Physical Sputter Deposition

RF- or DC-driven planar magnetron discharges are applied for spntter depositiom The pressures in the discharges are usually quite low, in this case 1-10 mTorr. The pressure is hmited in the physical sputter deposition system by the requirement that the sputtered atoms mean free path be larger than the separation between the sputtered target and substrate where the atoms should be deposited. The physical sputter deposition rate can be estimated by assuming that all sputtered material is deposited on the substrate  

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Physical Sputter Deposition Rate. Calculate the physical sputter deposition rate assuming a sputtering coefficient ysput = L an incident ion flux Fj = 10 cm s , and density of the deposited film f = 5 10 cm. Also assume that all sputtered material is deposited on the substrate, and the area of the sputtered target is equal to the substrate area where the film is deposited (At = Asub)-... 

Metallization layers are generally deposited either by CVD or by physical vapor deposition methods such as evaporation (qv) or sputtering. In recent years sputter deposition has become the predominant technique for aluminum metallization. Energetic ions are used to bombard a target such as soHd aluminum to release atoms that subsequentiy condense on the desired substrate surface. The quaUty of the deposited layers depends on the cleanliness and efficiency of the vacuum systems used in the process. The mass deposited per unit area can be calculated using the cosine law of deposition ... 

Physical Vapor Deposition Processes. The three physical vapor deposition (PVD) processes are evaporation, ion plating, and sputtering... 

There are several vacuum processes such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), sputtering, and anodic vacuum arc deposition. Materials other than metals, ie, tetraethylorthosiHcate, silane, and titanium aluminum nitride, can also be appHed. 

Chemical vapor deposition may be defined as the deposition of a solid on a heated surface from a chemical reaction in the vapor phase. It belongs to the class of vapor-transfer processes which is atomistic in nature, that is the deposition species are atoms or molecules or a combination ofthese. Beside CVD, they include various physical-vapor-deposition processes (PVD) such as evaporation, sputtering, molecular-beam epitaxy, and ion plating. 

The interconnecting holes are narrow and deep (at times less than 0.25 im wide and up to 2 im or more in depth) and, after a diffusion-barrier layer is applied, it must be filled completely with a high-conductivity metal (usually aluminum or tungsten) to provide the low-resi stance plug for inter-layer connections. Typically, CVD provides better step coverage and conformity than sputtering and other physical-vapor deposition processes. 

Chemical vapor deposition competes directly with other coating processes which, in many cases, are more suitable for the application under consideration. These competing processes comprise the physical vapor deposition (PVD) processes of evaporation, sputtering, and ion plating, as well as the molten-material process of thermal spray and the liquid-phase process of solgel. A short description of each process follows. For greater detail, the listed references should be consulted. 

From a reaction engineering viewpoint, semiconductor device fabrication is a sequence of semibatch reactions interspersed with mass transfer steps such as polymer dissolution and physical vapor deposition (e.g., vacuum metallizing and sputtering). Similar sequences are used to manufacture still experimental devices known as NEMS (for nanoelectromechanical systems). 

Electrocatalytic activity of supported metal particles has been investigated on surfaces prepared in an ultrahigh vacuum (UHV) molecular beam epitaxy system (DCA Instruments) modified to allow high throughput (parallel) synthesis of thin-film materials [Guerin and Hayden, 2006]. The system is shown in Fig. 16.1, and consisted of two physical vapor deposition (PVD) chambers, a sputtering chamber, and a surface characterization chamber (CC), all interconnected by a transfer chamber (TC). The entire system was maintained at UHV, with a base pressure of 10 °mbar. Sample access was achieved through a load lock, and samples could be transferred... 

It can clearly be seen from Figure 20 that the physics and chemistry of sputter deposition should be complex. Little fundamental work has been done in this area. 

Thin-Film Deposition Physical Vapor Deposition (sputtering, pulsed laser)... 

Thermal spray, laser deposition, physical vapor deposition, and magnetron sputtering are physical processes that are used for fabrication of electrolyte thin films. Sputtering is a reliable technique for film deposition and is being used in industry... 

This chapter examines the deposition of fluorinated polymers using plasma-assisted physical vapor deposition. Ultrathin coatings, between 20 and 5000 nm have been produced, using RF magnetron sputtering. The method of coating, fabrication, and deposition conditions are described. 

Increased control of film composition, structure and size can be achieved by limiting the rate of reaction. This is possible using gas phase deposition where the amount of reactant is relatively low. Gas phase deposition loosely covers any hybridization strategy where at least one of the hybrid components is in the gas phase. This includes chemical vapor deposition (CVD), physical vapor deposition (PVD) and atomic layer deposition (ALD) as well as various plasma, sputtering and evaporation processes. 

Although the sputter deposition technique can provide a cheap and directly controlled deposition method, the performance of PEM fuel cells with sputtered CLs is still inferior to that of conventional ink-based fuel cells. In addition, other issues arise related to the physical properties of sputtered catalyst layers, such as low lateral electrical conductivity of the thin metallic films [96,108]. Furthermore, the smaller particle size of sputter-deposited Ft can hinder water transport because of the high resistance to water transport in a thick, dense, sputtered Ft layer [108]. Currently, the sputter deposition method is not considered an economically viable alternative for large-scale electrode fabrication [82] and further research is underway to improve methods. 

Brault, R, Caillard, A., Thomann, A. L., Mathias, J., Charles, C., Boswell, R. W., Escribano, S., Durand, J., and Sauvage, T. Plasma sputtering deposition of platinum into porous fuel cell electrodes. Journal of Physics D Applied Physics 2004 37 3419-3423. 

In physical vapor-deposited as well as sputter-deposited films, incorporated gases can also increase stress and raise annealing temperatures. Similar effects are present in electron beam-evaporated films. 

Model catalysts have to be prepared directly on the IRE, which can be a challenging task. Thin metal films are an important type of model catalyst and can be made, for example, by physical vapor deposition or sputtering of the metal onto the IRE. Most suitable IRE materials for such applications are Ge and Si. The former has a high refractive index of 4.0, which results in a small penetration depth and therefore good discrimination against bulk solvent. The metal film should not be too thick, so that the evanescent field can reach the outer interface of the metal film. 

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