Method for Film Thickness Mapping with an Astigmatic Optical Profilometer
Journal
Sensors
Journal Volume
22
Journal Issue
8
Date Issued
2022
Author(s)
Abstract
An astigmatic optical profilometer is a precision instrument with advantages such as high resolution, high bandwidth, a compact size, and low cost. However, current astigmatic optical profilometers measure only surface morphology, and their potential for capturing subsurface information remains underutilized. In this study, we developed a method for measuring the thickness of transparent thin films with an astigmatic optical profilometer. Experimental results demonstrate that the thickness of transparent films tens of micrometers thick can be accurately measured. The maximum thickness measurable through our system is approximately 100 µm, which may be increased to 1.2 mm through the use of a scanner with a greater travel range. A coupling problem occurs for films <25 µm in thickness. However, to solve this problem, we devised a decoupling method, which was experimentally implemented to successfully measure a 18-µm-thick film. Moreover, the ability to obtain 3D images, including of both the upper and lower surfaces, was demonstrated. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.
Subjects
astigmatism; optical profilometer; thickness measurement
Other Subjects
Film thickness; Morphology; Profilometry; Surface morphology; Thin films; 'current; Astigmatism; Compact size; Film-thickness; High bandwidth; High resolution; Low-costs; Optical profilometer; Precision instrument; Thickness measurement; Thickness measurement
Type
journal article