Plasma Etching Endpoint Detection via In-Phase Artifact Removal
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Solution Overview
Problem
Conventional plasma processing techniques face challenges in accurately detecting the etching end point and residual film thickness due to artifacts generated by in-phase components, which distort the light emission intensity signal and bury the actual end point change, leading to inaccurate determination.
Innovation Solution
A plasma processing device equipped with a light detector, component detector, and determination unit that performs principal component analysis to identify highly correlated components, removes in-phase components, and uses a Kalman filter to generate a waveform with reduced noise, allowing for precise detection of etching amounts and end points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light emission intensity detection is used to detect etching end point, then etching end point detection capability is improved, but measurement precision deteriorates due to artifacts from in-phase components
Solution Approach 1:
The patent extracts and removes the harmful in-phase component from the light emission intensity signal. By identifying the in-phase component as a separate entity and subtracting it from the total signal, the system isolates the useful information related to etching progress while eliminating the artifact that causes measurement errors.
Solution Approach 2:
The patent introduces an intermediary processing step that analyzes the correlation between multiple wavelength signals. By using correlation analysis as an intermediary, the system identifies which components are artifacts (highly correlated across wavelengths) versus which components represent actual etching progress (less correlated), enabling selective removal of harmful factors.
2Measurement precision
If multiple wavelength light emission data is processed to remove in-phase components, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex hardware-based signal separation methods with computational analysis. Instead of using multiple physical detectors or complex optical systems to separate signals, the invention uses software-based correlation analysis and mathematical processing to identify and remove in-phase components, reducing hardware complexity while maintaining precision.
Solution Approach 2:
The patent makes the light detection system multi-functional by using the same detection apparatus to collect data at multiple wavelengths and then processing this data through correlation analysis. This universal approach allows a single system to perform both signal collection and artifact removal without requiring additional specialized components.
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 enables highly accurate detection of etching amounts and end points by reducing artifacts and distortion, ensuring precise control over the etching process and improving the accuracy of determining the residual film thickness and etching depth.
Implementation Method 1
light intensity of a specific wavelength included in light emission of the plasma in the processing chamber is changed in association with an etching progress
Implementation Method 2
an electric field or a magnetic field is supplied to processing gas supplied in the processing chamber, and plasma is formed by exciting atoms or molecules of the gas
Data Source
AI summary
A plasma processing device performing etching processing to a sample disposed in a processing chamber disposed in a vacuum vessel by using plasma formed in the processing chamber includes a light detector, a component detector, and a determination unit. The light detector detects light intensity of a plurality of wavelengths from the inside of the processing chamber at a plurality of times during the sample processing. The component detector detects, by using a result of a principal component analysis of time-series data, a highly correlated component between the time-series data of a plurality of the wavelengths at a certain time in a plurality of the times obtained from output of the light detector. The determination unit determines an amount or an end point of the etching processing based on a change in light intensity of at least one of a plurality of the wavelengths detected by using the time-series data from which the highly correlated component is removed.