stability contradiction by assigning different functional properties to each layer.
2Productivity
If high-density micro device arrays are integrated, then productivity increases, but manufacturing precision challenges arise
Solution Approach 1:
The patent segments the stabilization function into discrete stabilization posts rather than a continuous layer. Each post is positioned at specific locations corresponding to individual micro devices, enabling precise alignment and transfer. The posts are separated by pitches of 1 μm to 100 μm (specifically 1 μm to 10 μm), allowing high-density integration while maintaining manufacturing precision through localized support points.
3Productivity
If the entire transfer wafer is involved in the transfer process, then batch processing efficiency improves, but device stability deteriorates
Solution Approach 1:
The patent extracts the stabilization function from the entire transfer wafer structure and concentrates it into discrete stabilization posts. This extraction allows the bulk of the wafer to be removed or simplified while retaining the essential stabilization function at critical locations. The stabilization posts provide localized support that maintains device positioning stability without requiring the complexity of processing the entire wafer structure.
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 approach stabilizes micro devices on a carrier substrate, facilitating their transfer with high adhesion and low delamination risk, enabling high-density integration and assembly of micro devices into heterogeneous systems with improved transfer rates.
Implementation Method 1
the stabilization layer is formed of a thermoset material such as epoxy or benzocyclobutene (BCB) which is associated with 10% or less volume shrinkage during curing
Implementation Method 2
An adhesion promoter layer may be formed between the carrier substrate and the stabilization layer to increase adhesion
Data Source
AI summary
A method and structure for stabilizing an array of micro devices is disclosed. The array of micro devices is formed on an array of stabilization posts formed from a thermoset material. Each micro device includes a bottom surface that is wider than a corresponding stabilization post directly underneath the bottom surface.