Spherical Sector Ion Extraction System for Mass Spectrometry

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Solution Overview

Problem

Existing ion extraction systems in secondary ion mass spectrometry (SIMS) face challenges in minimizing the deflection and aberration effects on primary ion beams, which degrade the lateral resolution and efficiency of secondary ion collection, particularly due to the extraction field's impact on the primary beam's position and angle.

Innovation Solution

A charged particle beam deflecting system comprising inner and outer spherical sectors, an intermediate electrode, and side plates, which creates a deflecting gap and electrostatic fields to deflect charged particles by a given angle, reducing the focussing effect and achieving a substantially parallel secondary ion beam exit, while minimizing aberrations on the primary beam.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If an extraction field is applied to collect secondary ions, then the collection efficiency of secondary ions is improved, but the primary ion beam is deflected and aberrations are introduced, degrading lateral resolution

Engineering Contradiction:

Improvecollection efficiency of secondary ionsVSAvoidlateral resolution

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

A retarding field is introduced as an intermediary between the extraction field and the primary ion beam. This retarding field acts as a mediator that allows the extraction field to collect secondary ions while preventing the primary beam from experiencing harmful deflection and aberrations. The retarding field creates a potential barrier that selectively affects secondary ions while protecting the primary beam.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The extraction system employs locally optimized electric field distributions through specifically designed electrode geometries and potential distributions. Different regions of the extraction field have different characteristics: near the sample surface, the field is optimized for secondary ion collection, while in regions where the primary beam passes, the field is shaped to minimize aberrations. This local optimization allows simultaneous achievement of high collection efficiency and high lateral resolution.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If the extraction field strength is increased to improve secondary ion collection, then the transmission of secondary ions is improved, but the deflection of the primary beam increases, worsening the spot size

Engineering Contradiction:

Improvetransmission of secondary ionsVSAvoiddeflection of primary beam

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The retarding field serves as a protective intermediary that decouples the relationship between extraction field strength and primary beam deflection. By introducing this intermediate field, the system can increase extraction field strength to improve secondary ion transmission without proportionally increasing primary beam deflection, as the retarding field buffers the interaction between the extraction field and primary beam.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system optimizes multiple electric field parameters simultaneously, including the retarding field strength, extraction field distribution, and electrode potentials. By carefully adjusting these parameters, the system achieves high secondary ion transmission while keeping primary beam deflection within acceptable limits. The parameter optimization includes tuning the retarding potential to balance extraction efficiency with beam quality preservation.

Inventive Principle:

Principle #35Parameter changes

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 system enhances the quality and transmission of secondary ions, allowing for high lateral resolution analysis and efficient transport into subsequent optics, with the primary beam deflection kept below 10 μm and spot sizes as small as 10 nm, even at varying voltages up to 4000 V.

Implementation Method 1

the spherical sectors being biased at deflecting potentials in order to deflect the charged particle beam entering the deflecting gap by a given angle

Methodology Applied

Scientific EffectElectrostatic field: Electric Field

Implementation Method 2

the side plates being biased in order to create an electrostatic field perpendicular to the exit axis

Methodology Applied

Scientific EffectElectrostatic field: Electric Field

Data Source

PatentUS10770278B2Extraction system for charged secondary particles for use in a mass spectrometer or other charged particle device

Publication Date: 2020.09.08 LUXEMBOURG INSTITUTE OF SCIENCE AND TECHNOLOGY (LIST)

AI summary

The invention is directed to mass spectrometer comprising an extraction system for secondary ions. The system comprises: an inner spherical deflecting sector; an outer spherical deflecting sector; a deflecting gap formed between the sectors; a housing in which the sectors are arranged. The deflecting sectors are biased at retarding potentials in order to reduce the energy of the ion beam entering the deflecting gap. The system further comprises an exit disc electrode which is biased at the midvoltage of the average voltage of the sectors, and two side plates both facing the spherical sectors, the side plates being biased in order to create an electrostatic field perpendicular to the exit axis.