Actuator Drive Circuit for Inline Impedance Measurement in EUV Optics
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Solution Overview
Problem
In EUV lithography apparatuses, precise actuator positioning is hindered by external electromechanical crosstalk and resonance issues, which conventional impedance measuring devices are unable to address effectively due to high costs and lack of inline capability, and existing drive signals compromise between actuator driving and impedance measurement resolution.
Innovation Solution
A drive device with a frequency-dependent amplifier stage that separates drive and measurement signals into distinct frequency ranges, providing high gain for actuator driving in one range and high resolution for impedance measurement in another, using a specific transfer function to convolve voltage and current signals for accurate impedance determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high gain is chosen for the output stage to drive the actuator, then the actuator driving capability is improved, but the resolution for measuring the impedance of the actuator deteriorates
Solution Approach 1:
The drive signal is segmented into distinct frequency components: a low-frequency drive component for actuator actuation and a high-frequency measurement component for impedance measurement. The output stage amplifies these components differently, providing high gain for the drive component while maintaining high resolution for the measurement component, thus resolving the contradiction between driving capability and measurement precision.
Solution Approach 2:
The system dynamically adjusts the gain characteristics of the output stage based on frequency. The transfer function of the output stage is designed to provide frequency-dependent amplification, with higher gain for low-frequency drive signals and appropriate gain for high-frequency measurement signals. This dynamic frequency-selective amplification allows simultaneous optimization of actuator driving and impedance measurement.
2Measurement precision
If conventional impedance measuring devices are used, then impedance measurement capability is provided, but the devices are too cost-intensive and lack inline capability for lithography apparatus
Solution Approach 1:
The impedance measurement function is merged with the existing actuator drive circuitry. The output stage that drives the actuator also serves as the measurement interface by analyzing the actuator's response to high-frequency measurement signals. This integration eliminates the need for separate, expensive conventional impedance measuring devices and enables inline capability within the lithography apparatus.
Solution Approach 2:
The output stage is designed with multi-functionality, serving both as a drive amplifier for actuator actuation and as an impedance measurement interface. By injecting high-frequency measurement signals and analyzing the actuator's response through the same output stage, the system achieves impedance measurement capability without requiring additional dedicated measurement hardware, thereby reducing cost and complexity.
3Device complexity
If a uniform gain over all frequency ranges is used, then the drive signal amplification is simplified, but the resolution for measuring impedance in specific frequency ranges is compromised
Solution Approach 1:
The output stage employs a dynamic, frequency-dependent transfer function that automatically adjusts gain based on the input signal frequency. Low-frequency drive components receive high gain for effective actuator actuation, while high-frequency measurement components receive appropriate gain to maintain measurement resolution. This frequency-selective amplification behavior is achieved through the inherent characteristics of the output stage circuitry, maintaining relative simplicity while enabling precise impedance measurement.
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 precise and cost-effective inline impedance measurement and active calibration of actuators, improving actuator control and stability by distinguishing between drive and measurement frequencies, thus enhancing the overall performance of EUV lithography systems.
Implementation Method 1
a drive unit having a frequency-dependent first transfer function which is configured to amplify a time-dependent AC voltage signal with at least a first frequency range and a second frequency range to form a drive voltage for the actuator
Implementation Method 2
a voltage measuring unit for providing a measurement voltage, which is configured to convolve, in the time domain, a time-dependent voltage of the actuator with a second transfer function that is based on an inverse of the first transfer function
Implementation Method 3
a current measuring unit for providing a measurement current, which is configured to convolve, in the time domain, a time-dependent current of the actuator with a third transfer function that is based on an inverse of the first transfer function
Implementation Method 4
a determination unit for determining an impedance of the actuator on the basis of the measurement voltage and the measurement current
Implementation Method 5
A PMN actuator can help enable distance positioning in the sub-micrometre range or sub-nanometre range. In this case, the actuator, having actuator elements stacked one on top of another, can experience a force that causes a specific linear expansion as a result of a DC voltage being applied
Data Source
AI summary
A drive device for driving and measuring an actuator for actuating an optical element of an optical system comprises a drive unit, a voltage measuring unit and a current measuring unit having a frequency-dependent first transfer function configured to amplify a time-dependent