Lithographic Control Grid for Substrate Positioning and Process Variation
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Solution Overview
Problem
Current lithographic process control methods are limited in accuracy and efficiency, particularly in controlling across-substrate and within-field process variations, leading to sub-optimal pattern reproduction and yield in semiconductor manufacturing.
Innovation Solution
A control grid is defined based on the device layout, aligning with functional areas within a die, to optimize focus, dose, and overlay settings, allowing for precise positioning and correction of substrates during the lithographic process, thereby improving process control and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional process control methods are used, then the lithographic process can be performed with standard equipment, but the accuracy and precision of pattern reproduction are limited
Solution Approach 1:
The substrate is divided into multiple regions with different process characteristics. A control grid is superimposed on the device layout to identify representative control points within each region. This segmentation allows independent optimization of process parameters for different regions, improving overall pattern reproduction accuracy without requiring complete redesign of the lithographic system.
Solution Approach 2:
Different process parameters (focus, dose, overlay) are optimized locally for each region based on its specific characteristics. The control grid enables region-specific parameter control, allowing critical areas to receive enhanced attention and non-critical areas to use standard parameters, thereby improving manufacturing precision while maintaining manageable system complexity.
2Reliability
If a uniform control approach is applied across the entire substrate, then the process control is simple to implement, but across-substrate and within-field process variations cannot be adequately addressed
Solution Approach 1:
The substrate is divided into multiple regions with different process characteristics. A control grid is superimposed on the device layout to identify representative control points within each region. This segmentation allows independent optimization of process parameters for different regions, improving overall pattern reproduction accuracy without requiring complete redesign of the lithographic system.
Solution Approach 2:
The control grid methodology serves multiple functions: it identifies control points, defines regions, guides parameter optimization, and enables verification. This multi-functional approach improves process control consistency across the substrate while maintaining relatively simple implementation through a unified framework that can be applied systematically.
3Area of stationary object
If traditional scatterometer targets are used, then the measurement setup is straightforward, but the targets are large and cannot be surrounded by product structures
Solution Approach 1:
The substrate is divided into multiple regions with different process characteristics. A control grid is superimposed on the device layout to identify representative control points within each region. This segmentation allows independent optimization of process parameters for different regions, improving overall pattern reproduction accuracy without requiring complete redesign of the lithographic system.
Solution Approach 2:
Different process parameters (focus, dose, overlay) are optimized locally for each region based on its specific characteristics. The control grid enables region-specific parameter control, allowing critical areas to receive enhanced attention and non-critical areas to use standard parameters, thereby improving manufacturing precision while maintaining manageable system complexity.
4Manufacturing precision
If comprehensive process control is implemented for all areas, then the manufacturing precision is maximized, but the process complexity and measurement time increase significantly
Solution Approach 1:
From the complete device layout, only the most critical regions and control points are extracted for detailed process control and measurement. The control grid identifies representative control points that capture the essential process variations without requiring measurement or optimization of every area, thereby maintaining high manufacturing precision while reducing measurement and control time.
Solution Approach 2:
Instead of applying uniform comprehensive control to the entire substrate, partial action is taken by focusing enhanced control measures only on critical regions identified through the control grid. Non-critical regions use standard control procedures, optimizing the balance between manufacturing precision and process time.
Data Source
AI summary
A lithographic apparatus and associated method of controlling a lithographic process. The lithographic apparatus has a controller configured to define a control grid associated with positioning of a substrate within the lithographic apparatus. The control grid is based on a device layout, associated with a patterning device, defining a device pattern which is to be, and/or has been, applied to the substrate in a lithographic process.