Charged Particle Beam Inspection Phase Contrast
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Solution Overview
Problem
Existing substrate inspection methods using charged particle beams face challenges in obtaining clear images of concave and convex shapes due to low material and potential contrast, and reduced sensitivity to electromagnetic fields, especially when back scattering electrons are used to mitigate electromagnetic field influences.
Innovation Solution
A method involving the generation of a primary charged particle beam, condensation of secondary or transmitted charged particle beams with phase differences, and imaging these beams to detect defects based on phase differences, using a reference target for enhanced coherency and contrast, particularly through electron beam splitting and superposition techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If back scattering electrons are used to reduce electromagnetic field influence, then electromagnetic field interference is reduced, but inspection sensitivity regarding the electromagnetic field itself is significantly lowered
Solution Approach 1:
The patent segments the charged particle beam into multiple beams with different incident angles. By using multiple beams rather than a single back-scattering beam, the system can reduce electromagnetic field interference from specific angles while maintaining sensitivity through complementary information from other angles. The segmented beam approach allows selective mitigation of interference while preserving inspection capability.
Solution Approach 2:
The patent employs a composite inspection approach by combining signals from multiple charged particle beams with different incident angles. This composite signal processing allows the system to overcome the limitations of individual beams - using back-scattering electrons to reduce electromagnetic field interference while incorporating other beam types to maintain inspection sensitivity, creating a composite inspection result that benefits from both approaches.
2Measurement precision
If secondary beams from edge portions are used for imaging, then material contrast is enhanced, but information regarding concave and convex shapes is lost
Solution Approach 1:
The patent introduces a new dimension by varying the incident angles of charged particle beams across multiple angles rather than using a single normal incidence. This angular dimension allows the system to capture surface shape information (concave and convex features) that is lost in conventional normal-incidence imaging, while still obtaining material contrast through multi-angle signal composition.
Solution Approach 2:
The patent changes the incident angle parameter of the charged particle beam from a fixed normal incidence to multiple varying angles. By sweeping through different incident angles, the system can detect surface topography variations (concave and convex shapes) that are invisible at normal incidence, while maintaining material contrast through the composite signal from multiple angles.
3Measurement precision
If conventional charged particle beam inspection is used, then electromagnetic field influence is detected, but surface potential contrast is not imaged on the detector
Solution Approach 1:
The patent uses the charged particle beam as an intermediary that interacts with both electromagnetic fields and surface potentials. By analyzing the beam's interaction products (secondary electrons, back-scattering electrons) at multiple incident angles, the system can simultaneously detect electromagnetic field influences and surface potential contrasts that would otherwise be invisible to conventional single-angle inspection methods.
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 improves defect detection sensitivity and clarity by generating phase differences that highlight fine surface features and electromagnetic field influences, enabling more accurate inspection of semiconductor substrates with enhanced material and potential contrast.
Implementation Method 1
condensing a first secondary charged particle beam including at least one of secondary charged particles, reflected charged particles and back scattering charged particles which have been generated from the substrate
Implementation Method 2
a phase difference being generated in the secondary charged particle beam or in the transmitted charged particle beam in accordance with a structure of the inspection target
Data Source
AI summary
A substrate inspection method includes: generating primary charged particle beams; applying the generated primary charged particle beams to an inspection target of a substrate; condensing first secondary charged particle beams including at least one of secondary charged particles, reflected charged particles, and back scattering charged particles which have been generated from the substrate, or first transmitted charged particle beams which have transmitted the inspection target, a phase difference being generated between the secondary charged particle beams or between the transmitted charged particle beams in accordance with a structure of the inspection target; imaging the secondary charged particle beams or the transmitted charged particle beams; detecting the imaged secondary charged particle beams or transmitted charged particle beams and outputting a signal of a secondary charged particle beam image or a transmitted charged particle beam image including information on the phase difference; and detecting a defect in the inspection target by use of the information on the phase difference included in the secondary charged particle beam image or the transmitted charged particle beam image.