Silicidation and carburization of the tungsten filament in HWCVD with silacyclobutane precursor gases

Study of the tungsten filament alloying processes with different precursor molecules shows that silicidation occurs when using silacycobutane (SCB) and carburization with 1,1,3,3-tetramethyl-1,3-disilacyclobutane (TMDSCB). The difference in the decomposition chemistry with the two molecules is responsible for the observation. Comparison of the depth profile and temperature distribution of the Si or C content in the alloyed filament illustrates the interplay among the Si or C deposition onto, evaporation from, and diffusion into the filament. Examination of the time distribution of key products from secondary gas-phase reactions at various filament temperatures demonstrates that gas-phase reactions dominate only at low temperatures. Silicidation or carburization is the dominant process at high temperatures, which contributes to a large consumption rate of precursor gas and a reduction in formation rate of the gas-phase reaction products.