Numerical Simulation And Study Of Flow Field In Silane Decomposition Process Of CVD Reactor With Shaped Heat Pipes

Based on the study of flow field in the CVD reactors with 3 pairs of rods,the number of chassis electrodes was enlarged to 9 pairs.The comparison showed that the volume of CVD reactor with 9 pairs of rods was increased by 52.7 %,and the area ratio of silicon rods per unit volume was increased 41.3 %.The flow field in the CVD reactor was studied by Fluent software.The results showed that the gas velocities in the reactor increased with the increase of the inlet velocities,and when the inlet velocities were in the range of 20~30 m/s,the gas velocities in the reactor were 1~2 m/s,which was more suitable for polysilicon deposition.When the silicon rods were thickened from 60 mm to 140 mm,the gas velocities in the reactor maintained at 1.0~1.6 m/s,which was favorable for the deposition reaction.The temperature in the reactor decreased with the increase of the inlet velocities,when the inlet velocities increased from 10 m/s to 50 m/s,the temperature in tne reactor was reduced by 4.64 % and the outlet temperature in tne reactor was reduced by 4.47 %.The temperature in the reactor increased gradually with the thickening of the silicon rods,when silicon rods increased from 60 mm to 140 mm,the cross-section temperature increased by 9.44 %,the outlet temperature increased by 17.6 %,in the actual production,it is important to adjust the feeding gas velocities and electrode heating power,so that the temperature in the reactor remained stable.The temperature in the reactor was lower than the silane gas phase nucleation temperature under different conditions,and the addition of profiled heat pipes improved the temperature distribution in the CVD reactor.Based on the simulation results of the flow field of CVD reactor with profiled heat pipes,the silane deposition reaction model was added to the Fluent solution.The flow field and deposition rate of the CVD reactor with 9 pairs of rods were simulated.The results showed that the deposition rate at the surface of the silicon rods was uniform and increased with the increase of the gas velocities,and decreased with the growth of the silicon rods.The silane concentration at all the cross sections of the CVD reactor were kept uniform and increased with the increase of the gas velocities.With the growth of the silicon rods,the silane molar ratio should be increased in the actual production,so that the deposition rate was kept constant.The total heat in the CVD reactor increased with the height of reactor,however,the change was little,which decreased with the increase of gas velocities,increased with the silicon rods thicker.The temperature distributions in the CVD reactor were compared under two simulation conditions.It was found that both of temperature distributions showed the same trend.After adding the deposition reaction model,the temperature distributions of each section in the CVD reactor were still lower than that of the silane gas phase nucleation,and the chemical reaction in the CVD reactor mainly still was the surface deposition of silicon.In both cases,the temperature change rates of each section were within 20 %.