Single-Photon Detector Scanning for Time-Resolved IC Emission Imaging
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Solution Overview
Problem
Current photodetectors for Picosecond Imaging for Circuit Analysis (PICA) face challenges with high noise, hot-spots, non-uniformity, and high time jitter, limiting their sensitivity and imaging capabilities, especially in the Near-Infrared (NIR) region, which hinders the observation of weak emissions from p-type FETs and reduces the ability to measure signal delays and skews between different logic gate phases.
Innovation Solution
The use of high-performance single pixel photodetectors, such as Superconducting Single Photon Detector (SSPD) and InGaAs Single Photon Avalanche Diode (SPAD), in conjunction with a Scanning Time-Resolved Emission (S-TRE) system that focuses spontaneous light emissions onto these detectors, allowing for precise measurement of photon arrival times and enabling the creation of pseudo 2D images by combining measurements from equivalent emission locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If imaging photodetectors are developed for NIR sensitivity, then sensitivity to weak emissions is improved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The imaging function is segmented from the photodetector array and assigned to a scanning system with a single-point detector. The scanner divides the imaging task into sequential point-by-point measurements, allowing a simple single-point detector to achieve imaging capability through temporal and spatial segmentation of the detection process.
Solution Approach 2:
A scanning system acts as an intermediary between the single-point photodetector and the chip under test. The scanner mechanically or optically directs light from different chip locations to the fixed detector, enabling spatial mapping without requiring a complex array detector. This intermediary system transfers the imaging function from the detector to the scanning mechanism.
2Measurement precision
If single-point photodetectors are used, then sensitivity and time resolution are improved, but imaging capability is lost
Solution Approach 1:
The system employs dynamic scanning to convert a static single-point detector into a dynamic imaging system. By rapidly moving the scanner or steering the optical path across different chip locations during operation, the system captures spatial information sequentially, creating time-resolved emission images that combine both temporal precision and spatial mapping.
Solution Approach 2:
The system adds the time dimension to compensate for the loss of spatial dimension in a single-point detector. By measuring photon arrivals with picosecond time resolution and correlating them with scanner position, the system creates four-dimensional data (x, y, wavelength, time) from a single spatial detection point, enabling time-resolved imaging without requiring simultaneous multi-point detection.
3Ease of operation
If conventional photodetectors are used, then imaging capability is maintained, but sensitivity to weak NIR emissions deteriorates
Solution Approach 1:
The system uses a simple, inexpensive single-point photodetector that can be mass-produced with high yield, replacing expensive, complex imaging photodetectors. Although the single-point detector has limited inherent imaging capability, the scanning system compensates for this, achieving both cost-effectiveness and the required measurement precision through the combination of simple detector + scanning mechanism.
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 sensitivity and imaging capabilities of PICA, enabling the observation of weak emissions from p-type FETs and improving the measurement of signal pulse width, duty cycle, and delay/skews between signals with different phases, thereby simplifying data interpretation and failure localization.
Implementation Method 1
hot-carrier photon emission from very large scale integration (VLSI) circuits has been employed for localizing and identifying failures in circuits
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. The scanning system is configured to update the time-dependent map of the emissions based on combinations of the emissions of light at certain locations.