Isolating Semiconductor Photoemission via Point Spread Function Analysis
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Solution Overview
Problem
As semiconductor devices shrink in size, the increased density and proximity of transistors make it difficult to isolate which device is emitting light or modulating a laser beam, complicating the debugging and testing process, especially as emissions from neighboring devices interfere with optical testing systems.
Innovation Solution
The method involves convolving a point spread function with CAD data to compare calculated signal intensities against measured signals, using statistical methods like Chi-Square minimization to determine the most probable state combination of transistors, and iteratively adjusting CAD alignment to minimize errors, thereby isolating emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If design rule is shrunk to increase device density, then productivity is improved, but measurement precision deteriorates due to difficulty in isolating emitting devices
Solution Approach 1:
The patent segments the optical signal by decomposing the collected light emission into contributions from individual transistors using point spread function analysis. Each transistor's emission is treated as a separate component that can be mathematically separated from the total signal, enabling precise identification of emitting devices even in high-density configurations where emissions overlap spatially.
Solution Approach 2:
The patent transitions from spatial domain analysis to frequency domain analysis by applying Fourier transforms to the optical signals. This dimensional transformation allows separation of emissions based on their temporal/frequency characteristics rather than just spatial position, enabling resolution of closely spaced transistors that would be indistinguishable in the spatial domain alone.
2Productivity
If device size is reduced to increase density, then productivity is improved, but difficulty of detecting and measuring increases due to emission interference from neighboring devices
Solution Approach 1:
The patent introduces point spread functions as an intermediary mathematical model that characterizes the optical response of each transistor. This intermediary representation allows the system to separate and identify individual transistor emissions from the composite signal, acting as a mediator between the complex overlapping emissions and the detection system's ability to resolve individual sources.
Solution Approach 2:
The patent replaces physical spatial separation methods with computational signal processing techniques. Instead of relying on physical distance or optical filtering to separate emissions, the system uses mathematical algorithms including Chi-Square minimization and Fourier analysis to computationally separate and identify individual transistor emissions from the combined signal.
3Measurement precision
If statistical methods are used to determine transistor states, then measurement precision is improved, but device complexity increases due to computational requirements
Solution Approach 1:
The patent performs preliminary computational work by pre-calculating and storing point spread functions for each transistor location before actual measurement. This preliminary action creates a reference library that simplifies the real-time analysis, as the system only needs to compare measured signals against the pre-computed PSF database rather than performing complex calculations during measurement, thus reducing operational computational complexity.
Solution Approach 2:
The system uses the measured optical signals themselves to generate the point spread functions through iterative optimization processes. The measurement data serves dual purposes: both as the signal to be analyzed and as the basis for creating the analysis tools (PSFs), eliminating the need for separate calibration procedures or external reference measurements.
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 resolution of light emission from closely spaced transistors, allowing for accurate identification of emitting devices, even in high-density semiconductor chip configurations, by calculating the probability of each state combination and selecting the alignment with the smallest error, thus improving debugging and testing efficiency.
Implementation Method 1
semiconductor devices emit light upon change of states, e.g. transistors switching on/off
Implementation Method 2
use lasers to test and debug semiconductor circuits by examining modulations in the reflected laser light
Implementation Method 3
semiconductor devices emit light upon change of states
Data Source
AI summary
A method for isolating the emitting devices may be applied to various emission and laser microscopy systems. A point spread function is convolved with CAD data of devices involved in the emission. The calculated signal intensity of the devices is varied until the difference between the calculated signal and the measured signal provides best fit. The best fit is performed for each on/off state for all configurations of the involved devices. The variance of the best curve fit for all of the configurations is used to assign probability to each state. The best fit indicates the correct state of each of the involved devices, thereby indicating which devices emit. At times, when the transistors are extremely close, a weighted solution is calculated. The weights are based on the probability of each solution.