Single-Photon Detector Scanning for Time-Resolved Emission Imaging
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Solution Overview
Problem
Current imaging photodetectors for Picosecond Imaging for Circuit Analysis (PICA) face challenges such as high noise, hot-spots, non-uniformity, and high time jitter, limiting their ability to effectively measure the faint near-infrared light emissions from modern CMOS transistors, particularly from p-type FETs, which are weaker and shifted towards longer wavelengths, restricting imaging capability and sensitivity.
Innovation Solution
The use of high-performance single-point single photon detectors like Superconducting Single Photon Detector (SSPD) and InGaAs Single Photon Avalanche Diode (SPAD) for precise time-resolved measurements, combined with a Scanning Time-Resolved Emission (S-TRE) system that focuses spontaneous light emissions onto these detectors, allowing for improved sensitivity and reduced noise, enabling imaging capabilities for PICA by optimizing single-pixel performance and leveraging advanced optical systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If imaging photodetectors are used for PICA measurements, then spatial imaging capability is provided, but noise, hot-spots, non-uniformity, and time jitter increase significantly
Solution Approach 1:
The patent divides the imaging function from the detection function by using a single-point detector that scans across the device under test. The imaging capability is achieved through sequential scanning and spatial mapping rather than using a static imaging array, thereby avoiding the noise and non-uniformity problems of imaging photodetectors while maintaining spatial resolution
Solution Approach 2:
The patent introduces a scanning mechanism as an intermediary between the single-point detector and the device under test. This scanning system enables spatial mapping and imaging capability without requiring the detector itself to be an imaging array, thus preserving the low noise and high precision characteristics of single-point detectors
2Measurement precision
If single-point single photon detectors are used, then noise and time jitter are reduced, but imaging capability is lost
Solution Approach 1:
The patent transforms the static imaging problem into a dynamic scanning process. The single-point detector moves sequentially across the device under test, collecting photons at each location and building up a time-resolved emission image over time. This dynamic approach enables imaging with a single-point detector by trading spatial parallelism for temporal sequencing
Solution Approach 2:
The patent adds the time dimension to compensate for the loss of spatial dimensionality. Instead of capturing all spatial information simultaneously like a static imaging detector, the scanning system collects data sequentially in time and reconstructs the spatial image through coordinate mapping, effectively trading one dimension for another
3Measurement precision
If detection time is extended to improve signal quality, then measurement precision improves, but acquisition time increases
Solution Approach 1:
The patent changes the detection parameter from continuous integration to single-photon counting with time tagging. This allows for precise measurement of photon arrival times with high temporal resolution, improving signal quality without requiring long integration times. The time-tagged single-photon counting method enables efficient data collection that can be processed to create time-resolved emission images
Solution Approach 2:
The patent employs periodic scanning cycles where the single-point detector systematically visits each location on the device under test. By repeating the scanning pattern multiple times and accumulating photon counts at each location, the system improves signal quality through temporal averaging while maintaining relatively short acquisition times through efficient scanning protocols
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 significantly enhances the sensitivity and accuracy of PICA by reducing acquisition time for n-FET light pulses, enabling the observation of p-FET emissions and allowing for the evaluation of signal pulse width, duty cycle, and delay and skew calculations between signals with different phases, thereby regaining imaging capability for modern semiconductor technologies.
Implementation Method 1
scanning methods for creating time-resolved emission images of integrated circuits using a single-point single-photon detector
Implementation Method 2
a Scanning Time-Resolved Emission (S-TRE) system that focuses spontaneous light emissions onto these detectors
Data Source
AI summary
A Scanning Time-Resolved Emission (S-TRE) microscope or system includes an optical system configured to collect light from emissions of light generated by a device under test (DUT). A scanning system is configured to permit the emissions of light to be collected from positions across the DUT in accordance with a scan pattern. A timing photodetector is configured to detect a single photon or photons of the emissions of light from the particular positions across the DUT such that the emissions of light are correlated to the positions to create a time-dependent map of the emissions of light across the DUT. Updating the time-dependent map of the emissions based on variable dwell times at respective locations of the DUT.