Phase Revealing Optical X-ray Semiconductor Metrology
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor metrology techniques face ambiguities in determining the free-form scattering density map (SDM) from diffracted light due to the lack of absolute or relative phase information, leading to translational, space fraction, and vertical inversion ambiguities, which affect the accuracy of electron density measurements.
Innovation Solution
The method involves using a processor to fix a voxel map of the semiconductor wafer surface to match geometry measurements and apply uniform scaling of scattering density for all fixed surface voxels, combining phase retrieval from imaging and scatterometry methods to resolve ambiguities and achieve a unique SDM solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase retrieval from imaging and scatterometry methods is combined to resolve ambiguities, then measurement precision of electron density is improved, but device complexity increases
Solution Approach 1:
The patent combines phase retrieval from imaging methods with scatterometry methods to resolve ambiguities in SDM determination. By merging these two measurement approaches, the system achieves unique and accurate electron density measurements while addressing the limitations of individual methods
Solution Approach 2:
The patent uses an intermediary optimization process that matches simulated and measured diffraction patterns while regularizing the SDM. This intermediary computational step resolves the ambiguities between different measurement techniques and produces a unique solution
2Measurement precision
If multiple measurement techniques are combined to resolve ambiguities, then measurement precision is improved, but time to results increases
Solution Approach 1:
The patent applies preliminary regularization to the SDM during the optimization process, which constrains the solution space and accelerates convergence. This preliminary constraint prevents the system from exploring unnecessary solution variations, reducing processing time while maintaining accuracy
3Ease of operation
If the SDM is determined from diffracted light without phase information, then ease of operation is maintained, but measurement precision deteriorates due to ambiguities
Solution Approach 1:
The patent implements feedback by matching simulated diffraction patterns with measured diffraction patterns in an optimization loop. This feedback mechanism allows the system to iteratively refine the SDM determination while maintaining ease of operation, resolving ambiguities through comparative analysis rather than complex direct measurement
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 the accuracy of electron density measurements by reducing ambiguities and providing a more precise reconstruction of the SDM, improving the effectiveness of semiconductor metrology and reducing the time to results in tomography.
Implementation Method 1
a free-form scattering density map (SDM) is determined from diffracted light from a periodic planar target
Implementation Method 2
Density determination is the result of an optimization process that matches simulated and measured diffraction patterns while regularizing the SDM
Data Source
AI summary
The embodiments disclosed herein can enable a target on a semiconductor wafer to be reconstructed and/or imaged. A surface of a target on a semiconductor wafer is measured using a wafer metrology tool. A voxel map of the surface is fixed to match geometry measurements and using scattering density of expected materials. Uniform scaling of the scattering density of all fixed surface voxels can occur.