Study Of N-based Diffusion Barrier In Advanced BEOL

With the development of integrated circuits,RC delays,dynamic power consumption and crosstalk noise in interconnects have become more and more important to device performance.The combination of Cu/low-?can successfully reduce these effects.But since Cu diffuses easily into low-?dielectrics,it's necessary to to be separate these films by a diffusion barrier layer.In this dissertation,different growth process conditions were used to prepare and study Ta(N)metal diffusion barrier and AlN dielectric diffusion barrier.The main research and results of this dissertation are as follows:1.For Ta(N)metal diffusion barrier:Ta(N)films were deposited on silicon wafers by DC magnetron sputtering using different N₂flows,and the electrical,structural,chemical,optical properties and reveal the interrelationships between properties.Experimental results show that N₂flow will affect the electrical,structural,chemical and optical properties of Ta(N)film.And the influence of N₂flow on the optical properties(refractive index,extinction coefficient)of Ta(N)film may be caused by the different crystal structure and grain size of Ta(N)films deposited under different nitrogen flow rate.Studying optical properties is a fast,non-destructive and effective method to study diffusion barriers.2.For AlN dielectric diffusion barriers:Polycrystalline/amorphous AlN thin films were prepared by plasma-enhanced atomic layer deposition in the substrate temperature range of 100°C to 350°C.The crystallinity,surface morphology,chemical composition,optical properties(refractive index,extinction coefficient)of AlN films were studied.Experimental results show that 100?-200?is the self-limited growth region of AlN films.250?-350?is the temperature-dependent region,and the GPC of the temperature-dependent region is higher than that of the self-limited growth region.AlN films are all(110)oriented.The sample deposited at 250?-400 has the most AlN content.the AlN films deposited at 100?and 200?are polycrystalline,while the other samples are amorphous which meets the requirements for diffusion barriers.