Surface chemistry of precursors for film growth: pentakisdimethylamido tantalum

The behavior of the tantalum-bearing precursor, pentakisdimethylamido tantalum—Ta N CH3.2.5, PKDMATa—has been studied on Ni foil and on thin films derived from PKDMATa. In temperature-programmed desorption following adsorption on Ni at 100 K, molecular PKDMATa appears with a peak at 268 K, H2 with two peaks between 250 and 500 K, and N2 with a peak at 768 K. For multilayers, there are also small desorption peaks between 170 and 260 K tentatively assigned as CH3.2NN CH3.2. Ta, N, and C remain after heating to 900 K. C–H bonds begin dissociating below 250 K, C–N and Ta–N bonds are broken by 550 K and C begins diffusing into Ni above 550 K. With the substrates held at elevated temperatures, reaction products that evolve during dosing include H2, N2, CH4, and C2H4. The film composition, TaNxCy, is strongly temperature-dependent. q1999 Elsevier Science B.V. All rights reserved.