Observation of recording pits on phase-change film using a scanning probe microscope

A phase-change film is a key material for optical data storage media such as rewritable compact disks (CD-RW) and digital versatile disk random access memory (DVD-RAM). Data pits are recorded as differences in crystal state (crystallized state vs. amorphous state) on phase-change film. It is very important to distinguish the crystal state difference in a very small area for material research of phase-change film. Measuring size and shape of recorded data pits is also very important for the development to achieve good data reliability and high data density of optical data storage media. The crystal state difference in very small areas of phase-change film is successfully observed by Kelvin probe force microscopy (KFM) and scanning near-field optical/atomic force microscopy (SNOAM). The advantage of KFM and SNOAM for measuring physical property differences in a very small area is demonstrated.