Characteristics of TiAlN multilayer thin films deposited by metal organic atomic layer deposition method

Abstract

Binary nitrides such as TiN and TaN have been widely investigated as a metal diffusion barrier material for aluminum (Al) alloy metallization. Especially, TiN has been widely used as a diffusion barrier in ultra-large-scale-integrated (ULSI) circuits because of its good electrical and physical properties with low electrical resistivity of several tens mWcm. However, new barrier material systems and/or structures are needed as the semiconductor device dimensions scaled down to the sub-micron level. Also, ternary alloys including TiAlN and TaSiN have been identified as a potential barrier material, especially for the copper diffusion barrier, in sub-micron level device application. For these reasons, we investigated the interfacial stability and processing parameter effect on the characteristics of multilayer barrier structure of TiN and AlN deposited by metal organic atomic layer deposition (ALD) method using tetrakis(dimethylamino)-titanium (TDMAT) as Ti precursor, dimethyl(aluminum hydride)-ethylpiperidine (DMAH-EPP) as Al precursor, and ammonia (NH3) as reactant gas. In this experiment, TiN and AlN multiplayer structure films were deposited at the temperature between 150 and 300oC with a basic 90 cycles for each TiN and AlN layer at the total pressure of about 2 Torr. Multilayer films were heat treated at the temperatures between 400 and 700 oC to investigate the interface stability. The physical, chemical and electrical properties were characterized using x-ray diffractometer (XRD), Auger electron microscopy (AES), scanning electron microscope (SEM), cross-sectional transmission electron microscopy (XTEM) and four point probe measurements.