Multi-Wavelength Pattern Inspection for High-Aspect-Ratio Defects
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Solution Overview
Problem
Conventional pattern inspection apparatuses fail to accurately detect defects in high-aspect-ratio microstructures due to insufficient signal intensity and decreased signal-to-noise ratio, particularly in trench patterns where defects are located at varying depths, leading to defect detection failures and difficulty in determining defect height.
Innovation Solution
A pattern inspection method and apparatus that applies light of multiple wavelengths to a substrate, detects reflected light, and generates three-dimensional image data combining wavelength and signal intensity information, allowing for defect detection and height determination by comparing pixel data with a reference table, thereby enhancing defect detection accuracy and signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-wavelength optical inspection is used, then the inspection process is simple, but defect detection accuracy decreases for high-aspect-ratio structures
Solution Approach 1:
The patent changes the wavelength parameter of illumination light to resolve the contradiction. By illuminating the inspection target with multiple wavelengths of light and detecting reflected light at each wavelength, the system achieves high defect detection accuracy for high-aspect-ratio structures without requiring complex additional hardware beyond standard optical components.
Solution Approach 2:
The patent adds the wavelength dimension to the inspection process. Instead of using only spatial detection (x, y coordinates), the system incorporates spectral information (wavelength) as an additional dimension, creating three-dimensional image data that enhances defect detection capability while maintaining system simplicity.
2Reliability
If single-wavelength light is applied, then the signal processing is straightforward, but the signal-to-noise ratio decreases for deep defects
Solution Approach 1:
The patent changes the wavelength parameter to improve signal-to-noise ratio. By applying multiple wavelengths of light and detecting reflected light at each wavelength, the system enhances the reliability of defect detection for deep defects in high-aspect-ratio structures, as different wavelengths provide complementary information that improves signal discrimination.
3Measurement precision
If conventional inspection methods are used, then the inspection speed is maintained, but defect height determination is not possible
Solution Approach 1:
The patent adds the wavelength dimension to enable defect height determination. By creating three-dimensional image data that combines spatial coordinates (x, y) with wavelength information (z), the system can determine defect height without sacrificing inspection speed, as the additional information is obtained through spectral analysis rather than additional physical measurements.
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
The method effectively inhibits defect detection failures and improves the signal-to-noise ratio independent of defect depth, enabling accurate detection of defects and their heights in high-aspect-ratio microstructures.
Implementation Method 1
applying light generated from a light source to the same region of a substrate in which an inspection target pattern is formed; guiding, imaging and then detecting a reflected light from the substrate
Data Source
AI summary
In accordance with an embodiment, a pattern inspection method includes: applying a light generated from a light source to the same region of a substrate in which an inspection target pattern is formed; guiding, imaging and then detecting a reflected light from the substrate, and acquiring a detection signal for each of a plurality of different wavelengths; and adding the detection signals of the different wavelengths in association with an incident position of an imaging surface to generate added image data including information on a wavelength and signal intensity, judging, by the added image data, whether the inspection target pattern has any defect, and when judging that the inspection target pattern has a defect, detecting the position of the defect in a direction perpendicular to the substrate.