In this study, the interface chemistry and adhesion strengths between Cu and SiCN etch stop layers have been investigated under different plasma treatments. From the examination of interface microstructures and the analyses of chemical compositions and bonding configurations, an oxide layer was found to exist at the untreated Cu∕SiCN interface. After H2 and NnormalH3 treatments, the amount of oxides was effectively reduced. Some Cu silicides formed during SiCN deposition, and Cu nitrides even formed under NnormalH3 plasma treatment. The adhesion strengths of the Cu∕SiCN interfaces were measured by nanoindentation and nanoscratch tests under which interface delamination occurred around indented regions. The adhesion energy of the untreated Cu∕SiCN interface was obtained as about 4.98 and 0.98J∕normalm2 , respectively, by nanoindentation and nanoscratch tests. After H2 and NnormalH3 plasma treatments, the adhesion energy was effectively improved to 5.90 and 5.99J∕normalm2 by nanoindentation test, and to 1.74 and 2.58J∕normalm2 by nanoscratch test, respectively, because of the removing of oxides and the formation of Cu silicides and nitrides at the Cu∕SiCN interfaces.

Amorphous CoWP films have been studied as a capping or diffusion barrier layer to reduce Cu electromigration. However, the interface characterizations between the CoWP and Cu films have not been clarified. Thus, in this study, CoWP and Cu films are deposited by electroless plating, and their thermal stability and interface diffusion behaviors are investigated. By the activation of nanoscaled Pd catalysts, a continuous amorphous CoWP layer is obtained with stable concentrations of 82.5 atom % Co, 5.5 atom % W, and 12.0 atom % P, and then a smooth crystalline Cu film is directly deposited on the CoWP layer. Under thermal annealing at 500°C, the CoWP layer remains an amorphous structure, and no obvious interdiffusion between the Cu and CoWP films is found. The electrical resistivity of the CoWP layer and CoWP/Cu bilayer decreases to the lowest values of 35 and 3.3 ⍀ cm, respectively. However with increasing annealing temperature to 600°C, crystallization of the amorphous CoWP occurs, and much severe interdiffusion between the Cu and CoWP films is observed.Copper with low electrical resistivity and high thermal conductivity has been adopted as interconnect metallization in ultralargescale integrated circuits to reduce the problem of significant resistance-capacitance delay. 1-3 However, due to the high diffusivity of Cu and the easy formation of Cu silicides, early failure of microelectronic devices occurs. 3,4 An effective diffusion barrier layer with high thermal stability, low electrical resistivity, and good interface adhesion is thus needed at the interfaces between Cu and dielectric layers. 5 Moreover, the rapid electromigration of Cu along the interfaces between Cu and dielectric layers is also found to accelerate the failure of interconnect structures. 6-9 An appropriate thin buffer ͑cap-ping͒ layer with good interface bonding between Cu and dielectric layers will effectively reduce the electromigration phenomenon. 10-13 Therefore, a better diffusion barrier/capping layer has been under development to replace conventional TiN and TaN, which have high electrical resistivity.Cobalt and Ni with the incorporation of P ͑higher than 12 atom %͒ will tend to form an amorphous structure. 14,15 The amorphous structure is found to effectively inhibit the diffusion of atoms along grain boundaries and to enhance diffusion barrier ability. 14-18 Thus, amorphous Co-and Ni-based alloy films ͑such as Ni-P, 16 Co-P, 17 and Ni-Co-P 18 ͒, which are deposited by electroless plating, have been proposed as candidates for diffusion barriers in Cu metallization. The addition of a small amount of W in the Co-P films is found to further prevent the precipitation of minor crystalline phases and to improve the thermal stability of the films. 14,15,19 Besides good barrier performance, the electrolessly plated CoWP films also have high-deposition selectivity, good adhesion to Cu and dielectric layers, and high resistance to Cu electromigration, 20 exhibiting great potential application to both diffusion barriers and capping layers. Recentl...

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