Sputtering film structure

Sputtered Neutral Mass Spectrometry (SNMS) is the mass spectrometric analysis of sputtered atoms ejected from a solid surface by energetic ion bombardment. The sputtered atoms are ionized for mass spectrometric analysis by a mechanism separate from the sputtering atomization. As such, SNMS is complementary to Secondary Ion Mass Spectrometry (SIMS), which is the mass spectrometric analysis of sputtered ions, as distinct from sputtered atoms. The forte of SNMS analysis, compared to SIMS, is the accurate measurement of concentration depth profiles through chemically complex thin-film structures, including interfaces, with excellent depth resolution and to trace concentration levels. Genetically both SALI and GDMS are specific examples of SNMS. In this article we concentrate on post ionization only by electron impact. 

If the secondary ion component is indeed negligible, the measured SNMS ion currents will depend only on the ionizing mode, on the atomic properties of the sputtered atoms, and on the composition of the sputtered sample. Matrix characteristics will have no effect on the relative ion currents. SNMS analysis also provides essentially complete coverage, with almost all elements measured with equal facility. All elements in a chemically complex sample or thin-film structure will be measured, with no incompleteness due to insensitivity to an important constituent element. Properly implemented SNMS promises to be a near-universal analytical method for solids analysis. 

Fig. 2.27. AES sputter-depth profiles of the 0 -Al2O3-Ti thin-film structure on a smooth Si substrate covered with a TIN thin-film diffusion barrier, (A) as-deposited, (B) after heating to 500 °C, (C) after heating to 580 °C [2.147],...

Nagata A and Okayama H. Characterization of solid oxide fuel cell device having a three-layer film structure grown by RF magnetron sputtering. Vacuum 2002 66 523-529. 

Experimental determinations of barrier heights on oxide semiconductor interfaces using photoelectron spectroscopy are rarely found in literature and no systematic data on interface chemistry and barrier formation on any oxide are available. So far, most of the semiconductor interface studies by photoelectron spectroscopy deal with interfaces with well-defined substrate surfaces and film structures. Mostly single crystal substrates and, in the case of semiconductor heterojunctions, lattice matched interfaces are investigated. Furthermore, highly controllable deposition techniques (typically molecular beam epitaxy) are applied, which lead to films and interfaces with well-known structure and composition. The results described in the following therefore, for the first time, provide information about interfaces with oxide semiconductors and about interfaces with sputter-deposited materials. Despite the rather complex situation, photoelectron spectroscopy studies of sputter-deposited... 

Understanding the dependence of film structure and morphology on system layout and process parameters is a core topic for the further development of ZnO technology. Work is being performed on in situ characterization of deposition processes. Growth processes are simulated using Direct Simulation Monte-Carlo (DSMC) techniques to simulate the gas flow and sputter kinetics simulation and Particle-ln-Cell Monte-Carlo (PICMC) techniques for the plasma simulation [132]. 

Considering the obtained experimental data, it is possible to propose a model of the formation of a porous structure of the films of zirconia-based solid electrolytes. The model assumes the formation of pores and submicropores when vacancies, which are trapped during sputtering of the solid-electrolyte films (the sputtering temperature was Tf < 0.3Tmeit), pass to sinks and then condense [2,3,4,5], The sinks are boundaries between the crystallites forming the film structure. 

Table IV Adhesion and structural properties of aluminum sputtered film...

The initial thickness of most molybdenum disulphide coatings has an important influence on the performance and life of the coating . The special case of sputtered films is considered in Chapter 10, and there is little information about thickness effects for in situ or transfer films. Many workers have investigated the effect of film thickness on bonded films, but, as was pointed out earlier, much of this work appears confusing, and sometimes contradictory, because of failure to understand and analyse the effects of running-in or burnishing on the consolidation and resulting structure of the films. 

Figure 10.5 Structure of a Type I Sputtered Film (Ref.278, Courtesy of E W Roberts)...

Until the late nineteen-eighties it was generally accepted that the desirable sputtered films of molybdenum disulphide had the type of structure shown in Figure 10.5. The plate-like or rod-like crystals are oriented with their basal planes perpendicular to the substrate surface, and are superimposed on an amorphous, or perhaps partly micro-crystalline sub-layer. Such films are often referred to as Type I or Type A films, and their production and properties are now well understood. 

Rani R et al (1997) SmCo based sputtered films with CaCu and TbCUj structures. J Appl Phys 81 5634-5636... 

SEM photographs of sputtered films show that the layers are fairly dense and appear to crack into platelets when subjected to MEA fabrication. The dense films do not lend themselves to high surface areas therefore, there is substantial scope for enhancement of performance if the surface area can be increased. This may be achieved by producing porous 3-D Pt-Ru layered structures. One such method for creating such 3-D structures, that seem to be extremely promising, involves the pre-treatment of the membrane surface by ion-beam etching, which is then followed by sputter-deposition of the metal. This results in substantially enhanced surface area and very rough nanostructures. Next year s effort will include characterization of such films. 

Starting Material Sputtering method Film compoisition Film structure Useful transmittance range (nm) Refractive index (visible range) Ref... 

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