X‐Ray Photoelectron Spectroscopy Study on the Interaction of Yttrium–Aluminum Oxide with Fluorine‐Based Plasma

Abstract

We have prepared oxides having various yttrium to aluminum ratios and exposed them to fluorine‐based plasma. The etch rate of the aluminum oxide decreased abruptly with the addition of yttrium oxide and then slowly with further addition. The yttrium oxide had a more fluorinated surface than the aluminum oxide, indicating that the etch rate was not determined by the surface fluorination, contrary to the etching of Si‐based materials. From the X‐ray photoelectron spectroscopy (XPS) analysis of a multication YAlO 3 single crystal, a similar tendency was observed, showing a higher ratio of Y–F to Y–O bonding than the ratio of Al–F to Al–O. Angle resolved XPS and depth profiling analysis revealed the presence of a fluorinated layer of a few nanometer thick under a roughly 1 nm carboneous top layer. The etching behavior and surface chemical status of these oxides were discussed in terms of thermodynamic aspects of aluminum and yttrium fluoride.