Lithography Apparatus Rotational Inspection Reducing Vibrations
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Solution Overview
Problem
Conventional lithographic apparatuses require significant space and generate large vibrations due to linear movement, which is undesirable in clean environments where precision and minimal space are crucial for accurate exposure and scatterometry measurements.
Innovation Solution
A method involving projecting a patterned radiation beam onto a substrate, moving the substrate linearly to the detector's focal point, rotating the substrate about a perpendicular axis, and rotating the detector using a rotor to detect an angle-resolved spectrum, minimizing the need for extensive linear movement and reducing vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear movement is used to move the substrate table and detector, then inspection coverage is achieved, but space requirement increases and vibrations are generated
Solution Approach 1:
The patent applies rotational movement instead of linear movement to inspect different points on the substrate. The substrate table rotates about a first axis and the detector rotates about a second axis, eliminating the large linear displacements that generate vibrations. This rotational approach maintains inspection coverage while minimizing harmful vibrations in the clean environment.
2Measurement precision
If linear movement is used to move the substrate table and detector, then inspection coverage is achieved, but space occupation increases
Solution Approach 1:
The patent transitions from linear movement in one dimension to rotational movement around an axis. By rotating the substrate table and detector around a central axis rather than moving them linearly across space, the system achieves the same inspection coverage within a compact footprint, minimizing space occupation in the clean environment.
3Productivity
If linear movement is used, then substrate inspection is performed, but acceleration forces increase resulting in vibrations
Solution Approach 1:
The patent replaces linear acceleration with rotational motion. The substrate table and detector rotate around axes rather than accelerating linearly, which eliminates the large acceleration forces that cause vibrations. This maintains inspection productivity while minimizing harmful mechanical effects in the sensitive clean environment.
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 allows for precise inspection and measurement of substrates with reduced space occupation and minimized vibrations, enhancing the accuracy and efficiency of the lithographic process while maintaining a clean environment.
Implementation Method 1
detecting an angle resolved spectrum reflected from the substrate
Data Source
AI summary
To inspect all portions of the substrate, the substrate table can be moved rotationally and linearly. Furthermore, the detector can be moved rotationally. This allows all portions of a surface of the substrate to be inspected from all angles in a plane parallel to the substrate. In one example, as less linear motion is needed, the apparatus occupies a smaller volume and generates smaller vibrations.