Sputter Deposition Processes

Abstract

Sputter deposition is a widely used technique to deposit thin films on substrates. The technique is based upon ion bombardment of a source material, the target. Ion bombardment results in a vapor due to a purely physical process, i.e. the sputtering of the target material. Hence, this technique is part of the class of physical vapor deposition techniques, which includes, for example, thermal evaporation and pulsed laser deposition. The most common approach for growing thin films by sputter deposition is the use of a magnetron source in which positive ions present in the plasma of a magnetically enhanced glow discharge bombard the target. This popular technique forms the focus of this chapter. The target can be powered in different ways, ranging from dc for conductive targets, to rf for nonconductive targets, to a variety of different ways of applying current and/or voltage pulses to the target. Since sputtering is a purely physical process, adding chemistry to, for example, deposit a compound layer must be done ad hoc through the addition of a reactive gas to the plasma, i.e. reactive sputtering. The undesirable reaction of the reactive gas with the target material results in a non-linear behavior of the deposition parameters as a function of the reactive gas flow. To model this behavior, the fluxes of the various species towards the target must be determined. However, equally important are the fluxes of species incident at the substrate because they not only influence the reactive sputter deposition process, but also control the growth of the desired film. Indeed, the microstructure of magnetron sputter deposited films is defined by the identity of the particles arriving at the substrate, their fluxes and the energy per particle.

High power impulse magnetron sputtering discharge

“…49,52,72 But, not all the secondary electrons are confined in the target vicinity. To account for the electrons that are not trapped, Thornton and Penfold 52 assume an effective secondary electron emission coefficient,…”

SiNx Coatings Deposited by Reactive High Power Impulse Magnetron Sputtering: Process Parameters Influencing the Nitrogen Content

“…Here, SiNx films can be either deposited from a Si3N4 compound target 14 , by reactive magnetron sputtering using N2 as N-source [15][16] , or a combination of both 17 . One of the major growth parameters for the deposition of SiNx by reactive magnetron sputtering is the amount of N2 supplied to the glow discharge as it determines the deposition process characteristics 18 as well as the N content in the SiNx coatings. In studies [15][16]19 SiNx thin films were deposited by reactive radio frequency magnetron sputtering.…”

High-resolution characterization of TiN diffusion barrier layers

“…Most importantly for the sputtering process, bombardment with energetic particles leads to the ejection of target atoms, under the condition that the energy transferred in the collision is sufficient to overcome the atom's surface binding energy. The atom can be sputtered due to a single knock-on event, or as a result of a collision cascade [17,31]. In addition to the energy, the sputter yield (the ratio of incident ions to sputtered atoms) also depends on the mass of the bombarding ion and the target material.…”

“…Stray electrons present in the working gas are accelerated towards the anode and collide with neutral gas atoms, thereby transforming them into positively charged ions. Due to charge conservation this impact ionization process in turn releases two electrons, as shown using the example of Ar [17,30,31]:…”