Magnetic Die Alignment in Die Bonding for Fine Pad Pitches
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Solution Overview
Problem
The increasing integration of semiconductor devices has led to smaller pad pitches, making precise alignment of dies during the die bonding process challenging, particularly in Through Silicon Via (TSV) bonding, where misalignment can occur due to the complexity of the die bonding process.
Innovation Solution
A die bonding apparatus that uses regions of magnetic material on the dies and an electromagnet to generate a magnetic field, allowing for precise alignment of the dies in the vertical direction, enabling accurate positioning and bonding without physical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a picker is used to transfer dies during the die bonding process, then the dies can be moved from the wafer to the substrate, but misalignment of the dies occurs due to the complexity of the process and decreasing pad pitches
Solution Approach 1:
The patent replaces the mechanical contact-based picker system with a magnetic field-based alignment system. Electromagnets generate magnetic fields that interact with magnetic materials embedded in the dies, enabling non-contact alignment and positioning. This substitution eliminates mechanical interference and improves alignment precision while maintaining die transfer capability.
Solution Approach 2:
The patent introduces magnetic fields as an intermediary between the picker system and the dies. The electromagnetic generation unit creates magnetic fields that mediate the alignment process, allowing precise positioning without direct mechanical contact. This intermediary field-based approach resolves the contradiction between mechanical transfer and precision alignment.
2Productivity
If the pad pitch of dies is decreased to increase integration degree, then more devices can be integrated, but precise alignment becomes more difficult to achieve
Solution Approach 1:
The patent replaces mechanical alignment methods with electromagnetic field-based alignment. The electromagnetic generation unit produces controlled magnetic fields that interact with magnetic materials in the dies, enabling sub-micron alignment precision required for decreased pad pitches. This non-contact field-based approach achieves the precision needed for high integration without mechanical limitations.
Solution Approach 2:
The patent changes the physical state and interaction parameters by using magnetic fields instead of mechanical forces. By controlling electromagnetic field strength, direction, and distribution, the system achieves precise alignment of dies with decreased pad pitches. The magnetic field parameters can be dynamically adjusted to match the reduced dimensional tolerances required for higher integration degrees.
3Ease of manufacture
If traditional die bonding methods are used, then the bonding process can be completed, but alignment errors occur that reduce device reliability
Solution Approach 1:
The patent substitutes mechanical contact-based bonding with electromagnetic field-based alignment followed by controlled bonding. The electromagnetic generation unit ensures precise alignment before bonding occurs, eliminating alignment errors that compromise reliability. This approach maintains ease of manufacture by automating the alignment process while significantly improving device reliability through non-contact precision positioning.
Solution Approach 2:
The patent performs preliminary alignment using electromagnetic fields before the actual bonding process. The electromagnetic generation unit positions the dies with high precision prior to bonding, ensuring that alignment is achieved before the bonding operation begins. This preliminary electromagnetic alignment action prevents alignment errors from occurring during the bonding process itself, thereby improving device reliability.
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
The apparatus achieves precise alignment with an error rate less than 1% of the die's width, significantly reducing alignment errors and improving the reliability and stability of semiconductor devices by allowing non-contact picking and movement of dies.
Implementation Method 1
an electromagnet arranged on a surface of each of the pickup head or the stage, and a controller configured to apply a current to the electromagnet to generate a magnetic field when the first die and the second die are disposed at a predetermined distance from each other in a vertical direction
Implementation Method 2
because of the magnetic field generated by the electromagnet, the regions of magnetic material arranged on the first die and the second die are aligned with one another in a vertical direction
Data Source
AI summary
A die bonding apparatus comprising a stage configured to support a first die, a pickup head configured to pick up a second die, regions of magnetic materials arranged on the first die and the second die, an electromagnet arranged on a surface of the pickup head or the stage; and a controller configured to apply a current to the electromagnet to generate a magnetic field when the first die and the second die are disposed at a predetermined distance from each other in a vertical direction. As a result of the magnetic field generated by the electromagnet, the regions of magnetic material arranged on first die and the second die are aligned with one another in the vertical direction.