PREPARATION AND DEPOSITION MECHANISM OF TANTALUM NITRIDE FILMS BY CVD

Tantalum nitride films were prepared by CVD using a reactant gas mixture of TaCl5, N2, H2 and Ar under atmospheric pressure. Fused silica was used as the substrate. The effects of deposition temperature, total gas flow rate and input gas composition on the deposition rate and the constituent phase of the films were investigated. At 700°C and under a total gas flow rate of 2.0l/min, the deposition rate was controlled by a surface reaction. The rate-controlling mechanisms were identified by comparing the reaction orders obtained from the experimental data with those obtained from rate equations derived for each possible rate-controlling step. When pTaCl5 was low, the reaction orders with respect to pTaCl5 and pH2 were 1.0 and 1/3.1, respectively. When pTaCl5 was high, they were 1/2.6 and 1/2.1 respectively. The rate-controlling reaction was determined to be the reduction of tantalum chloride by hydrogen. © 1990, The Society of Chemical Engineers, Japan. All rights reserved.