Wafer-Level Bond Strength Measurement Using PDMS Probe and Optical Fiber Sensor
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Solution Overview
Problem
Current methods are unable to effectively measure bond strength on devices with sizes down to approximately 5 micrometers at the wafer level, which is crucial for advanced technologies like MicroLED transfer and three-dimensional integrated circuit applications.
Innovation Solution
A wafer-level bond strength measurement system using a polydimethylsiloxane (PDMS) probe and optical fiber sensor assembly to apply an external force and monitor separation distance, enabling the determination of bond strength between copper-to-copper bonds on micro-scale devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional bond strength measurement methods are used, then measurement capability is sufficient for large devices, but measurement precision deteriorates for micrometer-size devices
Solution Approach 1:
The patent segments the measurement process into distinct functional modules: a probe assembly for applying controlled force, an optical fiber sensor assembly for measuring separation distance, and a processing system for calculating bond strength. This segmentation allows each module to be optimized for micrometer-scale measurements independently, resolving the contradiction between measurement precision and device size
Solution Approach 2:
The patent introduces a PDMS probe as an intermediary between the measurement system and the bonded surfaces. The probe mediates the application of external force and the interaction with micrometer-size devices, enabling precise measurement without direct contact that would compromise measurement precision
2Productivity
If wafer-level measurement is implemented, then productivity improves by measuring multiple devices, but device complexity increases
Solution Approach 1:
The measurement system is designed with universal components that can measure multiple devices at the wafer level. The probe assembly and optical fiber sensor assembly can be positioned to measure different locations on a wafer, enabling simultaneous or sequential measurement of multiple devices without requiring separate measurement systems for each device, thus improving productivity while managing complexity through standardized interfaces
Solution Approach 2:
The patent uses optical fiber sensors to create optical copies or representations of the separation distance between bonded surfaces. This allows indirect measurement that simplifies the physical interaction required, enabling wafer-level measurement without proportionally increasing system complexity
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 measurement of bond strength on small-scale devices, supporting the development of cost-effective and efficient MicroLED transfer and 3DIC technologies by ensuring reliable copper-to-copper bonding.
Implementation Method 1
A bond strength measurement system may comprise a wafer-level bond strength measurement apparatus suitable for bonds of two materials with micrometers dimensions... The bond strength between the probe and the top surface may be strong enough to separate the two metals and break the bond between them
Implementation Method 2
As the force increases, the separation distance is monitored using an optical fiber sensor assembly to determine the bond strength that held the two metals together
Data Source
AI summary
This disclosure describes systems, methods, and devices related to bond strength measurement. A device may comprise a first portion of a plate connected to a movement mechanism, a second portion of the plate comprising a sticky probe and a third portion of the plate comprising a mirror with a reflective side pointing outwards. The device may further comprise an optical fiber sensor assembly comprising an optical fiber bundle for sending light through a first optical fiber and receiving light reflected from the mirror through a second optical fiber.