X-ray Scatterometry Model for Semiconductor Hole Shape Distortion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current metrology systems face challenges in accurately measuring high aspect ratio semiconductor structures due to penetration issues and correlation problems with complex, three-dimensional geometries, leading to reduced device yield and inaccuracies in process control.
Innovation Solution
The implementation of a geometrically parameterized measurement model with more than two degrees of freedom, using a piecewise assembly of conic sections, to characterize the in-plane shape of semiconductor structures, enabling more accurate capture of distorted shapes and improved process control through real-time monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If longer wavelengths are used to penetrate deep into high aspect ratio structures, then penetration depth is improved, but sensitivity to small anomalies and measurement precision deteriorates
Solution Approach 1:
The measurement model segments the structure into multiple depth layers and uses a piecewise assembly of conic sections to characterize the in-plane shape at different depths. This allows the system to capture distorted geometries throughout the deep structure without requiring a single wavelength that compromises either penetration or sensitivity.
2Adaptability or versatility
If complex three-dimensional geometries are measured using traditional optical scatterometry, then measurement capability is extended, but parameter correlation increases and measurement precision deteriorates
Solution Approach 1:
The patent introduces a depth dimension by using a geometrically parameterized measurement model with more than two degrees of freedom. The piecewise assembly of conic sections characterizes the in-plane shape as a function of depth, transforming the measurement approach from two-dimensional projection to three-dimensional reconstruction, which enables better parameter decoupling for complex 3D structures.
3Device complexity
If traditional ellipse-based measurement models are used for deep structures, then model simplicity is maintained, but measurement accuracy deteriorates due to distorted geometry
Solution Approach 1:
The patent changes the geometric parameters of the measurement model from a simple ellipse (two degrees of freedom) to a piecewise assembly of conic sections with more than two degrees of freedom. This parameter expansion allows the model to accurately represent distorted in-plane shapes of deep structures while maintaining computational tractability through real-time monitoring capabilities.
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 measurement accuracy and stability, allowing for precise estimation of structural parameters and process corrections, thereby improving device yield and reducing registration errors in semiconductor fabrication.
Implementation Method 1
X-ray scatterometry techniques offer the potential for high throughput without the risk of sample destruction
Implementation Method 2
Optical radiation is often unable to penetrate layers constructed of these materials
Data Source
AI summary
Methods and systems for estimating values of geometric parameters characterizing in-plane, distorted shapes of high aspect ratio semiconductor structures based on x-ray scatterometry measurements are presented herein. A parameterized geometric model captures the scattering signature of in-plane, non-elliptical distortions in hole shape. By increasing the number of independent parameters employed to describe the in-plane shape of hole structures the model fit to the actual shape of high aspect ratio structures is improved. In one aspect, a geometrically parameterized measurement model includes more than two degrees of freedom to characterize the in-plane shape of a measured structure. In some embodiments, the geometric model includes a closed curve having three degrees of freedom or more. In some embodiments, the geometric model includes a piecewise assembly of two or more conic sections. Independent geometric model parameters are expressed as functions of depth to capture shape variation through the structure.