Abstract
Topographic surface profiling is a powerful tool for characterizing physical features of surfaces at a micro or nanoscopic scale. This technique provides information about height and roughness of a surface for surface quality control in manufacturing, characterization of biological surfaces, and identification of defects in lithography processes. By providing accurate and precise measurements of surface topography, this technique enables researchers and engineers to optimize surface properties and performance.
Non-contact optical interferometric microscopy (OIM) measures the surface profile by optically illuminating a surface and retrieves the reflected light with interference to obtain accurate surface height information. The OIM consists a broadband light source with a center wavelength of 540 nm and a spectral bandwidth of 40 nm, a 50:50 beam splitter, a pair of 10 x objective lenses, a piezoelectric actuator, a reference mirror, and a monochrome CMOS camera. The fringes resulted from the sample surface reflected beam and the reference mirror reflected beam on the camera are acquired with controlled phase changes through the piezoelectric actuator. By evaluating the interference fringes with phases, we can obtain the object surface topographic contour image. Our single-camera OIM technique can produce a surface topography with a field of view of 310 μm x 230 μm, 3.31 nm axial resolution, 270 nm height range, and 488 nm width resolution.