ISSN:
1077-3118
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Delamination of TiN/Ti bilayers on SiO2 is a serious problem during W chemical vapor deposition (CVD) using WF6 to form vertical interconnects in integrated circuits. In order to obtain insight into the delamination mechanism, we have determined depth-distributions of W and F in sputter-deposited TiN/Ti bilayers on SiO2 as a function of WF6 exposure time tWF6 at 445 °C. Even for tWF6〈6 s, significant concentrations of both W (≈3.5 at. %) and F (≈2 at. %) penetrate through the 106-nm-thick TiN film. W piles up at the TiN/Ti interface, while F rapidly saturates the TiN layer and accumulates in the Ti underlayer at concentrations up to ≈10 at. % for tWF6=60 s. Cross-sectional and scanning transmission electron microscopy analyses demonstrate that WF6 penetrates into the TiN layer through nanometer-scale intercolumnar voids spanning the entire film thickness and reacts with the Ti underlayer. We propose that the high F concentrations in the Ti layer weakens the Ti/SiO2 interface leading to adhesion failure of the TiN/Ti bilayer. © 1996 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.117953
