Physico-chemical Characterization of Thin Oxide Films: Difficulties and Solutions

Abstract

ABSTRACTOxides have always been an integral part of semiconductor manufacturing both in front and back-end processing. With the necessary increase in performance, the demand on these oxides has been increasing leading to their (future) replacement by more complex materials, such as high-k's in gate oxide and metal gates. With the increasing material complexity, a thorough characterization of all aspects of these materials is necessary, covering, for instance, surfaces and interfaces, nucleation, growth, atomic structure, …This article focuses on the characterization of front-end oxides and their interfaces. It shows that detailed information can be achieved by sophisticated experimental techniques such as synchrotron radiation, high energy ERD or AtomProbe but that adequate sample preparation and/or analysis by a combination of more routinely available techniques may achieve similar results. This is shown through the study of three different systems/problems in the gate stack analysis. We will first focus on the determination of substrate surface preparation conditions before deposition and their influence on growth mode and the growth characteristics by different growth techniques (ALD, MOCVD, …). Second, we present the possibilities of compositional depth profiling of thin layers both with nuclear techniques and Angle-Resolved XPS. Finally, we will show that using conventional XPS and a combination of front and back-side analysis, the interface between high-k oxide and metal gates can be investigated. More examples of gate stack characterization can be found elsewhere