Microstructure of Cu film sputter deposited on TiN

Abstract

The correlation between the microstructure of Cu films and the deposition conditions of the sputtering method was investigated to obtain larger grain size and higher (111) texture. Cu film was deposited on SiO2 and TiN by varying substrate temperature, Ar gas pressure, and rf power. It is found that the texture of the Cu film has very little dependence on the deposition conditions. The Cu grains are more oriented to (111) on a TiN substrate than on a SiO2 substrate, and the (111) ratio of the Cu films on the TiN substrate increases as the (111) ratio of the TiN film is increased. The maximum increase in grain size was tenfold by reducing the Ar pressure from 3 to 1 mTorr, fivefold by increasing the deposition temperature from room temperature to 300 °C, and twofold by increasing the sputtering power from 1.1 to 4.4 W/cm2. Thus, it is revealed that the lowering of Ar gas pressure is the dominant factor for enlarging the grain size. An increase in the energy of Cu particles brought about by reducing the Ar gas pressure is discussed as one of the factors contributing to the increase in the grain size.