Correlation between the formation of particle defects on sputtered Cu seed layers and Cu targets

Abstract

For advanced copper (Cu) interconnection applications, this work investigated the influence of impurity particles in the Cu target on the formation of particle defects on the sputtered Cu film. By using a liquid particle counter detection system and X-ray photoelectron spectroscopy, the properties of the impurity particles in the Cu targets were characterised. It is revealed that the impurity particles in the Cu target contain 98.5% carbon, and around 75% impurity particles have a size <1 μm and about 10% ones have a size larger than 2 μm. Subsequently, the correlation between carbon particles in the Cu target and particle defects on the sputtered Cu film is explored. For the carbon particles larger than 0.15 μm in the Cu target, the particle defects formed on the Cu seed layer exhibit a pronounced linear increase as a function of the carbon particle number. However, such a linear relationship becomes unclear for the bigger carbon particles; meanwhile, a small quantity of bigger carbon particles in the Cu target also can generate more particle defects on the Cu seed layer in comparison with smaller carbon particles. Moreover, the formation mechanism of particle defects on the Cu seed layer was also discussed.