Chemical vapor deposition of TiN for ULSI applications

TiN has been recognized as an excellent barrier material for W as well as Al planarization gap filling of contacts and vias. The need for conformality over extreme topography necessitates the use of CVD rather than sputtering for the deposition of TiN. In this paper we will first review the various deposition techniques of CVD TiN. Then, we will present a recently developed approach: thermal decomposition of TDMAT followed by nitrogen-based rf plasma treatments for resistivity reduction. This approach utilizes the advantages of thermal decomposition: excellent step coverage, good barrier properties, and low particle content. The resistivity reduction of the post deposition plasma treatment is followed by excellent stability upon long term air exposure. Vias and salicide contacts utilizing this unique process exhibit resistance values equivalent to those obtained when sputtered TiN is used. Conformal films as thin as 200 Angstrom can be utilized as excellent barriers for deep sub-0.5 mu m devices with large aspect ratios, where sputtered TiN can not be used any more.