Dielectric Characteristics Of Rf Sputtered Oxide Films

Results of a study on the deposition of thin-film dielectrics by RF sputtering are discussed. Source materials were silicon dioxide, aluminum oxide, tantalum oxide, and hafnium oxide, each of which was deposited onto metal electrodes and counterelectroded to complete the metal oxide metal capacitor structures for evaluation purposes. Depositions were conducted normally at 0.002 torr pressure utilizing a triode type sputtering system. Comparative rates of deposition of the dielectric materials ranged from 60 to 225 A/min for the maximum available power. The deposited films were amorphous in structure, although crystallites were dispersed in the hafnium oxide. Generally, the films displayed electrical and physical characteristics comparable to their counterparts formed by other processes, indicating that the sputtering process has the potential for translating the source materials to the substrates in a form suitable for thin-film dielectric applications. Yield study results are included in terms of non-shortened capacitors and their capability to withstand predetermined dielectric field strengths as a function of electrode areas ranging from 200 to 30,000 sq mil. (Author).

The physical and electrical properties of aluminum oxide films deposited on silicon by rf sputtering from an alumina target in an argon atmosphere were investigated as a function of sputtering power density in the range from 0.5 to 3 W/sq cm. The deposition rates ranged from 20 to 80 A/min. The density, index of refraction, and dielectric constant of the films increased while the etch rate decreased with increasing power density. The surface charge at the aluminum oxide-silicon interface was typically larger than 10 to the 12th. This charge increased with increasing sputtering power density and could be reduced to 7-8 x 10 to the 11th e/sq cm by annealing. The films exhibited trapping instabilities at room temperature but no polarization was observed under biastemperature stress. The characteristics of composite layers of thermally grown silicon dioxide and sputtered aluminum oxide layers on silicon were also investigated and found to exhibit low surface charge densities, no hysteresis, and a 'contact potential' as well as charge stored at the interface between the two insulators. (Author).

As new semiconductor systems are developed and implemented in niche or mainstream applications, the need for new dielectric materials becomes prevalent. Sputter deposition is a versatile approach to preparing candidate materials for thin film dielectrics, affording a large processing space for optimization. The choices made for these sputtering parameters can effect significant variation in dielectric properties. We find that for the complex amorphous dielectric oxide of Zr0.2 Sn0.2 Ti0.6 O2 , the dielectric constant is strongly dependent on substrate temperature during reactive sputter deposition, with [epsilon]r ~55 if deposited at 150 to 280 ? C; at higher and lower temperatures, the dielectric constant falls to ~3035. A high quality dysprosium-substituted titania is prepared by reactive RF sputter deposition on unheated substrates. Preparation by thermal oxidation of a sputtered metal film, however, results in an oxide with a defect polarization along phase boundaries. Finally, we develop a methodology to co-sputter dielectric oxides in a composition gradient. When deposited from an oblique sputtering source, such as that used in composition spreads, dielectric thin films exhibit an abnormal low frequency polarization. We implement a negative electrical bias to the substrate, which eliminates the void-mediated polarization and recovers the intrinsic properties of the dielectric. The validity of this technique is demonstrated in the model system Ta2 O5 . Implementation of the technique and its implications for resputtering are considered in the mixed TaO x -GeO x dielectric system.

High permittivity dielectrics are studied intensively in the view of their use in the integrated circuits. However, the real emergence of tantalum oxide (Ta2O5) as a dielectric material happened due to its high-dielectric constant, chemical and thermal stability with the promise of compatibility in microelectronic processing. This book covenants with the optimized deposition conditions of Ta2O5 films formed on quartz and p-type Si substrates using dc and rf reactive magnetron sputtering method for structural and optical studies. Further, aluminum metal deposited as a top electrode on Ta2O5 and Si stack to prepare metal oxide semiconductor device for investigating electrical and dielectric properties. The possible ways for depositing good quality Ta2O5 layers on Si, to obtain high dielectric constant explained in this book are quite useful to prepare high quality metal oxide semiconductor device for capacitor applications.

Transparent electronics is emerging as one of the most promising technologies for the next generation of electronic products, away from the traditional silicon technology. It is essential for touch display panels, solar cells, LEDs and antistatic coatings. The book describes the concept of transparent electronics, passive and active oxide semiconductors, multicomponent dielectrics and their importance for a new era of novel electronic materials and products. This is followed by a short history of transistors, and how oxides have revolutionized this field. It concludes with a glance at low-cost, disposable and lightweight devices for the next generation of ergonomic and functional discrete devices. Chapters cover: Properties and applications of n-type oxide semiconductors P-type conductors and semiconductors, including copper oxide and tin monoxide Low-temperature processed dielectrics n and p-type thin film transistors (TFTs) – structure, physics and brief history Paper electronics – Paper transistors, paper memories and paper batteries Applications of oxide TFTs – transparent circuits, active matrices for displays and biosensors Written by a team of renowned world experts, Transparent Oxide Electronics: From Materials to Devices gives an overview of the world of transparent electronics, and showcases groundbreaking work on paper transistors

The physical and electrical properties of barium titanate films approximately 1 micrometer thick, prepared by rf sputtering onto silicon substrates in both pure argon and 95% argon-5% oxygen glow discharges were investigated. The deposition rate, crystal structure, and refractive index of the films were investigated as a function of deposition temperature and sputtering gas. The electrical characteristics of the films, including the dielectric constant, loss tangent, conductivity, insulator bulk charge, charge storage at the BaTiO3-SiO2 interface, and ferroelectricity were also investigated. (Author).

This volume, Nanomaterials-Based Composites for Energy Applications: Emerging Technology and Trends, covers the importance of nanomaterials-based composites for renewable and alternative energy applications. Taking a multidisciplinary approach, it looks at using composites without losing the extraordinary strength of the nanomaterials, preparing new composites with high dielectric permittivity, improving load-carrying capacity, and more. Simulation and experimental work is included, providing a current view of the research that is going on in laboratories all over the world. The book will be a rich reference for professors and instructors, professionals, researchers, and engineering students interested in applying the emerging field of nanoscience and nanotechnology to energy applications.