Langasite Crystal Microbalance Used for In-Situ Monitoring of Amorphous Silicon Carbide Film Deposition

An in-situ measurement method using a langasite crystal microbalance (LCM) was evaluated for monitoring chemical vapor deposition. When an amorphous silicon carbide film was formed from monomethylsilane gas at 600°C, the weight increase caused by the film deposition could be measured by the LCM frequency decrease after reaching the steady-state of various parameters, such as the gas density, the gas viscosity, and the temperature, in the reactor. The changing rate of the LCM frequency at the monomethylsilane gas concentration of 5% was −10 Hz/s. This value corresponded to the silicon carbide film deposition rate of 0.4 nm/min, which was evaluated from the film thickness obtained using the same growth condition. Although the LCM frequency also depends on the pressure and temperature, the film deposition rate can be more accurately controlled by the LCM in-situ monitoring when the film deposition rate is on the order of nm/min.