Atomic Layer Deposited Co(W) Film as a Single-Layered Barrier/Liner for Next-Generation Cu-Interconnects

Comparison of tungsten films grown by CVD and hot-wire assisted atomic layer deposition in a cold-wall reactor

“…It is well established that radicals can form upon dissociation of gas molecules on a hot tungsten (W) filament. [14][15][16][17][18] For instance, molecular hydrogen (H 2 ) [19][20][21] and NH 3 (Ref. 22) can effectively decompose on a W filament heated up to 1500-2000 C. By replacing plasma by a hot-wire, we aim to avoid substrate damage, limit the number of radicals formed, and thereby achieve a better control of the reactant supply to the growing surface.…”

Role of W and Mn for reliable 1X nanometer-node ultra-large-scale integration Cu interconnects proved by atom probe tomography

“…Co(W) can be used to form a combined diffusion barrier and liner, [11][12][13][14] and Co(W) grown by atomic layer deposition (ALD) has been shown to exhibit favorable adhesion strength with Cu compared with Ta, together with a lower resistivity than TaN, and provides comparable diffusion barrier properties to TaN. 11,12,14 These properties have been evaluated numerically in previous studies; the diffusion barrier property has been investigated in Co(W) based on the Cu diffusion coefficient, and the adhesion strength has been investigated by evaluating the wetting angle of Cu grains formed by annealing the Cu film overlying Co(W).…”

“…11,12,14 These properties have been evaluated numerically in previous studies; the diffusion barrier property has been investigated in Co(W) based on the Cu diffusion coefficient, and the adhesion strength has been investigated by evaluating the wetting angle of Cu grains formed by annealing the Cu film overlying Co(W). 15,16 In addition, transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDX) studies have shown that W segregates within the grain boundaries of Co, indicating that W acts to prevent the diffusion of Cu through the grain boundaries of Co, and Co provides good adhesion to Cu.…”

“…15,16 In addition, transmission electron microscopy (TEM) coupled with energy dispersive X-ray spectroscopy (EDX) studies have shown that W segregates within the grain boundaries of Co, indicating that W acts to prevent the diffusion of Cu through the grain boundaries of Co, and Co provides good adhesion to Cu. 11,14 Future aggressive scaling will eventually require ultrathin barriers; e.g., the 17-nm node scheduled for fabrication in 2017 requires a 1.5-nm-thick barrier layer, 17 in which the diffusion barrier properties cannot be achieved using current methods, largely due to the existence of pinholes formed within the barrier layer. 18 This represents another challenge for Cu interconnects in order to realize a robust Cu diffusion barrier.…”

“…The W content was optimized based on the results of our previous studies to achieve good adhesion strength with Cu with favorable barrier properties and resistivity. 11,13,14,16 Co[ t Bu-Et-(Et)amd] 2 , bis(tert-butylimido)-bis-(dimethylamino)tungsten(IV) [BTBMW], and NH 3 were used as the Co precursor, W precursor, and reducing agent, respectively, and were selected as a suitable precursor combination to eliminate the incorporation of O impurities into the film. Details of the ALD of Co(W) have been reported previously.…”