Optical Projection System Tuning for Image-Edge Placement
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Solution Overview
Problem
Current photolithography technologies face challenges in precisely determining and correcting pattern edge placement across multiple layers of integrated devices, leading to potential device malfunction and reduced yield, due to the lack of effective methods for optimizing the optical projection system to minimize pattern overlay errors and align image edges accurately.
Innovation Solution
The method involves adjusting optical and geometrical parameters of the lithographic exposure tool's projection system, including illumination and aberration modifications, to optimize image edge placement by using a comprehensive edge-placement error model and cost functions to minimize image edge placement errors across the image field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography is used without optimized projection system tuning, then the fabrication process is simpler and faster, but pattern overlay errors occur leading to misaligned image edges and reduced device yield
Solution Approach 1:
The patent applies preliminary action by performing projection system tuning and optimization before actual lithographic patterning. The system pre-calculates and pre-adjusts optical parameters (illuminator and projection lens aberrations) to compensate for expected overlay errors, ensuring accurate pattern placement without requiring complex real-time corrections during fabrication.
Solution Approach 2:
The patent implements feedback through the use of edge placement error models and cost functions that continuously monitor and evaluate pattern edge positions. The system uses measured overlay mark positions and pattern edge locations to feedback-adjust the projection system parameters, creating a closed-loop control mechanism that minimizes misalignment errors and improves manufacturing precision.
2Measurement precision
If projection system parameters are adjusted to minimize image edge placement errors, then pattern alignment accuracy improves, but the tuning process becomes more complex and time-consuming
Solution Approach 1:
The patent applies parameter changes by systematically varying optical parameters of the projection system, specifically adjusting illuminator and projection lens aberration parameters. The system modifies these parameters to optimize the imaging characteristics and minimize edge placement errors, using mathematical models to determine optimal parameter values that balance accuracy with tunability.
Solution Approach 2:
The patent implements dynamics by making the projection system parameters adjustable and adaptable rather than fixed. The system dynamically tunes optical parameters based on specific patterning requirements and measured overlay conditions, allowing flexible optimization for different pattern types and fabrication processes without requiring complete system redesign.
3Productivity
If comprehensive edge placement optimization is implemented, then integrated device yield improves, but the process requires more measurement and monitoring infrastructure
Solution Approach 1:
The patent applies self-service by enabling the lithographic system to automatically monitor, measure, and correct its own overlay errors using embedded sensors and error models. The system self-diagnoses misalignment conditions and self-corrects through automated projection tuning, reducing the need for external monitoring infrastructure and manual intervention while maintaining high device yield.
Data Source
AI summary
Method for minimization of degradation of images created by the projector tool turns on the optimization of the pattern-imaging by adjusting parameters and hardware of the projector to judiciously impact the placement of various image edges at different locations in the image field. Adjustments to the projector (exposure tool) include a change of a setup parameter of the exposure tool and/or scanning synchronization and/or a change of a signature of the optical system of the exposure tool determined as a result of minimizing the pre-determined cost function(s) that are parts of a comprehensive edge-placement error model.