Characterization of Si distribution at the tungstenrtitanium nitride interface using secondary ion mass spectrometry — an investigation of the dynamic response of a chemical vapor deposition chamber

Secondary ion mass spectrometry SIMS.was successfully used as an analytical method to characterize chemical vapor deposited CVD.tungsten W.processes. Blanket CVD tungsten film on titanium nitride TiN.barrier layers generally begins with the deposition of a tungsten nucleation layer by silane SiH4.reduction of tungsten hexafluoride WF6., followed by hydrogen H2. reduction of WF6alone to form the bulk tungsten layer. In the present work, the tungsten nucleation layer was formed by simultaneous SiH4and H2reduction of WF6. A two-step SiH4 gas flow scheme was used to determine the effects of magnitude and duration of SiH4 flow on the Si concentration at the WrTiN interface. SIMS was used to characterize the Si distribution at the CVD WrTiN interface. SIMS depth profiles indicate, with a constant SiH4 flow time of 3 s, the Si concentration at WrTiN interface does not vary significantly with the increase of SiH4 flow from 20 to 30 sccm. However, it increases dramatically with the increase of SiH4flow from 30 to 48 sccm. With a constant SiH4 flow of 40 sccm, the Si concentration at the WrTiN interface increases linearly with the increase of the SiH4 flow time. These results amply demonstrate that SIMS analysis can be used to evaluate the deposition process so as to meet the fill and barrier protection requirements for narrow trench or small via. q2000 Published by Elsevier Science B.V.