Reactive Sputter Deposition Processes

In quasi-reactive ion plating, as in other quasi-reactive sputter deposition processes, compound material is vaporized in a partial pressure of reactive gas that aids in replacing the species that are lost in the transport from the vaporization source to the substrate. 

Taguchi M, Hamaguchi S (2007) Md simulations of amorphous Sio2 thin film formation in reactive sputtering deposition processes. Thin Solid Films 515(12) 4879-4882... 

In reactive sputter deposition the gas (mass) flow is an important processing variable (Ch. 4). Gas flow is important in sweeping contaminants from the processing chamber. 

Taguchi et al. [68, 69] applied this technique to model the reactive sputter deposition of thin Si02 films and the effect of Ar bombardment on the Si02 deposition process. In this particular case, it was found that simulating the deposition process by MD alone resulted in films with a much lower density that those typically obtained from experiments under similar conditions. Applying the sequential MD/MC approach, amorphous Si02 films with properties consistent with experiments were obtained. 

A new two-step method, partial reactive sputtering deposition-wet oxidation, has been developed by the present authors. They found that modulation of precursors in the sputtering step can provide more opportunities for control of the structural and functional properties of the thermally grown oxides. This technique may also open a new way to fabricate porous ZnO films [205,218]. The innovative part of this processing is that a partial reactive deposition is introduced. 

The requirements of thin-film ferroelectrics are stoichiometry, phase formation, crystallization, and microstmctural development for the various device appHcations. As of this writing multimagnetron sputtering (MMS) (56), multiion beam-reactive sputter (MIBERS) deposition (57), uv-excimer laser ablation (58), and electron cyclotron resonance (ECR) plasma-assisted growth (59) are the latest ferroelectric thin-film growth processes to satisfy the requirements. 

By reactive sputtering, many complex compounds can be formed from relatively easy-to-fabricate metal targets, insulating compounds can be deposited using a d-c power supply, and graded compositions can be formed, as described. The process, however, is compHcated. 

Thermal CVD, reviewed above, relies on thermal energy to activate the reaction, and deposition temperatures are usually high. In plasma CVD, also known as plasma-enhanced CVD (PECV) or plasma-assisted CVD (PACVD), the reaction is activated by a plasma and the deposition temperature is substantially lower. Plasma CVD combines a chemical and a physical process and may be said to bridge the gap between CVD andPVD. In this respect, itis similar to PVD processes operating in a chemical environment, such as reactive sputtering (see Appendix). 

Up to the present, a number of conventional film preparation methods like PVD, CVD, electro-chemical deposition, etc., have been reported to be used in synthesis of CNx films. Muhl et al. [57] reviewed the works performed worldwide, before the year 1998, on the methods and results of preparing carbon nitride hlms. They divided the preparation techniques into several sections including atmospheric-pressure chemical processes, ion-beam deposition, laser techniques, chemical vapor deposition, and reactive sputtering [57]. The methods used in succeeding research work basically did not... 

Chemical vapor deposition (CVD) is a process whereby a thin solid film is synthesized from the gaseous phase by a chemical reaction. It is this reactive process that distinguishes CVD from physical deposition processes, such as evaporation, sputtering, and sublimation.8 This process is well known and is used to generate inorganic thin films of high purity and quality as well as form polyimides by a step-polymerization process.9-11 Vapor deposition polymerization (VDP) is the method in which the chemical reaction in question is the polymerization of a reactive species generated in the gas phase by thermal (or radiative) activation. 

Fig. 5.6. Reactive sputter process for depositing the compound film AB. (a) Balance of reactive gas flow Qtot, which is partially gettered at the target (Qt) and at the substrate (Qc) and partially pumped by the vacuum pump (Qp). The fraction of the target surface At that is covered by the compound AB is 6>t. The fraction of the collecting area Ac covered is Gc. j is the sputter current density, (b) Definition of particle fluxes that alter the target and collecting area coverage fractions 6>t and 6>c (see text), (modified from [70])...

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