Low temperature deposition of TiN using tetrakis(dimethylamido)-titanium in an ECR plasma process
High quality TiN layers were deposited in an electron cyclotron resonance (ECR) plasma process at substrate temperatures between 100 and 600 degree Celsius. Tetrakis(dimethylamido)-titanium (Ti(NMe sub 2)sub 4) as used as the precursor and introduced into the downstream region of an ECR plasma. As plasma gases nitrogen or ammonia have been used. The elctrical properties and the film compositions of the gold-colored TiN layers mainly depend on the deposition rate. ECR plasma activated nitrogen or ammonia reacts with Ti(NMe sub 2)sub 4 to form low resistivity (100-150 myOhmcm) crystalline TiN films even at a substrate temperature of 100 degree Celsius. Films deposited between 200 and 600 degree Celsius exhibited resistivities that decreased from 100 to 45 myOhmcm. Crystalline orientation is influenced by the chosen plasma gas. Prefered growth in the (111) and (100) directions were found by using ammonia and nitrogen, respectively. The measured resistivities and deposition temperatures ar e the lowest reported values for a plasma enhanced TiN deposition process. Experiments with labeled nitrogen show that the nitrogen for the TiN formation is almost exclusively derived from the plasma gas. The deposits were characterized by four point probe resistivity measurements, X-ray diffraction (XRD), forward recoil scattering (FRS), and Rutherford backscattering spectrometry (RBS). Step coverage was checked by a scanning electron microscopy (SEM) cross section of a contact via.