EUV Collector Reflectivity Monitoring via Data Matching
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Solution Overview
Problem
The efficiency and stability of laser-produced plasma (LPP) based extreme ultraviolet (EUV) radiation sources in semiconductor lithography are hindered by the synchronization challenges between target droplets and excitation laser pulses, leading to reduced EUV radiation intensity and collector mirror degradation, which necessitates frequent and costly maintenance.
Innovation Solution
Implementing a synchronization mechanism for the excitation laser pulses with the ejection of tin droplets in the LPP chamber, along with a data matching module that uses a timing gap tolerance to enhance data integrity and monitor collector mirror reflectivity, thereby maintaining EUV radiation intensity and reducing maintenance needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If synchronization between laser pulses and droplet ejection is not optimized, then EUV radiation intensity decreases, but implementing synchronization increases system complexity
Solution Approach 1:
The system employs a feedback mechanism where the position of each droplet is monitored and the laser pulse timing is adjusted accordingly. The controller receives position information and modifies the pulse ejection timing to ensure optimal synchronization, thereby maximizing EUV radiation intensity while managing system complexity through intelligent control
Solution Approach 2:
The synchronization mechanism is designed to be dynamic rather than static. The laser pulse timing is continuously adjusted based on the actual position of droplets, allowing the system to adapt to variations in droplet ejection and maintain optimal synchronization conditions for maximum EUV intensity
2Productivity
If collector mirror is not monitored, then operational costs increase due to frequent maintenance, but implementing monitoring increases device complexity
Solution Approach 1:
A monitoring system provides feedback on the collector mirror's reflectivity by measuring EUV radiation intensity. This feedback enables predictive maintenance scheduling based on actual mirror degradation rather than fixed intervals, improving operational efficiency while managing complexity through data-driven decision making
Solution Approach 2:
The system enables self-monitoring of collector mirror performance through automated reflectivity measurements. The monitoring apparatus continuously assesses mirror condition and provides data for maintenance planning, allowing the system to manage its own performance degradation without constant human intervention
3Measurement precision
If real-time monitoring of collector reflectivity is implemented, then maintenance timing is optimized, but data integrity challenges arise due to timestamp mismatches
Solution Approach 1:
The system performs preliminary actions by recording timestamp information for both droplet position data and reflectivity measurements before processing. This preliminary timestamp recording enables subsequent matching and correlation of data points from different sources, ensuring data integrity while maintaining measurement precision
Solution Approach 2:
Timestamp information serves as an intermediary element that connects and correlates data from different measurement systems. By using timestamps as a common reference, the system can match droplet position data with reflectivity measurements, maintaining data integrity across multiple data sources with different timing characteristics
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 improves the efficiency and yield of EUV lithography by ensuring optimal droplet-targeting and real-time monitoring of collector mirror reflectivity, reducing degradation rates and maintaining EUV radiation intensity, thus enhancing the overall performance and reducing operational costs.
Implementation Method 1
a high-power laser beam is focused on small tin droplet targets to form highly ionized plasma that emits EUV radiation with a peak maximum emission at 13.5 nm
Implementation Method 2
a sensor configured to detect intensity of the EUV radiation
Data Source
AI summary
A method of controlling a feedback system with a data matching module of an extreme ultraviolet (EUV) radiation source is disclosed. The method includes obtaining a slit integrated energy (SLIE) sensor data and diffractive optical elements (DOE) data. The method performs a data match, by the data matching module, of a time difference of the SLIE sensor data and the DOE data to identify a mismatched set of the SLIE sensor data and the DOE data. The method also determines whether the time difference of the SLIE sensor data and the DOE data of the mismatched set is within an acceptable range. Based on the determination, the method automatically validates a configurable data of the mismatched set such that the SLIE sensor data of the mismatched set is valid for a reflectivity calculation.