Characterization of Si distribution at the tungsten/titanium 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 analytic al method to characterize chemical vapor deposited (CVD) tungsten (W) proce sses. Blanket CVD tungsten film on titanium nitride (TiN) barrier layers ge nerally begins with the deposition of a tungsten nucleation layer by silane (SiH4) reduction of tungsten hexafluoride (WF6), followed by hydrogen (H-2 ) reduction of WF6, alone to form the bulk tungsten layer. In the present w ork, the tungsten nucleation layer was formed by simultaneous SiH4, and H-2 reduction of WF6. A two-step Sill, gas flow scheme was used to determine t he effects of magnitude and duration of SiH4 flow on the Si concentration a t the W/TiN interface. SIMS was used to characterize the Si distribution at the CVD W/TiN interface. SIMS depth profiles indicate, with a constant SiH 4 flow time of 3 s, the Si concentration at W/TiN interface does not vary s ignificantly with the increase of SiH4, flow from 20 to 30 seem. However, i t increases dramatically with the increase of SiH4, flow from 30 to 48 seem . With a constant SiH4, flow of 40 seem, the Si concentration at the W/TiN interface increases linearly with the increase of the SiH4 flow time. These results amply demonstrate that SIMS analysis can be used to evaluate the d eposition process so as to meet the fill and barrier protection requirement s for narrow trench or small via. (C) 2000 Published by Elsevier Science B. V.