Tactile Probing for EUV Metrology Interchangeable Object Calibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing EUV metrology systems face challenges in accurately calibrating the relative position of interchangeable-object holders with respect to calibration objects using optical methods, which are complex and may generate abrasion particles, especially in sensitive vacuum chambers.
Innovation Solution
The use of tactile probing with contact sensors, such as force sensors like coil power measurement units or piezoelectric load cells, to detect contact between abutment bodies, allowing for precise calibration without optical systems, thereby avoiding unnecessary component collisions and ensuring accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical calibration methods are used to calibrate the relative position of interchangeable-object holders, then measurement precision can be achieved, but device complexity increases and abrasion particles may be generated in vacuum chambers
Solution Approach 1:
The patent replaces optical calibration methods with a mechanical tactile probing system. A probe with a spherical tip mechanically contacts the interchangeable-object holder to determine its position relative to the calibration object. This mechanical approach eliminates the need for complex optical sensor systems and line connections in vacuum chambers, thereby reducing device complexity while maintaining calibration accuracy.
Solution Approach 2:
The patent extracts the calibration function from the complex optical system and implements it through a simplified mechanical probe. The probe only performs the essential function of detecting contact and determining position through mechanical interaction, removing unnecessary optical components and their associated complexity.
2Measurement precision
If optical sensor systems are used for calibration, then measurement precision is achieved, but the risk of generating abrasion particles in sensitive vacuum chambers increases
Solution Approach 1:
The patent substitutes optical sensing with mechanical tactile probing. The probe uses a spherical tip that mechanically contacts the interchangeable-object holder without generating abrasion particles. This mechanical contact method inherently avoids the particle generation issue associated with optical components in vacuum environments.
3Device complexity
If tactile probing with contact sensors is used, then device complexity is reduced, but measurement precision must be maintained through alternative means
Solution Approach 1:
The probe system is self-sufficient, using only the mechanical contact between the spherical probe tip and the interchangeable-object holder to determine position. The system leverages the inherent geometric relationship and mechanical interaction to achieve calibration without requiring external optical sensors or complex measurement systems.
Solution Approach 2:
The patent employs a spherical probe tip that contacts the interchangeable-object holder at a single point. This spherical geometry enables precise position determination through mechanical contact, as the curvature provides a well-defined contact interface that can be accurately measured and interpreted for calibration purposes.
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 method enables accurate and reliable calibration of interchangeable-object holders within EUV metrology systems, ensuring precise positioning and preventing abrasion particles, thus enhancing the handling and transfer of measurement objects and stops, even in unusual operational conditions.
Implementation Method 1
The contact between the holder abutment body and the calibration-object counter-abutment body can be detected by use of a contact sensor, which can be designed as a force sensor. Such force sensor may include a power measurement unit. It in particular may include a coil power measurement unit to measure a current through at least one coil of an actuator, in particular of a Lorentz actuator.
Implementation Method 2
coil power measurement unit to measure a current through at least one coil of an actuator, in particular of a Lorentz actuator
Implementation Method 3
the force sensor may be embodied as a wheatstone bridge, as a capacitive load cell or as a piezoelectric load cell
Data Source
AI summary
An interchangeable-object holding apparatus for an EUV metrology system serves for holding and providing an interchangeable object, which is intended to be used interchangeably within the EUV metrology system. An interchangeable-object holder is drivably displaceable via at least one holding drive. A calibration device serves for calibrating a relative position of the interchangeable object in the interchangeable-object holder with respect to a calibration object of the interchangeable-object holding apparatus. The calibration device has a plurality of holder abutment bodies, secured to the interchangeable-object holder, and a plurality of calibration-object counter-abutment bodies, secured to the calibration object. At least one contact sensor of the calibration device serves for detecting a contact between the respective holder abutment body and the respective calibration-object counter-abutment body. An evaluation unit is in signal communication with the holder drive and the contact sensor. The evaluation unit serves for determining the relative position of the interchangeable object in the interchangeable-object holder with respect to the calibration object from captured position and measurement data of the holder drive and of the contact sensor. The result is an interchangeable-object holding apparatus with which the interchangeable-object holder can be positioned relative to the calibration object with a specified level of accuracy and with less metrological complexity of the calibration device compared with the prior art.