Multi-Channel Scatterometry for Magnetic Media Defect Classification
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Solution Overview
Problem
Existing methods for inspecting magnetic storage media surfaces fail to effectively differentiate between flat particles, shallow dips, and pits, as well as spherical and non-spherical particles, which impairs the functionality of the media.
Innovation Solution
A system that directs radiation at two different angles of incidence, using a combination of specular and scattered radiation signals to differentiate between surface defects, including shallow bumps or dips, by employing a scatterometer with dual peak wavelengths and a micro-roughness blind scatterometer channel, allowing for the classification of defects such as pits, particles, and flat particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single radiation beam and collecting assembly is used, then the inspection system is simpler, but it cannot differentiate between flat particles, shallow dips, and pits
Solution Approach 1:
The inspection system is segmented into multiple independent collecting assemblies (first, second, third, and fourth collecting assemblies), each configured to collect scattered radiation at different angles or with different optical properties. This segmentation allows each assembly to capture specific defect characteristics, enabling differentiation between flat particles, shallow dips, and pits while maintaining modular system architecture
Solution Approach 2:
The system introduces an additional dimension of measurement by using multiple collecting assemblies that detect scattered radiation at different angles or with different polarizations. This multi-dimensional approach transforms the inspection from single-parameter detection to multi-parameter analysis, enabling precise defect classification without proportionally increasing system complexity
2Measurement precision
If radiation is directed at a single angle of incidence, then the inspection process is faster, but it cannot discriminate between different types of surface defects
Solution Approach 1:
Multiple radiation beams are directed at the substrate simultaneously at different angles of incidence, rather than sequentially. This preliminary action of setting up multiple detection paths enables parallel defect analysis, maintaining high inspection speed while achieving accurate defect classification through multi-angle scattered radiation analysis
Solution Approach 2:
The system maintains continuous inspection capability by using multiple collecting assemblies that operate simultaneously. Each assembly continuously monitors scattered radiation from its specific detection angle, ensuring uninterrupted defect detection and classification without requiring sequential measurements that would reduce productivity
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 the simultaneous detection and classification of surface defects, including shallow features, with improved accuracy, even at dimensions less than half a micron, by analyzing scatter amplitude ratios and polarization changes, thereby enhancing the reliability of magnetic storage media inspection.
Implementation Method 1
a first collecting assembly collects first radiation specularly reflected from the substrate
Implementation Method 2
a second collecting assembly collects first radiation scattered from the surface of the substrate by defects
Implementation Method 3
a third collecting assembly collects first radiation scattered from the surface of the substrate by defects and micro-roughness
Implementation Method 4
A fourth collecting assembly collects second radiation scattered from the substrate and produces fourth signals
Data Source
AI summary
A system to detect and classify defects on a surface of a substrate. A first targeting assembly directs radiation in a first beam onto the substrate. A first collecting assembly collects first radiation specularly reflected from the substrate and produces first signals, a second collecting assembly collects first radiation scattered from the surface of the substrate by defects and not micro-roughness and produces second signals, and a third collecting assembly collects first radiation scattered from the surface of the substrate by defects and micro-roughness and produces third signals. A second targeting assembly directs radiation in a second beam onto the substrate. A fourth collecting assembly collects second radiation scattered from the substrate and produces fourth signals. A processor receives the first, second, third, and fourth signals. A module coupled to the processor has logic instructions stored in a computer-readable medium, which configure the processor to analyze the signals to detect and classify the defects on the substrate.