Articulating Transfer Head Alignment for Micro Device Mass Transfer
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Solution Overview
Problem
Integration and packaging issues, such as alignment and thermal drift, hinder the commercialization of micro devices like RF MEMS microswitches, LEDs, and quartz-based oscillators due to limitations in existing transfer technologies like direct printing and transfer printing.
Innovation Solution
A micro device transfer tool with an articulating transfer head assembly, miniaturized cameras, and position sensors for precise alignment and thermal management, utilizing a piezoelectric stage assembly and kinetic sensors to minimize geometric errors and thermal drift during the transfer process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional direct printing or transfer printing technologies are used, then the transfer process can be completed, but alignment precision deteriorates due to thermal drift and geometric errors
Solution Approach 1:
The patent implements real-time feedback through cameras that capture alignment marks on both the transfer wafer and receiving wafer. The system continuously monitors positional deviations and dynamically adjusts the transfer head position to compensate for thermal drift and geometric errors, thereby maintaining high alignment precision throughout the transfer process
Solution Approach 2:
The patent replaces traditional mechanical alignment methods with an optical measurement system using cameras and image processing. This substitution eliminates mechanical contact errors and enables non-contact, high-precision alignment measurement that is immune to mechanical thermal drift
2Productivity
If the entire transfer wafer with array of devices is involved in the transfer process, then mass transfer can be achieved, but device complexity increases due to handling large substrate arrays
Solution Approach 1:
The patent segments the transfer process into independent, controllable units by using a transfer head with multiple individual transfer elements arranged in an array. Each element can independently pick up and place devices, allowing the system to handle large substrate arrays through coordinated action of multiple simple, identical units rather than manipulating the entire complex substrate structure
3Ease of operation
If electrostatic transfer heads are used to pick up micro devices, then transfer operation can be performed, but manufacturing precision deteriorates due to electrostatic attraction variability
Solution Approach 1:
The system uses real-time feedback from alignment cameras and position sensors to monitor the exact location of each micro device being transferred. This feedback enables dynamic adjustment of transfer head position and orientation, compensating for variations in electrostatic attraction and ensuring precise device placement despite operational simplicity
Solution Approach 2:
The patent implements dynamic control of the transfer head assembly, allowing real-time adjustment of position, orientation, and focus during the transfer operation. This dynamic adaptability enables the system to maintain manufacturing precision by compensating for electrostatic variability through continuous positional corrections based on optical feedback
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 accurate and efficient transfer of micro devices with reduced thermal drift and geometric errors, facilitating the integration and packaging of micro devices by providing precise alignment and real-time feedback for maintaining system stability.
Implementation Method 1
a piezoelectric stage assembly mounted underneath the tip-tilt assembly
Implementation Method 2
the transfer heads operate in accordance with principles of electrostatic grippers, using the attraction of opposite charges to pick up the micro devices
Data Source
AI summary
A micro device transfer tool and methods of operation in which the micro device transfer tool includes an articulating transfer head assembly capable of six degrees of motion. A miniatured camera assembly may be secured near the point of contact for the articulating transfer head assembly to aid in system alignment. In an embodiment, an encoder system is included for alignment of a micro pick up array and target substrate using complementary concentric grating patterns. In an embodiment a miniaturized position sensor design is included for sensing position of various system components during alignment or pick and place processes.