MEASUREMENT OF THE RETARDING EFFECT OF HCL ON THE RATE OF CVD OF TITANIUMDIBORIDE

摘要

The deposition rate of TiB_2 was measured in a hot-wall CVD reactor by means of a thermobalance at 1 bar in the temperature range 1000 to 1250 K at variable partial pressures of TiCl_4, BC1_3, H_2 and HC1. The deposition rate was found to be proportional to the feed gas partial pressures p°(TiCl_4) and p°(BCl_3) at low partial pressures. After a rate maximum the rate decreased with rising p°(TiCl_4) and p°(BCl_3). The deposition rate increased with the feed gas partial pressure of H_2 and decreased with rising HC1 contents, the reaction order was found to be -2 with respect HC1. The relationship between p°(BCl_3) and the deposition rate was modestly influenced by HC1, while the relationship between the rate and p°(TiCl_4) and p°?((H_2), respectively, showed a marked influence of HC1. The measured rates were primarily determined by chemical reactions rather than mass transport.