Lithography Mark Measurement Sequencing Within Stage Boundaries
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Solution Overview
Problem
The measurement of alignment marks on semiconductor substrates becomes time-consuming and affects the throughput of lithographic apparatuses as the number of marks to be measured increases, particularly for smaller features, without adequately considering the capabilities and restrictions of the positioning devices.
Innovation Solution
A method to determine a mark measurement sequence that takes into account the location data of marks and the capabilities and restrictions of the positioning device, using a boundary model to optimize the sequence and avoid overheating, thereby ensuring efficient and robust execution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of alignment marks to be measured is increased to obtain more detailed knowledge about layer position, then measurement precision is improved, but measurement time increases and throughput decreases
Solution Approach 1:
The patent applies preliminary action by pre-calculating an optimized measurement sequence based on the spatial distribution of marks and positioning device capabilities before actual measurement begins. The control unit determines the optimal sequence in advance, allowing the measurement system to execute efficiently without real-time computational delays, thus measuring more marks within the same time window and improving throughput while maintaining precision.
Solution Approach 2:
The patent implements dynamics by adapting the measurement sequence to the specific capabilities and boundary conditions of the positioning device. The control unit dynamically adjusts the measurement sequence based on real-time feedback about positioning performance, mark locations, and device boundaries, optimizing the measurement path to minimize travel time and maximize the number of marks measured within available time.
2Measurement precision
If a measurement sequence is determined solely based on location data without considering positioning device capabilities, then measurement precision may be improved, but the sequence becomes less robust and may cause damage to the positioning device
Solution Approach 1:
The patent applies parameter changes by incorporating positioning device capabilities as variables in the sequence optimization. The control unit adjusts measurement sequence parameters (order of marks, movement paths, measurement timing) based on the specific performance boundaries of the positioning device, such as maximum acceleration, jerk limits, and thermal constraints, ensuring the sequence remains within safe operational parameters while maintaining measurement precision.
Solution Approach 2:
The patent implements feedback mechanisms where the control unit continuously monitors positioning device performance and adjusts the measurement sequence accordingly. Feedback from positioning device status, mark measurement results, and device boundary conditions is used to refine and optimize the sequence in real-time, ensuring robust operation and preventing damage while maintaining accurate measurements.
3Speed
If the positioning device operates at high performance levels continuously, then measurement speed increases, but the device may overheat and require performance reduction
Solution Approach 1:
The patent applies periodic action by incorporating rest intervals and thermal management cycles into the measurement sequence. The control unit schedules measurement tasks in a periodic manner, allowing the positioning device to operate at high performance levels during measurement phases and then enters lower-power states during transition and positioning phases, preventing continuous overheating while maintaining high overall measurement throughput.
Solution Approach 2:
The patent uses preliminary action by pre-planning the measurement sequence to include thermal management considerations. The control unit anticipates thermal buildup and schedules measurement tasks to avoid continuous high-performance operation, inserting cooling periods and lower-power transitions before thermal limits are reached, thus maintaining sustainable high-speed measurement capability.
Data Source
AI summary
A method of determining a mark measurement sequence for an object comprising a plurality of marks, the method including: receiving location data for the plurality of marks that are to be measured; obtaining a boundary model of a positioning device used for performing the mark measurement sequence; and determining the mark measurement sequence based on the location data and the boundary model.