In Situ Gas-Phase Diagnostics for Titanium Nitride Atomic Layer Deposition

Abstract

This report describes the performance of a technique for the simultaneous, rapid measurement of major gas phase species present during titanium nitride thermal atomic layer deposition involving tetrakis(dimethylamido) titanium (TDMAT) and ammonia. In this chemical system, the three primary gas phase species are the two reactants, TDMAT and ammonia, and the reaction product, dimethyl amine. For the measurement of these three species, a direct absorption method based on a broadband infrared source with two different mid-infrared bandpass filters and utilizing amplitude modulation and synchronous detection was developed. By splitting the optical beam exiting the deposition chamber and selecting appropriate filters, all three species could be monitored simultaneously. It is also demonstrated that the high time resolution of this technique permits the observation of differences in the delivery into and removal from the deposition chamber of both TDMAT and ammonia with different carrier gases.