Wafer Bonding Alignment Using Deformation-Based Focus Maps
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Solution Overview
Problem
Current semiconductor device manufacturing techniques face challenges in accurately aligning and bonding semiconductor circuit substrates due to variations in wafer magnification and deformation, leading to overlay deviations and reduced throughput.
Innovation Solution
A bonding apparatus that includes a first stage for holding a first substrate, a second stage for holding a second substrate, measuring devices for aligning marks on each substrate, a stress generator to apply stress, and a controller to execute bonding processing by generating a focus map based on deformation and substrate shape, allowing for precise alignment and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bonding methods are used without deformation correction, then the bonding process is simple and fast, but overlay deviation occurs due to wafer magnification variation and deformation
Solution Approach 1:
The system performs preliminary actions by generating a deformation model before bonding based on substrate curvature measurements, and pre-calculates focus map data for various deformation amounts. This allows the alignment process to use corrected focus settings without adding physical complexity to the bonding apparatus itself.
Solution Approach 2:
The invention replaces mechanical deformation correction mechanisms with a computational approach using focus map data and image processing. Instead of mechanically adjusting the substrate or alignment system to compensate for deformation, the system uses software-based focus correction based on predicted deformation patterns.
2Manufacturing precision
If wafer deformation is corrected using traditional methods, then overlay accuracy improves, but measurement and alignment time increases
Solution Approach 1:
The system pre-calculates focus map data for multiple deformation amounts before actual bonding occurs. This preliminary preparation allows the alignment process to simply look up and apply the appropriate focus settings without performing complex real-time calculations, significantly reducing measurement and alignment time.
Solution Approach 2:
The system dynamically selects the appropriate focus map based on the measured substrate curvature and applies corresponding deformation compensation. This dynamic adaptation allows accurate alignment without requiring exhaustive measurement of all possible deformation scenarios during the actual bonding process.
3Measurement precision
If focus settings are adjusted for each deformation amount, then alignment precision improves, but processing complexity and time increase
Solution Approach 1:
The system pre-calculates and stores focus map data for various deformation amounts before actual bonding. This preliminary preparation creates a lookup table of focus settings that simplifies the actual alignment process to selecting and applying the appropriate pre-computed focus map based on measured substrate curvature.
Solution Approach 2:
The system creates a computational model (focus map) that represents the relationship between substrate deformation and optimal focus settings. This model serves as a copy or approximation of the complex optical interactions, allowing accurate focus adjustment without directly modeling all physical parameters in real-time.
Data Source
AI summary
According to one embodiment, a bonding apparatus includes first and second stages, first and second measuring devices, a stress generator, and a controller. The controller generates a focus map for each deformation amount of the first stage based on a deformation amount of the first stage deformed by the stress generator and the shape of the first substrate held by the deformed first stage. In the alignment processing of the first substrate, when causing the first measuring device to measure an alignment mark arranged on the first substrate held by the first stage, the controller uses a focus setting based on the focus map corresponding to the deformation amount applied to the first stage.