Spectrometer Lens System for Processing Chamber Cleaning Endpoint Detection
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Solution Overview
Problem
Current methods for detecting the end point of processing chamber cleaning in the semiconductor industry are inaccurate, leading to excessive cleaning time and potential damage to chamber components, particularly when dealing with large substrates like those used in flat panel displays.
Innovation Solution
A method and apparatus utilizing a spectrometer with a lens system to focus on a selected area within the processing chamber, amplifying radiation intensity and measuring the spectrum response over time to precisely determine when the cleaning process is complete, thereby minimizing wear on chamber components and reducing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant flow of NF3 is passed into the chamber for cleaning, then the cleaning process removes accumulated films from chamber walls and components, but it is difficult to accurately determine when the cleaning has completed, leading to extended cleaning time
Solution Approach 1:
The patent employs optical emission spectroscopy to monitor cleaning reactions in real-time, providing feedback on the cleaning process. The spectrometer detects characteristic emission lines from fluorine radicals and reaction products, allowing the system to determine when cleaning is complete based on signal thresholds, thus eliminating the need for fixed extended cleaning times.
Solution Approach 2:
The patent replaces mechanical/time-based cleaning control with optical detection and spectral analysis. Instead of relying on predetermined cleaning durations, the system uses optical emission spectroscopy to detect chemical reactions and determine endpoint automatically, substituting mechanical timing with optical sensing.
2Reliability
If an extra 20 to 30 percent of the expected cleaning time is added to the cleaning cycle to ensure thorough cleaning, then cleaning completeness is improved, but damage to chamber components increases
Solution Approach 1:
The real-time optical monitoring provides feedback to stop the cleaning process at the precise endpoint when all residues are removed. This prevents over-cleaning that would expose chamber components to unnecessary fluorine radical attack, thereby reducing component damage while maintaining cleaning completeness.
Solution Approach 2:
The cleaning process monitors its own progress through optical emission spectroscopy, detecting the presence or absence of cleaning reactions autonomously. The system self-regulates by continuing cleaning only as long as reaction signals are detected, automatically stopping when cleaning is complete without requiring external timing control.
3Ease of operation
If cleaning is performed based on trial and error or historical data, then the process is simple to operate, but the measurement precision of cleaning endpoint is poor
Solution Approach 1:
The patent replaces manual trial-and-error operation with automated optical detection. The spectrometer automatically detects cleaning reactions and determines endpoint based on signal thresholds, eliminating the need for operator experience while providing precise, objective endpoint detection.
Solution Approach 2:
The patent introduces an intermediary measurement system (optical emission spectroscopy) between the cleaning process and the control system. This intermediary provides objective, real-time data about cleaning progress, enabling precise endpoint detection without requiring direct operator intervention or historical data.
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 provides a precise indication of cleaning endpoint, reducing the need for extended cleaning cycles and minimizing defects, thereby improving operational efficiency and reducing costs associated with excess energy and gas usage.
Implementation Method 1
focusing a lens system on a selected area within the processing chamber via a viewport during the cleaning process; amplifying an intensity of radiation from a cleaning reaction at the selected area
Implementation Method 2
measuring a spectrum response over time of a cleaning reaction within the processing chamber during the cleaning process using a spectrometer coupled to the lens system
Implementation Method 3
A plasma is initiated from the fluorine-containing gas which reacts with coatings from prior depositions on the chamber walls and fixtures
Implementation Method 4
the NF3 creates free fluorine radicals 'F*' which react with Si-containing residues
Data Source
AI summary
Embodiments provide systems, methods and apparatus for detecting a cleaning endpoint of a cleaning process performed within a processing chamber. Embodiments include a spectrometer adapted to measure a spectrum response over time of a cleaning reaction within a processing chamber during a cleaning process; and a lens system coupled to the spectrometer and disposed to focus on a selected area within the processing chamber via a viewport and to amplify intensity of radiation from the selected area during the cleaning process. The selected area is chosen based on being the expected location of the last cleaning reaction during the cleaning process within the processing chamber (e.g., a corner in a rectangular chamber). Numerous other aspects are provided.