Lithographic Apparatus Measurement Frame Alignment
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Solution Overview
Problem
The existing lithographic apparatuses face inaccuracies in positioning substrates due to misalignment between measurement systems located above, below, and in-plane with the substrate, leading to less precise image transfer.
Innovation Solution
A lithographic apparatus design where a measurement frame supports both the encoder and measurement systems at different sides of a plane, allowing for improved coupling and alignment of these systems to enhance substrate positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple measurement systems are positioned at different locations (above, below, and in-plane with the substrate) to enable comprehensive substrate positioning, then the positioning capability is improved, but misalignment between these measurement systems occurs resulting in reduced positioning accuracy
Solution Approach 1:
The encoder system and measurement system are merged into a single integrated measurement frame structure. This integration ensures that both systems share a common reference frame and are mechanically coupled, eliminating relative misalignment between separate measurement systems while maintaining comprehensive positioning capability through multiple measurement points
Solution Approach 2:
The measurement frame acts as an intermediary structure that mechanically couples the encoder system and measurement system. This intermediary provides a stable, rigid connection that maintains precise geometric relationships between measurement components positioned at different locations, ensuring accurate coordinate transformation between measurement systems
Data Source
AI summary
A lithographic apparatus having a substrate table, a projection system, an encoder system, a measurement frame and a measurement system. The substrate table has a holding surface for holding a substrate. The projection system is for projecting an image on the substrate. The encoder system is for providing a signal representative of a position of the substrate table. The measurement system is for measuring a property of the lithographic apparatus. The holding surface is along a plane. The projection system is at a first side of the plane. The measurement frame is arranged to support at least part of the encoder system and at least part of the measurement system at a second side of the plane different from the first side.