Backside Adhesive Layers for Micro-Transfer Printing

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Solution Overview

Problem

Existing methods for adhering transferred chiplets to a destination substrate or backplane face challenges with adhesive deposition and patterning, particularly in applications where conventional adhesives interfere with the functionality of the substrate or components.

Innovation Solution

The use of a component source wafer structure with a sacrificial layer and anchors, where components are suspended over recessed portions with a backside adhesive layer, allowing for micro-transfer printing using visco-elastic stamps and directional removal of adhesive from the top side to prevent interference with van der Waals forces and ensure proper component transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If adhesive is deposited on the destination substrate or backplane to adhere chiplets, then adhesion is achieved, but adhesive deposition or patterning becomes problematic for transferred or receiving structures

Engineering Contradiction:

Improveadhesion strengthVSAvoidadhesive deposition difficulty

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

Instead of applying adhesive to the destination substrate to adhere chiplets, the patent inverts the approach by applying adhesive to the backside of the chiplets themselves. This allows the chiplets to be transferred with the adhesive already positioned, eliminating the need for complex adhesive deposition on the receiving structure.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The adhesive is applied to the backside of chiplets before the transfer process occurs. This preliminary application of adhesive ensures that the adhesive is already in place and properly positioned when the chiplet is transferred to the destination substrate, avoiding the need for post-transfer adhesive application.

Inventive Principle:

Principle #10Preliminary action

2Strength

If conventional adhesives are used to adhere transferred chiplets, then adhesion is achieved, but the adhesives interfere with the functionality of the substrate or components

Engineering Contradiction:

Improveadhesion strengthVSAvoidinterference with substrate functionality

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies adhesive only to the backside of the chiplet, creating a localized adhesive region that does not interfere with the front-side functionality of the chiplet or the destination substrate. This localized application ensures that the adhesive serves its bonding function without compromising the operational characteristics of the electronic components.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If adhesive is applied to ensure proper component transfer, then transfer accuracy is improved, but the adhesive interferes with van der Waals forces

Engineering Contradiction:

Improvetransfer accuracyVSAvoidvan der Waals force

Core Design Contradiction:

Manufacturing precisionVSForce

Solution Approach 1:

The patent segments the adhesive application to only the backside of the chiplet, separating the adhesive function from the transfer interface. This segmentation allows van der Waals forces to operate at the transfer interface (front side of chiplet) while the adhesive on the backside provides additional bonding support without interfering with the primary transfer mechanism.

Inventive Principle:

Principle #1Segmentation

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 functional transfer of micro-devices and components to a destination substrate without interfering with existing structures, ensuring consistent operation and mechanical isolation, while avoiding the limitations of conventional adhesives.

Implementation Method 1

The components are adhered to individual stamp posts by van der Waals forces

Methodology Applied

Scientific Effectvan der Waals forces: Van der Waals Force

Implementation Method 2

an adhesive layer can be provided on the destination substrate or backplane to adhere the chiplets to the destination substrate or backplane

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Data Source

PatentUS11398399B2Components with backside adhesive layers

Publication Date: 2022.07.26 DAKTRONICS INC

AI summary

A component source wafer comprises printable components having adhesive disposed on a backside of the printable components. A wafer substrate comprises a sacrificial layer having recessed portions and anchors. A component is disposed entirely over each recessed portion. A tether physically connects each component to at least one of the anchors. A layer of adhesive is disposed on a side of the component adjacent to the recessed portion. Each component is suspended over the wafer substrate and the recessed portion defines a gap separating the component from the wafer substrate.