Scanning: Setpoint, Detector Signal, and Error Signal
6
The SPM Image
6
The Z Feedback Loop
6
Scanning Tunneling Microscopy (STM)
7
Atomic Force Microscopy (AFM)
8
III. NEAR-FIELD SCANNING OPTICAL MICROSCOPY (NSOM)
9
IV. PRIMARY AFM IMAGING MODES
9
TappingMode AFM
10
Contact AFM
11
Non-contact AFM
11
Torsional Resonance Mode (TRmode) AFM
12
V. SECONDARY AFM IMAGING MODES
12
Lateral Force Microscopy
12
Phase Imaging
13
Magnetic Force Microscopy
14
Conductive AFM
14
Tunneling AFM (TUNA)
14
Electric Force Microscopy
14
Surface Potential Imaging
15
Force Modulation Imaging
15
Scanning Capacitance Microscopy
16
Scanning Spreading Resistance Microscopy (SSRM)
16
Scanning Thermal Microscopy
A Practical Guide to SPM
TABLE OF CONTENTS (continued)
17
VI. NON-IMAGING MODES
17
Spectroscopy
17
Scanning Tunneling Spectroscopy (STS)
17
Force Spectroscopy
19
Force Volume
19
Advanced Force Spectroscopy
20
Surface Modification Techniques
20
Nanolithography
20
Nanoindentation, Nanoscratching, Wear Testing
20
Nanomanipulation
21
VII. THE SCANNER
21
How Scanners Work
22
Hysteresis
23
Aging
23
Creep
23
Bow
24
VIII. PROBES
24
AFM Probes
24
Silicon Nitride
24
Silicon
25
Types of SPM Probes
26
IX. TIP SHAPE ISSUES
27
Resolution Issues
28
X. TYPICAL IMAGE ARTIFACTS
4
I. Introduction
In the early 1980s, scanning probe microscopes (SPMs) dazzled the world with the first real-space atomic-scale images of surfaces. Now,
SPMs are used in a wide variety of disciplines, including fundamental surface science, routine surface roughness analysis, and spectacular three-dimensional imaging — from atoms of silicon to micron-sized protrusions on the surface of a living cell.
The scanning probe microscope is an imaging tool with a vast dynamic range, spanning the realms of optical and electron microscopes. It is also a profiler with unprecedented resolution. In some cases, scanning probe microscopes can measure physical properties such as surface conductivity, static charge distribution, localized friction, magnetic fields, and elastic moduli. Hence, SPM applications are very diverse.
This guide was written to help you learn about SPMs, a process that should begin with a thorough understanding of the basics. Issues covered in this guide range from fundamental physics of SPMs to practical capabilities and instrumentation. Examples of applications are included throughout.
The origins of Veeco SPMs go back to the late 1980s. Since that time, we have maintained strong ties to the academic community and a corporate philosophy that combines technology leadership with a practical-applications orientation, working with customers to demonstrate the ability of our SPMs to meet their needs. We believe that the more you know about scanning probe microscopes, the more likely you will be to choose the best instrument for your work. We want to provide you with the basic facts about SPMs before you make your way through sales literature.
II. How an SPM Works
Scanning probe microscopes are a family of instruments used for studying surface properties of materials from the micron all the way down to the atomic level. Two fundamental components that make scanning probe microscopy possible are the probe and the scanner.
The probe is the point of interface between the SPM and the sample; it is the probe that intimately interrogates various qualities of the surface. The scanner controls the precise position of the probe in relation to the surface, both vertically
