IC Defect Detection via Laser-Induced Noise Spectral Analysis
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Solution Overview
Problem
Current methods, such as OBIC and TIVA, face challenges in distinguishing between defect and non-defect sites in integrated circuits, as many thermally sensitive sites produce similar responses, leading to ambiguous results and the need for destructive physical analysis.
Innovation Solution
A method utilizing a spectrum analyzer to monitor electrical signals and correlate noise levels with the location of a laser beam, which heats the IC point-by-point, differentiating defects by their characteristic noise signatures and increased noise rates compared to non-defect sites, and combining this with conventional TIVA analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If OBIC or TIVA techniques are used to detect defect sites, then thermal sensitivity detection is improved, but the ability to distinguish between defect and non-defect sites deteriorates
Solution Approach 1:
The patent transitions from spatial imaging (2D) to frequency domain analysis (adding a temporal dimension). By performing Fourier transforms on time-series voltage signals and analyzing power spectral density across different frequency bands, the system creates a multi-dimensional characterization of thermal responses that enables defect differentiation beyond what spatial imaging alone can provide.
Solution Approach 2:
The patent changes the measurement parameter from static voltage magnitude to dynamic frequency characteristics. By analyzing how voltage signals vary over time and decomposing them into frequency components, the system captures the dynamic thermal behavior of different circuit elements, allowing distinction between defective and non-defective sites based on their unique frequency signatures.
2Measurement precision
If conventional TIVA analysis is used, then optical transmission detection is improved, but diagnostic accuracy for defect identification deteriorates
Solution Approach 1:
The patent performs preliminary action by collecting extended time-series voltage data before analysis. By gathering multiple voltage measurements over time at each scanned location and storing them for subsequent Fourier transformation, the system prepares comprehensive raw data that contains hidden frequency information not visible in single-point measurements, enabling more accurate defect characterization.
Solution Approach 2:
The patent introduces the Fourier transform as an intermediary processing step between raw voltage measurement and defect identification. This mathematical transformation acts as a mediator that converts time-domain signals into frequency-domain representations, revealing characteristic frequency patterns that serve as intermediaries for identifying and characterizing different types of defects.
3Measurement precision
If laser scanning is used to heat IC die surface, then thermal response measurement is improved, but the ability to differentiate defect noise signatures deteriorates
Solution Approach 1:
The patent applies dynamics by analyzing the temporal evolution of voltage responses rather than static measurements. By scanning the laser across the die surface and recording voltage changes over time at each position, then performing frequency analysis on these time-series signals, the system captures the dynamic thermal behavior and noise characteristics that are unique to different defect types, enabling signature differentiation.
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
Effectively identifies defect regions by plotting noise amplitude versus frequency, allowing for non-destructive differentiation of defects from non-defects, reducing the reliance on physical analysis and improving diagnostic accuracy.
Implementation Method 1
The IC die surface is scanned with a laser. The laser beam irradiated locations on the IC die surface are tracked. The laser scanning heats active electrical elements underlying the scanned IC die surface.
Implementation Method 2
The laser scanning heats active electrical elements underlying the scanned IC die surface
Implementation Method 3
A frequency response of an IC die electrical interface is measured and correlated to irradiated locations. IC die defect regions are determined in response to identifying location-correlated frequency measurements exceeding a noise threshold.
Data Source
AI summary
A system and method are provided for testing an integrated circuit (IC) using thermally induced noise analysis. The method provides an IC die and supplies electrical power to the IC die. The IC die surface is scanned with a laser, and the laser beam irradiated locations on the IC die surface are tracked. The laser scanning heats active electrical elements underlying the scanned IC die surface. A frequency response of an IC die electrical interface is measured and correlated to irradiated locations. IC die defect regions are determined in response to identifying location-correlated frequency measurements exceeding a noise threshold. For example, a frequency measurement may be correlated to a die surface location, and if frequency measurement exceeds the noise threshold, then circuitry underlying that surface area may be identified as defective. Typically, die defect regions are associated with measurements in the frequency range between about 1 Hertz and 10 kilohertz.