Plasma Endpoint Detection Using Mutual Information Wavelength Selection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing plasma processing methods for semiconductor manufacturing face challenges in accurately detecting the endpoint of etching due to interference from substances adhering to window materials or inner walls, which reduces detection accuracy when using a single wavelength, and fail to appropriately select multiple wavelengths for improved detection.
Innovation Solution
A plasma processing method that selects at least two wavelengths with high mutual information for emission intensity changes during processing, using a joint distribution product and natural logarithm of marginal distributions to accurately determine the endpoint and etching amount, even when the fundamental wavelength is obscured.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single basic wavelength is used for endpoint detection, then the detection method is simple, but detection accuracy is reduced due to saturation or baseline increase from substance accumulation on window materials
Solution Approach 1:
The patent divides the detection task by selecting multiple wavelengths (at least two) instead of using a single wavelength. This segmentation allows the system to detect endpoint information through multiple spectral channels, reducing the impact of substance accumulation at any single wavelength and improving overall detection accuracy
Solution Approach 2:
The patent changes the detection parameter from a single wavelength to multiple wavelengths with high mutual information. By selecting wavelengths that have high correlation with each other in terms of emission intensity changes, the system maintains detection sensitivity while avoiding the saturation and baseline issues that affect single-wavelength detection
2Measurement precision
If multiple wavelengths are used for detection, then detection accuracy is improved, but the complexity of wavelength selection and processing increases
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing mutual information between wavelengths before the actual endpoint detection process. This allows the system to quickly select appropriate wavelength combinations during processing without performing complex real-time calculations, thereby reducing processing complexity while maintaining high detection accuracy
Solution Approach 2:
The patent introduces mutual information as an intermediary metric to facilitate wavelength selection. Instead of directly comparing complex spectral data, the system uses mutual information as a mediator to identify wavelengths with high correlation, simplifying the selection process while ensuring optimal detection performance
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 precise detection of etching amounts and endpoints, regardless of linear or nonlinear changes, enhancing the accuracy of semiconductor device pattern formation by selecting wavelengths with high dependency on emission intensity changes.
Implementation Method 1
an electric or magnetic field is supplied to a processing gas supplied into the processing chamber and thus atoms or molecules of the gas are excited to generate plasma
Implementation Method 2
intensity of light of a specific wavelength contained in plasma emission in the processing chamber varies with progress of etching
Data Source
AI summary
To provide a wavelength selection method or a plasma processing method to achieve accurate detection of residual thickness or etching amount, there is provided a plasma processing method, in which a processing object wafer is disposed within a processing chamber in the inside of a vacuum container, and plasma is generated by supplying a processing gas into the processing chamber and used to process a processing-object film layer beforehand formed on a surface of the wafer, and at least two wavelengths are selected from among wavelengths with large mutual information in emission of a plurality of wavelengths of plasma generated during processing of the processing-object film layer, and a temporal change in the emission of at least the two wavelengths is detected, and an endpoint of the processing of the film layer is determined based on a result of the detection.