Electronics Guide

Fundamental SPM Techniques

Scanning Tunneling Microscopy (STM)

Scanning Tunneling Microscopy, the first SPM technique developed in 1981, measures the quantum mechanical tunneling current between a conductive probe tip and a conductive sample. When the tip is brought within a few angstroms of the surface, electrons can tunnel through the vacuum gap, creating a measurable current that depends exponentially on tip-sample distance. This extreme distance sensitivity enables atomic-resolution imaging of conductive surfaces.

STM operates by maintaining constant tunneling current through a feedback loop that adjusts tip height as it scans across the surface. The resulting height map represents either constant-current topography or constant-height current variations. Beyond imaging, STM can measure local density of electronic states through scanning tunneling spectroscopy (STS), providing insight into electronic structure at the atomic scale. STM requires conducting samples and ultra-high vacuum for atomic resolution, though liquid and ambient-environment STM systems exist for specific applications.

Atomic Force Microscopy (AFM)

Atomic Force Microscopy extends SPM capabilities to insulating materials by measuring forces between the probe tip and sample rather than electrical current. The probe consists of a sharp tip mounted on a flexible cantilever beam. As the tip interacts with the surface through various forces (van der Waals, electrostatic, magnetic, capillary), the cantilever deflects. An optical lever system—typically a laser beam reflected from the cantilever onto a position-sensitive photodetector—measures these deflections with sub-angstrom sensitivity.

AFM can operate in multiple modes suited to different samples and measurement goals. Contact mode maintains constant force while scanning, suitable for hard surfaces but potentially damaging to soft samples. Tapping mode (intermittent contact) oscillates the cantilever near resonance, reducing lateral forces and enabling imaging of soft biological samples and polymers. Non-contact mode operates above the surface, sensing long-range forces without touching, ideal for delicate samples but requiring ultra-clean conditions. Dynamic modes including frequency modulation (FM-AFM) achieve true atomic resolution on various materials.

Advanced SPM Modes and Techniques

Magnetic Force Microscopy (MFM)

Magnetic Force Microscopy maps magnetic field distributions at nanoscale resolution by using a magnetized probe tip. MFM typically employs a two-pass technique: the first pass maps topography in tapping mode, while the second pass retraces the topography at a fixed lift height while measuring the phase shift caused by magnetic interactions. This approach separates magnetic forces from topographic effects, revealing magnetic domain structures, bit patterns in storage media, and stray fields from magnetic nanostructures.

MFM applications span data storage characterization (reading recorded bits on hard drives and examining write head fields), magnetic materials research (studying domain walls, magnetic anisotropy, and switching behavior), and magnetic device development (characterizing MRAM cells, magnetic sensors, and spin-electronic components). Quantitative MFM techniques can extract magnetic moment and field strength information, though interpretation requires careful consideration of tip-sample interactions and probe characteristics.

Electrical Characterization Methods

SPM provides numerous modes for measuring electrical properties at nanoscale resolution. Scanning Capacitance Microscopy (SCM) maps local capacitance variations, revealing dopant profiles in semiconductors with spatial resolution far exceeding traditional techniques. Kelvin Probe Force Microscopy (KPFM) measures surface potential and work function by nulling the electrostatic force between tip and sample through an applied DC bias, enabling characterization of electronic devices, photovoltaic materials, and contact potentials.

Conductive AFM (C-AFM) measures current flowing through the tip-sample contact while imaging topography, providing simultaneous mapping of conductivity and structure. This technique characterizes dielectric breakdown in thin films, current distribution in organic electronics, and conduction through individual molecules. Electrostatic Force Microscopy (EFM) detects long-range electrostatic interactions, mapping charge distributions, dielectric properties, and trapped charges in insulators and semiconductors. These electrical modes complement each other, with selection depending on whether contact or non-contact measurement is preferred, the sample's conductivity, and the specific property of interest.

Scanning Microwave Impedance Microscopy (sMIM)

Scanning Microwave Impedance Microscopy represents a more recent addition to SPM electrical characterization, operating by applying microwave frequency signals to the probe while scanning. The technique measures complex impedance at microwave frequencies (typically 1-20 GHz), simultaneously providing information about local capacitance and conductivity. Unlike KPFM or SCM that operate at low frequencies, sMIM can characterize high-speed semiconductor devices operating at their actual frequencies, measure carrier mobility in two-dimensional materials, and image dopant profiles with minimal interference from surface states.

Mechanical Property Mapping

Force Spectroscopy and Force Curves

Force spectroscopy extends AFM beyond imaging to quantitative measurement of mechanical properties. By recording cantilever deflection while approaching and retracting the tip from a specific surface location, force-distance curves reveal adhesion forces, elastic modulus, breakthrough forces through membranes, and bond rupture forces between molecules. Modern force spectroscopy achieves force resolution in the piconewton range, enabling detection of single molecular bonds and characterization of protein unfolding.

Force volume mapping combines force spectroscopy with imaging by recording complete force curves at each pixel, creating three-dimensional datasets containing topography and mechanical properties. Advanced analysis extracts Young's modulus, viscoelastic parameters, adhesion energy, and deformation behavior. Applications include biological cell mechanics, polymer characterization, thin film adhesion testing, and nanomechanical property mapping of composite materials.

PeakForce Tapping and Quantitative Nanomechanics

PeakForce Tapping mode represents a significant advance in quantitative nanomechanical mapping. Rather than oscillating at resonance like traditional tapping mode, this technique periodically touches the surface with precisely controlled force while recording the complete approach-retract cycle at each point. Real-time analysis of these force curves produces simultaneous maps of topography, elastic modulus, adhesion, deformation, and dissipation. The direct force control reduces tip wear and prevents sample damage while providing quantitative mechanical data at every pixel.

Contact resonance methods offer complementary mechanical characterization by exciting cantilever resonances while in contact with the surface. Since contact resonance frequencies depend on tip-sample contact stiffness, these techniques map elastic modulus and viscoelastic properties. Variants include contact resonance spectroscopy, atomic force acoustic microscopy (AFAM), and ultrasonic force microscopy, each optimized for different sample types and mechanical property ranges.

Thermal Property Measurement

Scanning Thermal Microscopy (SThM)

Scanning Thermal Microscopy measures local temperature and thermal properties using specialized probes incorporating miniature temperature sensors or heaters. Thermoresistive probes contain a resistor near the tip that changes resistance with temperature, enabling measurement of sample temperature distributions with sub-100 nm spatial resolution. Active SThM modes apply heat through the probe while measuring thermal response, characterizing thermal conductivity, diffusivity, and interface resistance at nanoscale.

SThM applications address critical needs in microelectronics thermal management, characterizing hot spots in integrated circuits, measuring thermal properties of nanomaterials and thin films, studying phase transitions in functional materials, and investigating heat dissipation in nanoelectronic devices. Quantitative thermal measurements require careful calibration and consideration of heat transfer through the probe, air gap (in ambient operation), and sample substrate. Recent advances include nanothermocouple probes and probes with integrated heating and sensing elements for improved quantitative capabilities.

Topography and Surface Characterization

High-Resolution Topography Mapping

At its foundation, SPM provides unparalleled topographic imaging capabilities. Modern AFM systems routinely achieve vertical resolution below 0.1 nm and lateral resolution of 1-5 nm, with specialized techniques reaching true atomic resolution. The ability to operate in ambient conditions, liquids, and controlled atmospheres makes SPM uniquely versatile compared to vacuum-based techniques like electron microscopy.

Topography measurements characterize surface roughness, measure feature heights and dimensions of nanostructures, verify fabrication results, and inspect surface quality. Critical dimension measurement using AFM provides traceable metrology for semiconductor manufacturing, measuring line widths, trench depths, and sidewall angles of nanoscale features. Large-area mapping capabilities, achieved through stitching multiple scans or using specialized long-range scanners, enable characterization from millimeter to atomic scales on the same instrument.

Phase Imaging and Material Contrast

Phase imaging, available in dynamic AFM modes, detects the phase lag between the cantilever drive signal and its response. Phase contrast arises from energy dissipation during tip-sample interaction, providing sensitivity to material properties including viscoelasticity, adhesion, and composition. Phase images often reveal material boundaries and compositional variations invisible in topography, making this technique valuable for composite materials, polymer blends, and biological samples.

The physical origins of phase contrast include viscoelastic energy dissipation, adhesion hysteresis, and tip-sample interaction forces varying with material properties. While qualitative phase imaging is straightforward, quantitative interpretation requires careful consideration of imaging parameters, tip properties, and energy dissipation mechanisms. Advanced techniques like bimodal AFM enhance material discrimination by simultaneously exciting two cantilever resonances, providing independent channels sensitive to different material properties.

Scanning Probe Lithography

Nanofabrication and Patterning

Beyond characterization, SPM techniques enable nanoscale fabrication through various lithography approaches. Mechanical SPL scratches or indents surfaces using high contact forces, creating patterns in resist layers or directly modifying hard substrates. Dip-pen nanolithography (DPN) uses the AFM tip as a nanoscale pen, delivering molecules from a tip-coated ink onto surfaces through capillary transport, enabling direct-write chemical patterning with sub-50 nm resolution.

Electrical lithography methods include anodic oxidation, where voltage applied to the tip induces local oxidation of surfaces like silicon or titanium in humid conditions, creating oxide patterns for subsequent etching or as functional structures. Thermal lithography uses heated probes to locally modify thermally-sensitive materials, enabling high-throughput parallel writing with arrays of probes. These SPL techniques bridge the gap between top-down and bottom-up nanofabrication, offering maskless, direct-write patterning for prototyping and specialized applications.

Tip-Induced Modification and Manipulation

At the ultimate limit, STM can manipulate individual atoms and molecules, positioning them on surfaces to create designed nanostructures. This atom manipulation, demonstrated on various metal surfaces at low temperatures, occurs through precise tip positioning and voltage pulses that transfer energy to overcome surface diffusion barriers. While not practical for large-scale fabrication, atom manipulation enables fundamental studies of quantum phenomena and serves as the ultimate test of position control.

Environmental Control and Operating Modes

Vacuum, Ambient, and Liquid Operation

SPM versatility stems partly from operation in diverse environments. Ultra-high vacuum (UHV) SPM, operating at pressures below 10⁻¹⁰ torr, enables atomic-resolution imaging and spectroscopy by providing atomically clean surfaces and eliminating water layer contamination. UHV systems achieve the highest resolution and most quantitative measurements but require complex vacuum systems and long preparation times.

Ambient-condition AFM operates in air, providing convenient sample access and rapid measurement at the cost of some resolution due to water layer contamination and thermal drift. This mode suits routine characterization, quality control, and samples incompatible with vacuum. Liquid-environment AFM enables in-situ study of biological samples, electrochemical processes, and solution-phase phenomena. Special design considerations for liquid operation include sealed fluid cells, gentle cantilevers for soft samples, and reduced thermal drift through temperature control.

Variable Temperature and Controlled Atmosphere

Temperature-controlled SPM enables study of thermally-activated processes, phase transitions, and temperature-dependent properties. Low-temperature SPM, typically operating at liquid nitrogen (77 K) or liquid helium (4 K) temperatures, reduces thermal vibrations for improved stability, studies quantum phenomena requiring cryogenic temperatures, and reduces thermal drift for extended measurements. High-temperature AFM characterizes materials processing, crystal growth, and high-temperature device operation.

Controlled-atmosphere capabilities allow SPM measurements in specific gases or controlled humidity, important for studying oxidation, corrosion, catalysis, and humidity-sensitive materials. Glove box integration enables measurement of air-sensitive samples under inert atmospheres. These environmental control options expand SPM applications from fundamental physics to applied materials science and device characterization under operating conditions.

Probe Technology and Tip Functionalization

Probe Design and Fabrication

SPM performance critically depends on probe quality. AFM probes consist of a cantilever beam, typically 50-450 μm long, with integrated tip extending from the free end. Silicon and silicon nitride represent the most common materials, offering reproducible fabrication through micromachining, controlled mechanical properties, and compatibility with various coatings. Cantilever spring constants range from 0.01 N/m for soft biological samples to 50 N/m or higher for hard materials, with resonance frequencies from tens of kilohertz to several megahertz.

Tip sharpness determines lateral resolution, with typical radii of curvature ranging from 2-10 nm for standard tips to sub-2 nm for ultra-sharp tips and carbon nanotube probes. Tip geometry includes cone angles affecting aspect ratio for imaging deep trenches and sidewall angles. Wear resistance becomes crucial for extended measurements or hard samples, addressed through diamond-like carbon coatings or diamond tips. Specialized probe geometries include tilted tips for improved imaging of tall structures and colloidal probes (spheres attached to cantilevers) for force measurements with well-defined geometry.

Functional Coatings and Chemical Modification

Tip functionalization extends SPM capabilities through specialized coatings and chemical modifications. Conductive coatings (metal films, doped diamond, or platinum-iridium) enable electrical measurements in C-AFM, KPFM, and EFM. Magnetic coatings provide sensitivity for MFM, with careful control of coercivity and moment orientation. Hard coatings improve wear resistance for extended measurements or abrasive samples.

Chemical functionalization attaches specific molecules to tips, enabling chemical force microscopy (CFM) that maps surface chemistry through specific molecular interactions. Self-assembled monolayers provide controlled tip chemistry for adhesion studies, while biotin-streptavidin and antibody-antigen functionalization enables single-molecule force spectroscopy of biological recognition. Hydrophobic and hydrophilic tip coatings characterize surface wetting properties. Advanced functionalization strategies continue expanding the range of tip-sample interactions accessible to SPM.

Calibration and Metrology

Dimensional Calibration

Quantitative SPM measurements require careful calibration of scanners, cantilever properties, and detection systems. Lateral calibration uses reference standards with certified pitch values (typical pitches: 1 μm, 3 μm, 10 μm) containing regular arrays of features. Scanning these standards determines the actual scan range and corrects nonlinearity in piezoelectric scanners. Vertical calibration employs step height standards with certified heights spanning the measurement range, enabling traceable height measurements.

Advanced calibration addresses scanner nonlinearity, hysteresis, and creep in piezoelectric actuators. Closed-loop scanners incorporating position sensors (typically capacitive or strain gauge) provide real-time position feedback, eliminating drift and nonlinearity at the cost of added complexity and reduced scan speed. Software linearization corrects systematic scanner errors through calibration matrices, while thermal drift compensation algorithms minimize temperature-related position changes during long measurements.

Cantilever Calibration

Quantitative force measurements require accurate knowledge of cantilever spring constant, typically specified by manufacturers with ±20% uncertainty. In-situ calibration methods improve accuracy: thermal noise calibration analyzes cantilever thermal fluctuations to extract spring constant, Sader method uses resonance frequency and quality factor with cantilever dimensions, and reference cantilever method compares unknown cantilevers to calibrated references.

Deflection sensitivity calibration converts photodetector voltage to cantilever deflection distance by measuring detector response while pushing the tip against a hard surface. This calibration, required for force measurements, depends on laser alignment and must be performed for each cantilever installation. Combined with spring constant calibration, it enables quantitative force measurements traceable to SI units.

Performance Verification

Regular verification ensures SPM system performance. Resolution test samples include atomically flat substrates (HOPG, mica) for atomic-resolution verification, sharp features (colloidal gold nanoparticles) for lateral resolution assessment, and rough surfaces for noise characterization. Systematic testing of resolution, noise floor, thermal drift, and scan artifacts enables early detection of degraded performance from worn tips, contamination, or instrument problems.

Data Analysis and Interpretation

Image Processing and Artifact Removal

SPM data analysis begins with processing raw scan data to remove artifacts and reveal true sample properties. Line-by-line leveling removes tilt and curvature from images, compensating for sample tilt relative to scan plane. Polynomial background subtraction eliminates bow from scanner nonlinearity or sample curvature. Scar removal and pixel interpolation correct artifacts from tip crashes or debris. Proper processing preserves real features while removing systematic artifacts.

Understanding common SPM artifacts prevents misinterpretation. Tip shape convolution causes broadening of sharp features, with measured width reflecting tip radius rather than true feature size. Double-tip imaging creates duplicate features when contamination or tip damage produces multiple asperities. Piezo creep causes image distortion at scan start, while thermal drift produces systematic position shifts. Recognizing these artifacts through their characteristic signatures enables correct data interpretation.

Quantitative Analysis

Quantitative analysis extracts numerical data from SPM images. Roughness parameters (Ra, Rq, Rmax) characterize surface texture following international standards. Feature measurement tools determine particle heights, diameters, and distributions. Cross-section analysis measures step heights, trench depths, and sidewall angles. Statistical analysis of large feature populations provides information about size distributions and uniformity.

Advanced analysis includes Fourier analysis revealing periodic structures and wavelength components, grain analysis for materials science applications, and fractal dimension calculation characterizing surface complexity. Machine learning approaches increasingly automate feature detection, classification, and anomaly identification in large SPM datasets. Proper analysis workflow combines automated processing with expert review to ensure accuracy and physical meaning.

Applications in Electronics and Nanotechnology

Semiconductor Device Characterization

SPM provides essential characterization throughout semiconductor device development and manufacturing. Critical dimension AFM measures gate lengths, interconnect widths, and via dimensions with sub-nanometer precision, providing metrology for process control in advanced nodes. Electrical AFM modes map dopant profiles, carrier concentrations, and contact resistance at scales matching device dimensions. Failure analysis employs SPM to locate defects, measure gate oxide thickness variations, and characterize interface quality.

Emerging device technologies including FinFETs, gate-all-around transistors, and three-dimensional integration create complex nanoscale structures requiring SPM's three-dimensional imaging and analytical capabilities. SPM characterizes atomic layer deposition uniformity, examines surface preparation quality before epitaxial growth, and verifies chemical mechanical polishing results. The ability to correlate topography with electrical, mechanical, and chemical properties in one instrument makes SPM indispensable for advanced semiconductor research and development.

Nanomaterials Characterization

SPM uniquely characterizes nanomaterials including nanoparticles, nanowires, carbon nanotubes, and two-dimensional materials. AFM measures nanoparticle size distributions, determining heights unambiguously despite tip convolution of lateral dimensions. C-AFM maps electrical connectivity in nanowire networks and carbon nanotube films, identifying conducting paths and junction resistances. KPFM characterizes work functions and band alignment in heterojunctions formed by different nanomaterials.

Two-dimensional materials including graphene, transition metal dichalcogenides, and hexagonal boron nitride benefit particularly from SPM characterization. AFM determines layer numbers through height measurement, identifies wrinkles and tears, and maps strain fields. Electrical modes characterize local conductivity variations, domain boundaries, and defect distributions. The ability to operate in ambient conditions makes SPM more accessible than ultra-high vacuum techniques for routine nanomaterial characterization.

MEMS and Sensor Characterization

Microelectromechanical systems and nanoscale sensors require characterization techniques matching their physical scale and multimodal operation. SPM measures MEMS surface topography, verifying fabrication dimensions and surface quality. Stroboscopic AFM techniques capture dynamic motion of vibrating MEMS structures including resonators, accelerometers, and gyroscopes, mapping displacement fields with nanometer resolution. Force spectroscopy characterizes mechanical properties of MEMS materials including silicon, silicon nitride, and metals.

Magnetic sensors benefit from MFM characterization of sensitivity patterns and response uniformity. Chemical sensors and biosensors undergo AFM characterization of surface modifications, measuring immobilized antibody layers or surface chemistry patterns. The ability to combine structural, mechanical, electrical, and magnetic characterization on operating devices makes SPM invaluable for MEMS development and quality assurance.

Future Directions and Emerging Techniques

High-Speed and Large-Area SPM

Traditional SPM limitations including slow scan speeds and small scan areas motivate ongoing development of high-speed techniques. Small cantilevers with high resonance frequencies enable faster scanning, while optimized feedback systems and scanner designs reduce settling time. Video-rate AFM achieves frame rates exceeding 10 frames per second for small scan areas, enabling observation of dynamic processes including protein assembly, crystal growth, and electrochemical reactions in real time.

Large-area AFM addresses the need to characterize macroscopic samples with nanoscale resolution. Techniques include long-range scanning systems imaging millimeter areas at nanoscale resolution, automated stage-scanner systems stitching many small images into large mosaics, and hierarchical approaches combining low-resolution overview scans with high-resolution detail imaging. These advances enable quality inspection of manufactured nanostructures and bridge length scales from device to wafer.

Multimodal and Correlative Techniques

Combining SPM with complementary techniques provides comprehensive characterization impossible with any single method. Integrated AFM-Raman systems correlate topography with chemical composition through Raman spectroscopy, important for polymer analysis and materials identification. AFM-optical microscopy combinations enable correlative imaging, locating regions of interest optically before nanoscale SPM characterization. AFM integrated with scanning electron microscopy (SEM) provides simultaneous high-resolution imaging with different contrast mechanisms and direct visualization of the probe-sample interaction.

Emerging multimodal approaches include AFM-infrared spectroscopy (AFM-IR) combining nanoscale topography with chemical identification through infrared absorption, and tip-enhanced Raman spectroscopy (TERS) using plasmonic enhancement at the probe apex to achieve nanoscale Raman imaging. These correlative techniques represent the frontier of nanoscale characterization, providing multiple information channels simultaneously to completely characterize complex materials and devices.

Machine Learning and Automation

Artificial intelligence and machine learning increasingly augment SPM capabilities. Automated approaches to optimal imaging parameter selection reduce operator skill requirements and accelerate measurements. Machine learning algorithms identify optimal probe landing locations, detect and avoid image artifacts, and automatically classify features in images. Deep learning enables sophisticated image analysis including automatic defect detection, semantic segmentation of material phases, and quantitative feature extraction from complex data.

Future developments will likely integrate autonomous experimentation where SPM systems automatically design and execute measurement sequences, iteratively refining hypotheses about sample properties through closed-loop experiment-analysis cycles. These intelligent systems will democratize SPM access, reduce measurement time, and enable exploration of large parameter spaces in materials optimization and device development.

Practical Considerations and Best Practices

Sample Preparation

Successful SPM measurement begins with proper sample preparation. Samples must be mechanically stable, adequately flat for the scanner range, and securely mounted to prevent motion during scanning. Conductive samples for STM require atomically clean surfaces, typically achieved through cleaving, sputtering and annealing, or chemical preparation in ultra-high vacuum. AFM samples benefit from cleaning to remove loose contamination, though ambient AFM tolerates less pristine conditions than STM.

Mounting techniques depend on sample geometry and measurement requirements. Typical approaches include adhesive mounting using double-sided tape or conductive adhesive for small samples, magnetic mounting for ferromagnetic samples on magnetic sample holders, vacuum chuck mounting for large flat samples, and specialized holders for liquids or controlled atmospheres. Proper mounting ensures mechanical stability, electrical connectivity (when needed), and thermal coupling while avoiding contamination of the sample area of interest.

Measurement Strategy and Optimization

Effective SPM measurement requires strategic planning. Initial low-resolution scans locate regions of interest and verify appropriate scan ranges. Progressive zoom-in on features of interest balances overview context with detail resolution. Imaging parameter optimization includes selecting appropriate scan speeds (balancing throughput with feedback stability), setpoint values (controlling interaction strength), and feedback gains (ensuring stable tracking without oscillation).

Different samples and features demand different techniques. Soft samples require gentle imaging modes like tapping with low amplitude setpoints, while hard samples tolerate contact mode for maximum speed. High-aspect-ratio features need sharp tips and careful scanning to avoid tip crashes. Routine monitoring of image quality indicators including trace-retrace consistency, feedback error signal, and feature repeatability ensures reliable measurements. When images show artifacts, systematic troubleshooting isolates problems from tip issues, environmental vibration, or incorrect parameters.

Maintenance and Troubleshooting

Regular maintenance ensures consistent SPM performance. Optical alignment verification and adjustment maintains optimal detection sensitivity. Laser safety protocols protect operators from exposure to alignment lasers. Scanner calibration verification using standard samples detects drift in calibration requiring recalibration. Environmental monitoring of temperature, humidity, and vibration identifies conditions affecting measurement quality.

Common problems include poor image quality from dull or contaminated tips (solution: change probe), thermal drift causing distortion (solution: allow thermal equilibrium, reduce temperature gradients), noise in images from vibration or electrical interference (solution: improve isolation, identify noise sources), and feedback instability causing oscillation or loss of tracking (solution: optimize gains and setpoint). Systematic troubleshooting methodologies and detailed record keeping accelerate problem resolution and maintain instrument productivity.

Conclusion

Scanning Probe Microscopy represents one of the most versatile and powerful toolsets in nanoscale science and technology. The ability to image and manipulate matter at atomic scale, measure diverse physical properties with nanometer resolution, and operate in varied environments from vacuum to liquids makes SPM indispensable across disciplines from fundamental physics to applied electronics engineering. Continuous technical advances expand capabilities through faster scanning, improved sensitivity, novel imaging modes, and integration with complementary techniques.

For electronics and nanotechnology, SPM provides essential characterization from research through manufacturing, enabling development of ever-smaller devices and novel materials. Understanding SPM principles, capabilities, and limitations empowers engineers and scientists to extract maximum information from measurements, properly interpret results, and push the boundaries of nanoscale characterization. As devices shrink and new nanomaterials emerge, SPM will remain at the forefront of characterization techniques enabling technological progress.