Multi-Beam Charged Particle Inspection Tool
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Solution Overview
Problem
Current charged particle beam inspection tools for semiconductor IC chip manufacturing face challenges in throughput and defect detection efficiency due to limitations in pattern defect monitoring and high operator intervention requirements, leading to reduced yield and increased costs.
Innovation Solution
A charged particle assessment tool utilizing a condenser lens array to divide a beam of charged particles into sub-beams, focused to intermediate foci, and projected onto a sample using objective lenses, with field curvature correctors to reduce aberrations, allowing for simultaneous inspection of multiple areas and improved defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single charged particle beam is used for inspection, then the inspection system is simpler, but the inspection throughput is lower
Solution Approach 1:
The patent divides a single charged particle beam into multiple sub-beams using a beam splitting element, creating a multi-beam system that can simultaneously inspect multiple areas of the sample. This segmentation of the beam enables parallel inspection, significantly increasing throughput while maintaining a relatively compact system architecture
Solution Approach 2:
The patent combines multiple sub-beams with corresponding objective lenses to simultaneously focus on different regions of the sample. By merging the functionality of multiple single-beam inspection systems into one unified multi-beam apparatus, the system achieves high throughput inspection without proportionally increasing overall system complexity
2Productivity
If multiple objective lenses are used to increase inspection area, then the throughput is improved, but the field curvature aberration increases
Solution Approach 1:
The patent introduces a field curvature corrector as an intermediary optical element between the objective lenses and the sample plane. This corrector specifically addresses the field curvature aberration introduced by multiple objective lenses, restoring image quality across the extended inspection area and enabling high-throughput parallel inspection without sacrificing manufacturing precision
Solution Approach 2:
The patent modifies the optical parameters of the inspection system by adding field curvature correctors that adjust the curvature of the focal plane. By changing these optical parameters, the system maintains sharp focus across multiple inspection areas simultaneously, resolving the trade-off between throughput and image quality
3Measurement precision
If chromatic aberration is not compensated, then the system is simpler, but the inspection accuracy is reduced
Solution Approach 1:
The patent exploits the chromatic aberration characteristics of the condenser lens array and objective lenses to achieve mutual compensation. By carefully designing the optical system so that the chromatic aberrations of different components have opposite signs, the system converts what would normally be harmful aberrations into a beneficial self-correcting mechanism, improving defect detection accuracy without adding complex active compensation systems
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 inspection throughput and accuracy by enabling the simultaneous scanning of multiple areas with reduced aberrations, thereby improving the yield and reducing the need for operator intervention, leading to increased efficiency and cost-effectiveness in semiconductor manufacturing.
Implementation Method 1
a condenser lens array configured to divide a beam of charged particles into a plurality of sub-beams and to focus each of the sub-beams to a respective intermediate focus
Implementation Method 2
a plurality of objective lenses downstream from the intermediate foci, each objective lens being configured to project a sub-beam from a corresponding condenser lens in the condenser lens array onto a sample
Data Source
AI summary
Charged particle assessment tools and inspection methods are disclosed. In one arrangement, a condenser lens array divides a beam of charged particles into a plurality of sub-beams. Each sub-beam is focused to a respective intermediate focus. Objective lenses downstream from the intermediate foci project sub-beams from the condenser lens array onto a sample. A path of each sub-beam is substantially a straight line from each condenser lens to a corresponding objective lens.