Compliant Micro Device Transfer Head with Spring Arm

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Traditional micro device transfer technologies face challenges in efficient integration and packaging, particularly in the debonding process of transfer wafers, which limits the commercialization of micro devices like RF MEMS and LED integration.

Innovation Solution

A compliant micro device transfer head and array are developed, featuring a base substrate, spring anchor, spring arm, and dielectric layer with electrodes, allowing for independent control and precise pick-up and release of micro devices, and including a strain sensor for defect detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional wafer bonding transfer technology is used, then device transfer can be achieved, but the process requires complex debonding steps and involves the entire transfer wafer, reducing efficiency and increasing complexity

Engineering Contradiction:

Improvedevice transfer efficiencyVSAvoidtransfer process complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The invention divides the transfer wafer into individual transfer heads, each capable of independently picking up and releasing a single micro device. This segmentation eliminates the need to handle the entire transfer wafer and enables parallel processing of multiple devices, significantly improving transfer efficiency and simplifying the debonding process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The transfer head incorporates a compliant spring arm that can dynamically adjust its position and apply controlled force to pick up and release devices. This dynamic mechanism allows for precise control of the transfer process, reducing complexity compared to rigid wafer-level bonding approaches.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If traditional transfer printing with multiple bonding/debonding steps is used, then device transfer is achieved, but the process time increases and manufacturing precision may be compromised

Engineering Contradiction:

Improvedevice placement precisionVSAvoidtransfer process time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The transfer head is pre-configured with electrodes and spring arms in a ready state, allowing for rapid pick-up and release operations. The compliant structure is pre-positioned to match device locations, eliminating the need for complex real-time alignment and multiple bonding steps, thus reducing process time while maintaining precision.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention replaces traditional mechanical bonding/debonding steps with an electrostatic-based system where electrodes control the pick-up and release of devices. This substitution eliminates complex mechanical operations and reduces process time while maintaining or improving placement precision through electrical control.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If rigid transfer structures are used, then structural stability is maintained, but the system cannot accommodate variations in device height or contamination, reducing adaptability

Engineering Contradiction:

Improveaccommodation of device variationsVSAvoidstructural stability

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The transfer head uses a flexible spring arm structure that can deflect and adapt to variations in device height, surface contamination, or positioning tolerances. This flexible component maintains contact with the device while accommodating dimensional variations, providing both adaptability and structural stability through elastic deformation.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The spring arm's mechanical properties (such as stiffness and deflection range) are designed to change parameters like contact force and position dynamically. This allows the system to adapt to different device conditions while maintaining stable operation within defined parameters, resolving the contradiction between rigidity and adaptability.

Inventive Principle:

Principle #35Parameter changes

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 high-speed, high-density transfer of micro devices with improved precision and reliability, accommodating variations in device height and contamination, and facilitating integration into heterogeneous systems.

Implementation Method 1

A compliant micro device transfer head and head array and method of forming a compliant micro device transfer head and head array are disclosed

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

a top electrode extending laterally from the spring anchor and over the mesa structure, and a bottom electrode extending laterally from the spring anchor underneath the mesa structure and wrapping around and over the mesa structure

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Implementation Method 3

The micro device transfer head may further include a strain sensor formed over the dielectric layer at an interface of the spring anchor and the spring arm

Methodology Applied

Scientific EffectStrain detection: Piezoresistive Effect

Data Source

PatentUS8945968B2Compliant micro device transfer head with integrated electrode leads

Publication Date: 2015.02.03 APPLE INC

AI summary

A compliant micro device transfer head and head array are disclosed. In an embodiment a micro device transfer head includes a spring arm having integrated electrode leads that is deflectable into a space between a base substrate and the spring arm.