Investigation of the tantalum chlorination with hydrogen chloride for LPCVD tantalum elaboration

A chlorination process is presented in order to produce tantalum chloride. Solid tantalum is used as started material whereas the reducing agent is hy drogen chloride. Previous thermodynamic calculations allow to determine tha t the more convenient chlorination reaction temperature is 670 degreesC. Hy drogen chloride flow rate is varied from 10 to 40 sccm whereas the chlorina tion chamber is maintained at a total pressure ranging from 10 to 40 mbar. This process has been evaluated for depositing tantalum films by LPCVD thro ugh hydrogen reduction of the just formed tantalum chloride. Chlorination p arameters such as HCl residence time, HCl partial pressure and chlorination chamber total pressure are investigated with respect to the tantalum weigh t deposited by LPCVD. By using the optimum set of parameters : HCl flow rat e of 10 sccm, and total pressure of the chlorination chamber of 36 mbar, ta ntalum films are deposited at 800 degreesC and under a total pressure of 3. 3 mbar at a deposition rate of 32.6 +/-2.9 mg/h that corresponds to 1.42 +/ -0.09 mum/h.