Basic study on optical probe lateral resolution by the collecting laser irradiation

Abstract

　　　An optical probe can measure the shapes of specimens in a perfectly non-contact condition, and has a high vertical resolution. Therefore, an optical probe is widely used for the profile measurement. However, optical probe has a problem that the low lateral resolution. Lateral resolution of an optical probe depends on the spot size of the laser at the measurement point, and is generally lower than one order of magnitude than the vertical resolution. By the improvement of the Lateral resolution of an optical prove, the improvement of the measuring accuracy and of the application can be expected. Therefore, this study newly proposed an optical probe with the high lateral resolution by the collecting laser irradiation. In this study, we constructed an optical probe utilizing concentrated laser irradiation from multiple directions and conducted the principle verification experiment. Furthermore, the relationship between the step profile and the optical probe output in the step standard specimen was investigated and the usefulness of the proposed measurement method for improving lateral resolution was evaluated.