LAB

The first session will serve primarily to introduce you to the system hardware and software and the different modes of operation of the Atomic Force Microscope (AFM) including contact mode and tapping mode AFM. You will learn how to place a sample on the stage and align the laser on the cantilever properly, tune the cantilever (for tapping mode) and engage the cantilever on the sample surface. Details of these procedures can be found in the Operating Manual.

Keep in mind that the system is very delicate and expen$ive. If you are not exactly sure what to do at any time after reading the manual, wait for (or go find) an instructor.

You will then be provided with a semiconductor grid sample with various shapes, sizes and spacings etched on the surface. To help you become familiar with the operation and analysis tools provided with the software, take measurements of the structures in different areas on the sample. Make measurements of the height, lateral size and spacing of the different shapes (either squares or circles) in the different areas on the sample. It will help to examine the sample ahead of time on the microscope to give you an overall view of the locations of the different areas on the sample. This is a good opportunity to explore the different views of the surface provided by the AFM including Height, sensor Height, deflection, lateral deflection, tapping mode amplitude and phase etc. Make measurements with the different views and see how they compare. You can also try changing the angle of the scan, the scan rate (mostly for contact mode since tapping mode requires a fairly slow scan rate of approx 1 hz) and proportional and integral gains of the feedback loop and see how these changes effect the quality of the image for different signals. While you are doing this, keep notes about how your measurements may have differed from the actual shape of the surface and try to understand why these differences come about. Later on you will be looking at samples where you may not know what to expect and you will have to use your previous experiences to interpret what you see or make adjustments to different scan parameters to improve your image.

Once you are comfortable with the basic operations of the system, you can explore some of the many samples available for the AFM and eventually try to come up with your own sample or measurement. The samples currently available include mica, graphite, MdOS2, cd/dvd/hddvd rom surfaces, semiconductor IC chips, silica aerogel, carbon nanotubes as well as several others.

Typical Lab Sequence