EUV Imaging Device Creep Compensation via Metrology Feedback
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Solution Overview
Problem
In microlithographic optical systems, especially those using extreme ultraviolet (EUV) light, conventional support structures face challenges with creep and settling effects, leading to changes in the static relative situation between supporting structures, which complicates maintaining high imaging accuracy and requires costly designs with large motion reserves to compensate for these changes.
Innovation Solution
A method to detect and compensate for changes in the static relative situation between supporting structures by adjusting the target state of optical elements, allowing for a simpler and cost-effective design by resetting the relative situation control device to its initial state after initial adjustment, thereby minimizing the required motion reserve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional support structures are used in EUV optical systems, then the system can maintain structural stability, but creep and settling effects cause changes in the static relative situation between supporting structures, requiring large motion reserves to compensate for these changes
Solution Approach 1:
The patent applies preliminary action by detecting creep and settling effects early in the system's operation and compensating for them proactively. The control device monitors the static relative situation between supporting structures and adjusts the target state of optical elements before significant imaging errors accumulate, thereby maintaining imaging accuracy without requiring excessive motion reserves
Solution Approach 2:
The patent implements feedback by continuously monitoring the static relative situation between the first and second supporting structures using the measuring device. The control device uses this feedback information to detect changes caused by creep and settling effects, and automatically adjusts the target state of optical elements to compensate for these changes, resolving the contradiction between structural stability and device complexity
2Manufacturing precision
If the relative situation control device is designed with large motion reserve to compensate for creep effects, then imaging accuracy can be maintained over the system lifetime, but the design becomes more complex and costly
Solution Approach 1:
The patent applies preliminary action by detecting creep and settling effects early in the system's operation and compensating for them proactively. The control device monitors the static relative situation between supporting structures and adjusts the target state of optical elements before significant imaging errors accumulate, thereby maintaining imaging accuracy without requiring excessive motion reserves
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the target state parameters of optical elements based on detected creep and settling effects. The control device modifies position and orientation parameters of the optical elements to compensate for changes in the supporting structures, thereby maintaining imaging accuracy without requiring the control device to be designed for extreme motion reserves
3Measurement precision
If the measuring device is supported on a separate metrology frame to ensure stable reference, then measurement precision is improved, but the device becomes more complex and the metrology frame requires additional support structures
Solution Approach 1:
The patent applies merging by integrating the metrology frame with the first supporting structure, eliminating the need for a completely separate support system. The measuring device is supported on the metrology frame which itself is supported on the first supporting structure, combining the functions of measurement and support while reducing overall system complexity
Solution Approach 2:
The patent applies universality by designing the metrology frame to serve multiple functions: it provides a stable reference for measurement, supports the measuring device, and maintains the required spatial relationship with the optical elements. This multi-functionality reduces the need for additional separate structures, thereby reducing device complexity while maintaining measurement precision
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 enables high imaging quality with reduced motion reserve needs, allowing for efficient compensation of creep and settling effects over the system's lifetime without the need for extensive dynamic travel capabilities, thus simplifying and cost-reducing the design of the relative situation control device.
Implementation Method 1
the metrology frame is frequently supported on the load-bearing structure in vibration-isolated or vibration-decoupled fashion by way of a vibration decoupling device. Typically, this is implemented by way of a plurality of supporting spring devices of the vibration decoupling device
Implementation Method 2
it was found, however, that, over long time scales, so-called creep effects or settling effects can arise in the area of the vibration decoupling device, for example in the area of the supporting spring devices
Data Source
AI summary
An arrangement of a microlithographic optical imaging device includes first and second supporting structures. The first supporting structure supports at least one optical element of the imaging device via an active relative situation control device of a control device. The first supporting structure supports the second supporting structure via supporting spring devices of a vibration decoupling device. The supporting spring devices act kinematically parallel to one another. Each supporting spring device defines a supporting force direction and a supporting length along the supporting force direction. The second supporting structure supports a measuring device of the control device. The measuring device is connected to the relative situation control device. The measuring device outputs to the relative situation control device measurement information representative for the position and/or the orientation of the at least one optical element in relation to a reference in at least one degree of freedom in space.