Recent aspects concerning DC reactive magnetron sputtering of thin films: A review

In this paper, attention is paid to DC reactive magnetron sputtering and it s implications, such as the hysteresis effect and the instability in the re active gas pressure, differential poisoning of magnetron cathode, as well a s the methods which are used to control the process. These methods include: (a) increasing the pumping speed, which requires considerable additional c osts; (b) increasing the target-to-substrate distance, which requires large r vacuum chambers (hence, higher costs) and also results in lower depositio n rates; (c) obstructing reactive gas flow to the cathode with the resultan t reduction of deposition rate and the need for complicated arrangements; ( d) pulsed reactive gas flow, which requires an extensive amount of process optimisation and a continuous monitoring and adjustment of the process para meters; (e) plasma emission monitoring; and (f) voltage control, which are inexpensive and have proved to be powerful techniques for monitoring and co ntrolling the reactive sputtering processes, in real time without disturbin g the discharge, for the deposition of high-quality films, reproducibly. In addition, arcing and methods to avoid it are reviewed; this includes, are initiations and their destructive effects (e.g. driving the process to beco me unstable, reducing the target lifetime and creating defects in the sputt ered films), time required for arcs to occur, and finally, methods of avoid ing arcs. The latter includes the use of unipolar or bipolar pulsing techni ques at frequencies in the range 10-70 kHz. (C) 2000 Elsevier Science S.A. All rights reserved.