Temporal evolution of ion fragment production from methylsilane by a hot tungsten wire

Abstract

Temporal evolution of ion fragment production from gaseous methylsilane in contact with a hot tungsten wire was measured with a use of a low-energy mass analyzed ion beam system. The mechanisms of molecular fragmentation in the system are similar to those for typical catalytic chemical vapor deposition processes. The fragmentation rates vary during the process due to surface modification of the tungsten wire. The extent of surface modification depends on the tungsten temperature. When the tungsten temperature was set to 1940°C, ion fragments were produced initially but the production terminated about 1h after the start of the experiment. The termination of ion production seems to be caused by the formation of a thick 3C-SiC layer on the tungsten surface, which was identified by x-ray diffraction measurement. When the tungsten temperature was set to 2220°C, ion fragment production continued at least for 8h. In this case the layer of deposited compounds, which mainly consist of WC, W2C, C, and 4H-SiC, was relatively thin.