Ultrasound-Assisted Self-Alignment for Direct Chip Bonding
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Solution Overview
Problem
Existing self-alignment techniques for direct bonding of electronic chips to substrates do not allow for exploration of all possible alignment configurations, leading to potential misalignment due to parasitic capillarity forces and other factors.
Innovation Solution
The method involves creating regions on the chip and substrate with distinct contact angles and using a fluid as a self-alignment medium, combined with ultrasound emission during fluid removal to achieve precise alignment by minimizing wetting energy and mechanical disturbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a water droplet is used as a self-alignment medium on a hydrophilic zone, then the chip can be aligned with respect to its location on the substrate, but misalignment due to parasitic capillarity forces can persist until the chip is fully secured to the substrate
Solution Approach 1:
The patent applies ultrasonic vibration to the substrate during the bonding process. This mechanical vibration disturbs the capillarity forces acting on the chip, preventing the chip from being stuck in misaligned positions. The vibration energy allows the chip to overcome parasitic capillarity forces and reach the correct alignment position, thereby resolving the contradiction between alignment precision and alignment stability.
Solution Approach 2:
The patent employs periodic ultrasonic oscillation at specific frequencies (typically 20-100 kHz) during the bonding process. This periodic action creates time-varying capillarity forces that prevent the chip from settling into misaligned positions. The periodic disturbance ensures that the chip can explore different positions and ultimately achieve optimal alignment, addressing both precision and stability requirements.
2Ease of operation
If the chip is misaligned by a few tens of degrees after a first positioning on the substrate, then this misalignment can be the consequence of parasitic capillarity forces, but the misalignment persists until the chip is fully secured to the substrate
Solution Approach 1:
Ultrasonic vibration is applied to the substrate to mechanically disturb the capillarity forces that cause misalignment. This vibration prevents the chip from being locked in incorrect positions and enables it to achieve proper alignment during the bonding process, thereby improving manufacturing precision while maintaining ease of operation.
Solution Approach 2:
The patent changes the physical parameters of the bonding process by introducing ultrasonic frequency and amplitude parameters. These parameter changes modify the behavior of capillarity forces, transforming them from harmful persistent forces into controllable disturbances that facilitate proper alignment, thus improving positioning accuracy without complicating the self-alignment capability.
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
This approach enhances self-alignment efficiency by allowing the chip to oscillate and settle into the optimum alignment position, ensuring secure and precise bonding without persistent misalignment.
Implementation Method 1
emitting ultrasound in the first fluid through the substrate or the second electronic chip
Implementation Method 2
The ultrasound passes through the substrate or the second electronic chip to be propagated thereafter in the first fluid acting as a self-alignment medium
Implementation Method 3
using a fluid as a self-alignment medium... depositing the first fluid onto the first part of the first face of the substrate or of the second electronic chip
Implementation Method 4
removing the first fluid until a securement of the first part of the face of the first electronic chip with the first part of the first face of the substrate or of the second electronic chip is achieved
Implementation Method 5
making, on each of a face of the first electronic chip and a first face of the substrate or of the second electronic chip, at least one first and one second part having a contact angle difference towards a first fluid
Implementation Method 6
making, on each of a face of the first electronic chip and a first face of the substrate or of the second electronic chip, at least one first and one second part having a contact angle difference towards a first fluid
Implementation Method 7
Molecular bonding is induced by all the electronic interaction attractive forces between the atoms or molecules of both surfaces to be bonded (Van der Waals forces)
Data Source
AI summary
A method for direct bonding an electronic chip onto a substrate or another electronic chip, the method including: carrying out a hydrophilic treatment of a portion of, a surface of the electronic chip and of a portion of a surface of the substrate or of the other electronic chip; depositing an aqueous fluid on the portion of the surface of the substrate or of the second electronic chip; depositing the portion of the surface of the electronic chip on the aqueous fluid; drying the aqueous fluid until the portion of the surface of the electronic chip is rigidly connected to the portion of the surface of the substrate or of the other electronic chip: and during at least part of the drying of the aqueous fluid, emitting ultrasound into the aqueous fluid through the substrate or the other electronic chip.