Design of an in-situ ellipsometer
Ellipsometry is a nondestructive analysis technique for studying surfaces, interfaces and thin films. The fabrication of multilayered structures, which can consist of several hundred layers, by sputter deposition of two materials having different refractive indices requires careful control of the individual layer thicknesses. In-situ monitoring of the deposition process is clearly the optimal way to achieve a high quality film and layer structure. An in-situ ellipsometer can be mounted on a
... be mounted on a deposition chamber and, through view ports, make a measurement of the complex reflection coefficient of the sample inside during the deposition process. Through an appropriate mathematical model, the thickness of the deposited layer can be determined from the ellipsometric data. This thesis presents an account of the design, construction and operation of an in-situ, rotating compensator ellipsometer. The completed prototype achieved a precision and repeatability of better than ± 1 A when measuring a Si02layer on a silicon substrate. Thicknesses obtained from measurements corrected for the birefringence of the vacuum port windows agreed with accepted values to within a monolayer for thin (< 1000 A) layers of Si02 on silicon, and to within 3monolayers for samples up to 2200 A thick.