Optical Measurement of 3D NAND Structures
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Solution Overview
Problem
Existing optical measurement systems struggle to achieve accurate and precise monitoring of complex semiconductor structures, particularly in 3D NAND structures, due to their high complexity and variability, leading to difficulties in measuring film thicknesses and feature depths in real-time during semiconductor processing.
Innovation Solution
A method and system that generate simplified optical models of semiconductor structures using effective medium approximations, reducing complexity by combining models of modified and unmodified portions, allowing for real-time monitoring and control of semiconductor processes with a reduced number of parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optical measurement systems are used to monitor complex semiconductor structures in real-time, then process control capability is improved, but measurement accuracy and precision deteriorate due to structural complexity and variability
Solution Approach 1:
The patent transforms the complex physical structure into an equivalent optical model by changing the representation parameters from physical dimensions to optical properties (refractive indices, layer thicknesses, absorption coefficients). This parameter transformation allows the measurement system to accurately characterize complex structures through optical responses rather than direct physical measurement, resolving the contradiction between real-time monitoring capability and measurement precision.
Solution Approach 2:
The patent introduces an optical model as an intermediary between the physical semiconductor structure and the measurement system. This optical model acts as a mediator that translates complex physical structures into simplified optical representations, enabling accurate real-time measurement without directly measuring the complex physical dimensions. The optical model serves as the bridge that reconciles the need for real-time control with the requirement for measurement accuracy.
2Device complexity
If simplified optical models are used to reduce complexity, then measurement capability is improved, but model accuracy may deteriorate due to approximations
Solution Approach 1:
The patent applies partial action by selectively simplifying only those aspects of the structure that are necessary for optical measurement purposes. Rather than oversimplifying the entire structure, the method identifies and models only the critical optical pathways and interactions, maintaining sufficient accuracy for measurement while reducing overall complexity. This partial modeling approach resolves the contradiction between simplicity and accuracy.
Solution Approach 2:
The patent changes the parameter representation from detailed physical geometry to effective optical parameters (effective refractive indices, equivalent layer thicknesses). This parameter transformation allows the model to capture essential optical behavior without requiring complete geometric detail, achieving the balance between model simplicity and measurement accuracy through parameter abstraction.
3Measurement precision
If detailed models of complex structures are used, then measurement accuracy is improved, but processing time and computational resources increase
Solution Approach 1:
The patent extracts only the essential optical characteristics from the complete structural information. By taking out and modeling only the parameters that significantly influence optical responses (key layer thicknesses, dominant refractive indices, critical interface properties), the method achieves accurate measurements without processing unnecessary structural details, thus reducing computational time while maintaining measurement precision.
Solution Approach 2:
The patent transforms detailed geometric parameters into simplified optical parameters that capture the essential measurement information. This parameter change from comprehensive geometric description to focused optical property representation reduces the computational burden while preserving measurement accuracy, as the optical parameters directly relate to the measurement signal without requiring full geometric reconstruction.
4Productivity
If in-situ measurement is implemented during etching, then process control is improved, but measurement reliability deteriorates due to plasma interference and dynamic conditions
Solution Approach 1:
The patent introduces the optical model as an intermediary that is insensitive to plasma interference. Rather than directly measuring physical dimensions in the plasma environment, the system measures optical properties through the optical model, which serves as a protective intermediary. This allows in-situ measurement during etching while maintaining reliability, as the optical measurement pathway is isolated from the harsh plasma conditions that would otherwise interfere with direct measurement.
Solution Approach 2:
The patent replaces direct physical/mechanical measurement methods with optical measurement methods. By substituting mechanical dimension measurement with optical property measurement, the system achieves in-situ monitoring capability during etching processes. Optical methods are less susceptible to plasma interference and dynamic conditions compared to mechanical measurement techniques, thus improving measurement reliability while enabling in-situ control.
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 enables accurate and precise monitoring of semiconductor structures during processing, reducing the need for off-line metrology and allowing for larger tolerances, while improving the ability to control etching processes with near real-time precision.
Implementation Method 1
an optical system that sends and receives light to and from the complex structure undergoing processing
Implementation Method 2
determining, as a function of at least one variable processing parameter, a simplified optical model of both a modified portion and an unmodified portion of the semiconductor structure employing effective medium approximation
Data Source
AI summary
A system and method of use for simplifying the measurement of various properties of complex semiconductor structures is provided. The system and method supports reduction of structure complexity and modeling for optical monitoring and permits determination of film thicknesses and feature depths during semiconductor manufacturing processes.