Epitaxial layer thickness monitoring - by recording light interference oscillations from substrate implanted coating with different optical properties

摘要

To measure and control the thickness of an epitaxially grown layer on a substrate, the latter is first subjected to an ion implantation treatment to form in the substrate a layer with optical properties different from the substrate material. As the epitaxial layer, consisting of a material similar to the substrate, grows, the light emitted by the substrate is collected and recorded as an interference oscillation. The layer thickness can be calculated from the latter. This requires no reference substratum which may contaminate the epitaxial layer by impurity atoms; it enables the thickness to be checked with a very high accuracy.