Substrate Alignment Imaging for Precise Direct Wafer Bonding
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Solution Overview
Problem
Existing substrate alignment methods in semiconductor fabrication struggle with accuracy, particularly in direct bonding processes where wafers are bonded without a separate medium, leading to challenges in aligning and bonding substrates effectively.
Innovation Solution
A substrate alignment method utilizing an imaging unit with multiple light sources of different wavelengths and a polarizing plate to enhance recognition of alignment keys, enabling precise alignment and bonding of substrates by capturing and processing images of alignment keys on both substrates before bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single light source is used in the imaging unit, then the device complexity is reduced, but the alignment accuracy deteriorates due to insufficient recognition of alignment keys under varying conditions
Solution Approach 1:
The imaging unit is segmented into multiple independent light sources, each emitting at different wavelengths (visible, near-infrared, far-infrared). This segmentation allows each light source to be optimized for specific recognition conditions, thereby improving alignment accuracy without requiring a single complex light source system
Solution Approach 2:
The system changes the wavelength parameter of light sources to adapt to different recognition needs. By incorporating light sources across the visible, near-infrared, and far-infrared spectrum, the imaging unit can adjust its spectral characteristics to optimize alignment key recognition under varying substrate conditions and environments
2Measurement precision
If multiple light sources with different wavelengths are used, then the recognition of alignment keys is enhanced, but the use of energy increases due to operating multiple light sources
Solution Approach 1:
The system performs preliminary action by pre-configuring multiple light sources at different wavelengths before the alignment process begins. This allows the imaging unit to quickly switch between wavelength bands as needed during alignment, rather than continuously operating all light sources, thereby reducing overall energy consumption while maintaining recognition accuracy
Solution Approach 2:
The imaging unit employs periodic action by activating different wavelength light sources in sequence or as needed during the alignment process. Rather than continuous operation of all light sources, the system periodically switches between visible, near-infrared, and far-infrared sources based on recognition requirements, optimizing energy efficiency
3Manufacturing precision
If alignment accuracy is improved through multiple light sources and polarizing plates, then the bonding quality is enhanced, but the device complexity increases due to additional optical components
Solution Approach 1:
The imaging unit merges multiple optical components (multiple wavelength light sources, optical lenses, and polarizing plates) into a single integrated unit. This consolidation allows the system to achieve high alignment accuracy through coordinated operation of these components while managing overall device complexity through unified design and control
Solution Approach 2:
The imaging unit is designed with multi-functionality, serving both as an illumination system (through multiple light sources) and as an optical detection system (through lenses and polarizing plates). This universal design allows a single integrated unit to perform multiple functions that would otherwise require separate devices, thereby improving bonding precision without proportionally increasing overall 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
Improves alignment accuracy and efficiency in substrate bonding processes, allowing for higher precision and productivity in semiconductor device fabrication by ensuring accurate alignment and bonding of substrates.
Implementation Method 1
an imaging unit to recognize at least one alignment key... a plurality of light sources on an upper side of an interior of the imaging housing
Implementation Method 2
the plurality of light sources include: two visible light sources; a near-infrared light source; and a far-infrared light source
Implementation Method 3
a polarizing plate beneath and spaced apart from the optical lens
Data Source
AI summary
A substrate alignment method includes inserting a first substrate and a second substrate into a substrate bonding apparatus, causing an imaging unit to recognize at least one alignment key, aligning the first substrate and the second substrate by using the at least one alignment key recognized by the imaging unit, and performing a bonding of the first substrate and the second substrate after confirming that the alignment is completed. The imaging unit includes an imaging housing, a plurality of light sources on an upper side of an interior of the imaging housing, an optical lens below the plurality of light sources, a polarizing plate downwardly spaced apart from the optical lens, and a reading module configured to read information about a position of the alignment key. The plurality of light sources includes two visible light sources, a near-infrared light source, and a far-infrared light source.