High-resolution Analysis of Materials at Nano Scales for Materials Scientists, Microscopists and Process Engineers

On the surface – Atomic Force Microscopy (AFM) provides sub-nanometer resolution surface topographic information (Z axis) in a 20×20, 10×10 or a 3×3 micron area. 

AFM may be done with a variety of tips to collect different information from the sample surface about its characteristics such as nano surface morphology, chemistry or magnetic properties. 

For a detailed description of the equipment and techniques available high-resolution analysis of materials, go to the Tools and Techniques page.

There are 4 clear advantages

1. It is ECONOMICAL and EASY.  It does not require sample preparation (conductive coatings) or mounting for vacuum compatibility – so can be used quickly and easily.
2. MATERIALS INDEPENDENT – Works on a wide variety of materials (even biological) at room temperature.
3. EASY TO UNDERSTAND – High resolution surface morphology and surface height representations are presented in image form- (with scales and roughness avg. available)
4. CAN BE EXTENDED – Sloped or vertical features can also be measured with modified tips. Further tip types can measure other features (magnetic zones, chemistry, zone axes etc)

Typical applications where AFM can offer high value information include:

1. Measuring the height of specific nano-structures like nano-optical elements
2. Measuring the surface roughness of a material before and after an etching or cleaning process.
3. Measuring the surface roughness of a material onto which a layer will be grown – for example, a compound semiconductor layer, or a Silicon on an Insulator device.
4. Calculating the particle density on a surface after distribution – this is often needed when adding seed crystals when growing a new layer on a device.
5. AFM can be used in combination with other techniques like SEM, this is called “Correlative Microscopy” and can be used to measure the height of a layer where the wider distribution has already been understood.

Analysis of Surface Roughness in III/V Semiconductors.

Forming strong contacts to compound semiconductors requires a low level of surface roughness. A rough surface can also have a negative effect on growth mechanisms of additional layers. AFM provides an powerful tool for characterising the surface roughness of these single crystal materials.

SRAM test structures

Images acquired on a Bruker Dimension Edge AFM. (Image size: 50 x 50 μm, z-scale: 900 nm).  Image courtesy of Dr Filip Gucmann, University of Bristol, UK

Self-organised microstructures

Imaged with a Bruker Multimode 8 AFM. (Image size: 100 x 100 μm, z-scale: 240 nm). Image courtesy of Dr. Georg Haehner and Mr. David Jones, University of St. Andrews, UK.