Multi-Angle Spectroscopy Pupil Segmentation
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Solution Overview
Problem
Existing optical metrology systems for semiconductor fabrication face limitations in throughput and accuracy due to the need for sequential measurements at multiple angles of incidence, which results in signal fidelity loss and extended measurement times, especially when characterizing complex high aspect ratio structures.
Innovation Solution
The implementation of a pupil segmentation and dispersion device that segments the measurement pupil into multiple segments and disperses them onto spatially distinct detector areas, allowing for simultaneous measurement of broad ranges of angles and azimuth angles with high signal-to-noise ratio, along with a multi-zone infrared detector and fine focus sensor for improved precision and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential measurements at multiple angles of incidence are performed, then measurement accuracy is improved, but measurement time increases and throughput decreases
Solution Approach 1:
The patent segments the measurement process by dividing the angular range into multiple discrete angles of incidence, with each angle measured by a dedicated detector element. This allows simultaneous acquisition of multiple angular measurements without sequential scanning, thereby maintaining high measurement accuracy while significantly improving throughput and eliminating time-dependent measurement errors.
Solution Approach 2:
The patent transitions from temporal separation of measurements to spatial parallelism by arranging detector elements at different angular positions. Instead of measuring angles sequentially over time, the system captures multiple angles simultaneously across the detector array, adding a spatial dimension to the measurement process that enables parallel data acquisition.
2Measurement precision
If sequential measurements at multiple angles of incidence are performed, then measurement accuracy is improved, but measurement time increases
Solution Approach 1:
The measurement process is segmented into simultaneous angular channels, with each detector element capturing reflectance data at a specific angle of incidence. This parallel segmentation eliminates the time required to sequentially rotate or scan between angles, reducing total measurement time while preserving the accuracy benefits of multi-angle data.
Solution Approach 2:
The system maintains continuous measurement action across all angles simultaneously, rather than interrupting the measurement process to change angles sequentially. The detector array continuously captures reflectance signals at multiple angles at the same time, eliminating idle time and ensuring uninterrupted data acquisition.
3Measurement precision
If mechanical shutters are used to block light for AOI selection, then angle-specific measurements are achieved, but device complexity increases and measurement speed decreases
Solution Approach 1:
The patent replaces the mechanical shutter system with a fixed angularly-resolved detector array. Instead of using moving mechanical components to block or redirect light for angle selection, the system uses stationary detector elements positioned at specific angles to directly capture angle-specific reflectance signals, eliminating mechanical complexity and improving measurement speed.
4Quantity of substance
If the full range of reflected angles is collected, then light throughput is maximized, but signal fidelity is lost due to angle integration
Solution Approach 1:
The patent segments the collected light by angle of incidence using a detector array where each element responds to a specific angular range. This angular segmentation preserves the full light throughput from the high numerical aperture objective while preventing angle integration, as each detector element measures only its designated angular channel, thereby maintaining both high throughput and signal fidelity.
Solution Approach 2:
Different regions of the detector array are assigned to different angular ranges, with each detector element optimized to measure reflectance at its specific angle of incidence. This local angular specialization allows the system to capture the full angular distribution of reflected light while maintaining angle-specific signal fidelity, as each detector element provides high-quality data for its designated angular region.
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 high throughput, precise, and accurate measurements of high aspect ratio structures by uniformly correcting wavelength errors and optimizing measurement speed and accuracy across a broad range of angles, thereby overcoming the limitations of sequential measurement methods.
Implementation Method 1
a pupil segmentation and dispersion device that segments the measurement pupil into multiple segments and disperses them onto spatially distinct detector areas
Implementation Method 2
disperses them onto spatially distinct detector areas
Implementation Method 3
multi-zone infrared detector
Data Source
AI summary
Methods and systems for performing simultaneous spectroscopic measurements of semiconductor structures over a broad range of angles of incidence (AOI), azimuth angles, or both, are presented herein. Spectra including two or more sub-ranges of angles of incidence, azimuth angles, or both, are simultaneously measured over different sensor areas at high throughput. Collected light is linearly dispersed across different photosensitive areas of one or more detectors according to wavelength for each subrange of AOIs, azimuth angles, or both. Each different photosensitive area is arranged on the one or more detectors to perform a separate spectroscopic measurement for each different range of AOIs, azimuth angles, or both. In this manner, a broad range of AOIs, azimuth angles, or both, are detected with high signal to noise ratio, simultaneously. This approach enables high throughput measurements of high aspect ratio structures with high throughput, precision, and accuracy.