The sputter-deposition process of TiO2 thin films was investigated. When an oxide target is used, high-rate deposition above 57 nm/min can be realized by sputtering under a condition of low oxygen gas content. Under this sputtering condition, a Ti rich surface layer is formed by selective sputtering of oxygen atoms, and a large amount of Ti atoms are sputtered from this layer. The deposition rate, however, decreases steeply as the oxygen gas content increases. This decrease can be explained as follows. When a sufficient amount of oxygen gas is supplied into the chamber during sputtering, the oxygen atoms which are missing from the target surface by selective sputtering are filled up immediately. This leads to a very low deposition rate of the film, because only oxygen atoms are sputtered from the target. Therefore, the suppression of the incidence of oxygen gas to the target surface and a sufficient of oxygen supply to the substrate are necessary to realize the high-rate deposition of stoichiometric TiO2 films. From this point of view, using an oxide target instead of a metal target is useful for realizing a stable high-rate deposition of the film, since the amount of oxygen gas introduced in to the sputtering chamber can be reduced significantly. In addition, it was confirmed that pulse sputtering method is a useful technique for the deposition of TiO2 thin films. Meanwhile, low-voltage sputtering technique was difficult to use for the film deposition because of its low deposition rate.

Service chaining technology realizes that packets are processed through virtual network functions (VNFs); the set of successive VNFs is called a service function chain (SFC). Routes of SFCs need to be updated in order to resolve a quality of service degradation due to concentration of processing loads on certain VNFs. When updating the SFC routes, states of migrated VNF instances need to be kept consistent to prevent a degradation of processing accuracy of the VNF instances. Existing studies determine SFCs to be updated, their routes, and an update scheduling in multiple phases; each decision does not necessarily minimize the total time required to update the SFC routes. This paper proposes a model that jointly determines SFCs to be updated, their routes, and an update scheduling while guaranteeing state consistency. The proposed model considers the time required to update flow entries of SFC routes, the time required to migrate states of VNF instances, and the delay time required to transmit, propagate, and process packets. The objective function is to minimize the total time required to update SFC routes under a constraint of processing load balancing among VNF instances. The proposed model is formulated as an integer linear programming problem. The proposed model is compared to a benchmark model based on the existing studies. Numerical results show that the proposed model can reduce the total update time compared to the benchmark model.