Effects of deposition parameters on tantalum films deposited by direct current magnetron sputtering in Ar-O_2 mixture

摘要

The structure, composition, and temperature coefficient of resistance of tantalum films sputtered in Ar-O_2 mixture were studied as a function of deposition parameters and substrates temperature. As the sputtering power increased from 25 to 100W, the samples deposited at 300 ℃ only consisted of the β phase, the preferred-growth orientation of films changed from (2 00) to (2 02) and the temperature coefficient of resistance reduced from -289.8 to -116.7ppm/℃. The decrease of the oxygen and other impurity in the films was observed as the increase of the sputtering power. In addition, the O/Ta ratio decrease and grain size reduction in the films related to a change of electrical resistivity were observed at substrate temperatures in the range of 300-500 ℃. These results suggested that the electrical properties were due to the oxygen and other impurity content and grain size in the films rather than to growth orientation. At 650 ℃, the deposited films contained both partial stable body-centered-cubic α phase with low resistivity and tetragonal β phase of Ta. The presence of α phase of Ta causes a sharp decrease of the electrical resistivity and a significant change in the microstructure of the samples.