In Situ XPS in Atomic Layer Deposition of Oxides on Ge (100)

Atomic layer deposition (ALD) is a film growth method that offers unprecedented control of film thickness, uniformity of deposition and low temperature processing on substrates with complex topography. Because ALD occurs by a series of self-limiting surface reactions of vapor phase precursors, there is great interest in understanding the mechanisms of precursor adsorption and how they affect the structure and properties of ALD-grown films and their interfaces with technologically-relevant substrates. In this paper, we describe experiments in which a differentially-pumped x-ray source and photoelectron spectrometer installed in an ALD chamber is used to probe ALD growth of metal oxide films. This in situ XPS system is capable of collecting data within 10's of seconds of an ALD precursor pulse, without moving the substrate or changing its temperature. An application of this system to oxidant treatment of the initial surface of Ge (100) substrates prior to Al2O3 ALD is also discussed.