Effect of oxygen on the characteristics of radio frequency planar magnetron sputtering plasma used for aluminum oxide deposition

The characteristics of a radio frequency magnetron sputtering plasma are studied with the help of compensating Langmuir probe and optical emission spectroscopy in both reactive and nonreactive modes in argon and oxygen environment. Langmuir probe is used to measure the electron temperature, while the optical emission spectroscopy is used to get an idea about the relative concentration of metal and metal oxide formed under the different discharge conditions of argon and oxygen flow. The root mean square value of the discharge voltage and dc negative self-bias are found to be dependent on the oxygen flow rate as well as total gas pressure of the discharge. The study clearly shows the transition of the discharge from the metallic mode to the reactive mode with the increasing flow rate of oxygen, which strongly influences the sputtering. The optimum values of the control variables have been determined for the formation of aluminum oxide.