Materials Integration Strategies
In this chapter, materials integration strategies for the fabrication of high-density nonvolatile ferroelectric random access memories (FeRAMs), are discussed, in which unique combinations of in situ and ex situ analytical techniques capable of providing information about thin-film surface and interface processes at the atomic scale are used. These methods are also useful for establishing composition--microstructure--property relationships critical for the integration of ferroelectric capacitors with silicon microcircuits. We demonstrate that Ti--Al layers can be used as a material with a double diffusion barrier/bottom electrode functionality for integration of ferroelectric capacitors with complimentary metal oxide semiconductor (CMOS) devices for the fabrication of FeRAMs. We discuss here results from systematic studies designed to understand Ti--Al film growth and oxidation processes using sputter-deposition in conjunction with complementary in situ atomic layer-resolution mass spectroscopy of recoil ion (MSRI) and surface-sensitive X-ray photoelectron spectroscopy (XPS) and ex situ transmission electron microscopy and electrical characterization.
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