Lithographic Inspection Apparatus for Systematic Error Correction
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Solution Overview
Problem
Lithographic processes suffer from systematic errors such as overlay and critical dimension errors, which are difficult to correct effectively using existing methods.
Innovation Solution
A method and apparatus for measuring errors in image characteristics of substrates formed using lithographic processes, determining corrections based on measured errors and product feature characteristics, and applying these corrections for subsequent feature formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inspection methods are used to measure overlay and critical dimension errors, then measurement capability is provided, but the ability to effectively correct systematic errors is insufficient
Solution Approach 1:
The patent segments the correction process by applying different correction models to different regions of the substrate. The method divides the substrate into multiple regions and applies region-specific correction parameters based on locally measured errors, enabling more effective systematic error correction compared to uniform correction approaches.
Solution Approach 2:
The patent implements local quality by using scatterometer measurements to detect local variations in overlay and critical dimension errors across different regions of the substrate. The correction process then applies location-specific adjustments based on these localized measurements, improving manufacturing precision by addressing regional systematic errors rather than applying blanket corrections.
2Productivity
If scatterometry is used for fast non-invasive inspection, then measurement speed is improved, but the complexity of error modeling and correction increases
Solution Approach 1:
The patent implements a feedback loop where scatterometer measurements of substrate errors are fed into correction models that generate adjustment parameters. These corrections are then applied to subsequent lithographic exposures, and the process continues with further measurements to verify improvement. This iterative feedback mechanism enables the system to handle modeling complexity systematically while maintaining fast inspection speeds.
Solution Approach 2:
The patent changes key parameters including the wavelength of radiation used in scatterometry, the angular range of scattered radiation measurement, and the correction model parameters themselves. By optimizing these parameters, the system achieves accurate error detection and correction with manageable complexity, balancing productivity and device complexity.
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 enables improved corrections to minimize systematic errors, optimizing image characteristics and improving the accuracy of subsequent exposures in lithographic processes.
Implementation Method 1
a scatterometer in which a beam of radiation is directed onto a target on the surface of the substrate and properties of the scattered or reflected beam are measured
Implementation Method 2
properties of the scattered or reflected beam are measured. By comparing the properties of the beam before and after it has been reflected or scattered by the substrate
Data Source
AI summary
A method of correcting an image characteristic of a substrate onto which one or more product features have been formed using a lithographic process, and an associated inspection apparatus method. The method includes measuring an error in the image characteristic of the substrate, and determining a correction for a subsequent formation of the product features based upon the measured error and a characteristic of one or more of the product feature(s).