Integrated SEM and Optical Metrology for Critical Dimension Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithography and dry etch processes in semiconductor manufacturing often result in critical dimension non-uniformity across substrates, which is challenging to characterize effectively with existing metrology and inspection tools, as SEM tools are slow while optical tools offer fast throughput but poor spatial resolution.
Innovation Solution
An integrated system combining scanning electron microscopy and optical analysis techniques, including a controller that generates critical dimension uniformity maps and determines process tool control parameters based on inspections and overlay measurements from both SEM and optical metrology systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SEM tools are used for inspection and metrology, then measurement precision and sensitivity are improved, but productivity deteriorates due to slow inspection speed
Solution Approach 1:
The inspection process is segmented into multiple passes: a first pass using optical inspection for rapid screening of the entire wafer, followed by a second pass using SEM for detailed inspection of only the defect-containing regions identified in the first pass. This segmentation allows the system to maintain high throughput while achieving high measurement precision where needed.
Solution Approach 2:
The system applies different inspection qualities to different regions of the wafer. Full-wafer optical inspection provides coarse but fast coverage, while SEM inspection provides fine but slow coverage only at defect-containing locations. This local quality approach ensures high precision is applied only where necessary, improving overall productivity.
2Measurement precision
If full wafer inspection is performed with high sensitivity tools, then measurement precision is improved, but loss of time increases due to extended inspection duration
Solution Approach 1:
A preliminary optical inspection pass is performed across the entire wafer to identify defect-containing regions before conducting detailed SEM inspection. This preliminary action filters out defect-free regions, allowing the time-consuming high-sensitivity SEM inspection to be applied only where necessary, thereby reducing total inspection time while maintaining high defect detection sensitivity.
Solution Approach 2:
Instead of applying full-sensitivity SEM inspection to the entire wafer, the system applies partial action by limiting high-sensitivity inspection only to regions containing defects as identified by the preliminary optical scan. This partial action approach maintains high defect detection sensitivity while significantly reducing the total time required.
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
This approach enhances data collection for advanced process control, improving sensitivity and throughput by integrating SEM and optical tools, enabling better feedback and feedforward loops for device variability compensation.
Implementation Method 1
A first inspection is performed with a scanning electron microscope (SEM) at the first plurality of selected regions of interest
Implementation Method 2
a second critical dimension uniformity map for the sample based on a second inspection performed by the optical inspection system
Implementation Method 3
overlay measurements performed on the sample by the optical metrology system
Data Source
AI summary
A sample analysis system includes a scanning electron microscope, an optical and/or eBeam inspection system, and an optical metrology system. The system further includes at least one controller. The controller is configured to receive a first plurality of selected regions of interest of the sample; generate a first critical dimension uniformity map based on a first inspection performed by the scanning electron microscope at the first selected regions of interest; determine a second plurality of selected regions of interest based on the first critical dimension uniformity map; generate a second critical dimension uniformity map based on a second inspection performed by the optical and/or eBeam inspection system at the second selected regions of interest; and determine one or more process tool control parameters based on inspection results and on overlay measurements performed on the sample by the optical metrology system.