Multi-Beamlet Distance Measurement Using a 2D Blocking Pattern
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Solution Overview
Problem
Current multi-beamlet lithography systems face challenges in accurately determining the position of charged particle beamlets with high precision and speed, especially when dealing with large numbers of beamlets, which affects the resolution and throughput of the lithography process.
Innovation Solution
A method using a sensor with a converter element and a two-dimensional blocking pattern with knife edges to measure the position of charged particle beamlets, allowing for precise determination of beamlet positions by scanning across the pattern and analyzing the intensity changes, which reduces sensitivity to pattern irregularities and line edge roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional beamlet position measurement methods are used, then beamlet position can be determined, but measurement time is excessive and reduces throughput
Solution Approach 1:
The patent segments the measurement process by dividing the sensor surface into multiple independent detection regions, each capable of measuring beamlet positions simultaneously. This parallel measurement approach reduces total measurement time while maintaining precision, as multiple beamlets can be measured at the same time rather than sequentially
Solution Approach 2:
The patent transitions from conventional point-by-point position measurement to a two-dimensional sensor surface measurement approach. By mapping beamlet positions onto a 2D detector plane, the system can capture position information for multiple beamlets simultaneously in a single measurement operation, dramatically reducing measurement time while preserving accuracy
2Productivity
If measurement speed is increased to improve throughput, then measurement time is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent implements preliminary calibration of the sensor surface with known reference patterns before actual measurements. This pre-calibration establishes accurate position-mapping relationships, enabling rapid subsequent measurements to maintain both high speed and high precision without compromising accuracy
Solution Approach 2:
The patent replaces slow mechanical scanning measurement methods with a static 2D sensor surface detection system. This substitution eliminates mechanical movement delays while maintaining measurement precision through the spatial resolution of the detector array, enabling simultaneous multi-beamlet position measurement
3Manufacturing precision
If beamlet position measurement accuracy is improved to reduce stitching errors, then resolution is enhanced, but measurement complexity increases
Solution Approach 1:
The patent introduces a 2D sensor surface with blocking patterns as an intermediary between the beamlets and the detection system. This intermediary converts complex beamlet position information into simplified spatial patterns on the detector, reducing measurement complexity while maintaining nanometer-level positioning accuracy for stitching applications
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 enhances the accuracy of beamlet position measurement, reduces measurement time, and improves the resolution of lithography systems by providing nanometer precision, thus increasing the throughput and reducing stitching errors in multi-beamlet exposure apparatuses.
Implementation Method 1
charged-particle beamlets are scanned over a converter element provided with a pattern of charged particle blocking and non-blocking areas. The beam portions that are impinging on the non-blocking areas are converted by the converter element into light beams
Data Source
Figure 1~2B
Figure 3~4
Figure 5A~7
AI summary
The invention relates to a method for determining a distance between two charged particle beamlets in a multi-beamlet exposure apparatus. The apparatus is provided with a sensor comprising a converter element for converting the energy of charged particles into light and a light sensitive detector. The converter element is provided with a sensor surface area provided with a two-dimensional pattern of beamlet blocking and non-blocking regions. The method comprises scanning a first beamlet over the two-dimensional pattern, receiving light generated by the converter element in response to charged particles being part of the first beamlet transmitted through the two-dimensional pattern, and converting the received light into a first signal by means of the light sensitive detector. Then the two-dimensional pattern and the first beamlet are moved relatively with respect to each other over a predetermined distance. Subsequently, the method continues with scanning a second beamlet over the two-dimensional pattern, receiving light generated by the converter element in response to charged particles being part of the second beamlet transmitted through the two-dimensional pattern, and converting the received light into a second signal by means of the light sensitive detector. Finally, the distance between the first beamlet and second beamlet is determined based on the first signal, the second signal and the predetermined distance.