Theoretical study of the gas-phase reaction of hexachlorodisilane by thermodynamic analysis and kinetics calculation

We conducted thermodynamic analysis and kinetics calculations for hexachlorodisilane (Si2Cl6), which is used as source gas for the CVD of silicon nitride films. Thermodynamic analysis clarified Si2Cl6 decomposes almost completely to SiCl4 and SiCl2 in the range of 600 degrees C-1100 degrees C under equilibrium condition. Therefore, it is estimated that the main gas-phase reaction of Si2Cl6 is represented by the reaction Si2Cl6. SiCl4 + SiCl2. Thermodynamic analysis also shows that the Si2Cl6 system has a larger equilibrium partial pressure of SiCl2 than SiHxCl4- x (x = 1 similar to 3) systems. Kinetics calculations revealed Si2Cl6 decomposes by 90% in 0.11 s at 600 degrees C, and 0.55 x 10-3 s at 800 degrees C, respectively. The time-dependent pyrolysis ratio of Si2Cl6 becomes larger as the total pressure decreases at 600 degrees C. On the other hand, the ratio is almost the same regardless of total pressure at 800 degrees C. These results will help optimize CVD process conditions using Si2Cl6. (c) 2024 The Japan Society of Applied Physics