Research On RMoB(R=Ni,Co) Diffusion Barrier Thin Film Micro-nanoscale ULSI-Cu Metallization

Currently, the wiring size of super large scale integration is from 45 nm to 32 nm, which is developing toward 10 nm. As the IC size is smaller and smaller, and the performance of the demand is higher and higher, traditional Al wiring cannot meet the demand, which need to find a new wire. Because Cu has high resistance to electric mobility, low resistivity, etc as the material instead of traditional Al wiring of a new generation of cabling. But there also are some problems. ①Cu react with Si easily to produce the high resistance of copper and silicon compounds; ②The adhesion of Cu and Si is very poor; ③ Cu is oxidized easily, etc. This article is mainly discussing the Cu spreading to Si substrate generate high resistance of copper and silicon compounds.The diffusion barrier layer is used to stop the spreading between Cu and Si. RMoB(R=Ni/Co) film, as diffusion barrier layer, were prepared between Cu and Si substrate via electroless deposition, and then annealing experiments of RMoB and RMoB/Cu/NiMoB/SiO2/Si (R=Ni/Co) samples among 400℃ and 700℃ were carried. The failure temperature and failure mechanism of RMoB thin film were analyzed, as the same time the reaction mechanism of RMoB deposition was analyzed. XRD, XPS, FPP and AFM were used to characterize the structure, composition, resistivity and the morphology of the thin films before and after annealing, respectively.The conclusions were obtained as following.①The Cu film was deposited on Si substrate and the optimization conditions were given:CuSO4·5H2O 7.5g/L; EDTA 17.35g/L; CHOCOOH 9ml/L; α-α’ bipyridine 10mg/L; pH 13; preparing temperature 70℃;② The NiMoB film was deposited on Si substrate and the optimization conditions were given:NiS4·6H2O 20g/L; Na2MoO4·2H2O 0.34g/L; Na3C6H5O7·H2O 25g/L; DMAB 0.05mol/L; NH4F 0.004g/L; C12H25NaO4S 0.004g/L; acetic acid 10ml/L; pH 11.5; preparing temperature 85℃;③ The CoMoB film was deposited on Si substrate and the optimization conditions were given:CoSO4·7H2O 0.087mol/L; Na2MoO4·2H2O 0.15g/L; Na3C6H5O7·2H2O 60g/L; DMAB(C2H10BN) 0.06mol/L; C,2H25NaO4S 0.06g/L; C2H4O2 10ml/L; preparing temperature 80℃; pH 11;④ The annealing experiments of RMoB and RMoB/Cu/NiMoB/SiO2/Si (R=Ni/Co) samples among 400℃ and 700℃ under argon protection were carried. It can be concluded that the anti-diffusion failure temperature of NiMoB and CoMoB thin film is 500℃ and 600℃, respectively. And the mainreason is that NiMoB and CoMoB crystallize and particles grow up after high temperature annealing, a large number of Cu particles passed through NiMoB and CoMoB via grain boundary and grain boundaries and reacted with Si substrate and oxygen to generate Cu4Si and CuO with high resistance. By Comparing, NiMoB film is better to resist the diffusion of Cu and Si during low temperatur; CoMoB film is better to resist the diffusion of Cu and Si during higher temperatur.