Wafer Bonding With Magnetic Alignment Marks for Sub-0.1 μm Precision
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Solution Overview
Problem
Existing semiconductor wafer bonding techniques face challenges in achieving precise alignment and efficient bonding methods to reduce the form factor of semiconductor devices, particularly in stacked configurations.
Innovation Solution
The use of magnetic alignment marks with opposite magnetic polarity on wafers that are magnetically attracted to each other during bonding, combined with optical alignment, to enhance the accuracy and precision of wafer alignment and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical alignment is used for wafer bonding, then alignment can be achieved, but alignment accuracy is insufficient to meet the requirement of less than 0.1 μm precision
Solution Approach 1:
Magnetic alignment marks are introduced as intermediary elements between the wafers to be bonded. These marks contain magnetic features that generate magnetic fields, serving as a mediator to induce magnetic attraction forces that pull the wafers into precise alignment. The magnetic marks act as a bridge that translates magnetic field interactions into mechanical alignment, achieving sub-0.1 μm precision that conventional optical methods cannot attain alone.
Solution Approach 2:
The patent replaces purely optical alignment mechanisms with a magnetic field-based alignment system. Instead of relying solely on optical detection and mechanical positioning, the invention uses magnetic fields generated by magnetic alignment marks to actively pull wafers into alignment. This substitution of mechanical/optical systems with magnetic field interactions enables higher precision alignment.
2Ease of manufacture
If wafer bonding is performed without magnetic alignment marks, then the bonding process is simpler, but alignment accuracy deteriorates and misalignment occurs
Solution Approach 1:
The magnetic alignment marks enable self-alignment of the wafers through magnetic attraction forces. The magnetic features on the alignment marks automatically generate attractive forces that pull the wafers into correct alignment positions without requiring complex external alignment equipment or manual intervention. This self-aligning mechanism maintains process simplicity while dramatically improving alignment precision.
3Volume of moving object
If stacked semiconductor devices are used to reduce form factor, then device size is reduced, but alignment precision requirements increase making bonding more difficult
Solution Approach 1:
The invention changes the physical parameter of alignment from optical detection to magnetic field interaction. By utilizing magnetic fields with specific strengths and configurations, the system achieves the enhanced alignment precision required for stacked devices. The magnetic parameters (field strength, mark size, spacing) are optimized to provide sufficient alignment force and precision for sub-0.1 μm accuracy needed in compact stacked configurations.
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 method improves the alignment accuracy between wafers to less than 0.1 μm, resulting in robust hybrid bonds with reduced misalignment and increased bonding strength, facilitating the production of smaller and more integrated semiconductor devices.
Implementation Method 1
magnetic alignment marks with opposite magnetic polarity on wafers that are magnetically attracted to each other during bonding
Data Source
AI summary
In an embodiment, a structure includes: a first device including a first dielectric layer and a first alignment mark in the first dielectric layer, the first alignment mark including a first magnetic cross, the first magnetic cross having a first north pole and a first south pole; and a second device including a second dielectric layer and a second alignment mark in the second dielectric layer, the second alignment mark including a second magnetic cross, the second magnetic cross having a second north pole and a second south pole, the first north pole aligned with the second south pole, the first south pole aligned with the second north pole, the first dielectric layer bonded to the second dielectric layer by dielectric-to-dielectric bonds, the first alignment mark bonded to the second alignment mark by metal-to-metal bonds.