Modified Cody-Lorentz Model for High-k Dielectric Band Gap Tracking
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Solution Overview
Problem
Current methods for characterizing high-k dielectric layers in semiconductor manufacturing are limited by their inability to provide accurate, high-throughput, non-destructive, and physically meaningful measurements of band gap and electrical characteristics, often requiring indirect measurements and introducing errors due to computational burdens and sensitivity to statistical errors.
Innovation Solution
A modified Cody-Lorentz model with continuous first derivatives is used to accurately characterize the band structure of high-k dielectric layers, enabling direct estimation of optical band gap and correlation with leakage current, thereby predicting electrical performance and controlling manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods (electrical measurements, transmission electron microscopy, x-ray spectroscopy) are used to characterize high-k dielectric layers, then measurement precision may be adequate, but productivity is severely limited due to destruction of sample, requirement of post-deposition processing steps, and separation from production line
Solution Approach 1:
The patent replaces destructive physical measurement methods with optical measurement methods. Specifically, spectroscopic ellipsometry uses optical radiation to measure band gap and electrical characteristics of high-k dielectric layers non-destructively, eliminating the need for sample destruction, post-deposition processing, and separation from production lines, thereby dramatically improving measurement throughput while maintaining accuracy
Solution Approach 2:
The patent introduces optical radiation as an intermediary to indirectly measure electrical characteristics. By measuring optical properties (reflectance, ellipsometry parameters) that correlate with electrical properties (band gap, leakage current), the system enables non-destructive, high-throughput characterization without direct electrical contact or sample destruction
2Productivity
If direct inversion methods are used to extract band gap from optical data, then measurement speed improves, but measurement precision deteriorates due to computational burdens and sensitivity to statistical errors
Solution Approach 1:
The patent performs preliminary action by pre-establishing the relationship between optical dispersion parameters and band gap through the modified Cody-Lorentz model. The model parameters (edge energy, amplitude, width) are directly correlated to band gap, allowing accurate extraction without computationally intensive post-processing or inversion algorithms, thus maintaining both speed and precision
Solution Approach 2:
The patent changes the parameter representation from raw optical data to physically meaningful model parameters. The modified Cody-Lorentz model transforms spectral data into parameters (E0, A, Γ) that have direct physical interpretation and correlation to band gap, reducing sensitivity to statistical errors and eliminating computational inversion burdens
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
The modified Cody-Lorentz model allows for robust, reliable, and stable in-line characterization of high-k dielectric layers, improving device performance by accurately monitoring band gap and leakage current, leading to enhanced process control and increased manufacturing efficiency.
Implementation Method 1
the spectroscopic ellisometry (SE) measurement technique includes a parametric representation of a measured optical dispersion
Implementation Method 2
the selected dispersion model includes a modified Cody-Lorentz model constrained to have continuous first derivatives to describe the complex bulk band structure of high-K dielectric layers
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 continuous Cody-Lorentz model having continuous first derivatives that is sensitive to a band gap of a layer 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.