Detection of Residual Oil Film on Polished KDP Crystal by Atomic Force Microscope

Abstract

In this paper, the bimodal amplitude-and frequency modulation method of atomic force microscopy (AFM) is applied to investigate the residual oil film on KDP crystal surface after polishing and surface cleaning. The thickness map of residual oil film is obtained based on the relationship between the cantilever resonant frequency shift and the surface stiffness. The thickness maps measured by AFM and spectroscopic imaging ellipsometry methods are compared, and the results obtained by two methods are consistent. The measurement scheme extends the application of AFM technology to characterize the residual oil on the KDP surface quality quantitatively after polishing and surface cleaning.