Nitrides reactive sputtering

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... 

W. A. Bryden and T. J. Kistenmacher, Growth of Group III-A Nitrides by Reactive Sputtering N. Newman, Thermochemistry of III-N Semiconductors S. J. Pearton and R. J. Shul, Etching of III Nitrides... 

Reactive sputter deposition is a useful technique not only for coating but also for obtaining metastable phases, especially nitrides. Nitrogen gas is activated in a plasma to enhance nitride formation and heating at high temperature is not required. It is possible to obtain metastable nitrides by sputter deposition in which species in the plasma are quenched on substrates. Compounds with different crystal structures normally do not form solid solutions, but by co-sputter deposition metastable solid solutions may form. 

Thin films of carbides and nitrides of Group 6 metals were synthesized by reaction of a metal film with a reactive gas at high temperature and by reactive sputtering. The phases obtained depended on the experimental conditions. High temperatures metastable phases (/i-WC, v and 6-MoC]. ) were obtained by reactive sputter deposition of films. The carbon concentration in such films depended on the temperature of the substrate and on the pressure. In some cases ordered sublattices of carbon and nitrogen were observed and epitaxial relationships between the deposit and the substrate were studied. 

Synthesis of carbide and nitride films by reactive sputtering. Table 14.3 presents a summary of the experimental conditions for the formation of carbides and nitrides. The phases formed are different from those in Table 14.2. As sputtering is a non-equilibrium technique, it was possible to synthesize the 6-MoC and the fi-WCi x carbides and the... 

Among the physical techniques, reactive sputtering is used most frequently because it produces films of high purity with relative ease and good reproducibility. In addition, many compound types can be prepared (carbides, nitrides, oxides, carbonitrides, oxicarbonitrides) including metastable phases. 

Table 14.3 Synthesis of carbide and nitride films by reactive sputtering. The reacting gas consisted either in a 10% CH4/Ar or pure N... 

Following all the results presented here, there seems to be a strong difference between the formation of carbides and nitrides by reactive sputtering if the substrate temperature increases, the nitrogen concentration in the film decreases while the carbon concentration increases. 

The dissociation energy of chemical compounds is in the order of 10 to 100 eV. Of course, such a compound can be expected to decompose if bombarded with keV ions. Part of the volatile products thus arising are pumped away with the sputtering gas so that the growing film shows a deficit of these components. This is why stoichiometric compound films as oxides, nitrides, sulphides, etc. usually can only be prepared by sputtering by the addition of small amounts of O2, N2, H2S, etc., to the sputtering gas, hence in a form of reactive sputtering which replaces the losses. 

Compound films such as oxide, nitride and carbide can be produced by reactive sputtering as mentioned above. Electrically non-conducting substances are processed by rf sputtering. Whether the noble gas ions required for sputtering originate from a gas discharge plasma in the plant, from special ion guns or from other set-ups does not have any influence on the choice of material. 

Property Direct Thermal CVD Ge3N4 (107, Thermal in Hydrazine Reactive Sputtering (104,106) Thermal nitrid-ation of Ge02 (35)... 

Molybdenum nitrides are studied for their interesting properties in catalytic reactions such as for the desulfurization and denitridation of oil products which is of increased importance for use in cars where sulfur can destroy the activity of the catalyzer. These powders can be produced with a high surface area by reaction of M0O3 or M0S2 with NH3. Also layers of molybdenum nitrides, prepared by various techniques such as reactive sputtering or ion beam deposition. 

Amorphous silicon nitride (a-Si3N4) is used extensively in the microelectronics industry in the form of thin films, which are prepared by both normal and reactive sputtering, chemical vapor deposition (CVD), ion-beam-assisted deposition, and ion... 

Ishihara A, Doi S, Mitsushima S, Ota K (2008) Tantalum (oxy)nitrides prepared using reactive sputtering for new cathodes of polymer electrolyte fuel cell. Electrochim Acta 53 (16) 5442-5450... 

Simultaneous ion-enhanced deposition leads to a more homogeneous coating. Such processes are described in a number of articles and patents [88 to 100]. While ions are accelerated to energies of 120 keV, a modification of such methods involves the use of low-energy nitrogen ion beams (from 200 to 5000 eV) [101 to 106]. The dependence of the formation of p-BN on the bias voltage has been studied in the reactive diode sputtering of boron nitride [107]. Sputter-deposition of BN layers is also mentioned in patents [89 to 110]. 

TiN coatings are deposited by CVD, reactive evaporation, reactive sputtering, and ion-beam-assisted deposition. They can also be obtained by thermal spray. TiN powder is produced by the nitridation of Ti metal with nitrogen or ammonia at 1200°C (see Chs. 14 and 15). 

Vanadium nitride is produced mostly on an experimental basis. Coatings are deposited by CVD, reactive evaporation, reactive sputtering. 

---