Effect of d.c. bias on the deposition rate using r.f-d.c. coupled magnetron sputtering for SnNx thin films

In an r.f.-d.c. coupled magnetron sputtering system, the magnetron discharge was generated by a 13.56 h MHz r.f. source, and a d.c. power was simultaneously applied to a tin target through a low-pass filter in order to control the incident ion energy on the target. When an extremely low r.f. power 5 W and d.c. power sources were applied simultaneously to the target, the glow discharge took place at a low d.c. bias of - 30 V whose value was about one-seventh of that in the case of the d.c. magnetron discharge. SnNx films have been prepared at the r.f. power value of 5 W and the d.c. bias voltage values of - 50 V to - 350 V, The obtained values of the deposition rate varied from 1-40 nm/min. It was shown that the deposition rate of SnNx films is significantly influenced by the target d.c. bias. The compositional ratio (N/Sn) of sputtered films was increased with the decrease of the target d.c. bias. The SnNx film could be prepared at the target d.c. voltage lower than the discharge voltage in the d.c. magnetron sputtering, with the result that the formation of SnNx films became possible at low ion energies. The resistivity of the SnNx film prepared at the d.c. bias voltage value of - 100 V was 0.3 x 10(-2) Omega cm. (C) 2000 Elsevier Science Ltd. All rights reserved.