Sputter deposition synthesis and characterization of thin films: Amorphous carbon and titanium nitride shape memory alloys.

摘要

Carbon is of both scientific and practical significance since it can exist in three different bonding configurations, i.e., tetrahedral ( sp3), trigonal (sp2), and linear (sp1), and it may form various crystalline and disordered structures. In this dissertation, sputtered amorphous carbon (a-C) films, also named as diamondlike carbon (DLC) films, are synthesized by low-pressure Ar radio-frequency (rf) discharge, and characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS), and X-ray photoelectron spectroscopy (XPS). An important characteristic of DLC films is the sp3 carbon content, which depends strongly on the deposition technique and associated conditions.;The characteristics of low-pressure Ar rf discharge in film deposition environment is investigated, and the observed effects of process conditions on the rf discharge are interpreted in terms of energy balance and sheath capacitance considerations. It is observed that the absorbed rf power, substrate bias voltage, and working pressure have strong effects on the target self-bias voltage and ion current density of the discharge. The effect of low-pressure rf discharge on the growth of sputtered a-C films is studied by AFM and TEM. It is found that the Ar+ bombardment on the growing film surface controls the development of the film surface topography, and that the film thickness is linearly dependent on the product of the sputtering rate and deposition time.;A large compressive residual stress occurs in sputtered a-C films. Evaluation and relaxation of the compressive residual stresses in low-pressure rf sputtered a-C films are investigated by experiments, and explained in terms of the effects of Ar+ bombardment, thermal spike, and interfacial tension. The stress level is essentially dependent of Ar+ bombardment on the growing film surfaces, and can reach to a value as high as -10 GPa with intensive Ar+ bombardment. The origin and development of the compressive residual stress are related to Ar+ bombardment kinetic energy and ion flux. The compressive residual stress in rf sputtered a-C films relaxes due to thermal spike processes or interfacial tension effects.;The cross-sectional microstructures of sputtered a-C films are explored by high-resolution TEM and analytical electron microscopy (AEM). TEM and EELS analysis reveal a two-layer cross-sectional structure consisting of ∼35 A thick interfacial layer and a-C film, which is different from other DLC films produced by highly energetic carbon ions, forming a three-layer cross-sectional structure that can be understood by the subplantation. (Abstract shortened by UMI.)