LOW-TEMPERATURE DEPOSITION OF TIN USING TETRAKIS(DIMETHYLAMIDO)-TITANIUM IN AN ELECTRON-CYCLOTRON-RESONANCE PLASMA PROCESS

High quality TiN layers were deposited in an electron cyclotron resonance (ECR) plasma process at substrate temperatures between 100 and 60-degrees-C. Tetrakis(dimethylamido)-titanium [Ti(NMe2)4] was used as the precursor and introduced into the downstream region of an ECR plasma. Nitrogen or ammonia have been used as plasma gases. The electrical 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(NMe2)4 to form low resistivity (100-150 muOMEGAcm) crystalline TiN films even at a substrate temperature of 100-degrees-C. Films deposited between 200 and 600-degrees-C exhibited resistivities that decreased from 100 to 45 muOMEGAcm. Crystalline orientation is influenced by the chosen plasma gas. Preferred growth in the (111) and (100) directions were found by using ammonia and nitrogen, respectively The measured resistivities and deposition temperatures are 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 resisivity measurements, x-ray diffraction, forward recoil scattering, and Rutherford backscattering spectrometry. Step-coverage was checked by a scanning electron microscopy cross section of a contact via.