Evaluation of Intermittent Contact Mode AFM Probes by HREM and Using Atomically Sharp CeO 2 Ridges as Tip Characterizer (original) (raw)
Related papers
2013
Wear is one of the main factors that hinders the performance of probes for atomic force microscopy (AFM), including for the widely-used amplitude modulation (AM-AFM) mode. Unfortunately, a comprehensive scientific understanding of nanoscale wear is lacking. We initially investigate and discuss the mechanics of the tip-sample interaction in AM-AFM. Starting from existing analytical formulations, we introduce a method for conveniently choosing an appropriate probe and free oscillation amplitude that avoids exceeding a critical contact stress to minimize tip/sample damage. We then introduce a protocol for conducting consistent and quantitative AM-AFM wear experiments. The protocol involves determining the tip-sample contact geometry, calculating the peak repulsive force and normal stress over the course of the wear test, and quantifying the wear volume using high-resolution transmission electron microscopy (TEM) imaging. The peak repulsive tip-sample interaction force is estimated from a closed-form equation accompanied by an effective tip radius measurement procedure, which combines TEM and blind tip reconstruction. The contact stress is estimated by applying Derjaguin-Müller-Toporov contact mechanics model and also numerically solving a general contact mechanics model recently developed for the adhesive contact of arbitrary axisymmetric punch shapes. We discuss the important role that the assumed tip shape geometry plays in calculating both the interaction forces and the contact stresses. We find that contact stresses are significantly affected by the tip geometry, while the peak repulsive force is mainly determined by experimentally-controlled parameters, most critically, the free oscillation amplitude. The applicability of this protocol is demonstrated experimentally by assessing the performance of diamond-like carbon-coated and silicon nitride-coated silicon probes scanned over ultrananocrystalline diamond substrates in repulsive-mode AM-AFM. There is no sign of fracture or plastic deformation in the case of diamond-like carbon (DLC); wear could be characterized as a gradual atom-by-atom process. In contrast, silicon nitride wears through apparent removal of the cluster of atoms and plastic deformation. DLC's gradual wear mechanism can be described using reaction rate theory, which predicts an exponential dependence of the rate of atom removal on the contact average normal stress, allowing us to estimate kinetic parameters governing the wear process.
Atomic force microscopy and direct surface force measurements (IUPAC Technical Report
Pure and Applied Chemistry, 2005
Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the need for formal IUPAC permission on condition that an acknowledgment, with full reference to the source, along with use of the copyright symbol ©, the name IUPAC, and the year of publication, are prominently visible. Publication of a translation into another language is subject to the additional condition of prior approval from the relevant IUPAC National Adhering Organization.
Thin Solid Films, 1996
Using a recently developed atomic force microscopy (AFM) simulator ACCESS (AFM simulation Code for Calculating and Evaluating Surface Structures), effects of tip apex size on AFM images were examined. A metal tip-metal sample system consisting of iron tip and copper sample was employed as 3 model system. Structures with half the surface periodicity, which have been observed in actual AFM measurements, were observed atcertain tip apex registries. Conditions for their appearances were examined,
A Simple and Effective Method of Evaluating Atomic Force Microscopy Tip Performance
Langmuir, 2001
The morphology of a surface imaged by dynamic force mode atomic force microscopy is obtained through an interaction between the probe tip and surface features. When the tip is contaminated and the size of the contaminant is comparable to the size of the features on the sample surface, artifacts attributable to the contaminant are observed to dominate the image. To reduce the possibility of effects from such artifacts, the tip performance should be checked by scanning a reference sample of known surface morphology. We demonstrate a simple and effective method of evaluating tip performance by the imaging of a commercially available biaxially oriented polypropylene (BOPP) film, which contains nanometer-scale-sized fibers. This sample is appropriate for use as a reference because a contaminated tip will not detect the fiberlike network structure. In addition, BOPP has a soft, highly hydrophobic surface of low surface energy, thus ensuring that the tip will not be damaged or contaminated during the evaluation process.
Atomic force microscopy and direct surface force measurements
Pure and Applied Chemistry, 2005
Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the need for formal IUPAC permission on condition that an acknowledgment, with full reference to the source, along with use of the copyright symbol ©, the name IUPAC, and the year of publication, are prominently visible. Publication of a translation into another language is subject to the additional condition of prior approval from the relevant IUPAC National Adhering Organization.
In situ determination of effective tip radius in dynamic atomic force microscopy
MRS Proceedings, 2014
Atomic force microscopy (AFM) suffers from an important limitation: it does not provide quantitative information about the scanned sample. This is because too many unknowns come into play in AFM measurements. The shape of the tip is probably the most important. A technique able to characterize in situ the shape of the tip apex would represent an important step ahead to turn the AFM into a quantitative tool. Standard methods can be destructive to the tip and are time consuming. Two main methods are currently used to characterize the tip radius in situ without affecting its shape. The first consists of characterizing the tip radius by monitoring the dynamics of the cantilever. The value of free amplitude, for which transitions from the attractive to repulsive force regimes are observed, strongly depends on the curvature of the tip. The second method to characterize the tip radius consists instead on fitting the capacitance curve of the tip-sample system with an analytical function. In this work we compare the two methods to characterize in situ the tip radius and results are verified with SEM images. The value of the free amplitude is correlated with the value of R while the capacitance curve is derived with a method we proposed. Tips with different tip radii are used. The investigation is conducted with the aim of determining the most reliable technique for characterizing the tip radius for both sharp and blunt tips. 4 65
Advanced atomic force microscopy probes: Wear resistant designs
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2005
Tip ͓in this article, tip refers to the apex region of an atomic force microscopy ͑AFM͒ probe. A probe consists of substrate, cantilever, and tip.͔ wear is a phenomenon that can reduce the accuracy and reliability of AFM. As both tip size and specimen approach nanometer scale, tip shape change due to wear becomes critical to topographical measurements such as critical dimensions and deep trenches. This article presents probe designs with specific wear-resistant features. Three categories of probe modification were selected to lessen wear, thereby improving lifetime and performance. These are probe material, surface coatings, and selective shape.
Volume 7: 5th International Conference on Micro- and Nanosystems; 8th International Conference on Design and Design Education; 21st Reliability, Stress Analysis, and Failure Prevention Conference, 2011
Atomic-scale wear is one of the main factors that hinders the performance of probes for atomic force microscopy (AFM) , including for the widely-used amplitude modulation (AM-AFM) mode. To conduct consistent and quantitative AM-AFM wear experiments, we have developed a protocol that involves controlling the tip-sample interaction regime, calculating the maximum contact force and normal stress over the course of the wear test, and quantifying the wear volume using high-resolution transmission electron microscopy imaging (HR-TEM). The tip-sample interaction forces are estimated from a closed-form equation that uses the Derjaguin-Müller-Toporov interaction model (DMT) accompanied by a tip radius measurement algorithm known as blind tip reconstruction. The applicability of this new protocol is demonstrated experimentally by scanning silicon probes against ultrananocrystalline diamond (UNCD) samples. The wear process for the Si tip involved blunting of the tip due to tip fragmentation and plastic deformation.
Porous thin films for the characterization of atomic force microscope tip morphology
Thin Solid Films, 2002
We investigated the use of a novel class of porous thin films for the characterization of tapping mode atomic force microscope (AFM) tips. Chromium and titanium films were evaporated using the technique of glancing angle deposition (GLAD) onto rotating silicon substrates. The morphology of the resulting films consisted of isolated vertical posts of sub-micron size. These isolated topographical features are small enough to provide useful information about tip morphology and aid in assessing tip wear and damage. The films were imaged using an AFM, and previously published tip reconstruction algorithms were used to obtain three-dimensional tip functions. These compared well with envelope profiles determined from scanning electron microscope images of the tips.