Lithography Inspection Apparatus for Overlay Error Measurement
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Solution Overview
Problem
Conventional lithographic processes require large targets for measuring overlay errors, which occupy valuable space and compromise device functionality, making it undesirable to position them within patterns.
Innovation Solution
A method and apparatus that project radiation onto a substrate, detect reflected radiation, form Fourier transform data, remove and interpolate data corresponding to targets, and subtract the target data from the pattern data to measure properties accurately without the need for large targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If large targets are used for measuring overlay errors, then measurement precision is improved, but substrate area available for device patterns is reduced
Solution Approach 1:
The invention extracts and removes the target structure from its conventional location in the scribe lane and repositions it within the product pattern area. By taking out the target from its traditional location and integrating it into the pattern itself, the method eliminates the need for separate scribe lane targets, thereby maximizing substrate utilization while maintaining measurement functionality
Solution Approach 2:
The invention merges the target structure with the product pattern by positioning the target within the pattern area rather than in separate scribe lanes. This merging allows the target to serve dual purposes: as a measurement reference for overlay error and as part of the overall pattern structure, thereby optimizing substrate space
2Area of stationary object
If targets are positioned within patterns, then substrate space utilization is improved, but target size must be reduced which may compromise measurement precision
Solution Approach 1:
The invention applies local quality by creating a target with specific dimensional characteristics (e.g., 1-10 micrometer size) that is optimized for its dual role within the pattern. The target is designed with local structural features that enhance its measurement precision while maintaining a compact size suitable for integration within the product pattern area
Solution Approach 2:
The invention changes the dimensional parameters of the target from conventional large scribe lane targets to smaller dimensions (1-10 micrometers) that fit within the pattern. By adjusting the target size parameter and its structural configuration, the method achieves both compact footprint for space efficiency and sufficient measurement precision for overlay error detection
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
Enables the measurement of overlay errors and other substrate properties with high precision using smaller targets, allowing for more efficient use of substrate space and improved device functionality.
Implementation Method 1
detecting the radiation reflected by the substrate
Implementation Method 2
forming a set of fourier transform data based on the detected radiation
Data Source
AI summary
A system detects targets located within patterns. It operates in the pupil plane by filtering the received signal from the surrounding pattern. A method includes illuminating a target and a surrounding pattern with radiation, detecting the radiation reflected by the target and the surrounding pattern and forming a first set of data based on the detected radiation, removing portions of the first set of data which correspond to the target to form reduced data, interpolating the remaining portions of the reduced data over the removed portions to form product data, and subtracting the product data from the first set of data to form target data.