Electron Beam Inspection for Semiconductor Defect Detection
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Solution Overview
Problem
Conventional inspection methods using electron beams are unreliable for detecting defects in small semiconductor patterns due to the small amounts of secondary electrons generated, making it difficult to distinguish between patterns with and without defects.
Innovation Solution
A method involving repetitive detection operations to accumulate secondary electron amounts from a pattern with defects, where the electron beam is irradiated, interrupted, and the secondary electron amount is detected after a reference electron-decay time has elapsed, allowing for more reliable identification of defects by maximizing the secondary electron accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electron beam inspection methods are used on small semiconductor patterns, then the inspection process is simple and fast, but the detection reliability is poor due to small amounts of secondary electrons generated
Solution Approach 1:
The patent applies periodic action by repeatedly irradiating the electron beam to the same pattern multiple times and accumulating secondary electron amounts. The inspection process performs detection operations N times on the same detection target pattern, with each operation contributing to the accumulated secondary electron signal. This repetitive periodic irradiation and detection allows small secondary electron amounts from defective patterns to accumulate to detectable levels, while non-defective patterns maintain lower accumulated amounts, thereby improving defect detection reliability without requiring faster inspection speeds
Solution Approach 2:
The patent implements preliminary action by introducing a detection waiting time period after interrupting the electron beam before detecting the secondary electron amount. This waiting time allows excess secondary electrons to decay and be removed, ensuring that the detected secondary electron amount primarily reflects the accumulated signal from the current and previous irradiations rather than residual electrons. This preliminary decay period enhances the accuracy of defect detection by removing background noise
2Measurement precision
If the electron beam is continuously irradiated to maximize secondary electron accumulation, then defect detection accuracy improves, but the inspection time increases
Solution Approach 1:
The patent resolves this contradiction by using periodic action with a specific cycle: irradiate the electron beam for a fixed irradiation time, interrupt the beam, wait for a detection waiting time period, then detect the secondary electron amount. This cycle is repeated N times on the same pattern. The periodic irradiation allows secondary electrons to accumulate progressively with each cycle, improving measurement accuracy for defective patterns, while the finite number of cycles and controlled timing prevent excessive inspection time
Solution Approach 2:
The patent applies preliminary action by implementing a detection waiting time period after each electron beam interruption before performing detection. This waiting time allows excess secondary electrons to naturally decay and be removed from the pattern surface. By performing this preliminary decay action before each measurement, the system ensures that the detected secondary electron amount reflects the accumulated signal from the irradiation cycles rather than excess residual electrons, thereby improving measurement accuracy without requiring continuous or excessively long irradiation
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 reliability of defect identification in small semiconductor patterns by accumulating and distinguishing secondary electron amounts, improving the accuracy of defect detection.
Implementation Method 1
irradiating an electron beam to the detection target pattern, interrupting the electron beam and detecting a secondary electron amount of the detection target pattern
Data Source
AI summary
Methods and apparatuses for inspecting a semiconductor device using electron beam are provided. The methods may include performing detection operations on a detection target pattern N times and determining a number of detection operations which have been performed until a maximum secondary electron amount of the detection target pattern is obtained. Each of the detection operations may include irradiating the detection target pattern with an electron beam, interrupting the irradiating and detecting a secondary electron amount of the detection target pattern after a detection waiting time has elapsed since the interrupting the irradiating.