Overlay Target Selection Using E-Beam Simulation for Precision Metrology
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Solution Overview
Problem
Current semiconductor fabrication processes face challenges in achieving high precision and uniformity of device features due to the need for submicron features, increased transistor and circuit speeds, and improved reliability, requiring accurate monitoring and examination of semiconductor wafers during fabrication.
Innovation Solution
A system and method that utilizes a processor and memory circuitry to simulate image data of overlay targets using electron beam examination systems, determining optimal overlay targets based on estimated probabilities of meeting measurement quality criteria, and selecting these targets for actual manufacturing to enhance accuracy and efficiency in overlay measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple overlay targets are manufactured and examined using electron beam examination systems, then measurement data can be obtained for overlay analysis, but the manufacturing operations and time are increased
Solution Approach 1:
The system performs preliminary simulation of image data for multiple overlay targets before actual manufacturing. By predicting measurement quality metrics in advance, the system identifies optimal targets that will provide the best measurement precision, allowing manufacturers to produce fewer physical targets while maintaining high measurement accuracy.
Solution Approach 2:
The system creates virtual copies of overlay targets through simulation. Instead of manufacturing multiple physical targets to test different designs, the system generates simulated image data that replicates what would be obtained from actual electron beam examination, enabling virtual evaluation of multiple target designs without physical production.
2Measurement precision
If simulation of image data is performed for multiple overlay targets, then optimal target selection is improved, but computational complexity and time increase
Solution Approach 1:
The system extracts only the essential features and parameters needed for overlay measurement from the complete design data of each target. By focusing simulation on critical measurement-related properties rather than full geometric detail, the system reduces computational complexity while maintaining sufficient accuracy for optimal target selection.
Solution Approach 2:
The system varies simulation parameters such as electron beam energy, focal conditions, and target geometry to evaluate different measurement scenarios. By systematically changing parameters to identify optimal measurement conditions, the system achieves high target selection accuracy without requiring exhaustive simulation of all possible variations.
3Reliability
If design variations are predicted through simulation, then measurement quality can be optimized, but the examination process becomes more complex
Solution Approach 1:
The system uses simulation results to provide feedback on how design variations affect measurement quality. By analyzing predicted measurement outcomes and comparing them against quality criteria, the system identifies which design variations will produce the most reliable measurements, enabling optimization without manual trial-and-error examination.
Data Source
AI summary
There are provided systems and methods comprising obtaining design data of each of a plurality of given overlay targets comprising a plurality of stacked layers, using at least part of the design data to simulate image data of each given overlay target that would have been acquired by an electron beam examination system, using the image data to determine, before actual manufacturing of each given overlay target, second data informative of estimated probability that each given overlay target, upon being manufactured according to the design data, provides measurement data in an overlay measurement process meeting a measurement quality criterion, and using the second data of each given overlay target to select at least one optimal overlay target among the plurality of different overlay targets, wherein the at least one optimal overlay target is usable to be actually manufactured on the semiconductor specimen.