EUV Lithography Sensor Module for Mirror Alignment Monitoring
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Solution Overview
Problem
In extreme ultra-violet lithography systems, small errors in mirrors cause significant pattern formation errors due to the increased difficulty in the exposure process, necessitating precise monitoring of EUV light distribution.
Innovation Solution
A monitoring device comprising a sensor module and processor that generates and processes images to measure the intensity and alignment of EUV light across multiple mirrors, using Fourier transformations and algorithms to optimize the pupil region for precise alignment and intensity mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple mirrors are used in illumination and projection optical systems, then light transmission and pattern formation are enabled, but small errors in mirror alignment cause significant pattern formation errors
Solution Approach 1:
The patent implements a feedback mechanism by placing sensor modules on the substrate stage to detect the actual position and alignment of EUV light after it passes through multiple mirrors. The detected information is fed back to a control system that adjusts mirror positions in real-time, compensating for alignment errors and maintaining pattern formation precision despite the complexity of the multi-mirror optical system.
2Productivity
If EUV light is used for finer semiconductor circuit line widths, then shorter wavelength exposure is achieved, but the exposure process becomes increasingly difficult and sensitive to errors
Solution Approach 1:
The patent replaces complex mechanical alignment adjustments with a sensor-based detection and computational correction system. Instead of relying solely on precise mechanical mirror positioning, the system uses sensor modules to detect EUV light distribution and employs algorithms to calculate and correct alignment errors, substituting mechanical precision requirements with optical detection and computational processing.
3Measurement precision
If mirror alignment is monitored to improve pattern formation, then measurement precision is enhanced, but the monitoring system complexity increases
Solution Approach 1:
The patent introduces sensor modules as intermediary devices that indirectly measure mirror alignment by detecting the actual EUV light distribution pattern on the substrate stage. Instead of directly measuring mirror positions, the sensor modules capture light intensity information that reflects alignment status, providing a simplified measurement approach that maintains high precision while reducing the complexity of direct mechanical measurement systems.
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 real-time monitoring and correction of EUV light intensity and alignment, reducing pattern formation errors by identifying and correcting misalignments and intensity losses in the illumination and projection optical systems.
Implementation Method 1
a sensor module which is disposed on a substrate stage that supports the substrate, and which generates a first image representing a light intensity distribution
Implementation Method 2
a processor performing a Fourier transformation on the first image to generate a second image representing a first pupil region defined by a first center point and a plurality of second center points
Implementation Method 3
a field facet mirror which includes a plurality of first mirrors that collect the light transmitted from the source module
Implementation Method 4
a pupil facet mirror which includes a plurality of second mirrors that transmit the light transmitted from the field facet mirror to a reticle
Data Source
AI summary
An extreme ultra-violet (EUV) lithography system includes a source module generating light, a field facet mirror including first mirrors that collect the light transmitted from the source module, a pupil facet mirror including second mirrors that transmit the light transmitted from the field facet mirror to a reticle, a projection optical system transmitting the light reflected from the reticle to a substrate, a sensor module disposed on a substrate stage that supports the substrate and generating a first image representing a light intensity distribution, and a processor performing a Fourier transformation on the first image to generate a second image representing a first pupil region defined by a first center point and a plurality of second center points each spaced apart from the first center point by a first distance. The first center point is located at a center of the first pupil region.