Semiconductor Sample Inspection via Absorbed Electron Current Imaging
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Solution Overview
Problem
Existing techniques for analyzing faulty points in semiconductor samples, particularly those with low resistance or complex wiring, struggle to clearly differentiate faulty points from normal points in absorbed electron current images, and there is a risk of electric discharge damage during inspection.
Innovation Solution
The method involves obtaining multiple absorbed electron current images under varying conditions such as temperature changes, optical condition alterations, and probe position adjustments, and then using weighted addition or subtraction to enhance contrast, along with three-dimensional image reconstruction to intuitively display faulty points, while automatically adjusting electro-optical conditions to prevent electric discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If probes are brought into contact with the sample to measure absorbed electron current, then faulty points can be detected, but electric discharge may occur between the probe and sample causing damage
Solution Approach 1:
The patent applies preliminary action by adjusting the electro-optical conditions of the electron beam before probe contact to prevent electric discharge. The control unit adjusts beam parameters in advance to ensure safe operating conditions when probes contact the charged sample surface, thereby preventing harmful discharge while enabling faulty point detection
2Ease of operation
If absorbed electron current images are obtained under fixed conditions, then measurement is simple, but faulty points with low resistance or in complex wiring are difficult to identify
Solution Approach 1:
The patent applies parameter changes by varying electro-optical conditions (acceleration voltage, beam current, focus) to obtain multiple absorbed electron current images under different conditions. This enables faulty points with low resistance or in complex wiring to be identified by comparing brightness changes across different imaging conditions, thereby improving measurement precision while maintaining operational simplicity through automated control
3Measurement precision
If multiple images are obtained to improve faulty point identification, then identification accuracy improves, but inspection time increases
Solution Approach 1:
The patent efficiently obtains multiple images under varied electro-optical conditions by systematically changing parameters such as acceleration voltage and beam current. The control unit automates this process to capture essential fault information across different conditions without excessive time consumption, balancing identification accuracy with inspection efficiency
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 allows for easier identification of faulty points by emphasizing brightness changes and providing intuitive three-dimensional displays, reducing the risk of electric discharge damage during the inspection process.
Implementation Method 1
scan the wiring pattern on the semiconductor sample with an electron beam and measure/image a current flowing through the probes
Implementation Method 2
the surface of a semiconductor sample is irradiated with an electron beam and a current absorbed from the wiring or a secondary signal emitted from the semiconductor sample is analyzed/imaged
Data Source
AI summary
A sample inspection apparatus in which a fault in a semiconductor sample can be measured and analyzed efficiently. A plurality of probes are brought into contact with the sample. The sample is irradiated with an electron beam while a current flowing through the probes is measured. Signals from at least two probes are supplied to an image processing unit so as to form an absorbed electron current image. A difference between images obtained in accordance with a temperature change of the sample is obtained. A faulty point is identified from the difference between the images.