Cody-Lorentz Model for High-K Dielectric Defect Characterization
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Solution Overview
Problem
Current methods for characterizing high-k dielectric layers in semiconductor manufacturing are limited in their ability to accurately represent defects such as charge trapping centers, especially in amorphous materials, and are not suitable for high-throughput inspection and process control.
Innovation Solution
A generalized Cody-Lorentz model augmented with additional Lorentz peaks is used to describe the complex bulk band structure of high-k dielectric layers, enabling accurate characterization of defects and interface states, and improving the representation of optical and transport measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the harmonic oscillator model is used to represent optical dispersion of high-k dielectrics, then the model can represent defect states in principle, but it does not work for amorphous materials including high-K dielectrics and has indirect connection between model parameters and meaningful physical values
Solution Approach 1:
The patent transitions from the harmonic oscillator model parameters to the Cody-Lorentz model parameters, changing the mathematical form of the dispersion relation. The Cody-Lorentz model uses a different parameterization that is specifically suited for amorphous materials, with parameters that have direct physical meaning related to defect states such as activation energy and defect concentration. This parameter change resolves the contradiction by maintaining defect state representation capability while ensuring applicability to amorphous high-k dielectric materials.
2Productivity
If traditional spectroscopic ellipsometry measurement techniques are used for high-throughput inspection, then the number of unknown parameters can be reduced, but the ability to accurately characterize defects such as charge trapping centers is limited
Solution Approach 1:
The patent segments the optical dispersion into distinct contributions: the Cody-Lorentz term representing the bulk amorphous dielectric response and additional Lorentz oscillators representing specific defect states. This segmentation allows the model to maintain computational efficiency for high-throughput measurement while accurately characterizing defects by assigning separate parameters to different physical mechanisms, thereby resolving the contradiction between throughput and precision.
3Ease of manufacture
If the Tauc-Lorentz model or Cody-Lorentz model is employed to represent optical dispersion, then the imaginary part of the dielectric function can be represented by a parameterized dispersion function, but these models are limited in their ability to characterize defects such as charge trapping centers
Solution Approach 1:
The patent creates a composite optical model that combines the Cody-Lorentz dispersion function (suitable for amorphous bulk materials) with additional Lorentz oscillator terms (specifically designed to represent defect states). This composite approach maintains the ease of implementation and parameterization of the Cody-Lorentz model while enhancing defect characterization capability by adding dedicated defect terms, thus resolving the contradiction between model simplicity and defect characterization accuracy.
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 allows for quick and accurate representation of experimental results, providing insight and control over the manufacturing process, improving device performance by effectively controlling charge trapping centers and enhancing the characterization of high-k dielectric layers.
Implementation Method 1
Spectroscopic ellipsometry (SE) is a non-invasive characterization technique suitable for identifying process-induced defects, such as charge trapping centers, during device fabrication.
Implementation Method 2
The described embodiments relate to systems for wafer inspection, and more particularly to characterization and defect detection of thin films used in semiconductor manufacturing.
Data Source
AI summary
Methods and systems for determining band structure characteristics of high-k dielectric films deposited over a substrate based on spectral response data are presented. High throughput spectrometers are utilized to quickly measure semiconductor wafers early in the manufacturing process. Optical models of semiconductor structures capable of accurate characterization of defects in high-K dielectric layers and embedded nanostructures are presented. In one example, the optical dispersion model includes a Cody-Lorentz model augmented by one or more oscillator functions sensitive to one or more defects of the unfinished, multi-layer semiconductor wafer. These models quickly and accurately represent experimental results in a physically meaningful manner. The model parameter values can be subsequently used to gain insight and control over a manufacturing process.