Wafer Bonding Using Magnetic Self-Alignment to Reduce Warpage
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Solution Overview
Problem
Existing semiconductor wafer bonding techniques face challenges in achieving precise alignment and reducing misalignment and warpage, which affect the accuracy and efficiency of stacked semiconductor devices.
Innovation Solution
The use of magnetic alignment marks with opposite magnetic polarity on semiconductor wafers, allowing for magnetic self-alignment during bonding, which includes a hybrid bonding process combining optical and magnetic alignment to enhance precision and reduce misalignment and warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bonding techniques are used, then bonding process is simple, but alignment precision deteriorates
Solution Approach 1:
Alignment marks with magnetic features are formed on the wafers before the bonding process. These pre-formed magnetic alignment marks enable magnetic self-alignment during bonding, achieving sub-0.1 μm precision without requiring complex real-time alignment systems during the bonding process itself.
Solution Approach 2:
Magnetic fields are introduced as an intermediary mechanism to facilitate alignment between wafers. The magnetic alignment marks interact through magnetic attraction and repulsion forces, serving as a mediator that guides the wafers into precise alignment during the bonding process without requiring direct mechanical or optical contact.
2Manufacturing precision
If conventional alignment methods are used, then process is straightforward, but misalignment occurs
Solution Approach 1:
The magnetic alignment marks enable the wafers to self-align through magnetic interactions during the bonding process. The magnetic attraction and repulsion forces automatically guide the wafers into correct alignment without requiring external alignment systems or manual intervention, achieving both high precision and efficiency.
3Manufacturing precision
If high precision alignment is pursued, then alignment accuracy improves, but warpage increases
Solution Approach 1:
The magnetic field parameters (strength, direction, distribution) are carefully controlled and optimized to achieve precise alignment while minimizing warpage. By adjusting the magnetic field parameters and the configuration of magnetic alignment marks, the system achieves sub-0.1 μm alignment precision while maintaining wafer flatness through hybrid bonding processes.
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 magnetic alignment marks improve the accuracy of wafer alignment, reducing misalignment to less than 0.1 μm and minimizing warpage, thereby enhancing the overall precision and reliability of stacked semiconductor devices.
Implementation Method 1
magnetic alignment marks with opposite magnetic polarity on semiconductor wafers, allowing for magnetic self-alignment during bonding
Data Source
AI summary
In an embodiment, a method includes: receiving a first wafer and a second wafer, the first wafer including a first alignment mark, the first alignment mark including a first grid of first magnetic features, the second wafer including a second alignment mark, the second alignment mark including a second grid of second magnetic features; aligning the first alignment mark with the second alignment mark in an optical alignment process; after the optical alignment process, aligning the first alignment mark with the second alignment mark in a magnetic alignment process, north poles of the first magnetic features being aligned with south poles of the second magnetic features, south poles of the first magnetic features being aligned with north poles of the second magnetic features; and forming bonds between the first wafer and the second wafer.