Multi-Height Substrate Level Sensing With Broadband Beamlets
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Solution Overview
Problem
Current level sensors in charged-particle beam inspection systems face limitations in detecting substrate displacement at multiple target heights, leading to inaccurate measurements and potential damage due to instability and lack of sensitivity, especially with materials sensitive to narrowband spectra and wide dynamic ranges.
Innovation Solution
A multi-working height level sensor system that uses a configurable broadband radiation source, beam splitters, and detectors to split radiation beams into multiple beamlets, each reflecting off the substrate at different target heights, enabling accurate detection of height deviations and tilt, and minimizing material effects through wideband radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-target-height level sensor is used, then the device complexity is low, but the adaptability to multiple target heights is insufficient
Solution Approach 1:
The level sensor is segmented into multiple independent detection channels, each with its own beam splitter and light reflecting component configured for a specific target height. This allows each segment to independently detect substrate height at its designated target height, enabling multi-target height detection while maintaining simple individual channel structures.
Solution Approach 2:
The level sensor system is designed to perform multiple functions by detecting substrate height at multiple different target heights simultaneously using a single integrated sensor unit. Each detection channel within the sensor is configured with different optical path lengths to accommodate various target heights, making the system universally applicable to different inspection requirements.
2Measurement precision
If narrowband radiation is used, then the measurement precision for specific materials may be improved, but material-induced errors increase for sensitive materials
Solution Approach 1:
The system changes the radiation parameter from narrowband to broadband spectrum. The broadband radiation source emits multiple wavelengths simultaneously, and the level sensor detects height information across this broad spectrum. This parameter change reduces material-induced errors because different wavelengths interact differently with materials, allowing the system to find optimal detection wavelengths and minimize harmful material effects.
3Productivity
If the substrate is not properly leveled, then the inspection throughput may be maintained, but the imaging resolution and detection accuracy deteriorate
Solution Approach 1:
The level sensor provides real-time feedback on substrate height and levelness at multiple target heights. The inspection system uses this feedback information to dynamically adjust the substrate position or focus settings, ensuring that the substrate is properly leveled during inspection. This closed-loop feedback mechanism maintains both high throughput and high detection accuracy by continuously correcting substrate positioning errors.
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 allows for high-accuracy detection of substrate height variations across a broader range, enabling high-quality imaging with electron beams of multiple landing energies, reducing material-induced errors, and ensuring the substrate is parallel to the reference surface, thus preventing damage.
Implementation Method 1
a beam splitter configured to split the radiation beam into multiple beamlets that each reflect off the substrate
Data Source
AI summary
An inspection apparatus for adjusting a working height for a substrate for multiple target heights is disclosed. The inspection apparatus includes a radiation source configured to provide a radiation beam and a beam splitter configured to split the radiation beam into multiple beamlets that each reflect off a substrate. Each beamlet contains light of multiple wavelengths. The inspection apparatus includes multiple light reflecting components, wherein each light reflecting component is associated with one of the beamlets reflecting off the substrate and is configured to support a different target height for the substrate by detecting a height or a levelness of the substrate based on the beamlet reflecting off the substrate.