Biomedical Engineering Reference
In-Depth Information
Fig. 7.30. Examples of applications in the data storage industry. Left: Three-dimensional represen-
tation of magnetic domains, in a 24
m MFM image of a hard disk drive, allowing measurement of
domain structure and spacing. Centre: 20
m height image of a DVD. Automated software allows
measurement of many properties from images such as this. Right: 16
m height image of a laser
bump in a hard disk landing zone. The scratch-like features are burnish marks, intentionally applied
to allow air to escape while the head flies over the disk platter.
facilitate the landing of the drive head when not in use. They are created in the landing
zone of the disk surface with a short laser pulse. The bumps are not very deep and cover a
small area of the disks surface. The AFM helped with the development of the process to
create these pits; the height of the pit's lip as well as the depth of the pit can be directly
measured with an AFM. Some examples of these applications from the data storage
industry are shown in Figure 7.30.
7.4.2.3 MEMS devices
One of the first commercial applications for MEMS devices was the cantilevers/probes
used in the atomic force microscope. Applications for the AFM in MEMs devices include
measuring the surface roughness of reflective surfaces, measuring the forces required
to move MEMS fabricated devices, and metrology measurements on MEMS devices.
Figure 7.31 illustrates a device imaged by both SEM and AFM, showing how the true
10793 nm
0 nm
x: 71.8 µm
y: 71.8 µm
Fig. 7.31. Example of imaging of a MEMS device. The AFM image, on the left, gives quantitative
height information, while the SEM image (right) does not.
