Electrostatic Mass Transfer Tool for Micro Devices

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Solution Overview

Problem

Integration and packaging issues, such as transfer wafer bonding and de-bonding steps, pose obstacles for the commercialization of micro devices like RF MEMS microswitches, LED display systems, and quartz-based oscillators, as existing transfer technologies are inefficient and complex.

Innovation Solution

A mass transfer tool with an articulating transfer head assembly, electrostatic voltage source connection, and actuator assembly that adjusts spatial relationships in multiple degrees of freedom, allowing precise alignment and transfer of micro devices between substrates using electrostatic forces and sensors for feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional wafer bonding and de-bonding steps are used for transferring micro devices, then the transfer process can be completed, but the process complexity and time consumption increase significantly

Engineering Contradiction:

Improvetransfer process completenessVSAvoidprocess complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the transfer wafer from the traditional bonding-debonding process. Instead of using a separate transfer wafer to pick up and transfer devices, the invention allows devices to be transferred directly from the donor substrate to the receiving substrate, removing the intermediate transfer medium and simplifying the overall process

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the transfer process into independent functional zones within the same chamber: a donor substrate zone, a receiving substrate zone, and electrostatic actuation zones. This allows different operations (release, transfer, bonding) to occur simultaneously in different spatial locations without requiring sequential bonding-debonding cycles

Inventive Principle:

Principle #1Segmentation

2Reliability

If traditional transfer printing with two bonding/de-bonding steps is used, then device transfer can be achieved, but the manufacturing time and process steps increase

Engineering Contradiction:

Improvedevice transfer accuracyVSAvoidmanufacturing throughput

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent enables continuous device transfer by maintaining electrostatic actuation throughout the process. Devices are released from the donor substrate, transferred to the receiving substrate, and bonded in a continuous sequence without interrupting the electrostatic field, eliminating the idle time associated with cooling and re-heating cycles in traditional methods

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The patent applies preliminary electrostatic actuation to prepare devices for transfer before actual contact with the receiving substrate. The electrostatic field pre-positiones and orients devices, ensuring accurate alignment and reducing the need for post-transfer adjustment or re-bonding cycles

Inventive Principle:

Principle #10Preliminary action

3Productivity

If the entire transfer wafer with array of devices is involved in transfer, then mass transfer is achieved, but the de-bonding step remains complex and time-consuming

Engineering Contradiction:

Improvemass transfer capabilityVSAvoidde-bonding time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent replaces mechanical de-bonding operations with electrostatic field control. Instead of physically separating substrates through forceful mechanical means, the electrostatic field is simply deactivated or reversed, causing devices to release from the donor substrate and bond to the receiving substrate through field-controlled adhesion

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 efficient and precise transfer of micro devices with high process throughput and yield, improving system reliability and longevity by allowing for substrate replacement and operation at elevated temperatures.

Implementation Method 1

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Implementation Method 2

The mounting surface can include a vacuum port coupled with a vacuum source to apply suction to the substrate

Methodology Applied

Scientific EffectVacuum suction: Suction

Data Source

PatentUS10183401B2Mass transfer tool

Publication Date: 2019.01.22 APPLE INC

AI summary

Systems and methods for transferring a micro device from a carrier substrate are disclosed. In an embodiment, a mass transfer tool includes an articulating transfer head assembly, a carrier substrate holder, and an actuator assembly to adjust a spatial relationship between the articulating transfer head assembly and the carrier substrate holder. The articulating transfer head assembly may include an electrostatic voltage source connection and a substrate supporting an array of electrostatic transfer heads.