Integrated Metrology Model for Semiconductor Process Parameter Measurement
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Solution Overview
Problem
Current optical metrology techniques face challenges in accurately characterizing complex nanoscale semiconductor structures due to increasing complexity, small resolution requirements, and multi-parameter correlation, leading to increased measurement time and uncertainty.
Innovation Solution
Integration of a process-based target model with a metrology-based target model to constrain metrology model parameters, reducing the solution space and parameter correlation, and directly measuring process parameter values from measurement signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If measurements are performed over a large ranges of several machine parameters (wavelength, azimuth and angle of incidence), then the characterization capability is improved, but the measurement time and computation time increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-defining a reduced set of machine parameters and measurement conditions based on process model constraints. Instead of performing measurements over large ranges of all possible parameters, the system pre-determines which parameters are actually needed based on what the process model can constrain, thereby reducing measurement and computation time while maintaining characterization capability.
Solution Approach 2:
The patent changes the approach from using many machine parameters to using fewer parameters by leveraging process model information. The process model provides constraints that allow the system to work with a reduced parameter set, transforming the problem from one requiring extensive parameter sweeps to one that can be solved with targeted measurements at specific wavelengths and angles.
2Measurement precision
If measurements are performed over a large ranges of wavelengths, then the characterization capability is improved, but the illumination intensity at any particular wavelength decreases and signal uncertainty increases
Solution Approach 1:
The patent changes the wavelength selection from a broad range approach to a targeted approach. By using process model constraints to identify which wavelengths provide the most useful information for characterizing specific process parameters, the system concentrates illumination intensity at those specific wavelengths rather than spreading it thin across a large range, thereby improving signal quality.
3Measurement precision
If the number of parameters required to characterize complex structures increases, then the characterization completeness is improved, but the parameter correlation increases and measurement reliability decreases
Solution Approach 1:
The patent introduces the process model as an intermediary that bridges the measurement data and the complex structure parameters. The process model acts as a mediator that provides constraints and relationships between parameters, allowing the system to characterize complex structures with many parameters while using fewer independent measurements. The process model decouples the parameter estimation problem by providing prior knowledge about parameter relationships.
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 improves the accuracy and efficiency of measurement models by reducing parameter correlation and measurement time, enabling more precise characterization of complex semiconductor structures.
Implementation Method 1
optical metrology based techniques including scatterometry and reflectometry implementations
Implementation Method 2
scatterometry and reflectometry implementations
Implementation Method 3
scatterometry and reflectometry implementations
Data Source
AI summary
Methods and systems for performing measurements based on a measurement model integrating a metrology-based target model with a process-based target model. Systems employing integrated measurement models may be used to measure structural and material characteristics of one or more targets and may also be used to measure process parameter values. A process-based target model may be integrated with a metrology-based target model in a number of different ways. In some examples, constraints on ranges of values of metrology model parameters are determined based on the process-based target model. In some other examples, the integrated measurement model includes the metrology-based target model constrained by the process-based target model. In some other examples, one or more metrology model parameters are expressed in terms of other metrology model parameters based on the process model. In some other examples, process parameters are substituted into the metrology model.