Scanning Probe Microscope Cantilever Contact Detection

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Solution Overview

Problem

Conventional scanning probe microscopes face issues with wear and deformation when measuring inclined surfaces due to varying pressing forces required for contact detection, as they rely solely on bending measurements, which can lead to excessive force application and damage.

Innovation Solution

A scanning probe microscope system that utilizes both bending and torsion measurements of a cantilever to determine contact with a sample surface, allowing for reduced force variation by considering all deformation directions, thereby minimizing wear and deformation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If only bending measurement is used to detect probe-sample contact, then the detection method is simple, but the pressing force varies significantly on inclined surfaces causing probe wear and sample deformation

Engineering Contradiction:

Improvedetection method complexityVSAvoidcontact detection accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent transitions from one-dimensional bending measurement to two-dimensional deformation measurement by incorporating both bending and torsion detection. This dimensional expansion allows the system to capture the full deformation state of the cantilever, enabling accurate contact detection on inclined surfaces without excessive pressing force.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent changes the detection parameters from solely bending deflection to include both bending and torsion components. By monitoring multiple deformation parameters simultaneously, the system can distinguish between contact-induced deformation and inclination-induced deformation, thereby maintaining consistent pressing force across different surface orientations.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If greater pressing force is applied to ensure contact detection on inclined planes, then contact detection reliability improves, but probe wear and sample deformation increase

Engineering Contradiction:

Improvecontact detection reliabilityVSAvoidprobe wear and sample deformation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs feedback control by continuously monitoring both bending and torsion signals and adjusting the pressing force accordingly. When contact is detected through the characteristic change in the ratio between bending and torsion signals, the system modulates the applied force to maintain optimal contact without excessive pressure, thereby preventing probe wear and sample damage.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces dynamic adjustment of pressing force based on real-time deformation measurements. By making the pressing force adaptive rather than static, the system can respond to varying surface conditions and maintain appropriate contact levels, reducing harmful effects while ensuring reliable detection.

Inventive Principle:

Principle #15Dynamics

3Duration of action of moving object

If intermittent measurement method is used to reduce contact time, then probe wear and sample damage are reduced, but measurement precision decreases on inclined surfaces

Engineering Contradiction:

Improvecontact durationVSAvoidshape measurement precision

Core Design Contradiction:

Duration of action of moving objectVSMeasurement precision

Solution Approach 1:

The patent performs preliminary detection of contact state using both bending and torsion signals before conducting the actual height measurement. This preliminary action allows the system to identify inclined surfaces and adjust measurement parameters in advance, ensuring high precision even with brief contact periods characteristic of intermittent measurement.

Inventive Principle:

Principle #10Preliminary action

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 enables accurate contact detection on inclined surfaces with reduced force variation, minimizing probe wear and sample deformation, and improving measurement precision.

Implementation Method 1

detect both a bending amount and a torsion amount of the cantilever

Methodology Applied

Scientific EffectBending: Deformation

Implementation Method 2

detect both a bending amount and a torsion amount of the cantilever

Methodology Applied

Scientific EffectTorsion: Deformation

Data Source

PatentUS10151773B2Scanning probe microscope and probe contact detection method

Publication Date: 2018.12.11 HITACHI HIGH TECH ANALYSIS CORP

AI summary

According to this invention, a scanning probe microscope for scanning a surface of a sample with a probe by bringing the probe into contact with the surface of the sample, comprises a cantilever having the probe at its tip; a displacement detection unit to detect both a bending amount and a torsion amount of the cantilever; and a contact determination unit to determine a primary contact of the probe with the surface of the sample, based on the bending amount and the torsion amount detected by the displacement detection unit in all directions from an undeformed condition of the cantilever.