Angular-Resolved Spectroscopy Scatterometer Motion Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional scatterometry apparatus in lithographic environments occupy significant space and generate large vibrations due to linear movement requirements, which is undesirable in clean environments where space is limited and accuracy is crucial.
Innovation Solution
A scatterometer design that minimizes space usage by allowing the substrate table to move linearly and rotate about an axis perpendicular to the plane, while the detector moves rotationally around a similar axis, reducing the need for extensive linear motion and associated vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the substrate table and detector are moved linearly in two directions to inspect every point on the substrate, then complete substrate inspection is achieved, but the space required increases significantly
Solution Approach 1:
The patent introduces rotational movement as a new dimension to replace part of the linear movement. The substrate table rotates about an axis perpendicular to the substrate plane, allowing the detector to inspect different points on the substrate through rotation rather than linear translation in two directions, thereby reducing the apparatus footprint.
Solution Approach 2:
The patent employs dynamic rotational movement of the substrate table combined with linear movement in one direction. This dynamic combination allows the detector to access all points on the substrate through a hybrid motion pattern that requires less total space than static two-directional linear movement would require.
2Measurement precision
If the substrate table and detector are moved linearly by at least 300 mm to inspect every point, then complete substrate coverage is achieved, but large acceleration forces generate significant vibrations
Solution Approach 1:
By introducing rotational movement about a perpendicular axis, the patent reduces the linear travel distance required. Rotation allows the detector to sweep across the substrate surface without requiring long linear translations, thereby reducing acceleration forces and resulting vibrations.
Solution Approach 2:
The patent replaces part of the mechanical linear translation system with a rotational mechanism. This substitution reduces the mechanical stresses and vibrations associated with large-scale linear acceleration while maintaining the ability to inspect all substrate points.
3Measurement precision
If the detector is moved linearly in a second direction perpendicular to the first, then every point on the substrate can be inspected, but the apparatus occupies excessive space in clean environments
Solution Approach 1:
The patent adds rotational degree of freedom about an axis perpendicular to the substrate plane. This allows the detector to access points across the substrate through rotation rather than requiring linear movement in two perpendicular directions, significantly reducing the apparatus footprint for clean room installation.
4Measurement precision
If rotational asymmetry in the apparatus is accounted for by detecting every point from every rotational angle, then measurement accuracy is improved, but the detector and substrate must be configured for extensive two-directional movement
Solution Approach 1:
The patent uses rotation about a perpendicular axis to achieve the required rotational angle detection. This single rotational degree of freedom simplifies the configuration compared to requiring coordinated two-directional linear movements while maintaining the ability to detect from all rotational angles.
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 configuration enables efficient measurement of substrate properties with reduced vibrations and space occupancy, enhancing the accuracy and operational efficiency in lithographic processes.
Implementation Method 1
a beam is reflected off the surface of the substrate, for example at an alignment target, and an image is created on a camera of the reflected beam
Implementation Method 2
detecting portion configured to detect an angle-resolved spectrum redirected 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 enables all portions of a surface of the substrate to be inspected from all angles in a plane parallel to the substrate. Less linear motion is needed, so the apparatus occupies a smaller volume and generates smaller vibrations.