Microlithography Lens Aberration Adjustment via Segmented Timing
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Solution Overview
Problem
Microlithographic projection exposure apparatuses face frequent downtimes due to the need for rapid adjustments to counteract irreversible changes in optical properties of lenses, which slower manipulators cannot adequately address within short adjustment times, leading to economic disadvantages and reduced availability for lithographic production.
Innovation Solution
A method involving two partial adjustments is proposed, where quickly changing aberrations are adjusted rapidly and slowly changing aberrations are adjusted over a longer duration, allowing for parallel but independent temporal adjustments using different classes of manipulators, optimizing the use of quicker and slower manipulators based on their respective capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid adjustments are performed to counteract quickly changing aberrations, then quickly changing aberrations are corrected, but slowly changing aberrations are not adequately addressed within the short adjustment time
Solution Approach 1:
The adjustment process is segmented into two independent partial adjustments: a first partial adjustment for quickly changing aberrations with short duration, and a second partial adjustment for slowly changing aberrations with longer duration. This segmentation allows each adjustment to be optimized for its specific time scale without compromising the other.
Solution Approach 2:
The system dynamically adapts the adjustment duration based on the aberration type. The control unit prescribes different temporal adjustment durations (t1 for quick aberrations, t2 for slow aberrations) and executes corresponding partial adjustments, allowing the adjustment process to be flexible and adaptive to different aberration characteristics.
2Reliability
If frequent adjustments are performed to maintain lens specifications, then optical quality is maintained, but downtime frequency increases and productivity decreases
Solution Approach 1:
The system implements periodic adjustments with different frequencies for different aberration types. The first partial adjustment occurs more frequently for quickly changing aberrations, while the second partial adjustment occurs less frequently for slowly changing aberrations. This periodic action maintains optical quality while minimizing overall downtime.
Solution Approach 2:
The adjustment frequency is dynamically optimized by prescribing different temporal durations for different partial adjustments. The control unit manages the timing and sequencing of adjustments based on real-time aberration characteristics, reducing unnecessary adjustments and maximizing production availability.
3Ease of operation
If a single adjustment process is used for all aberrations, then the system is simple to operate, but both quick and slow aberrations cannot be optimally adjusted within the same time frame
Solution Approach 1:
The adjustment process is divided into two independent partial adjustments that are automatically managed by the control unit. The first partial adjustment handles quickly changing aberrations, while the second handles slowly changing aberrations. This segmentation enables precise adjustment for each aberration type while maintaining ease of operation through automated control.
Solution Approach 2:
The control unit serves multiple functions: it prescribes temporal adjustment durations, selects which partial adjustment to execute, and manages the sequencing of both adjustment types. This multi-functionality allows the system to handle different aberration types with different requirements through a single integrated control interface.
Data Source
AI summary
Aberrations of a projection lens for microlithography can be subdivided into two classes: a first class of aberrations, which are distinguished by virtue of the fact that their future size increases by a non-negligible value after a constant time duration, independently of their current size, and a second class of aberrations, which, after reaching a threshold, only increase by a negligible value after each further time duration. An adjustment method is proposed, which adjusts these two classes of aberrations in parallel in time with one another.