Differential EBAC Imaging for Fault Direction in Thin Sample Cutting
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Solution Overview
Problem
Existing fault analysis methods for semiconductor devices, such as superimposing EBAC and SEM images, fail to specify the direction of short-circuit faults, leading to improper cutting of fault spots during thin piece sample fabrication, resulting in lost information.
Innovation Solution
A charged particle beam apparatus that scans a sample with electron beams to measure differential potential differences between conductors, generating a DI-EBAC image to specify fault direction, and a thin piece sample fabrication apparatus that uses this information to cut the fault spot in the correct direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional EBAC imaging is used to locate fault spots, then fault position can be identified, but fault direction cannot be specified
Solution Approach 1:
The patent segments the fault detection process into two distinct imaging modes: conventional EBAC imaging for locating fault spots, and a new differential EBAC imaging mode for determining fault direction. By dividing the inspection function into separate operational modes, the system can first identify the fault position using established methods, then switch to differential mode to extract directional information without losing either type of data.
Solution Approach 2:
The patent introduces a new dimension of measurement by implementing differential EBAC imaging that captures potential difference changes in addition to the conventional current absorption data. This additional dimensional information enables the system to not only locate faults but also determine their directional orientation, transforming a one-dimensional position detection into a two-dimensional characterization including direction.
2Productivity
If fault spots are cut without direction information, then sample fabrication can proceed, but fault information may be lost
Solution Approach 1:
The patent performs preliminary action by acquiring differential EBAC images and determining fault direction information before the actual sample cutting operation. This advance preparation ensures that when the FIB or FIB-SEM apparatus cuts the fault spot, the directional information is already available to guide the cutting process, preventing information loss while maintaining fabrication efficiency.
3Device complexity
If only current absorption is measured, then simple imaging is achieved, but directional fault characteristics are missed
Solution Approach 1:
The patent implements dynamics by making the imaging system adaptable through different operational modes. The system can dynamically switch between conventional EBAC imaging mode for simple location identification and differential EBAC imaging mode for detailed directional characterization. This dynamic capability allows the system to adjust its measurement approach based on the specific inspection requirements, maintaining simplicity when sufficient while providing enhanced precision when needed.
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
Enables accurate specification of fault direction, preventing loss of information during sample cutting and ensuring precise fabrication of thin piece samples.
Implementation Method 1
a detector for detecting secondary electrons generated from the sample when the sample is irradiated with the electron beam
Implementation Method 2
A distribution image of a signal (absorbed current signal) obtained based on the current (absorbed current) absorbed by the wiring is called an electron beam absorbed current (EBAC) image
Data Source
AI summary
A sample inspection apparatus is provided. The invention is directed to a sample inspection apparatus 200 that includes an inspection means that is executed when a sample 11 is placed on a stage 8, the inspection means including the steps of (a) scanning a surface of the sample 11 with an electron beam EB1 with a probe 10a in contact with a conductor 11a and a probe 10b in contact with a conductor 11b, (b) measuring a differential value of a change in potential difference between the probes 10a and 10b while synchronizing with the scanning of the electron beam EB1, (c) acquiring a DI-EBAC image in which a fault spot 12 existing between the conductors 11a and 11b is shown as a bright part and a dark part based on the differential value of the change in the potential difference, and (d) specifying a direction of the fault spot 12 from the DI-EBAC image.