Dependence of Texture in Al Bondpads on Ta/TaN Bilayer Barrier and its Correlation to Optical Reflectivity in 0.13μm IC Technology

In this paper, the dependence of crystallographic orientation in Aluminum thin films grown on different barrier-metal substrate schemes (Ta or Ta/TaN) will be presented. The orientation of Al grains will be shown to have a bearing on the material characteristics, which are important in IC fabrication from the perspective of both the device functionality and reliability. X-ray powder diffraction studies indicate that the films deposited on a single Ta layer are randomly oriented. On the other hand, a Ta/TaN bilayer substrate scheme results in preferred orientation along Al(111). A correlation will be established between the grain orientation and optical reflectivity properties of Al films. Moreover, the optical appearance of bondpads and their bondability are also influenced by the orientation of Al grains.