Wafer Bonding Alignment Using Deformation-Based Focus Mapping
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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 both substrates, a stress generator to apply stress to the first stage, and a controller to execute bonding processing. The controller generates a focus map based on the deformation amount of the first stage and corrects the optical axis of the measuring device to improve alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional alignment methods are used without considering stage deformation, then the device complexity is lower, but the manufacturing precision deteriorates due to overlay deviations
Solution Approach 1:
The patent applies preliminary action by measuring the deformation amount of the first stage before performing alignment, and using this pre-acquired deformation information to generate a focus map and correct the optical axis. This allows the alignment process to compensate for stage deformation without adding complex real-time measurement systems during alignment.
Solution Approach 2:
The patent introduces a focus map as an intermediary element that bridges the deformation measurement and the alignment process. The focus map, generated based on deformation amount, serves as a mediator that translates deformation information into optical axis correction parameters, simplifying the overall control system.
2Measurement precision
If conventional focus settings are used without deformation compensation, then the measurement process is simpler, but the measurement precision deteriorates due to incorrect focus positions
Solution Approach 1:
The patent changes the focus parameter dynamically based on the deformation amount. By generating a focus map that correlates deformation with optimal focus positions, the system adjusts the focus setting to match the deformed state of the stage, thereby maintaining measurement precision without requiring complex hardware modifications.
3Productivity
If traditional bonding processes are used without deformation compensation, then the process time is shorter, but the productivity deteriorates due to rework and lower yield
Solution Approach 1:
The patent replaces mechanical trial-and-adjustment alignment methods with an optical measurement system that uses a camera and focus map. This substitution enables rapid, automated alignment based on deformation compensation, reducing measurement time while maintaining high precision, thus improving overall productivity.
Data Source
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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.