Pick-Up Head Force Detection for µLED Transfer Accuracy
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Solution Overview
Problem
Conventional pick and place techniques are unsuitable for transferring small semiconductor devices due to difficulties in controlling forces applied during transfer, especially for devices like very small light emitting diodes (µLEDs) with diameters or widths smaller than 100 µm.
Innovation Solution
A system comprising a pick-up tool (PUT) with a deformable structure and a force detection device that captures images or uses sensors to determine the force applied during transfer, allowing precise control of forces for accurate placement and bonding of semiconductor devices on a target substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pick and place techniques are used, then the transfer process is simple, but force control precision deteriorates
Solution Approach 1:
The patent replaces direct mechanical force measurement with optical measurement. An imaging assembly captures images of a deformable structure (such as a beam or cantilever) that deflects under applied force. The deflection is measured optically and converted to force information, eliminating the need for complex mechanical force sensors while achieving precise force control.
Solution Approach 2:
The patent introduces a deformable structure as an intermediary between the pick-up tool and the semiconductor device. This structure transmits the applied force while providing a measurable deformation that correlates to the force magnitude. The deformable structure acts as a mediator that converts mechanical force into optical or electrical signals for precise measurement and control.
2Manufacturing precision
If force detection and control is implemented, then device placement accuracy improves, but system complexity increases
Solution Approach 1:
The patent replaces complex mechanical force sensing mechanisms with optical imaging. The imaging assembly and image processing system provide precise force measurement without requiring complex mechanical sensors, thereby improving placement accuracy while keeping the added complexity manageable through optical rather than mechanical means.
Solution Approach 2:
The patent implements a feedback control system where the measured force (through deformable structure deflection) is continuously monitored and used to adjust the pick-up tool's force application. This feedback loop ensures precise force control throughout the transfer process, maintaining optimal force levels for accurate device placement without causing damage.
3Object-affected harmful factors
If precise force control is applied, then device damage is minimized, but measurement and control complexity increases
Solution Approach 1:
The patent replaces difficult-to-implement mechanical force measurement with optical imaging of a deformable structure. This substitution makes force measurement straightforward and non-contact, enabling precise force control that minimizes device damage without requiring complex mechanical sensing equipment.
Solution Approach 2:
The deformable structure serves as an intermediary that amplifies and makes visible the applied force through its deflection. This intermediary converts subtle force applications into measurable optical displacements, making force detection easier and more precise while protecting the fragile semiconductor device from excessive force.
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 precise and controlled transfer and bonding of small semiconductor devices by accurately measuring and adjusting the force applied, ensuring accurate placement and minimizing damage to the devices.
Implementation Method 1
The imaging assembly captures one or more images of a structure that is formed within at least in the first leg portion or the second leg portion of the PUT and deformable under the force applied by the PUT
Implementation Method 2
a structure that is formed within at least in the first leg portion or the second leg portion of the PUT and deformable under the force applied by the PUT
Implementation Method 3
The capacitance measuring device measures a capacitance between the first electrode and the second electrode
Data Source
AI summary
A pick-up head picks up a semiconductor device from a carrier substrate. The pick-up head includes a first leg portion, a second leg portion, a raised bridge base portion between the first and second leg portions, and a tip portion mounted on the raised bridge base portion. The tip portion engages with the semiconductor device to pick up the semiconductor device from the carrier substrate. The pick-up head is associated with a force detection mechanism that detects a force applied to the pick-up head for picking up the semiconductor device. The force detection mechanism includes cavities formed on the first leg portion and/or second leg portion, pillars arranged on the pick-up head, a force detection device arranged in a mount assembly that is attached on the pick-up head, or electrodes arranged on the mount assembly. Actuation of the pick-up head is determined based on the detected force.