Multi-axis Magnetic Lens for Charged Particle Beam Inspection
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Solution Overview
Problem
Current semiconductor manufacturing processes require separate tools for defect/particle inspection and review, leading to reduced throughput and increased costs due to the need for transferring wafers/masks between different tools, and existing multi-axis magnetic lenses suffer from geometric aberrations caused by high-order harmonics.
Innovation Solution
A multi-function apparatus using a multi-axis magnetic lens with magnetic sub-lenses and radial gaps to reduce high-order harmonics, allowing for simultaneous high-throughput inspection and high-resolution review of specimen surfaces, incorporating multiple sub-columns with adjustable magnetic objective lenses for different functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate tools are used for defect/particle inspection and review, then each tool can be optimized for its specific function, but the throughput is reduced and costs increase due to wafer/mask transfers between tools
Solution Approach 1:
The patent combines defect/particle inspection and review functions into a single apparatus with multiple sub-columns, eliminating the need for wafer/mask transfers between separate tools. The multi-axis magnetic lens enables multiple beams to share common components, achieving both high throughput and high resolution in one integrated system.
Solution Approach 2:
The apparatus performs multiple functions (inspection and review) simultaneously using a multi-axis magnetic lens that can focus multiple charged particle beams. Each sub-column is configured for different functions, allowing the single apparatus to handle both high-throughput inspection and high-resolution review without transferring wafers/masks.
2Adaptability or versatility
If multiple single-axis magnetic objective lenses are placed in one apparatus, then each tool can perform its specific function, but the spatial interval between tools must be large enough to physically accommodate the lenses
Solution Approach 1:
The patent merges multiple single-axis magnetic objective lenses into a single multi-axis magnetic lens that can focus multiple charged particle beams simultaneously. This shared lens structure eliminates the need for large spatial intervals between separate lenses, reducing the apparatus footprint while maintaining multi-function capability.
Solution Approach 2:
The multi-axis magnetic lens serves multiple functions by focusing multiple beams for different operations (inspection and review). This universal lens replaces multiple specialized lenses, reducing the spatial requirements while enabling diverse functionalities within a compact configuration.
3Productivity
If a multi-axis magnetic lens is used to reduce spatial interval, then the number of available tools is doubled, but geometric aberrations occur due to high-order harmonics in the magnetic field
Solution Approach 1:
The patent extracts and eliminates high-order harmonics from the magnetic field using specifically designed magnetic pole pieces and shielding structures. By removing these harmful harmonic components, the multi-axis magnetic lens maintains imaging quality while enabling multiple tools in a compact configuration.
Solution Approach 2:
The patent converts the potentially harmful high-order harmonics into a benefit by using them to generate the necessary magnetic field distribution for multi-beam focusing, while simultaneously employing pole piece designs that minimize aberrations. The harmonic fields that would normally cause distortion are harnessed to create the complex multi-axis field pattern needed for multiple beams.
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 apparatus significantly increases throughput and reduces costs by performing multiple functions in a single apparatus, while minimizing geometric aberrations through the use of radial gaps and adjustable magnetic fields, enabling efficient defect/particle inspection and review in semiconductor manufacturing.
Implementation Method 1
a multi-axis magnetic objective lens which forms multiple magnetic objective sub-lenses
Implementation Method 2
an apparatus of charged particle beam, which can perform multi-functions
Implementation Method 3
a common excitation coil which provides a common magnetic flux
Implementation Method 4
radial gaps and forming magnetic circuit gaps therebetween
Data Source
AI summary
An apparatus of plural charged particle beams with multi-axis magnetic lens is provided to perform multi-functions of observing a specimen surface, such as high-throughput inspection and high-resolution review of interested features thereof and charge-up control for enhancing image contrast and image resolution. In the apparatus, two or more sub-columns are formed and each of the sub-columns performs one of the multi-functions. Basically the sub-columns take normal illumination to get high image resolutions, but one or more may take oblique illuminations to get high image contrasts.