Manipulating Material Properties of Atomic Layer Deposited Oxide Thin Films by Electric Field: Experimental and Computational Design (ALDBIAS)

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The ALDBIAS project follows both technological and fundamental scientific objectives. On the technological side, ALDBIAS targets the advancement of plasma-enhanced (PE) atomic layer deposition (ALD) by applying an electric field (BIAS) to tailor the material properties at an atomic level. The scientific objective of the project is the profound understanding of relationships between material properties and factors influencing PEALD synthesis of thin oxide films, both with and without bias. ALDBIAS is expected to shed light on the influence of external electric field on the growth process of oxidic materials, mechanisms of material densification and crystallization, void formation, intermixing and mechanical properties of oxide composites. Combing this knowledge with the extensive expertise of the PP 1959 consortium in solid-state phenomena of oxides is essential for designing composite materials with tailored properties and for developing novel synthesis routes within ALDBIAS. Conversely, the results of ALDBIAS are also expected to impact research in other projects within the consortium. PEALD allows for only limited control of material properties by variation of plasma parameters. In contrast, applying bias to the substrate during ALD extends the available degrees of freedom in the manipulation of matter. In PEALD, this approach is still novel and significant advancement in thin films controlled by applying bias will be possible. This technology will be highly valuable not only for optical applications but also for high and low k dielectrics and to extend the efficiency and lifetime of ALD barrier coatings.Ultimately, achieving optimal control over the properties of PEALD grown layers requires a detailed knowledge of their structure, formation mechanisms and their dependence on external fields at an atomic level. However, such knowledge is difficult to access experimentally due to the complex structure of the layers, complicated formation mechanism and difficulties in measuring processes at the nanoscale. Therefore, the fundamental scientific objective of ALDBIAS is to target these questions combining both experimental and computational studies. The mechanisms in which bias influences PEALD process will be investigated in details at an atomic level using a hierarchy of systems with increasing complexity, starting with well-defined crystalline surfaces and advancing to single- and multicomponent amorphous models. This reductionist approach will facilitate comparison between experimental data and results of computer simulations. The results obtained in this part will guide the synthesis of PEALD coatings with improved mechanical properties by providing a profound atomistic understanding of the structure and mechanisms of void formation due to defects, ligands and reactive species and mechanism of film stress due to adhesion forces within film and at the interfaces.