INFLUENCE OF MIXED REDUCTANTS ON THE GROWTH-RATE OF WF6-BASED W-CVD

The influence of adding dichlorosilane (SiH2Cl2) or germane (GeH4) to the SiH4-based reduction reaction of tungsten-hexafluoride (WF6) has b een investigated in order to enhance the properties of the silane W-CV D process: e.g. selectivity and step-coverage, It is shown that the ki netics of the silane-dichbrosilane process can be characterised by a s urface reaction limitation, thus improving the control of the process. For the mixed SiH4-GeH4 reduction reaction of WF6 it is shown that th e GeH4 process dominates the reaction kinetics, Also addition of SiH2C l2 to the GeH4-based reduction of WF6 has been examined. It is found t hat in this case the formation of W is only slightly influenced, The r eaction kinetics are similar to that of the unmodified deposition proc ess.