Target poisoning during reactive sputtering of silicon with oxygen and nitrogen

SiOxNy thin films have been prepared by DC reactive sputtering of a Si target in Ar with varying amounts of oxygen and nitrogen added to the process gas. With the addition of oxygen to the process gas, an abrupt transition from metallic mode to poison mode occurs at around 4.5% oxygen addition, and the typical hysteresis common with reactive sputtering is observed. With the addition of nitrogen, the hysteresis effect is not observed, and a more gradual transition to the poison mode occurs beginning around 10%. With a combination of reactive gases, we observe a gradual shift between the abrupt transition observed with only oxygen to the gradual poisoning as observed with nitrogen. XPS spectra indicate an increase in the ON and NN bonding as the reactive gas component is increased.