Diffraction Grating Deformation Correction in Exposure Apparatus
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Solution Overview
Problem
Existing exposure apparatuses face measurement errors in positioning the substrate stage due to drawing errors, mounting errors, temperature changes, and strain of diffraction gratings, which affect the precision of pattern transfer in semiconductor device fabrication.
Innovation Solution
A measurement apparatus that includes diffraction gratings on both the reference frame and the substrate stage, with first and second heads to detect the deformation of the gratings and correct the position of the substrate stage based on these deformations, ensuring accurate positioning by accounting for errors caused by grating deformation and deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If diffraction grating is used for position measurement, then measurement capability is provided, but measurement errors occur due to drawing errors, mounting errors, temperature changes, and strain
Solution Approach 1:
The patent implements a feedback mechanism where the deformation amount of the diffraction grating is measured and used to correct the position measurement results. The correction amount is calculated based on the detected deformation, and this correction is applied to compensate for measurement errors, thereby maintaining both measurement capability and accuracy despite grating deformation
Solution Approach 2:
The patent introduces a correction mechanism as an intermediary between the raw position measurement and the final accurate position. The deformation amount of the diffraction grating serves as an intermediate parameter that mediates the correction process, allowing the system to account for grating errors without directly measuring the final corrected position
2Measurement precision
If diffraction grating deformation is corrected, then position measurement accuracy is improved, but device complexity increases due to additional measurement and correction processes
Solution Approach 1:
The patent merges the deformation measurement function with the existing position measurement system. By integrating the diffraction grating deformation detection into the same measurement apparatus used for position measurement, the system avoids adding separate complex measurement devices, thereby reducing overall device complexity while still achieving accurate correction
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 solution enhances the accuracy of substrate stage positioning, reducing measurement errors and improving the precision of pattern transfer in semiconductor device fabrication by accounting for grating deformation and deviation, leading to higher-quality device fabrication.
Implementation Method 1
a first measurement unit which includes a diffraction grating provided on the first object, and a first head and a second head provided on the second object
Data Source
AI summary
The present invention provides a measurement apparatus which measures a position of a second object relative to a first object, the apparatus including a first measurement unit which includes a diffraction grating provided on the first object, and a first head and a second head provided on the second object, and is configured to measure the position of the second object relative to the first object by the first head or the second head, and a processing unit configured to perform a process of obtaining the position of the second object relative to the first object.