Angular Phase Metrology for OCD Measurement Precision
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current optical critical dimension (OCD) metrology techniques face challenges in accurately measuring patterned structures on semiconductor wafers due to limitations in sensitivity and information richness, particularly in multi-layer structures, where existing methods struggle to provide comprehensive geometrical and material characterization.
Innovation Solution
The implementation of angular phase metrology, which measures the relative phase between incident and reflected light beams across different angles and wavelengths, allowing for the generation of 2D or 3D information sets that can be processed to determine structural parameters, using an optical system with illumination and detection assemblies and a control unit for data processing and analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional spectral reflectometry and spectral ellipsometry are used for OCD metrology, then the measurement system is relatively simple and easy to operate, but the sensitivity and information richness are insufficient for accurately characterizing multi-layer patterned structures
Solution Approach 1:
The patent transitions from conventional intensity-based measurements to phase-based measurements, adding a new dimension (phase information) to the measurement space. This enables extraction of additional structural parameters with higher precision without proportionally increasing system complexity
Solution Approach 2:
The patent employs wavelength-tunable laser illumination, changing the optical parameter (wavelength) to enhance sensitivity to different structural features. This allows precise measurement of critical dimensions, side wall angles, and material properties by analyzing phase variations across multiple wavelengths
2Loss of information
If conventional intensity-based optical techniques are used, then the system is simpler to implement, but the ability to provide comprehensive geometrical and material characterization is limited
Solution Approach 1:
The patent introduces a reference beam as an intermediary that interferes with the sample beam. This reference beam carries known phase information that, when combined with the sample beam, enables extraction of both geometrical and material parameters through interference pattern analysis
Solution Approach 2:
The patent combines multiple measurement modalities (reflectometry, ellipsometry, and phase measurements) into a composite measurement approach. This integrated method provides comprehensive characterization of both geometric structures and material properties simultaneously
3Measurement precision
If standard optical metrology methods are applied to multi-layer structures, then the measurement process is straightforward, but sensitivity to thin films and thick layers is insufficient
Solution Approach 1:
The patent employs a tunable laser wavelength system that dynamically adjusts the illumination wavelength to optimize sensitivity for different layer thicknesses. This dynamic parameter adjustment enables precise measurement of both thin films and thick layers by matching the wavelength to the specific structural features being measured
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 provides sensitive and information-rich OCD measurements, enabling precise determination of structural parameters such as critical dimensions, side wall angles, and refractive indices, with improved sensitivity to thin films and thick layers, and the ability to integrate with other metrology techniques for comprehensive characterization.
Implementation Method 1
an optical system configured for detecting light reflection of incident radiation from the structure and generating measured data indicative of angular phase of the detected light components corresponding to reflections of illuminating light components
Data Source
AI summary
A metrology system is presented for measuring parameters of a structure. The system comprises: an optical system and a control unit. The optical system is configured for detecting light reflection of incident radiation from the structure and generating measured data indicative of angular phase of the detected light components corresponding to reflections of illuminating light components having different angles of incidence. The control unit is configured for receiving and processing the measured data and generating a corresponding phase map indicative of the phase variation along at least two dimensions, and analyzing the phase map using modeled data for determining one or more parameters of the structure.