In this paper an alternative approach to surface profilometry based on a combined time-spectral domain white-light interferometer is shown. Within the setup a reference interferometer arm contains of a fixed mirror and a material with known dispersion while the object arm is aligned to a sample e.g. a wafer surface. Under the usage of a translation stage different height profiles in the nm - regime are emulated and measured accordingly with the interferometer. The signal analysis and calculation of interesting parameters is performed by a fitting algorithm. This algorithm is based on theoretical considerations on a dispersion affected interferometer which are also shown in the work. The experimental configuration allows a measurement range of 12 μm while a theoretical average resolution of 28 nm is possible. In the results it is observable that the measurement of height changes on a surface with an RMS error of 18 nm at the maximum is possible. In conclusion sources of error and further improvement possibilities are discussed.

Date Published: 21 May 2015
PDF: 6 pages
Proc. SPIE 9517, Smart Sensors, Actuators, and MEMS VII; and Cyber Physical Systems, 95170W (21 May 2015); doi: 10.1117/12.2179022

Published in SPIE Proceedings Vol. 9517:
Smart Sensors, Actuators, and MEMS VII; and Cyber Physical Systems
José Luis Sánchez-Rojas; Riccardo Brama, Editor(s)