SEM Electron-Beam Fault Isolation Through Phase-Resolved Imaging
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Solution Overview
Problem
Existing nano-probing tools for fault isolation in semiconductor device fabrication face inefficiencies due to increased complexity and difficulty in accessing circuit nodes, leading to prolonged throughput times and challenges in interpreting AC signals, particularly in multi-cell probing scenarios.
Innovation Solution
Utilizing an electron beam from a scanning electron microscope (SEM) in conjunction with a lock-in amplifier and imaging digitizer to raster and demodulate electron emissions from a circuit, allowing for the generation of phase-resolved images without the need for physical probes on output pins, thereby reducing the number of physical probes required and improving signal interpretation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional nano-probing tools are used for fault isolation, then physical contact with circuit nodes can be achieved, but throughput time increases significantly due to the need to probe multiple nodes and inputs/outputs
Solution Approach 1:
The patent replaces the mechanical probing system with an electron beam-based imaging system. Instead of using physical probes to contact circuit nodes, the invention uses a scanning electron microscope (SEM) to image the circuit and detect voltage contrast at different nodes. This substitution eliminates the need for physical contact while maintaining the ability to measure circuit states, thereby dramatically reducing throughput time while preserving fault isolation accuracy.
Solution Approach 2:
The patent introduces an intermediary system consisting of the SEM electron beam and voltage contrast detection mechanism. Rather than directly probing circuit nodes with physical contacts, the electron beam serves as an intermediary that indirectly detects circuit states through voltage-dependent secondary electron emission. This intermediary approach enables non-contact measurement and parallel imaging of multiple nodes simultaneously.
2Measurement precision
If the number of probes is increased to access more circuit nodes, then measurement coverage improves, but device complexity and operation difficulty increase
Solution Approach 1:
The patent makes the SEM electron beam a multi-functional tool that simultaneously performs imaging and voltage contrast detection across multiple circuit nodes. A single electron beam can scan and image numerous nodes within the SEM field of view, replacing the need for multiple individual probes. This universal approach allows the system to maintain comprehensive measurement coverage while significantly reducing the number of physical probes required.
Solution Approach 2:
The patent transitions from one-dimensional point-by-point probing to two-dimensional parallel imaging. By utilizing the SEM's ability to image entire regions of the circuit simultaneously, the system can detect voltage contrast at multiple nodes across a two-dimensional field of view in a single scan, rather than sequentially probing each node individually. This dimensional change enables comprehensive coverage with reduced complexity.
3Loss of information
If AC signals are measured with traditional probing methods, then signal information can be obtained, but electromagnetic interference and jitter affect measurement accuracy
Solution Approach 1:
The patent replaces electrical probing that directly contacts circuit nodes with electron beam imaging that detects voltage contrast indirectly. This substitution eliminates the introduction of electromagnetic interference and jitter that occurs with physical probe contacts, particularly when measuring AC signals. The electron beam method provides signal information without the electromagnetic interference problems inherent in traditional electrical probing.
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 reduces throughput time and enhances the accuracy of fault isolation by enabling simultaneous imaging and signal demodulation, allowing for efficient detection of circuit conditions and reducing interference from electromagnetic jitter.
Implementation Method 1
The method includes rastering the circuit with an electron beam from a scanning electron microscope (SEM) and collecting a signal based on electron emissions from the circuit
Data Source
AI summary
Methods and apparatus for fault isolation with scanning electron microscope probing are disclosed. An example apparatus to test a circuit includes interface circuitry operatively coupled to an electron detector, the electron detector to output a signal corresponding to electron emissions from the circuit as the circuit is driven with a signal source and the circuit is rastered with an electron beam, machine readable instructions, and programmable circuitry to at least one of instantiate or execute the machine readable instructions to demodulate the signal, and generate an image based on the demodulated signal for determination of a condition of the circuit.