Lithographic Apparatus Force Measurement for Sensor Frame Deformation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In advanced lithographic apparatuses, the noise of acceleration sensors is too large compared to the small accelerations of the sensor frame, making it unreliable for determining deformation, and their measurement accuracy is insufficient for low frequencies, which affects the precision of position control for optical elements and substrates.
Innovation Solution
A lithographic system that includes a force measurement device to generate data on the forces exerted on the sensor frame, allowing for accurate control of the relative position of the substrate and patterned radiation beam based on this data, thereby compensating for mechanical deformation and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acceleration sensors are used to measure sensor frame deformation, then position measurement can be performed, but the noise of the acceleration sensor is too large compared to the small accelerations of the sensor frame, making the measurement unreliable
Solution Approach 1:
The patent replaces acceleration sensors with force sensors to measure the forces exerted on the sensor frame. This substitution allows direct force measurement without the noise problems of acceleration sensors, and force measurements can then be converted to deformation information through mechanical models.
Solution Approach 2:
The patent changes the measurement parameter from acceleration to force. By measuring forces directly on the sensor frame and using mechanical models to determine deformation, the system avoids the noise issues inherent in acceleration measurements while maintaining the ability to track sensor frame position and deformation.
2Measurement precision
If acceleration sensors are used to measure sensor frame deformation, then position control can be performed, but the measurement accuracy is insufficient for low frequencies (0.01 Hz-1 Hz)
Solution Approach 1:
The patent replaces acceleration-based measurement with force-based measurement. Force sensors provide accurate measurements across the low frequency range needed for sensor frame deformation monitoring, enabling reliable position control at frequencies between 0.01 Hz and 1 Hz where acceleration sensors fail.
3Manufacturing precision
If the sensor frame deforms due to mechanical forces, then position measurement of optical elements is affected, but using acceleration sensors to correct for this deformation introduces noise that worsens the measurement accuracy
Solution Approach 1:
The patent introduces force sensors as an intermediary measurement device. Instead of directly measuring optical element positions through sensors mounted on the deformable sensor frame, the system measures forces on the sensor frame and uses these force measurements to calculate and correct for frame deformation, thereby maintaining accurate position measurements.
Solution Approach 2:
The patent substitutes acceleration-based deformation correction with force-based deformation correction. By measuring forces directly on the sensor frame and using mechanical models to determine deformation, the system achieves accurate correction without the noise problems of acceleration sensors.
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 solution enhances the precision of position control by using force measurement data to correct for sensor frame deformation, improving the accuracy of pattern projection onto substrates, especially at low frequencies where acceleration sensors fail.
Implementation Method 1
a force measurement device which is adapted to generate force measurement data relating to a force which is exerted on the sensor frame by the sensor frame support
Data Source
AI summary
The present invention relates to a lithographic apparatus, comprising:a projection system configured to project a patterned radiation beam onto a substrate, comprising optical elements,a sensor frame,a first position measurement system configured to measure a position of an optical element relative to the sensor frame, comprising a sensor adapted to monitor an optical element, with a sensor element mounted to the sensor frame,a sensor frame support supporting the sensor frame on a reference,a force measurement device adapted to generate force measurement data relating to force exerted on the sensor frame by the sensor frame support,a position control device adapted to control the relative position of the substrate and the patterned radiation beam wherein the position control device is configured to receive the force measurement data and to control said relative position based on at least the force measurement data.