Lithographic Apparatus Height Map Anomaly Removal
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Solution Overview
Problem
Lithographic manufacturing processes face performance degradation due to substrate contamination causing localized height deviations, leading to focus spots and reduced yield, which existing technologies struggle to address without compromising throughput.
Innovation Solution
A lithographic apparatus and method that utilize a height map to identify and partially disregard height anomalies, such as contamination-induced deviations, by modifying the height map or using anomaly map data to control imaging, thereby improving focus and yield without requiring hardware changes or additional input data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the height map is used to control imaging focus, then manufacturing precision is improved, but localized height anomalies from contamination cause focus spots that degrade yield
Solution Approach 1:
The patent extracts and removes height anomaly data from the height map that corresponds to contaminated regions. By identifying localized height deviations caused by contamination and excluding them from the focus control calculations, the system prevents these anomalies from creating focus spots, thereby maintaining both manufacturing precision and yield
Solution Approach 2:
The patent applies different processing to different regions of the height map. Clean regions are used for normal focus control, while contaminated regions are identified and treated differently by removing their height anomaly data. This local differentiation allows the system to maintain focus precision in clean areas while eliminating the harmful effects of contamination in affected areas
2Reliability
If interventions are made to clean contamination, then yield is improved, but throughput is reduced due to process interruptions
Solution Approach 1:
The patent performs preliminary identification and removal of height anomaly data from contaminated regions before the imaging process. By detecting and excluding contamination effects in advance through height map analysis, the system prepares a cleaned height map for focus control, allowing continuous operation without interrupting for cleaning interventions
Solution Approach 2:
The patent converts the harmful effect of contamination into beneficial information by using height map analysis to identify contaminated regions. This information is then used to exclude those regions from focus control, transforming the contamination problem into an opportunity for automated quality control that maintains throughput while improving yield
3Reliability
If focus control is adjusted for localized anomalies, then yield is improved, but device complexity increases due to additional processing
Solution Approach 1:
The patent uses the existing height map infrastructure for multiple purposes: normal focus control in clean regions and contamination detection/exclusion in affected regions. By making the height map processing system multi-functional, the patent avoids adding separate dedicated systems while still achieving anomaly removal, thus limiting the increase in device complexity
Data Source
AI summary
A lithographic apparatus obtains a height map of a substrate and uses the height map when controlling imaging of the pattern to the substrate. The apparatus is arranged to disregard at least partially height anomalies when controlling the imaging. The height anomalies may be identified by processing the height map. For example, in some embodiments the height anomalies are identified using a shape recognition model. In some embodiments, a modified version of the height map is produced in which the height anomalies are at least partially removed, and the modified version of the height map is used in controlling the imaging. An anomaly map may be used together with the (unmodified) height map to control imaging.