Comparative study of polycrystalline Ti, amorphous Ti, and multiamorphous Ti as a barrier film for Cu interconnect

Abstract

Ultrathin (10nm) Ti films with various structures were deposited by physical vapor deposition (PVD) and chemical vapor deposition (CVD) processes. CVD-Ti films with low-temperature(<500°C) plasma-enhanced chemical vapor deposition using TiCl4 and H2 as reactants is an amorphous structure. This result is different from PVD-Ti films deposited by magnetron sputtering, which have a columnar structure. Ammonia plasma was further employed to post-treat the CVD-Ti barrier layer to improve barrier properties. An amorphous Ti(N,H) layer was formed on the surface of the CVD-Ti layer after ammonia plasma post-treatment. The resultant films had a bilayered amorphous Ti(N,H)∕Ti structure. Furthermore, the effective resistivity of the resultant Ti(N,H)∕Ti film decreased to 122μΩcm. The thermal stability of Cu∕PVD-Ti∕Si and Cu∕CVD-Ti∕Si contact systems was evaluated by thermal stressing at various annealing temperatures. For the Cu∕PVD-Ti∕Si, the highly copper titanium compound was formed after 450°C annealing. The PVD Ti barrier failed initially due to the reaction of Cu and the Ti barrier, in which Cu atoms penetrated into the Si substrate after annealing at high temperature. However, no copper-titanium and copper-silicide compounds were found for amorphous Ti and plasma-treated Ti[Ti(N,H)∕Ti] barriers, even after annealing at 500 and 600°C, respectively. Improved barrier capability against Cu diffusion was found for the Ti(N,H)∕Ti barrier layer because the Cu∕Ti(N,H)∕Ti∕n+-p junction diodes retained low leakage current densities even after annealing at 500°C for 1h. Ti(N,H)∕Ti barrier layers present lengthened grain structures to effectively impede Cu diffusion, thus acting as much more effective barriers than conventional Ti and TiN films.

Enhancing the reliability of n+–p junction diodes using plasma treated tantalum barrier film

“…As the technology node move to 0.18 lm and below, a thin barrier layer is necessary to lower the resistance of the total line interconnect and/or via. It becomes probably inappropriate to use a multilayered barrier thicker than 30 nm, and hence investigations of the thermal stability and barrier properties of ultrathin barrier layers in the Cu metallization system are important [13,14,[16][17][18][19][20]. In paral- lel with the development of technology, the sizes of node move to 0.18 lm and below, a thin barrier layer is necessary to lower the resistance of the total line interconnect and/or via.…”

Electron Transport in Graphene-Versus Al/Pd-Coated Thin Cu Films With Low-Surface Roughness: A First Principles Study

“…However, not only the geometry structure, but the electronic structure at the surface needs to be smoothed. Common liner materials like Ti, Ta, Ru, Al, Au and Pd have been examined experimentally [1], [13]- [15]. Among these materials, Al [16], [17] and Pd [17] were found to decrease the resistivity of the Cu thin film.…”

Agglomeration and Dendritic Growth of Cu/Ti/Si Thin Film

“…Ti is resistant to external influences and has good adhesive and gettering properties [2]. In the past two decades, Cu/Ti thin film system due to its potential applications has been studied, such as the kinetics of solid-phase interactions [3,4], microstructure [5], metallurgical [6], the formation of interface layers [7,8], thermal oxidation [9], mechanical behavior [5,6,10], and electrical properties [11]. In some Cu film systems [12][13][14][15][16][17][18], remarkable agglomeration occurs at the interfaces on annealing.…”