Ti-Si-N-O films were grown by radio frequency reactive magnetron sputtering of a titanium target with nitrogen and silane gases introduced at a temperature of 40°C. X-ray diffraction and X-ray photoelectron spectroscopy results show that Ti-N, Si-N, Ti-Si, Ti-O, Si-O, and Si-N-O compounds are formed. High-resolution-transmission-electron-microscopy reveals that the film consists of Ti-N, Si-N, Ti-Si nanocrystals embedded in an amorphous Ti-O, Si-O, and Si-N-O matrix. This type of microstructure gives rise to very high stability against copper diffusion under bias temperature stressing ͑BTS͒ compared to binary barrier materials. The BTS result shows that Ti 24 Si 12 N 35 O 29 film can effectively block copper ion diffusion for up to 200°C at 0.5 MV/cm.It is now well recognized that future improvements in the performance of integrated circuits will depend heavily on improvements in the efficiency with which circuit elements are interconnected. Use of the Cu interconnects in microelectronic devices require development of barrier layers which can effectively prevent Cu diffusion into dielectric layers and Si substrates under the influence of electrical and thermal stresses. Extensive work in the deposition of TiN barrier film by both sputtering 1,2 and chemical vapor deposition 3,4 have been reported. A common denominator underlying many of the above references is the columnar structure of TiN, typically with a ͑111͒ or ͑200͒ preferred orientation. Such a structure can lead to short-circuit diffusion paths via grain boundaries and result in the failure of the devices. With the down-scaling of devices and more stringent reliability requirements, there is a need for more effective barrier materials. To this end, a class of refractory, ternary nitride materials, such as Ti-Si-N, 5 Ta-Si-N, 6 and W-Si-N 7 have been proposed as candidates for the next generation diffusion barrier in copper/low-k dielectric back-end-of-line device fabrication. 8,9 One of the advantages of these ternary barrier films is attributed to the mixed microstructure which consists of nanocrystalline M-N ͑M = Ti, Ta, W͒ embedded in amorphous matrix ͑Si-N͒.The barrier material that we have investigated is Ti-Si-N-O films which consist of nanocrystals embedded in an amorphous matrix, but the amorphous matrix in this Ti-Si-N-O film is contributed by Ti-O, Si-O, and Si-N-O phases rather than the Si-N phase. It exhibits excellent barrier properties against Cu ion diffusion under biastemperature stress.In this article, we present a process for low-temperature physicalchemical vapor deposition of Ti-Si-N-O barrier films. Film composition, microstructure, and chemical bonding state have been analyzed. The barrier films showed excellent stability against bias temperature stressing ͑BTS͒, which makes them attractive candidates as future generation barrier materials.A 630 nm thick plasma enhanced chemical vapor deposition ͑PECVD͒ SiO 2 layer was first deposited on a p-type silicon substrate using tetraethyl orthosilicate, ͓Si͑OC 2 H 5 ͒ 4 ͔ and oxygen as pre...
b Chartered Semiconductor Manufacturing, Limited, 738406, Singapore Catalytic Pd nucleation is a crucial preparatory step for the activation of electroless ͑EL͒ Cu deposition. We have observed that the time evolution of catalytic Pd nucleation can be classified into stages according to the Pd nuclei density and the nucleus size distribution. We have tentatively labeled these stages as growth, secondary nucleation, and ripening. The stage identification is assisted with the observation of distribution range and semi-interquartile range. In this study we found that the smoothest EL Cu film can be achieved with Pd activation corresponding to the beginning of the ripening stage.Activation process is required to overcome the energy barrier in electroless ͑EL͒ Cu process. 1 Bindra and Roldan determined that Pd and Pt are the best catalyst in alkaline media. 2 Various activation methods have been proposed to pretreat the specimen surface for EL Cu deposition, such as excimer lamp and laser-assisted processes. 3-7 However, Dubin et al. have proposed a nonvacuum, cost-effective, contact-displacement method for the purpose of Cu bulk-fill. 1 Besides the advantages mentioned, this method provides good selectivity and good adhesion to the substrate.EL Cu deposition is initiated on the randomly distributed catalyst particles on the substrate, and the initial Cu grain structure is largely determined by the surface morphology. Patterson et al. reported that Cu morphology and grain structure are dependent on the Pd activation process and the control of the subsequent Cu plating. 8,9 Nakahara and Okinaka have also found that the properties of the seed layer determine the EL Cu morphology. 10 The nature and distribution of Pd nuclei formed during the activation process have been proven to be very important to the EL deposition behavior and deposit quality. 11 However, detailed investigations of the effect of Pd nuclei on the resultant EL film have yet to be carried out. Previous investigations showed that the roughness of EL Cu film was closely related to the Pd nuclei density and size. Pd nucleation process was categorized into three stages based on the change in Pd nucleus size and nuclei density. The stages are growth, secondary nucleation, and ripening. We report our analysis on Pd nucleation stages utilizing Pd nuclei size distributions. This corresponds well with previous analyses of nucleation stages based on nucleus size and nuclei density changes. ExperimentalA chemical vapor deposition ͑CVD͒ titanium nitride ͑TiN͒ barrier film of 250 Å was deposited on 5000 Å plasma-enhanced CVD ͑PECVD͒ SiO 2 /Si(100) substrate. Before the substrate is catalyzed, standard RCA cleaning was carried out to remove the organic and inorganic contaminants. The removal of organic and inorganic contaminants was done with the following solutions: ͑i͒ H 2 O:H 2 O 2 :NH 4 OH 5:1:1 and (ii) H 2 O:HCl:H 2 O 2 6:1:1, respectively, at room temperature. A 10 Ϫ3 M combined Pd/HF solution used in this study was proposed by Patterson et al. 8 The HF etch...
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