Graphene Contamination Sensor for EUV Lithography Uptime
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Solution Overview
Problem
EUV lithographic scanners face performance issues due to carbon contamination, leading to sensor and fiducial drift, requiring frequent cleaning and downtime, which negatively impacts availability and uptime.
Innovation Solution
A device comprising a layer of non-conducting material and a semi-metal with electrodes for measuring resistivity changes, allowing real-time monitoring and prediction of contamination levels, reducing the need for frequent sensor calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequent cleaning by hydrogen radical generation is performed to remove carbon contamination, then sensor and fiducial drift is corrected, but lithographic apparatus availability and uptime are reduced
Solution Approach 1:
The contamination sensor is placed in the EUV beam path to detect carbon contamination buildup before it causes significant sensor and fiducial drift. By detecting contamination early, the system can schedule cleaning operations at optimal times rather than reacting to performance degradation, thereby maintaining reliability while minimizing interruptions to productivity.
Solution Approach 2:
The contamination sensor provides real-time feedback on carbon contamination levels in the EUV beam path. This feedback enables the control system to monitor contamination accumulation continuously and trigger cleaning operations only when contamination thresholds are reached, optimizing the balance between maintaining sensor/fiducial performance and maximizing apparatus availability.
2Measurement precision
If frequent sensor matching and calibration are performed to correct drift caused by carbon contamination, then measurement precision is maintained, but loss of time and productivity increase
Solution Approach 1:
By continuously monitoring carbon contamination levels in the EUV beam path, the system can predict when contamination will reach levels that affect measurement precision. This allows scheduling of calibration and cleaning operations in advance during planned maintenance windows, rather than performing urgent corrections that cause unplanned downtime and loss of productivity.
Solution Approach 2:
The contamination sensor provides early warning feedback about carbon buildup that would eventually affect measurement precision. This enables proactive maintenance scheduling and allows the system to maintain measurement accuracy by performing calibration only when contamination reaches critical levels, thereby minimizing the frequency and total time of maintenance interruptions.
3Productivity
If the lithographic apparatus operates continuously to maximize productivity, then carbon contamination accumulates on sensors and fiducials, but availability is improved
Solution Approach 1:
The contamination sensor acts as an intermediary element placed in the EUV beam path to detect carbon contamination. This intermediary sensor allows the system to operate continuously for maximum productivity while independently monitoring contamination levels, enabling scheduled cleaning operations without interrupting the overall production flow and thus maintaining high availability.
Solution Approach 2:
The contamination monitoring system enables the lithographic apparatus to self-manage its contamination issue by providing continuous feedback on carbon buildup levels. The system can autonomously determine when cleaning is needed and schedule maintenance operations, allowing continuous operation to be maintained while contamination is managed through planned, minimal-intervention cleaning cycles.
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
Enables continuous operation by predicting and adjusting for contamination, minimizing downtime and increasing the availability of the lithographic apparatus.
Implementation Method 1
measuring a change in resistivity of the layer of the semi-metal using a voltage and/or a current source connected to the at least two electrodes
Data Source
AI summary
The disclosure provides a device and method for measuring contamination. The device comprises: a layer of a non-conducting material; a layer of a semi-metal arranged on the layer of the non-conducting material; at least one set of electrodes, each electrode being in electrical contact to the layer of the semi-metal; and an electrical source of a voltage or current connected to the at least two electrodes. The semi-metal may be graphene. The non-conducting material may be hexagonal boron nitride. The method includes measuring a change in resistivity of the layer of the semi-metal using a voltage and/or a current source connected to the at least two electrodes.