In this paper, scanning tunneling microscopy (STM) is used to investigate the microstructure of organic films in optical recording. Bubbles are found for phthalocyanine thin films after laser irradiation. Laser pulses of different energies produce bubbles of various minute structures. The disc performance closely correlates with the sizes of the bubbles. It is demonstrated that STM is a powerful tool to investigate the microstructure of the optical disc.