Predicting thin-film stoichiometry in reactive sputtering

Abstract

The electrical, optical, and mechanical properties of a compound film depend strongly on the composition of the film. Therefore, it is interesting to study a wide variety of compositions of many new compound materials. Reactive sputtering is a widely used technique to produce compound thin films. With this technique it is possible to fabricate thin films with different compositions. However, it has not yet, to any great extent, been possible to predict the composition of the sputtered film. In this article we will present a model that enables us to predict both sputtering rate and film composition during reactive sputtering. The results point out that there exists a very simple linear relationship between processing parameters for maintaining constant thin-film composition in the reactive sputtering process. Based on these results, it is possible for the first time to combine information of both sputtering rate and film composition into the same graphical representation. Access to this new and simple graphical representation may eliminate much of the ‘‘trial and error’’ work that earlier has been associated with the reactive sputtering process.

Influence of the Plasma Chemistry on the Composition of ZrOx and NbOx Thin Films Deposited by Reactive Magnetron Sputtering

“…For both discharges two deposition modes can be recognized: the TM and at larger (O 2 ) values the CM. In the TM mode the target surface is partially covered and in the CM fully covered by a compound layer [21].…”

“…As the oxygen partial pressure ( p(O 2 )) is increased and O + and O − ions dominate the plasma chemistry, close-to-stoichiometric films are grown. Close-to-stoichiometric ZrO 2.1 thin films are grown in the so called compound mode (CM) [21], while close-tostoichiometric Nb 2 O 4.7 thin films can be grown in the compound [21] as well as at lower p(O 2 ) in the so called transition mode (TM) [21] when the target is not fully covered by an oxide layer and the deposition rate is considerably larger. This can be understood, based on the plasma chemistry data presented here, by considering the power input into the plasma and the associated dissociation and ionization phenomena.…”

Nano-crystalline Zr2ON2 thin films deposited by reactive magnetron sputtering

“…It is essential to regulate the relative rates of metal atoms arrival and reactive species at the substrate which give the final stoichiometry [12]. The former is determined by the sputtering rate, the latter by the reactive gas partial pressure and sticking coefficient [13]. All the depositions are performed in water vapor/nitrogen atmosphere at constant total pressure and RF power applied to zirconium target.…”

High rate deposition of tin-doped indium oxide films by reactive magnetron sputtering with unipolar pulsing and plasma emission feedback systems

“…On the other hand, the reactive dc magnetron sputtering process using a metal or alloy target is considered to have higher potential for the large area coatings with very high deposition rates and low cost. The reactive sputtering process, however, is highly non-linear, where the deposition rate shows the 'hysteresis' with respect to the reactive gas flow rate [15][16][17][18][19][20]. Such a behavior originates from the oxidation state of the target surface, resulting in drastic changes in the sputtering yield.…”