LPCVD OF TUNGSTEN STUDIED WITH INSITU RBS

The deposition of W on Si from WF6 at low pressure was studied in a high-vacuum reactor equipped with an in-situ RBS facility. The W deposition was found to stop within 1 or 2 minutes, for all temperatures investigated in the range of 150-600 ° C. The temperature dependence of this self-limiting thickness displays an Arrhenius-type behaviour, corresponding to an apparent activation energy of 0.33 eV. This energy is proposed to be related to Si transport determining the ultimate W film thickness. The deposition of W is accompanied by a 1.5-3 times larger Si consumption, governed by the reaction temperature. Both the occurrence of self-limiting deposition and of Si consumption can be effectively suppressed by adding H2 to the reactor at a partial pressure ratio exceeding H2 WF6 = 10. © 1990.