Optical Calibration Device for Plasma Chamber Signal Matching
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Solution Overview
Problem
Conventional optical monitoring systems in semiconductor processing chambers face challenges in accurately calibrating optical signals due to factors like wavelength and intensity calibrations, transmission properties of optical components, and variations in chamber conditions, leading to inconsistent processing results across multiple chambers.
Innovation Solution
An optical calibration device is positioned within the processing chamber to emit a continuous spectrum light that approximates plasma emission, coupled with an optical coupling system and spectrometer to measure and report optical signal data, allowing for the determination of reference and operational intensity ratios and characterization ratios for chamber matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical monitoring methods are used, then optical signals can be monitored, but calibration accuracy deteriorates due to wavelength and intensity calibration variations, transmission properties of optical components, and chamber condition variations
Solution Approach 1:
A calibration device is introduced as an intermediary component within the processing chamber to provide a known reference spectrum. This calibration device emits light at specific wavelengths with known intensity characteristics, serving as a mediator between the optical monitoring system and the plasma process. By comparing the measured calibration signal against the known reference, the system can identify and correct for variations in optical component transmission and chamber conditions, thereby improving calibration accuracy and cross-chamber consistency
Solution Approach 2:
The system employs parameter changes by measuring optical signals at multiple wavelengths and using intensity ratios rather than absolute intensities. This approach transforms the measurement parameters from absolute intensity values (which are sensitive to transmission variations) to ratio-based parameters that are more stable and less affected by systematic variations in optical component transmission and chamber conditions
2Productivity
If optical signals are monitored to determine processing status, then process monitoring is achieved, but measurement precision deteriorates due to systematic errors from optical component transmission variations
Solution Approach 1:
The system implements feedback by continuously measuring the calibration device signal and comparing it against the known reference spectrum. This feedback mechanism allows the system to detect deviations caused by optical component transmission variations and chamber condition changes, and to adjust or correct the measurements accordingly. The feedback loop ensures that process monitoring maintains high precision despite systematic errors in the optical path
Solution Approach 2:
The calibration device acts as an intermediary reference that enables precise measurement without being affected by the plasma process itself. By providing a stable known reference that passes through the same optical path as the plasma emission, it allows the system to separate and correct for optical path variations, thereby maintaining measurement precision while enabling continuous process monitoring
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 precise calibration and matching of processing chambers, ensuring uniform processing conditions and reducing the impact of systematic errors, thereby improving the accuracy and consistency of semiconductor processing.
Implementation Method 1
an optical source located within the enclosure and configured to provide a source light having a continuous spectrum
Implementation Method 2
an optical coupling system coupled to the viewport and positioned to receive calibrating light emitted by the optical calibration device
Implementation Method 3
a spectrometer optically coupled to the optical calibration device via the optical coupling system and configured to generate and report measured optical signal data
Data Source
AI summary
The disclosure provides an optical calibration device for in-chamber calibration of optical signals associated with a processing chamber, a characterization system for plasma processing chambers, methods of characterizing plasma processing chambers, and a chamber characterizer. In one example, the optical calibration device includes: (1) an enclosure, (2) an optical source located within the enclosure and configured to provide a source light having a continuous spectrum, and (3) optical shaping elements located within the enclosure and configured to form the source light into a calibrating light that approximates a plasma emission during an operation within the processing chamber.