Spectral Analysis Module Calibration Using Reference Light Source
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Solution Overview
Problem
In semiconductor lithography, the accuracy of spectral feature measurements, such as bandwidth and wavelength, is compromised due to disturbances like temperature gradients and optical distortions, leading to inaccuracies in controlling the minimum feature size and critical dimension on the wafer, especially when external spectrometers have limited calibration accuracy and optical components degrade over time.
Innovation Solution
A calibration apparatus is introduced that uses a calibration light source and a material with a known energy transition to detect characteristics of the interaction between the light beam and the material, allowing for the determination of a reference spectral profile, which is compared to the sensed spectral profile to adjust the scale of the spectral detection system, thereby improving measurement accuracy and maintaining precise control over spectral features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external spectrometers are used for spectral measurement, then measurement capability is provided, but measurement precision deteriorates due to limited calibration accuracy and optical component degradation
Solution Approach 1:
The patent applies preliminary action by performing calibration of the spectral analysis module using a reference light source with known spectral characteristics before actual measurements. This pre-calibration establishes accurate reference data that compensates for optical component degradation, thereby maintaining measurement precision without requiring frequent external recalibration.
Solution Approach 2:
The patent implements feedback by continuously comparing measured spectral features against reference spectral profiles obtained from the reference light source. The system uses this comparison to detect drifts in measurement accuracy and triggers recalibration when deviations exceed predefined thresholds, ensuring sustained measurement precision despite component aging.
2Manufacturing precision
If spectral analysis is performed to control light beam properties, then control of minimum feature size is achieved, but measurement accuracy deteriorates due to temperature gradients and optical distortions
Solution Approach 1:
The patent introduces an intermediary reference light source with stable and known spectral characteristics that serves as a mediator between the light beam under test and the spectral analysis module. This reference source provides a stable benchmark that compensates for environmental disturbances like temperature gradients and optical distortions, enabling accurate spectral measurements for precise minimum feature size control.
3Duration of action of stationary object
If optical components are used over time, then system operation is maintained, but measurement accuracy deteriorates due to component degradation
Solution Approach 1:
The patent applies preliminary action by establishing baseline calibration data using a reference light source at the beginning of system operation. This initial calibration creates a reference framework that accounts for the specific state of optical components, allowing the system to maintain measurement accuracy throughout extended operation periods even as components gradually degrade.
Solution Approach 2:
The patent implements continuous feedback monitoring by regularly comparing spectral measurements against the reference profile. When degradation-induced deviations are detected, the system automatically triggers recalibration procedures, enabling the system to maintain measurement precision over extended operational durations despite cumulative component wear.
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 enhances the accuracy of spectral feature measurements, ensuring precise control over the light beam's spectral properties, even as optical components degrade, by providing an absolute bandwidth reference and adjusting the measurement scale to match the reference profile, thus maintaining the desired spectral features for improved lithography results.
Implementation Method 1
detecting an aspect associated with an absorption profile of the testing light beam by the material
Implementation Method 2
detecting the characteristic associated with the interaction between the material and the primary light beam while the primary light beam is directed through the material
Data Source
AI summary
An apparatus includes a material having an optical transition profile with a known energy transition; and a detector configured to detect a characteristic associated with the interaction between the material and the testing light beam. The testing light beam is either a primary light beam produced by an optical source or a calibration light beam. The apparatus also includes a spectral analysis module placed in a path of the primary light beam; and a control system connected to the detector and to the spectral detection system. The control system is configured to determine a reference spectral profile of the primary light beam based on the detected characteristic; compare the reference spectral profile of the primary light beam with a sensed spectral profile of the primary light beam output from the spectral detection system; and based on this comparison, adjust a scale of the spectral detection system.